Investigating the prevalence and determinants of HIV, HBV, HCV, and Treponema pallidum among blood donors in Douala, Cameroon

Abstract

The epidemiology of hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and Treponema pallidum among Cameroonian blood donors was addressed in this study. This prospective study was conducted from December 2021 to February 2022 at the Blood Transfusion Centre (BTC) of Douala Laquintinie Hospital. Blood bags were screened for HBV, HCV, HIV, and T. pallidum using standard tests. Donors’ medical records and the BTC database were consulted to collect data of interest. A total of 1,728 blood bags were included in the study; among them, 805 (46.6%) were from first-time donors. The overall prevalence of TTIs was 19.6%. HCV infection (9.3%) was the most frequent recorded TTI. Co-infections (3.2%) were mainly caused by HCV + T. pallidum (1.2%) and HCV + HIV (0.8%). The risk of TTI was higher in donors aged 35–45 years (aOR = 1.62, p = 0.04) and ≥ 45 years (aOR = 2.59, p = 0.0009). A high education level and being a family donor were protective factors for TTIs, HIV, and T. pallidum. Our findings will contribute to ongoing efforts by the government of Cameroon to improve the safety of transfusion-related systems and strategies at both the regional and national levels.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-025-00927-9.

Introduction

Blood safety is crucial for saving and preserving lives and improving the well-being of people in need around the world. Blood transfusion is a rapid and effective public health intervention for individuals with multi-factorial life-threatening anaemia [1]. However, blood transfusion remains a huge public health challenge in developing countries such as sub-Saharan Africa and Asian countries [2, 3]. Although millions of human lives are saved every year globally, blood transfusion, if unsafe, can be a source of immunological adverse reactions and transfusion-transmissible infections (TTIs), which are mainly caused by viruses (e.g., hepatitis B and C viruses– HBV/HCV, Human immunodeficiency virus– HIV), bacteria (e.g., Treponema pallidum) and parasites (for example, Plasmodium falciparum and Babesia parasites) [4].

TTIs can exist asymptomatically in blood donors; thus, these donors should be screened for TTIs before blood transfusion [5]. African countries are facing rapid and high demand for blood product transfusion. Again, these are regions of the world where the TTIs burden is high, and thus, blood safety is particularly challenging [3]. TTIs are still a serious public health concern in Africa because they are responsible for enormous morbidity and mortality burdens alongside economic losses and are an important limiting factor to guaranteeing blood safety [4]. During the last two decades, many governments have made tremendous efforts to develop, implement, scale up, and improve their delivery systems and strategies for blood supply. This success was the result of several actions including recruitment of regular and volunteer non-remunerated blood donors, implementation of appropriate buildings, regular training and evaluation of health facility staff, systematic screening for major TTIs, effective quality control systems, and boosting funding [6].

According to the Cameroon National Blood Transfusion Program, 94,873 blood bags were collected in 2018, representing ~ 25% of the total need estimated at 400,000 blood bags (https://pnts-minsante.cm/accueil). TTIs are a major public health concern in the country. The government of Cameroon promulgated diverse laws in favour of better and safer blood transfusion systems and the management of blood transfusion-related complications [7]. Infectious diseases such as malaria, viral hepatitis, and HIV are highly prevalent in Cameroon [8, 9], and their epidemiology is constantly changing, thereby justifying the need for continuous surveillance of TTI risk related to these diseases, to refine and/or optimize donor recruitment strategies. Studies documenting the epidemiology of TTIs in the country are lacking [10, 11]. Therefore, in the present study, we appraised the prevalence and associated factors of TTIs in Douala, the most populated town in Cameroon.

Materials and methods

Study design

A cross-sectional study was conducted from December 2021 to February 2022 at the blood transfusion centre (BTC) of the Douala Laquintinie Hospital (DLH) in the town of Douala, Littoral region, Cameroon. After obtaining administrative, research, and ethical authorizations, the study was conducted at the DLH. We screened all eligible blood donors recorded in 2022 at BTC for major TTIs using standard tests. The medical records of donors were extracted, and data of interest were reported using data collection sheets. All data of interest included age, gender, occupation, marital status, educational level, blood donation strategy, and donor type.

