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PLOS One logoLink to PLOS One
. 2023 Jul 21;18(7):e0289012. doi: 10.1371/journal.pone.0289012

Evaluation of CRP as a marker for bacterial infection and malaria in febrile children at the Douala Gyneco-Obstetric and Pediatric Hospital

Yembu Ngwengi 1,☯,¤a,*, Guy Pascal Ngaba 1,2,, Martine Nida 1,3,☯,¤b, Dominique Enyama 4,5,
Editor: Marc Reismann6
PMCID: PMC10361518  PMID: 37478118

Abstract

Background

C reactive protein (CRP), a marker for the presence of inflammation, has been extensively studied for distinguishing bacterial from non-bacterial infection in febrile patients, but its role in excluding malaria in the febrile child has not been thoroughly evaluated.

Method

This was a cross-sectional study at the Douala Gyneco-Obstetric and Pediatric Hospital which included all patients between the ages of one month and 16 years presenting with fever. Consenting patients received complete clinical examinations, then venous blood samples were collected and tested for CRP values, bacterial infection and malaria.

Results

Samples of 220 children were analyzed. 142/220 had viral infections, 50/220 had malaria and 49/220 had bacterial infections. 7/220 had both malaria and bacterial infection. There was no significant difference between mean CRP values in malaria and bacterial infection (p = 1), but CRP means were significantly higher in malaria/bacterial infection than in viral infection (p<0.0001). Area Under the Receiver Operating Characteristics Curve (AUROC) values were 0.94 for malaria and 0.86 for bacterial infection, with a calculated cut-off of 23.6mg/L for malaria and 36.2mg/L for bacterial infection. At these cut-offs, CRP had a Positive Predictive Value (PPV) of 68.75% and 85.00% for malaria and bacterial infection respectively, with a Negative Predictive Value (NPV) of 94.74% and 89.05% respectively.

Conclusion

CRP can effectively exclude malaria and bacterial infection in febrile children in low-resource settings without the need for additional tests.

Introduction

Fever is the most common reason that children and infants are brought to the emergency department, being responsible for as much as 20% of pediatric consultations [1]. Fever, also called pyrexia, is an elevated body temperature due to an increase in the body temperature’s set point [2,3]. The upper limit of normal temperature most often used in pediatric populations is 37.8°C in the evening and 37.5°C in the morning [4,5]. Fever with Systemic Inflammatory Response Syndrome (SIRS) can result from a variety of conditions, with infections being the paramount cause in developing countries [6,7]. Many infectious agents can cause fever, including parasitic, bacterial, fungal and viral pathogens, which are difficult to distinguish from each other based on clinical presentation alone, especially in pediatric patients, in whom signs of severe infection are often subtle [7], and so most febrile children in low-resource settings receive antibiotics unnecessarily [8].

Malaria is a leading cause of fever and death in pediatric patients in developing countries, with a prevalence of 26.10% and a mortality of 3.8% in a recent study in Cameroon [9], and bacterial infections are a large determinant of pediatric mortality [10], with pneumonia being the leading cause of death (60% of deaths) in children under five years [11]. Many potential biomarkers have been evaluated to enable the prediction of bacterial infection in febrile patients, with C reactive protein (CRP) showing a lot of promise.

CRP is an acute-phase reactant that is produced by the liver whose concentrations rise during acute inflammation [12]. Many biomarkers commonly used in hospitals like leucocyte count (WBC- White Blood Cell count), absolute neutrophil count (ANC) and band cell count might aid in differentiating between causes of infection, but none have performed consistently enough to be used as standard point-of care tests [1315]. CRP has been shown to be one of the only sufficiently accurate biomarkers that could safely and effectively reduce the prescribing of antibiotics; in a study in Beijing in 2015, CRP was as effective as procalcitonin (PCT) in predicting bacteremia, and more effective at predicting severe sepsis [16]; while in a study in Iran in 2017, it performed better than PCT and WBC at predicting bacterial meningitis [17]. A multicenter Swiss study in 2017 found CRP to be as effective as pneumococcal Polymerase Chain Reaction (p-PCR) at predicting bacterial pneumonia [18]. However, the majority of studies evaluating the diagnostic performance of CRP have taken place in high-resource settings.

Malaria has been shown to be a confounding factor for CRP analysis in developing countries. Several studies attest to the fact that it causes a significant rise in CRP values, and often with levels comparable to those seen in bacteremia; in Tanzania it outperformed WBC and ANC at predicting bacterial infection, but could not distinguish between bacterial infection and malaria on its own [19]. Independently of bacterial infection, CRP has been shown to accurately predict Plasmodium parasitemia in studies in Angola and Ghana [20,21]. Very little data are available on the subject in Cameroon.

It is therefore important to study the relationship between CRP, malaria and bacterial infection in detail so as to determine CRP’s use in differentiating between these conditions, especially in pediatric populations where these two conditions are prevalent. Moreover, in developing countries, an affordable and easily performed test will help improve management protocols for clinicians faced with a febrile child [22,23]. It would also tremendously lessen the financial burden on patients and caregivers, encouraging better compliance to treatment [24].