Study site

The study was conducted at the BTC of DLH located in the town of Douala, Littoral Region, Cameroon (Additional file 1). Douala is the economic capital and most populated town of Cameroon, with a high heterogeneity of ethnic groups which are mainly represented by Duala, Bamileke, and Bassa [12]. The BTC is structured into two sections: a sampling section where blood samples are collected (tubes and blood bags) and a screening section where tubes and blood bags are checked for conformity and screening of blood bags for TTIs. Blood samples collected in tubes are used to determine the blood group and haemoglobin levels. Both healthy and contaminated blood bags are labelled, and associated information is recorded in the respective databases. Contaminated blood bags are stored in a room dedicated to the incineration of non-qualified blood products, whereas healthy blood bags are distributed to different wards of the DLH. Medical doctors, nurses, clinical biologists, technicians, and non-medical constitute the staff of BTC.

Population and sample size

In Cameroon, the main selection criteria for blood donors, regardless of culture, religion or socioeconomic status, including (i) age between 18 and 65 years, (ii) a body weight ≥ 50 kg, (iii) being recognized as suitable for donation by a doctor from the BTC, and (iv) being in good health (e.g. no anaemia, normal blood pressure) (https://pnts-minsante.cm/accueil).

The sample size was computed using the sample size formula N = [p × (1– p) × Z²]/d², where N = sample size required, p = assumed prevalence of TTI, Z = statistic for the desired confidence level (1.96 for 95% confidence level), and d = accepted margin of error (0.05). Based on the latest study on TTIs in Douala [13], the maximum prevalence was 13.7%. Thus, the minimum sample size was estimated as N = 181.67 ≈ 182.

Screening for TTIs

Venous blood samples were collected in 5-mL vacutainers from each blood bag and stored at 4 °C. Serum was separated by centrifugation at 3000 × g for 5 min and then used for further screening of TTIs within 24 h of the blood collection. Screening and confirmation of viral infection at the BTC were based on the detection of viral antigens using rapid diagnostic tests (RDTs), ELISA, and hemagglutination assays as depicted in Fig. 1.

Fig. 1.

Clinical algorithm used for screening of HBV and HIV (a), HCV (b) and T. pallidum (c)

Quality assurance

Training was provided to the data collectors on the objectives, eligibility criteria, and data keying. A study sheet was generated to collect the data of interest. Principal investigators and senior members of the research group checked the collected data daily to maintain the accuracy and completeness of the data.

Operational definitions

Several definitions were used in this study [14, 15].

• TTI: Infection in which a pathogen– generally viruses, bacteria, and parasites– can be transmitted in donated blood through a transfusion to a recipient.

• Single infection: Presence of only one pathogen species in an individual.

• Co-infection: Presence of at least two pathogen species in an individual.

• Donor: A person in defined good health condition who voluntarily donates blood or blood components.

• First-time donor: A donor whose blood or plasma is tested for the first time for infectious disease markers in a blood establishment.

• Repeat donor: Any individual who donates blood regularly without any break for a longer duration between donations.

• Prevalence: The rate of identified infection, including both past and present infections, at a specified point time in a defined population.

Ethical statements

The study was approved by the institutional review board of the University of Douala (No. 2950 CEI-UDo/01/2022/M). Administrative and research authorizations were also sought from the Delegation of Public Health for Littoral Region and Laquintinie Douala Hospital. In the present study, permission from all respective authorities was obtained to access raw data in the BTC. Patient-informed consent was not required in this case. Secondary data obtained from the electronic database was fully anonymized before researchers accessed the data.

Statistical analysis

Data collected during the study were keyed, coded, and verified for consistency in an Excel spreadsheet (Microsoft Office 2016, USA). Data were then performed using GraphPad v8.03 for Windows (GraphPad PRISM, California, USA), StatView v5.0 for Windows (SAS Institute, Inc., Chicago, Illinois, USA), and the statistical package for social sciences v16 for Windows (SPSS, IBM, Inc., Chicago, Illinois, USA) for statistical analyses. Quantitative variables were summarized as mean ± standard deviation (SD) while qualitative variables were summarized as frequency (n), percentage (%), and confidence interval at 95% (95%CI) in figures and tables where appropriate. Quantitative variables were tested for Gaussian distribution using the Agostino-Pearson test. Pearson’s independence chi-square (χ²) and Fisher’s exact tests were used to compare proportions upon respect to Cochran’s rule. Multiple correspondence analysis (MCA) was used to evaluate patterns of relationship between TTIs and patients’ characteristics (i.e. gender, age, educational level, marital status, occupation, blood donation strategy, and type of blood donors). A Venn diagram was generated using the InteractiVenn tool to depict the different single infections and co-infections found in the study [16]. Univariate and multivariate logit models were used to identify determinants of TTIs and carriage of multiple pathogens. The association between independent variables and each TTI was quantified by crude and adjusted odds ratio (cOR and aOR), 95%CIs, and level of statistical significance. The independent variables included in the logit model were gender, age, educational level, marital status, occupation, blood donation, and type of blood donors. The goodness-of-fit of the final models was appraised by the Wald test and coefficient of multiple determination (R²). A two-sided p-value < 0.05 was considered statistically significant for all analyses.