Methods

Study characteristics

This was a hospital based, cross-sectional analytic study, carried out from November 15th 2020 to May 15th 2021, for a duration of six months. This study was carried out at the Douala Gyneco-Obstetric and Pediatric Hospital (DGOPH). Douala is the capital city of the Littoral Region of Cameroon, a country in sub-Saharan Africa. It is the largest city and the economic capital of the country, with a population of more than 3.5 million inhabitants [25].

Study population and sampling

The study targeted children presenting with fever at the Emergency Department (ED) or Out Patient Department (OPD) at DGOPH. Sampling was consecutive. Febrile children presenting at DGOPH were screened for eligibility. Inclusion criteria were: Children between the ages of one month to sixteen years (192 months) who presented with acute or subacute fever (T° > 37.1°C axillary- used for children above 2 years of age or rectal temperature > 37.6°C- used for children below two years of age, of ≤14 days duration) at the ED or OPD of DGOPH. Exclusion criteria included patients with neoplasm, inflammatory diseases, liver failure, and those who had suffered trauma or injury.

Ethical considerations

The study was conducted only after ethical and administrative clearance had been obtained from both the University of Douala (No.2550 IEC-UD/04/2021/M) and the Review Board of DGOPH (No.0068 HGOPED/DG/CEI). All participants (or their parents/guardians) signed a consent form explaining the details of the study, including risks and benefits, before being included in the study. Autonomy was respected, as participants had the right to withdraw from the study at any time. Risks to participants were minimized to the best of our ability. The confidentiality of patients was maintained by using serial numbers rather than names on questionnaires. Privacy was maintained during all stages of interviews and physical examination of the patients. Samples were obtained following recommended guidelines and coded to ensure anonymity.

Study procedure and laboratory analysis

Patients were approached at presentation at the ER or in the OPD. After obtaining informed consent, patients underwent a clinical interview, then received a complete physical exam in line with the Integrated Management of Childhood Illness (IMCI) recommendations by the WHO [26]. Clinical interview identified sociodemographic characteristics (age and sex), characterized the fever (degree and duration), and investigated past history. Topographical examination was done to search for infectious foci. The final diagnosis was based on clinical findings and results of investigations.

Specimen collection is described in detail in the full study protocol. About 2-5ml of venous blood was collected in sterile syringes and transferred to specialized aerobic and anaerobic Bact/Alert ® collection tubes for hemoculture analysis. About 2ml of venous blood was inserted into plastic dry tubes, to be used for immunoturbidimetric CRP analysis with Cobas C111®. About 1ml of blood was inserted into plastic EDTA tubes, to be used for thick smears. A drop of blood (about 0.05ml) was used for an HIV antibody-based Rapid Diagnostic Test (RDT) and another drop for a SARS-COV-2 antibody-based RDT, as part of the hospital policy for all children presenting in the pediatric department. Where indicated, biological fluids from infectious foci were also collected.

Samples for CRP analysis were analyzed within two hours of collection, so no freezing was required. Samples were centrifuged in the BIOBASE ® centrifuge at a g-force of 1006 for five minutes, then plasma was used for immunoturbidimetric analysis with the Cobas C111®. All CRP assays were read independently by two operators, both blinded to the final diagnosis (at this stage neither smear or culture results were available.)

Blood for thick smears was stained with the Giemsa stain and examined under an electrically-powered optical microscope (Optika ®) at 100x magnification. Hemocultures were performed with the Bact/Alert ® detection system. All other cultures used the standard methods.

Only the principal investigator had results of the index test (CRP values) and reference tests (culture and thick smears). All other operators were blinded to both the final diagnosis and the results of the other tests. Besides the principal investigator, each test was read independently by two operators.

Quality control and assessment

Laboratory investigations were carried out at the Douala Gyneco-Obstetric and Pediatric Hospital, Cameroon. Quality control was performed daily for each parameter before analysis of patient samples. All procedures were performed according to standard guidelines and instructions from product manufacturers.

Statistical analysis and definitions

Data was entered into and analyzed with Epi Info Version 7. Sample size was calculated using Cochran’s formula and a similar study [19]. Mahende and co. reported the prevalence of fever to be at 14.35% for pediatric consultations, which was the value we used to determine how many febrile children to sample. The resulting size was 196 children, though we eventually accumulated a larger sample. Out of the 250 children sampled, 220 had complete laboratory and clinical data. Quantitative variables were presented as means, standard deviation and medians where appropriate, or as frequencies and percentages after categorizing using predetermined or calculated cut-offs. Qualitative variables were presented as percentages and frequencies. CRP value, the outcome variable, was compared with each of the variables above. The means were compared with the two-sample t-test for means. CRP was considered positive if greater than 5mg/L, the cut-off used in all similar studies and recommended by the manufacturer [1719]. CRP values less than 5mg/L, between 5-20mg/L, between 20-40mg/L, between 40-100mg/L and above 100mg/L were used to categorize patients with respect to the final diagnosis, values similar to those used in clinical decision-making, and which have been used in similar studies [1921]. Thick smear positivity was defined by identification of trophozoites in any of the microscopic fields. Culture positivity was determined by growth in one or more inoculated media.

As per the STARD guidelines, Receiver Operating Curves (ROC) were plotted for CRP distribution, with the Area Under the Curve (AUROC) used to define diagnostic performance. Optimal CRP values were calculated from the ROC curves- this involved the use of Youden’s J to select the best index from the plotted values, then sensitivity and specificity of CRP in both bacterial infection and malaria as well as positive and negative predictive values (PPV and NPV), were then calculated at the optimal cut-offs provided by the ROC curves.

Statistical significance was set at p < 0.05.

Results

Demographic and clinical characteristics

A total of 250 patients with fever were enrolled in the study. Thirty (12%) were excluded: twenty-four (9.6%) due to incomplete laboratory data, three (1.2%) due to neoplasm, two (0.8%) due to liver failure and one (0.4%) due to Kawasaki disease. The remaining 220 patients (88%) had complete clinical and laboratory data and no other likely source of fever other than infection. The median age was 32 months, the modal age range was 1–24 months (infants). Girls accounted for 115 (52.27%) of patients. The modal presenting temperature was 39°C, while the mean duration of fever was three days for viral infection and four days for bacterial infection and malaria. Twenty-one of the 220 children had mixed infections, while 199/220 had monoinfections with a single etiological agent- 29 children had only malaria, 42 had bacterial monoinfection and 128 had viral monoinfections. The most frequent diagnosis was viral upper respiratory tract infection, with 59 patients (26.81%), followed by viral gastroenteritis with 31 patients (14.09%). The most frequent bacterial infection was urinary tract infection with 10 patients (4.54%). 50 patients (22.72%) had malaria. Other clinical diagnoses are indicated in Table 1. Of the 220 blood cultures, 14 (6.3%) had growth of clinically significant organism, with the leading bacterium being Klebsiella spp. (28.57%). A total of 217 urine cultures were done and 11 (5.07%) were positive, with Escherichia coli as the predominant organism (72.73%). Stool cultures had a yield of 18.52%, with the leading bacterium being Salmonella spp. Pus cultures had a 100% yield, with the predominant organism being Proteus mirabilis. Among malaria patients, the minimum parasitemia was 15 Trophozoites of Plasmodium Falciparum per microliter (TPF/μl), while the maximum was 241,600 TPF/μl. The mean parasitemia was 39,638TPFμl/.

Table 1. Demographic and clinical characteristics of the study population.

Age (in months) Number
(N = 220)
Percentages
(%)
1–24 (infants) 92 41.82
25–72 (preschoolers) 82 37.27
73–144 (school-aged children) 37 16.82
145–192 (adolescents) 9 04.09
Sex Number
(N = 220)
Percentages
(%)
Male 105 47.73
Female 115 52.27
Degree of Fever Number
(N = 220)
Percentages
(%)
38–38.9oC 67 30.45
39–39.9oC 96 43.64
≥40oC 57 25.91
Duration of Fever Number
(N = 220)
Percentages
(%)
<7 days (acute) 194 88.18
7–14 days (subacute) 26 11.82
Total Malaria N = 50 100.00%
Total Bacterial Infection N = 49 Percentages
(%)
Otitis Media 3 6.12
Tonsillitis 8 16.32
Rhinitis/Rhinopharyngitis/Rhinobronchitis 2 4.08
Gastroenteritis/Enteritis 8 16.33
Pneumonia/Superinfected Bronchiolitis 7 14.29
Meningitis/Enchephalitis 2 4.08
Urinary Tract Infection 10 20.41
Impetigo/Folliculitis/Abscess 2 4.08
Fever without source 7 14.29
Total Viral Infection N = 142 Percentages
(%)
Rhinitis/Rhinopharyngitis/Rhinobronchitis 38 26.76
Tonsillitis 21 14.79
Pneumonia/Bronchiolitis 17 11.97
Gastroenteritis/Enteritis 31 21.83
Meningitis/Encephalitis 4 2.81
Viral exanthem 3 2.11
COVID-19 4 2.81
Fever without source 24 16.90

CRP levels

The arithmetic means (with min and max values shown in parentheses) of CRP in malaria, bacterial infection and viral infection were 80.79mg/L (6.0–315.7), 84.41mg/L (0.23–324.0) and 17.82mg/L (0.2–237.36), respectively. Distribution of CRP levels according to patient diagnosis is shown in Table 2. No children with malaria had CRP levels less than 5mg/L. Most children with viral monoinfection (106/128) had CRP levels less than 20mg/L, while most children with bacterial monoinfection (30/42) and malaria monoinfection (23/29) had CRP levels greater than 20mg/L. The highest CRP levels were found in children with mixed bacterial infections and malaria, where all had CRP levels >40mg/L. Among patients with bacterial infection, CRP levels were highest in those with fever without source and lowest with skin infections. Among patients with viral infection, CRP levels were highest in those with COVID-19 and lowest in those with viral exanthems. Among malaria patients, CRP levels were independent of parasitemia. The degree of fever had no effect on CRP levels, but levels were lower in patients who presented after 7 days of fever than in those who presented before 7 days. Age had no effect on CRP levels, but levels were higher in females than males of almost every age group.

Table 2. Distribution of CRP levels according to final diagnosis.