Results

Characteristics of blood donors

A total of 1,728 blood donors were included in the study; among them, 805 (46.6%) and 923 (53.4%) were first-time donors and repeat donors, respectively. The mean age ± SD of individuals was 31.0 ± 8.1 years (range 18–63 years) for first-time donors and 32.9 ± 8.9 years (range 18–62 years) for repeat donors, and the difference was statistically significant (p < 0.0001). As presented in Table 1, the sociodemographic profile of donors varied significantly concerning the type of donor. Indeed, the proportion of males was lower in first-time donors as compared to that in repeat donors (84.1% vs. 90.6%, p < 0.0001). In contrast, the proportion of individuals who completed university studies was higher in first-time donors (40.5% vs. 39.7%, p < 0.0001). In both groups, the bulk of donors were working in the informal sector in comparable proportions, but with a higher proportion of students in the first-time donor group (24.8% vs. 7.4%, p = 0.0005) (Table 1).

Table 1.

Details of blood donors

	First-time donors (n = 805)		Repeat donors (n = 923)		Total (N = 1728)
Variables	n	%	n	%	N	%	χ 2 (df)	p -value
Gender
Females	128	15.9	87	9.4	215	12.4	105.3 (4)	< 0.0001*
Males	677	84.1	836	90.6	1513	87.6
Age (years)
[18–25]	185	23.0	143	15.5	328	19.0	564.3 (12)	< 0.0001*
[25–35]	381	47.3	436	47.2	817	47.3
[35–45]	184	22.9	231	25.0	415	24.0
≥ 45	55	6.8	113	12.2	168	9.7
Educational level
Primary	56	7.0	60	6.5	116	6.8	495.1 (8)	< 0.0001*
Secondary	423	52.5	497	53.8	920	53.2
University	326	40.5	366	39.7	692	40.0
Marital status
Single	556	69.1	624	67.6	1180	68.3	182.6 (8)	< 0.0001*
Married	245	30.4	294	31.9	539	31.2
Divorced/Widow (er)	4	0.5	5	0.5	9	0.5
Occupation
Student	200	24.8	161	17.4	361	20.9	19.8 (4)	0.0005*
Formal sector	163	20.2	214	23.2	377	21.8
Informal sector	357	44.3	418	45.3	775	44.8
Unemployed	57	7.1	73	7.9	130	7.5
Other	28	3.5	57	6.2	85	4.9
Blood donation
Volunteer	121	15.0	153	16.6	274	15.9	128.5 (8)	< 0.0001*
Family replacement	672	83.5	711	77.0	1383	80.0
Remunerated	12	1.5	59	6.4	71	4.1

Data are presented as frequency and percentage

Pearson’s independence chi-square test was used to compare groups

χ²: Decision variable of chi-square test, df: Degree of freedom

*Statistically significant at p-value < 0.05

Prevalence of TTIs among blood donors

The overall prevalence of TTIs was 19.6% (n = 336, 95%CI 17.8–21.5%) in this study. The most frequent TTI recorded in the study was HCV which was found at an overall prevalence of 9.3% (n = 161, 95%CI 8.0–10.8%) while HBV was less frequently found in blood samples at 3.4% (n = 58, 95%CI 2.6–4.3%) (Fig. 2a). TTIs were found to be either single infections (16.4%) or co-infections (3.2%), which were mainly represented by HCV + T. pallidum (n = 21, 1.2%) and HCV + HIV (n = 13, 0.8%) (Fig. 2b). Three types of co-infections were found in individuals and were represented by HBV + HCV + HIV (n = 2, 0.1%), HBV + HCV + T. pallidum (n = 2, 0.1%), and HBV + HIV + T. pallidum (n = 2, 0.05%) (Fig. 2b).

Fig. 2.

Overall prevalence of each TTI (a), and Venn diagram of distribution of TTIs as either single infections or co-infections (b) The area of each part of the Venn diagram is not proportional to the sample size 95%CI: Confidence interval at 95%, HBV: Hepatitis B virus, HCV: Hepatitis C virus, HIV: Human immunodeficiency virus, TTIs: Transfusion-transmissible infections

Prevalence of TTIs and associations of TTIs with donors’ characteristics

As summarised in Additional file 2, no statistically significant association was found between HBV prevalence and blood donors’ characteristics. The prevalence of HCV was higher in donors who had completed secondary studies (11.0%, p = 0.03) and in repeat blood donors (10.6%, p = 0.04). HIV infection was more frequently seen in remunerated blood donors (14.1%) compared to volunteers (6.9%) and family donors (3.4%), and the difference was statistically significant (p < 0.0001). Carriage of T. pallidum was significantly higher in those aged ≥ 45 years (14.3%, p < 0.0001) and in those having completed primary studies (8.6%, p = 0.003) (Additional file 2).

The distribution of different associations of TTIs was biased only by the donor’s age and type of blood donation (Additional file 3 a - g). The proportion of mono-infection with either T. pallidum (11.3%), HIV (5.4%), or HBV (3.0%) was significantly higher in donors aged ≥ 45 years, while mono-infections with HCV (9.4%) were more frequently seen in donors aged 35–45 years (χ² = 84.32, df = 39, p < 0.0001) (Additional file 3b). The number of different TTIs in donors increased with age, ranging from 8 types of associations of TTIs in donors aged 18–35 years to 10 types of associations of TTIs in donors aged ≥ 45 years. Two co-infections, namely HBV + HCV + HIV (0.5%) and HBV + HCV + T. pallidum (0.5%) were only seen in donors aged 35–45 years. Likewise, HBV + HIV + T. pallidum (0.6%) and HBV + T. pallidum (0.6%), were only seen in donors aged ≥ 45 years (Additional file 3b). Regarding the type of blood donation, we noted that (i) the proportion of mono-infection with HBV was higher in volunteer donors (4.4%), (ii) the proportion of mono-infection with HCV was higher in family replacement donors (7.2%), and (iii) the proportions of mono-infections with HIV and T. pallidum were higher in remunerated donors (9.9% and 5.6%, respectively) (Additional file 3f). A higher number of types of co-infections was found in family replacement donors (8 types of co-infections), while 5 and 4 co-infections were found in volunteer donors and remunerated donors, respectively. The co-infections HBV + HCV + HIV (0.1%), HBV + HCV + T. pallidum (0.1%), and HBV + HIV + T. pallidum (0.1%) were only recorded in family donors, while the co-infection HBV + T. pallidum (0.4%) was only seen in volunteer donors (Additional file 3f).

A high correlation was found between donors’ characteristics and TTIs, as depicted in Fig. 3 a & 3b. Four clusters of variables were identified from MCA, and included educational level, blood donation strategy, gender (cluster 1), occupation (cluster 2), marital status and age (cluster 3), and donor type, HBV, HIV, HCV, and T. pallidum (cluster 4) (Fig. 3a). For instance, first-time donors were more frequently aged 25–35 years and negative for HCV, HIV, and T. pallidum. In contrast, repeat donors were mostly aged 35–45 years or more than 45 years, and positive for HBV and HIV. In addition, an association was found between primary educational level, occupation (unemployed, informal sector), HCV, and T. pallidum (Fig. 3b).

Fig. 3.

Multiple correspondence analysis of the association between (a) variables, and (b) TTIs and patients’ characteristics. HBV: Hepatitis B virus, HCV: Hepatitis C virus, HIV: Human immunodeficiency virus In Fig. 3a, four groups of association are identified between the variables analysed. The groups are depicted by coloured circles In Fig. 3b, the modalities of the patients’ characteristics are presented. For example, the green circle depicts an association between the presence of HIV, HBV, being married, and aged 35–45 years or more than 45 years