Final Diagnosis CRP
N (%)
< 5mg/L 5–20 mg/L 21–40 mg/L 41-100mg/L > 100mg/L
Malaria monoinfection N = 29 00 (0.00) 06 (20.69) 07 (24.14) 11 (37.93) 5 (17.24)
Bacterial monoinfection N = 42 07 (16.67) 05 (11.90) 04 (9.52) 17 (40.48) 09 (21.43)
Viral monoinfection N = 128 66 (51.56) 40 (31.25) 17 (13.28) 05 (3.91) 00 (00.00)
Viral infection plus malaria N = 14 00 (00.00) 00 (00.00) 01 (7.14) 09 (64.29) 04 (28.57)
Bacterial infection plus malaria N = 7 00 (00.00) 00 (00.00) 00 (00.00) 04 (57.14) 03 (42.86)

ROC analysis showed that CRP levels were positively correlated with positive cultures (Fig 1) and Plasmodium parasitemia (Fig 2). AUROC was 94.1% for malaria and 85.7% for bacterial infection. The optimal cut-off value of CRP was calculated to 36.2mg/L for bacterial infection and 23.6mg/L for malaria. Using these cut-offs, positive and negative fraction tables were drawn for malaria (Table 3) and bacterial infection (Table 4) which demonstrated that at these cut-offs, CRP had PPVs of 68.75% and 85.00% for malaria and bacterial infection respectively, with NPVs of 94.74% and 89.05% respectively.

Fig 1. Receiver operating characteristics curve for CRP in bacterial infection.

Fig 1

Fig 2. Receiver operating characteristics for CRP and malaria.

Fig 2

Table 3. Positive and negative values for CRP and malaria using optimal cut-off.

INFECTION CRP <23.6 CRP≥23.6
MALARIA 6 (FN) 44 (TP)
VIRAL INFECTION 108 (TN) 20 (FP)

Table 4. Positive and negative values for CRP and bacterial infection using optimal cut-off.

INFECTION CRP <36.2 CRP≥36.2
BACTERIAL INFECTION 15 (FN) 34 (TP)
VIRAL INFECTION 122 (TN) 6 (FP)

Discussion

This study described CRP levels among febrile children presenting at a tertiary hospital in urban Cameroon.

CRP means were comparable in bacterial infection and malaria, and in both of these conditions, levels were significantly higher than in viral infections (p<0.0001). Our study was unable to find a CRP value beyond which we could safely exclude either bacterial infection or malaria, as the highest CRP values found in both conditions were very similar (both > 300mg/L). These results were similar to those of a similar study in Cambodia, where peak CRP values > 150mg/L were shared by both malaria and bacterial infection [27]. Few patients with malaria (6/50) and bacterial infection (12/49) had CRP levels < 20mg/L, the threshold most commonly used to eliminate viral causes with quantitative CRP analysis [1921,27]. On the contrary, most viral monoinfections (106/128) had CRP < 20mg/L. Most patients with malaria (36/50) and bacterial infection (33/49) had CRP > 40mg/L. This is comparable to published data from similar studies [19,27], suggesting that CRP is effective for distinguishing both malaria and bacterial infections from viral infections, but cannot separate malaria from bacterial infections in the febrile child on its own.

The available data indicates that CRP dosing has the potential to assist rational decision-making in febrile patients in lower-resource settings. AUROC values in our study were very similar to results from Cambodia and Tanzania (0.86 compared to 0.83 in both studies) [19,27]. These values are significantly higher (p<0.0001) than most other biomarkers used commonly to predict bacterial infection (PCT at 0.74, WBC at 0.56, ANC at 0.42) [19,27,28], suggesting that CRP may currently be the best biomarker for predicting bacterial infection in lower resource settings.

Based on the cut-off CRP values obtained by plotting Youden’s J on the ROC curves, predictive values were calculated for malaria and bacterial infection. Positive predictive values (PPV) represent the proportion of true positives among the positive patients [29], as defined by CRP > 23.6mg/L for malaria and CRP > 36.2mg/L for bacterial infection. PPV with this cut-off was 68.75% for malaria, lower than comparable PPV with the widely used histidine-rich protein malaria RDT, whose PPV was at 82.7% in a Rwandan study [30]. Both are inferior to the gold standard, thick smear. This suggests that CRP is less effective than RDTs in predicting malaria, and should not be used for this purpose. PPV for bacterial infection was at 85.00%, which is lower than the gold standard of bacterial culture. However, as mentioned above, CRP performs better in this regard than other alternatives like WBC count or ANC.

Negative predictive values (NPV) represent the proportion of true negatives among negative patients [29], as defined by CRP < 23.6mg/L for malaria and < 36.2mg/L for bacterial infection. NPV with this cut-off was 94.74% for malaria, a value higher than that of malaria RDTs in a similar study (85.4%), though still inferior to the gold standard. This suggests that CRP, at a cut-off of 23.8mg/L, performs better than malaria RDTs for excluding malaria in febrile children. NPV for bacterial infection with this cut-off was 89.05%. This is inferior to the gold standard of bacterial culture, but seemingly superior to other biomarkers currently in use for this purpose (60% for PCT) [27]. This suggests that CRP, at a cut-off of 32.6mg/L, might be the best available diagnostic test for excluding bacterial infection in febrile children in lower-resource settings.

It is important to note, however, that predictive values must be interpreted while taking the prevalence of the conditions in the target populations into consideration, as prevalence directly affects the predictive values. The most recent estimated prevalence of malaria in the pediatric population of Cameroon is about 26.10% [9], a value similar to the 22.7% found in this study. This implies that CRP can perform adequately for excluding malaria in this setting. However, many malaria-endemic areas have prevalence values lower (around 10% in both the Tanzanian and Cambodian studies used for comparison [19,27]) or higher (around 67% in the Rwandan study cited above [30]) than that used in this study, which would mean that comparing predictive values across these settings should be done cautiously. Nonetheless, the vast majority of sub-Saharan African countries have a prevalence between 10 and 50% [31], which means the values found in this study can be reasonably applied to most malaria-endemic countries in Africa.

Another important point to consider when analyzing the ROC curves and predictive values is that for clinical purposes, those with malaria and viral infections were considered in the malaria group, so only those with viral monoinfection were considered in the ‘negative’ group. Also, those with both malaria and bacterial infections were counted both in the malaria and bacterial infections groups, as statistically they both would test ‘positive’ for the various infection types. From the distribution of CRP levels shown in Table 1, it is evident that children with mixed infections generally had higher levels than children with monoinfection, with the more serious infection being the one predominantly affecting the CRP level. The viral monoinfection group, therefore, emerges as the best ‘control’ or ‘negative’ group, as the low values here correspond to the entity being excluded- that is, the definition of a negative case, a child with neither malaria nor bacterial infection. The ROC curves and predictive values thus gotten show that values below the optimum cut-off are likely to have only viral infections, and thus do not need antimalarials or antibiotics. Those with values above the cut-offs orient to any of the positive cases- that is, they could have malaria only, bacterial infection only, malaria and bacterial infection, or malaria and viral infection. This is a large group, but once viral monoinfection is definitely excluded, distinguishing between them is fairly easy even in a low-income setting.

These values, taken globally, would suggest that a negative CRP (defined as <24mg/L for malaria and <36mg/l for bacterial infection), is usually correct in excluding malaria and bacterial infection in a febrile child. On the other hand, a positive CRP (defined as >24mg/L for malaria and >36mg/l for bacterial infection) is not enough to predict malaria in a febrile child on its own. Such a child would benefit from further evaluation with thick smears and malaria RDTs. However, if such a child tests negative for malaria (and confounding factors such as COVID-19 are excluded), then evidence suggests that there is a bacterial infection, and thus the patient would probably benefit from antibiotics.

Limitations

It was a hospital-based, one center limited study and thus is not truly representative of the entire population of Douala, especially since DGOPH is a tertiary care center which is not accessible to a large proportion of the population. The study was limited to children presenting with fever, even though in some cases both bacterial infection and/or malaria present without fever. We were not able to exclude with 100% certainty all children who had received prior antibiotics or antimalarials, which could have resulted in false negatives with our cultures and thick smears. Evidence of viral infection could not be confirmed except in the cases of COVID-19. There may thus be a bias in the control group, which were considered to be viral infections because bacterial infection and malaria had been excluded.

Research in context

There is a large body of evidence suggesting that CRP is an effective marker for distinguishing bacterial from non-bacterial infection, though most of these studies took place in high-resource settings (Alcoba and co., Switzerland, 2017, and Zhao and co., Beijing, 2020), and very few considered malaria (Lubell and co., Cambodia, 2015 and Mahende and co., Tanzania, 2017). To get the evidence needed, the authors searched the PubMed and Google Scholar databases, where search criteria included all studies from January 2010 to November 2020 which evaluated CRP’s role in determining the type of infection in febrile patients, both pediatric and adult populations, and in all the regions of the world, though a focus was on lower-resource settings, that is, sub-Saharan Africa and Asia. The Pan African Medical Journal, the Plos One Journal and the BMC Infectious Diseases Journals were then searched for full articles. Search terms used included ‘CRP use in febrile patients’, ‘CRP use to predict bacterial infection’ and ‘CRP use to predict malaria’. This evidence had been meta-analyzed by Escadafal and co. in 2020 in the BMJ Global Health Journal, with the pooled estimate being that CRP predicted malaria and bacterial infection with equal efficacy, but could not distinguish between both, and CRP was at least as effective as other common biomarkers like PCT, WBC count and ANC count in doing so. However, the authors admitted to widely different diagnostic performance across studies and the need for more thorough investigation in lower resource settings. This evidence is considered to be of very high quality, as all these studies were observational, thus eliminating recall bias; almost all the continents of the world were included in the analysis, eliminating regional bias; both adult and pediatric populations were considered, and the data had been previously meta-analyzed.

The authors feel that this study added the following contributions to the existing evidence:

  • We correlated the degree and duration of fever to the final diagnosis and the level of inflammation, using CRP levels.

  • We examined the prevalence of various viral and bacterial foci of infection in febrile children in a low-income setting, as well as Plasmodium parasitemia.

  • We described bacterial species prevalence patterns in blood, stool, pus and urine cultures in febrile children in a low-income setting.

  • We correlated CRP levels to a particular focus of bacterial or viral infection and Plasmodium parasitemia.