Determinants of TTIs among blood donors

On univariate logistic analysis, two determinants were found to be associated with the risk of TTIs among blood donors: age and educational level (Table 2). The risk of TTIs was two-fold (cOR = 2.04, 95%CI 1.31–3.18, p = 0.001) higher in donors aged ≥ 45 years compared to their younger counterparts aged 18–25 years. The risk of TTIs was reduced by 46% (cOR = 0.54, 95%CI 0.34–0.86, p = 0.009) in those with university educational level compared to those with primary educational level. Three determinants of TTIs, i.e., donor age, educational level, and type of blood donation, were identified in multivariate logistic analysis (Table 2). The odds of being infected with at least one pathogen were nearly doubled in donors aged 35–45 years (aOR = 1.62, 95%CI 1.01–2.59, p = 0.04) and nearly tripled in donors aged ≥ 45 years (aOR = 2.59, 95%CI 1.48–4.53, p = 0.0009) compared to those aged 18–25 years. The risk of TTIs was reduced by 44% (aOR = 0.56, 95%CI 0.34–0.94, p = 0.02) in those with university educational level compared to those with primary educational level. Finally, we noted that the risk of TTIs was reduced by 31% (aOR = 0.69, 95%CI 0.48–0.98, p = 0.03) in family replacement donors compared to their volunteer counterparts (Table 2).

Table 2.

Univariate and multivariate logistic regression analysis of determinants of TTI

Variables	N	n (%)	cOR (95%CI)	p	aOR (95%CI)	p
Gender
Females	215	40 (18.6)	1		1
Males	1513	298 (19.7)	1.07 (0.74–1.55)	0.71	1.17 (0.78–1.76)	0.45
Age (years)
[18–25]	328	55 (16.8)	1		1
[25–35]	817	143 (17.5)	1.05 (0.75–1.48)	0.77	1.15 (0.78–1.71)	0.48
[35–45]	415	91 (21.9)	1.39 (0.96–2.02)	0.07	1.62 (1.01–2.59)	0.04*
≥ 45	168	49 (29.2)	2.04 (1.31–3.18)	0.001*	2.59 (1.48–4.53)	0.0009*
Educational level
Primary	116	30 (25.9)	1		1
Secondary	920	198 (21.5)	0.79 (0.50–1.23)	0.30	0.87 (0.55–1.37)	0.55
University	692	110 (15.9)	0.54 (0.34–0.86)	0.009*	0.56 (0.34–0.94)	0.02*
Marital status
Single	1180	229 (19.4)	1		1
Married	539	106 (19.7)	1.02 (0.79–1.31)	0.89	0.76 (0.55–1.03)	0.08
Occupation
Other	361	59 (16.3)	1		1
Student	377	66 (17.5)	0.63 (0.36–1.13)	0.12	1.09 (0.57–2.09)	0.78
Formal sector	775	165 (21.3)	0.69 (0.39–1.22)	0.19	0.94 (0.51–1.72)	0.84
Informal sector	130	28 (21.5)	0.88 (0.52–1.49)	0.63	1.02 (0.59–1.76)	0.95
Unemployed	85	20 (23.5)	0.89 (0.46–1.71)	0.73	1.08 (0.55–2.14)	0.82
Blood donation
Volunteer	274	61 (22.3)	1		1
Family replacement	1383	258 (18.7)	0.80 (0.58–1.10)	0.17	0.69 (0.48–0.98)	0.03*
Remunerated	71	19 (26.8)	1.28 (0.70–2.32)	0.42	1.02 (0.54–1.94)	0.94
Type of blood donor
First-time	805	142 (17.6)	1		1
Repeat	923	196 (21.2)	1.26 (0.99–1.60)	0.06	1.15 (0.89–1.47)	0.28

95%CI: Confidence interval at 95%, cOR: Crude odds ratio, aOR: Adjusted odds ratio, TTIs: Transfusion-transmissible infections

Univariate and multivariate logistic regression was used to identify determinants of TTIs

*Statistically significant at p < 0.05

Determinants of TTIs with HBV, HCV, HIV or T. pallidum

Based on multivariate logistic analysis, only occupation was identified as a determinant of HBV infection, while marital status and donor type were determinants of HCV infection (Table 3). The risk of HBV infection was reduced by 78% (aOR = 0.22, 95%CI 0.05–0.89, p = 0.03) in students. Married donors were less at risk of HCV infection (aOR = 0.64, 95%CI 0.42–0.98, p = 0.04) compared to singles (Table 3). In contrast, the risk of HCV was increased by 1.41 times (95%CI 1.01–1.99, p = 0.04) in repeat donors compared to first-time donors.

Table 3.

Univariate and multivariate logistic regression analysis of determinants of HBV and HCV infections

Variables	HBV				HCV
	cOR (95%CI)	p	aOR (95%CI)	p	cOR (95%CI)	p	aOR (95%CI)	p
Gender
Females	1		1		1		1
Males	0.88 (0.41–1.89)	0.75	1.02 (0.45–2.33)	0.96	1.32 (0.77–2.26)	0.31	1.21 (0.68–2.16)	0.51
Age (years)
[18–25[	1		1		1		1
[25–35[	1.21 (0.54–2.72)	0.64	0.71 (0.29–1.78)	0.47	0.80 (0.51–1.25)	0.32	0.91 (0.55–1.52)	0.72
[35–45[	1.71 (0.73–4.01)	0.22	0.85 (0.30–2.39)	0.76	1.30 (0.81–2.07)	0.28	1.71 (0.93–3.13)	0.08
≥ 45	2.26 (0.86–5.98)	0.09	1.07 (0.33–3.53)	0.91	0.78 (0.40–1.52)	0.46	1.19 (0.53–2.67)	0.67
Educational level
Primary	1		1		1		1
Secondary	0.47 (0.20–1.11)	0.08	0.52 (0.22–1.23)	0.14	1.31 (0.66–2.58)	0.40	1.28 (0.64–2.55)	0.51
University	0.56 (0.24–1.33)	0.18	0.61 (0.23–1.61)	0.32	0.83 (0.41–1.68)	0.60	0.93 (0.43–2.00)	0.91
Marital status
Single	1		1		1		1
Married	1.57 (0.92–2.68)	0.09	1.11 (0.59–2.09)	0.74	0.78 (0.54–1.12)	0.18	0.64 (0.42–0.98)	0.04*
Occupation
Other	1		1		1		1
Student	0.22 (0.06–0.79)	0.02*	0.22 (0.05–0.89)	0.03*	1.28 (0.52–3.17)	0.59	1.64 (0.61–4.35)	0.32
Formal sector	0.76 (0.27–2.11)	0.59	0.69 (0.23–2.05)	0.51	0.98 (0.39–2.45)	0.96	1.23 (0.47–3.17)	0.67
Informal sector	0.58 (0.22–1.54)	0.27	0.62 (0.23–1.69)	0.35	1.52 (0.64–3.59)	0.34	1.53 (0.64–3.66)	0.34
Unemployed	0.51 (0.13–1.95)	0.32	0.53 (0.13–2.12)	0.37	1.98 (0.75–5.25)	0.17	2.17 (0.80–5.87)	0.13
Blood donation
Volunteer	1		1		1		1
Family replacement	0.53 (0.29–0.97)	0.03*	0.56 (0.28–1.10)	0.09	1.37 (0.84–2.24)	0.20	1.11 (0.66–1.88)	0.69
Remunerated	0.50 (0.11–2.24)	0.37	0.59 (0.12–2.83)	0.51	1.17 (0.45–3.04)	0.74	0.82 (0.30–2.21)	0.69
Type of blood donor
First-time	1		1		1		1
Repeat	0.93 (0.55–1.57)	0.79	0.83 (0.48–1.43)	0.50	1.40 (1.00–1.95)	0.04*	1.41 (1.01–1.99)	0.04*

95%CI: Confidence interval at 95%, cOR: Crude odds ratio, aOR: Adjusted odds ratio, HBV: Hepatitis B virus, HCV: Hepatitis C virus

Univariate and multivariate logistic regression analysis was used to identify determinants of viral hepatitis infections among blood donors

*Statistically significant at p < 0.05

The age of donors and type of blood donation were associated with HIV infection (Table 3). Blood donors aged ≥ 45 years were more than three times more at risk of HIV compared to those aged 18–25 years (aOR = 3.17, 95%CI 1.08–9.28, p = 0.03). In contrast, the risk of HIV infection was reduced by 51% (aOR = 0.49, 95%CI 0.26–0.91, p = 0.02) in family replacement donors compared to volunteer donors. Regarding T. pallidum infection, two determinants were identified, and these included age and educational level. The risk of T. pallidum infection was ~ 5 times higher in donors aged ≥ 45 years compared to those aged 18–25 years (aOR = 4.94, 95%CI 2.05–11.92, p = 0.004). Again, this risk was reduced by 70% (aOR = 0.30, 95%CI 0.13–0.71, p = 0.006) in donors with university educational level compared to those with primary educational level (Table 3).