  • We quantitatively compared maximum and minimum CRP thresholds in different infectious states in febrile children in a low resource setting.

Combined with the existing evidence, this study has the potential to provide clinicians in low-income settings with a rational protocol on management of febrile children in malaria-endemic settings. Such a protocol has been described in the full study (available in the library of the Faculty of Medicine and Pharmaceutical Sciences, University of Douala and the library of the Douala Gyneco-Obstetric and Pediatric Hospital). This protocol has the potential to reduce patient expenditure by reducing the need for expensive etiological tests, to reduce the over-prescription of antibiotics and to reduce misdiagnosis of febrile pediatric patients and thus reduce the infant mortality rate in low-resource settings.

Data availability statement:

The Data Availability Statement is under discussion and will be provided in a forthcoming update to this article.

Funding Statement

The authors received no specific funding for this work.

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Decision Letter 0

Marc Reismann

4 Apr 2023

PONE-D-23-00167EVALUATION OF CRP AS A MARKER FOR MALARIA AND BACTERIAL INFECTION IN FEBRILE CHILDREN AT THE DOUALA GYNECO-OBSTETRIC AND PEDIATRIC HOSPITALPLOS ONE

Dear Dr. Ngwengi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

I personally appreciate attempts to investigate the use of existing parameters for important applications under given resource conditions - particularly regarding diagnostics for malaria. The submitted manuscript has good potential to contribute to clarification of this significant issue. However, the study has some formal and methodological weaknesses which might limit the validity of the statements, especially regarding the selection of statistical parameters in different prevalence settings. The particular points of criticism by the reviewers are listed beyond. I would appreciate if you could revise the manuscript based on the reviewers´ comments.

Please submit your revised manuscript by May 19 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

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If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Marc Reismann, MD, PhD

Academic Editor

PLOS ONE

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2. Please amend your current ethics statement to address the following concerns:

a) Did participants provide their written or verbal informed consent to participate in this study?

b) If consent was verbal, please explain i) why written consent was not obtained, ii) how you documented participant consent, and iii) whether the ethics committees/IRB approved this consent procedure.

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We will update your Data Availability statement to reflect the information you provide in your cover letter.

Additional Editor Comments:

Thank you for submission of the interesting manuscript. I personally appreciate attempts to investigate the use of existing parameters for important applications under given resource conditions - particularly regarding diagnostics for malaria. The submitted manuscript has good potential to contribute to clarification of this significant issue. However, the study has some formal and methodological weaknesses which might limit the validity of the statements, especially regarding the selection of statistical parameters in different prevalence settings. The particular points of criticism by the reviewers are listed beyond. I would appreciate if you could revise the manuscript based on the reviewers´ comments.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: No

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I am honoured to have reviewed this article.

I have the following comments:

Throughout the paper, the decimal points have not been well placed making it difficult to appreciate data. Please check on the PDF format to appreciate this. This requires revision for appropriate interpretation.

In the main text, it is better not to start sentences with numerical eg 30. Better to have thirty for example.

In the abstract, it is documented that 220 were retained, once is unable to understand the meaning of this until the main results section has been read. Probably change to data was analysed for 220 participants or any other appropriate phrase.

The study period is indicated as 15th November to 15th May 2021, could the intention be 15th November 2020 to 15th May 2021?

In the Discussion, in interpreting the results, while it is true there appears to be greater value in NPV, the authors should choose the comparative words carefully, e.g 92.19% is not very close to 100% neither is 94.8 the same as 100%. Revision of the wording is suggested.

Reviewer #2: This study examines the levels of plasma C-reactive protein (CRP) levels among febrile paediatric patients, comparing among those with viral infection, bacterial infection and malaria (or combinations). It is concluded that low levels of CRP can effectively exclude malaria and bacterial infection and may be of use in resource-limited settings.

While this use of CRP to exclude malaria in such patients would appear to have potential in the setting described here, in which about 23% of the febrile children actually had malaria, the same predictive values would not apply in settings where the prevalence of malaria among febrile children was much different (higher). This issue should be pointed out in the manuscript.

Furthermore, making valid comparisons with the performance reported in other studies or using other markers needs to consider the prevalence of malaria among those study populations. Thus, the study in Rwanda using a malaria rapid diagnostic test was conducted on a group in which around 67% had malaria. Other things being equal, if that RDT had been conducted on the population with only 23% having malaria, the NPV would be around 97%, which is not dissimilar to (actually slightly higher than) the approximately 95% with CRP in the current study.

According to the literature, the prevalence of malaria among paediatric AFI cases in several malaria endemic countries is indeed around or slightly above 20%, but there are several settings in which the prevalence has been reported to be considerably higher than the 23% reported here. In these settings, low levels of CRP may not be as useful for excluding malaria as implied in this study.

Rather than making comparison of PPVs and NPVs across studies and markers without reference to the prevalence, estimating the markers’ performances using likelihood ratios (posterior odds/prior odds) would provide a fairer means of comparison. These could then be interpreted in terms of predictive values in different prevalence settings.

Other (minor) points:

Methods

• Study population and sampling: Was the duration of fever for inclusion actually less than 14 days or less than or equal to 14 days? (Compare with Table 1 “1-14 days”).

• Study Procedure and Laboratory Analysis: When stating the centrifuging values, it is better to state the relative centrifugal force (i.e., the “g” value) rather that the RPM. Without knowledge of the particular model of centrifuge used (the radius of rotation) the conditions are not explicit.

• Quality Control and Assessment: Was “…instruments…” intended to be “…instructions…”?

• Statistical Analysis and Definitions: The information on sample size calculation does not indicate the variables or measure(s) for which the calculation is being made.

• “Optimal CRP values were calculated from the ROC curves….” Could the definition of “optimum” be given? Was the calculation based on Youden’s J?

Results.

• Demographic and Clinical Characteristics: The intensity of parasitaemia is given in units of TPF/mm3. Assuming TPF refers to true positive fraction, the units do not seem to make sense. Should it be TP/mm3 (true positives per unit volume)?

• CRP levels: The CRP levels are given as geometric means, but what is the meaning of the values shown in parentheses following these geometric means? They do not appear to be distribution-based confidence intervals or min and max. They should be explained.

Discussion

• Third and fourth paragraphs: It is a tautology to state that the PPV or the NPV of the gold standard is 100%. They cannot be anything other.

• Fourth paragraph: Is the citation of reference [25] in the fourth paragraph correct?

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6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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PLoS One. 2023 Jul 21;18(7):e0289012. doi: 10.1371/journal.pone.0289012.r002

Author response to Decision Letter 0


1 May 2023

I have responded to these comments in a separate file labeled ‘Response to Reviewers’.

Attachment

Submitted filename: RESPONSE TO REVIEWERS.docx

pone.0289012.s002.docx (15.2KB, docx)

Decision Letter 1

Marc Reismann

23 May 2023

PONE-D-23-00167R1Evaluation of CRP as a marker for bacterial infection and malaria in febrile children at the Douala Gyneco-Obstetric and Pediatric Hospital.PLOS ONE

Dear Dr. Ngwengi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Most of the recent reviewer remarks have been addressed highly satisfactorily. One of the reviewers points at some particular statistical issues. I would be grateful if you could check your calculations and values based on the reviewers comments (see below).

Please submit your revised manuscript by Jul 07 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Marc Reismann, MD, PhD

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I do acknowledge, issues raised have been handled. I am grateful to have been part of the reviewers for this work.

Reviewer #2: Some of the issues that I raised on the previous draft of the manuscript have been addressed. However, there remain a few points that need further explanation and revision.

The first of these concerns the presentation of the sample size required for the study. The additional information is given that the prevalence of fever was expected to be 14.35%. It is not clear how this relates to the sample size calculation as all children in the study had at least some degree of fever. Furthermore, it is stated that the “resulting sample size (196 children) was assumed to give a 95% CI.” But a 95% CI of what measure and of what size? Could it be the CI of the area under the ROC curve, or, perhaps the CI around the value of expected positive predictive value for malaria or for bacterial infection after establishing an optimal cut-point, etc?

In the “CRP Levels” section of the Results, a revision has been made in which what were formerly referred to as geometric means, with possibly 25th and 75th percentiles in parentheses, are now called “mean levels (with 25th and 75% confidence intervals in parentheses) of CRP…” So, perhaps they are arithmetic means. However, it is still not certain what the values in parentheses are. I am fairly certain that the numbers in parentheses are not 25th and 75th confidence intervals. They appear possibly to be 25th and 75th percentile values, but normally these are given after presenting the median not the mean value. However, there is nothing intrinsically wrong in presenting the mean followed by 25th and 75th percentiles (i.e., the interquartile range) in parentheses, so long as the reader is adequately informed.

I am wondering if the number of children with malaria mono-infection who had CRP values greater the 20mg/L should be 23/29 rather than 23/26.

I am rather confused over the virtual summary tables (“virtual”, as they are not actually included in the manuscript) which contain the numbers of true and false positives (TP and FP) and false and true negatives (FN and TN) based on the optimal cut-points of CRP level for malaria and for bacterial infection. Given the values of PPV and NPV in the manuscript, I assume the numbers for the malaria table (TP, FP, FN and TN) would be 44, 25, 6 and 110. These numbers indicate a PPV of 63.77% and a NPV of 94.83% - almost the same as given in the manuscript. The sensitivity would then be 0.88 and the specificity 0.65. The vertical line on Figure 2 appears to be placed at too high a level of specificity.

For bacterial infection, I cannot satisfactorily work out what the numbers in the virtual table should be using the values of PPV and NPV given in the manuscript. The closest I can get is 39, 40, 11 and 130. These give a NPV of 92.19% (as reported) but a PPV of 49.37% (not 69.05% as reported in the manuscript). The sensitivity would then be 0.78 and the specificity 0.76. Again, the vertical line in Figure 1 does not exactly indicate this specificity. However, I may be wrong in my estimation of the numbers in the cells of the virtual tables.

The point of all this is that the reader might benefit from seeing the contents of these virtual tables.

I appreciate your explanation of TPF and apologize for my misunderstanding in the earlier review.

Minor point

Introduction, last sentence of 4th paragraph: “…data is available…” -> “…data are available…”

If these remaining issues can be satisfactorily addressed, the manuscript merits publication as it could make a valuable contribution to the clinical management of febrile children in Cameroon and other malaria-endemic countries.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: Yes: Dr Justus Simba, MBChB, PhD.

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

PLoS One. 2023 Jul 21;18(7):e0289012. doi: 10.1371/journal.pone.0289012.r004

Author response to Decision Letter 1


4 Jun 2023

I have responded to the reviewers in a separate file

Decision Letter 2

Marc Reismann

22 Jun 2023

PONE-D-23-00167R2Evaluation of CRP as a marker for bacterial infection and malaria in febrile children at the Douala Gyneco-Obstetric and Pediatric Hospital.PLOS ONE

Dear Dr. Ngwengi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

In the reviews it is pointed towards a bias due to patient selection for the calculation of specificities and sensitivities affecting particularly ROC curves and tables 3 and 4. Double infections were not considered. Predictive values are probably affected. I subscribe in this point of view und would appreciate if you could revise the manuscript according to the reviewers´comments.

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Reviewers' comments:

Reviewer's Responses to Questions

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Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #1: Yes

Reviewer #2: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: No

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4. Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer #1: Yes

Reviewer #2: No

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Reviewer #1: Yes

Reviewer #2: Yes

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6. Review Comments to the Author

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Reviewer #1: My initial concerns were earlier addressed, the additional queries on data analysis by the other reviewer are well captured in the current manuscript.

Reviewer #2: I appreciate the revisions to the manuscript made by the authors, although I did not receive their detailed responses to my previous comments.

Some light on the issues with interpretation of the screening using CRP that I raised in my previous review has been shed by the 2-by-2 tables (Tables 3 and 4) now included in the R2- revised manuscript.

In order to use the concept of specificity the outcome variable must be categorized into “yes” and “no”. That is, if malaria is the outcome of interest, the two levels of outcome should be “yes” (referring to any case with malaria, whether malaria monoinfection, malaria plus viral infection or malaria plus bacterial infection) and “no” (referring to all cases without malaria infection, i.e., bacterial monoinfection and viral infection monoinfection). Doing so will yield different ROC curves and probably also different “optimum” cut-points for malaria and bacteria. Crucially, the predictive values, especially the positive predictive values, will be quite different from those reported in the manuscript. This is, of course, because when applying the CRP to screen for malaria, a positive value is true if the case actually has malaria but false if the case does not, i.e, could be viral infection or bacterial infection (it is not possible to identify those cases with only viral infection at the time of screening). A similar situation exists if one is trying to screen for bacterial infection (we should be comparing any case of bacterial infection (bacterial monoinfection or bacterial infection plus malaria) with cases not having any bacterial infection (which comprise viral monoinfection and malaria monoinfection).

As they stand, Tables 3 and 4 do not include all 220 cases and give a biased values for the specificity, PPV and NPV (and maybe sensitivity too).

It is recommended that the ROC curves be re-constructed for each of malaria and bacterial infection using the binary classifications of “yes” and “no” as indicated above, and thence the optimal cut-points, sensitivities, specificities and predictive values be re-determined. Tables 3 and 4 can then be re-constructed to include all 220 cases under study.

Don’t forget to include the units (mg/L) in the first sentence of the CRP Levels section of the Results.

Only a subset of the data has been included in the supplementary files.

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Reviewer #1: Yes: Dr Justus M Simba, MBChB, PhD.

Reviewer #2: Yes: Dr Alan Geater

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PLoS One. 2023 Jul 21;18(7):e0289012. doi: 10.1371/journal.pone.0289012.r006

Author response to Decision Letter 2


25 Jun 2023

The response to the reviewers can be found in the file named ‘Response to Reviewers 3’.

Attachment

Submitted filename: RESPONSE TO REVIEWERS 3.docx

pone.0289012.s003.docx (18.5KB, docx)

Decision Letter 3

Marc Reismann

10 Jul 2023

Evaluation of CRP as a marker for bacterial infection and malaria in febrile children at the Douala Gyneco-Obstetric and Pediatric Hospital.

PONE-D-23-00167R3

Dear Dr. Ngwengi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Marc Reismann, MD, PhD

Academic Editor

PLOS ONE

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: No further comments, the authors have incooperated suggested earlier comments into their work that makes the work flow.

Reviewer #2: The added paragraph in the Discussion of this paper adequately addresses my previous concerns over the presentation of the results. I have no further concerns.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: Yes: Dr Justus Simba MBChB, PhD.

Reviewer #2: No

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Acceptance letter

Marc Reismann

14 Jul 2023

PONE-D-23-00167R3

Evaluation of CRP as a marker for bacterial infection and malaria in febrile children at the Douala Gyneco-Obstetric and Pediatric Hospital.

Dear Dr. Ngwengi:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Marc Reismann

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    Attachment

    Submitted filename: RESPONSE TO REVIEWERS.docx

    pone.0289012.s002.docx (15.2KB, docx)
    Attachment

    Submitted filename: RESPONSE TO REVIEWERS 3.docx

    pone.0289012.s003.docx (18.5KB, docx)

    Data Availability Statement

    The Data Availability Statement is under discussion and will be provided in a forthcoming update to this article.


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