Determinants of single and multiple carriage of transfusion-transmitted pathogens

We stratified the risk analysis of TTIs based on the number of pathogens (i.e., one pathogen and more than one pathogen), as summarised in Table 4. The findings indicated that the risk of infection with only one pathogen was significantly modulated by age and educational level, based on both univariate and multivariate logistic regression analyses. The risk of carrying only one pathogen was higher in donors aged 35–45 years (aOR = 1.78, 95%CI 1.06–2.99, p = 0.02) and nearly tripled in donors aged ≥ 45 years (aOR = 2.71, 95%CI 1.47–4.99, p = 0.001) compared to those aged 18–25 years. Donors with a university educational level had 47% fewer chances (aOR = 0.53, 95%CI 0.31–0.91, p = 0.02) of being infected with one pathogen compared to those with a primary educational level (Additional file 4). Besides, only donor type and marital status were associated with multiple carriage of pathogens in univariate and multivariate analyses, respectively. Indeed, the risk of multiple carriage of pathogens was nearly doubled in repeat blood donors (cOR = 1.82, 95%CI 1.03–3.24, p = 0.04) compared to first-time blood donors. In contrast, this risk was reduced by 62% (aOR = 0.38, 95%CI 0.17–0.84, p = 0.01) in married women as compared to singles (Additional file 4).

Table 4.

Univariate and multivariate logistic regression analysis of determinants of HIV and syphilis infections (Continued and end)

Variables	HIV				Treponema pallidum
	cOR (95%CI)	p	aOR (95%CI)	p	cOR (95%CI)	p	aOR (95%CI)	p
Gender
Females	1		1		1		1
Males	0.94 (0.47–1.85)	0.85	1.18 (0.55–2.54)	0.67	1.50 (0.74–3.02)	0.26	1.82 (0.79–4.20)	0.16
Age (years)
[18–25[	1		1		1		1
[25–35[	1.47 (0.72–2.99)	0.29	1.45 (0.66–3.19)	0.36	0.77 (0.44–1.36)	0.37	1.12 (0.57–2.19)	0.74
[35–45[	1.44 (0.66–3.17)	0.36	1.80 (0.70–4.62)	0.22	0.91 (0.48–1.71)	0.77	1.39 (0.61–3.18)	0.44
≥ 45	2.45 (1.03–5.79)	0.04*	3.17 (1.08–9.28)	0.03*	2.71 (1.44–5.11)	0.002*	4.94 (2.05–11.92)	0.004*
Educational level
Primary	1		1		1		1
Secondary	0.81 (0.34–1.96)	0.64	1.11 (0.42–2.93)	0.84	0.83 (0.42–1.67)	0.61	0.90 (0.44–1.85)	0.77
University	0.86 (0.35–2.11)	0.74	1.24 (0.43–3.58)	0.69	0.40 (0.19–0.85)	0.01*	0.30 (0.13–0.71)	0.006*
Marital status
Single	1		1		1		1
Married	0.79 (0.47–1.33)	0.37	0.58 (0.31–1.07)	0.08	1.08 (0.70–1.67)	0.72	0.76 (0.44–1.30)	0.32
Occupation
Other	1		1		1		1
Student	0.70 (0.22–2.21)	0.53	0.92 (0.26–3.28)	0.90	0.59 (0.25–1.39)	0.23	1.68 (0.60–4.68)	0.32
Formal sector	0.96 (0.31–2.92)	0.94	1.05 (0.33–3.40)	0.93	0.45 (0.19–1.09)	0.08	0.90 (0.34–2.38)	0.83
Informal sector	0.99 (0.34–2.84)	0.98	1.26 (0.43–3.71)	0.68	0.65 (0.30–1.42)	0.28	0.83 (0.35–1.94)	0.67
Unemployed	1.15 (0.33–4.06)	0.83	1.57 (0.43–5.75)	0.49	0.55 (0.19–1.57)	0.26	0.78 (0.25–2.42)	0.67
Blood donation
Volunteer	1		1		1		1
Family replacement	0.47 (0.27–0.82)	0.007*	0.49 (0.26–0.91)	0.02*	0.93 (0.54–1.59)	0.79	0.65 (0.35–1.21)	0.17
Remunerated	2.20 (0.97–4.97)	0.05	2.26 (0.90–5.65)	0.08	1.15 (0.41–3.22)	0.80	0.70 (0.23–2.10)	0.52
Type of blood donor
First-time	1		1		1		1
Repeat	1.44 (0.89–2.30)	0.13	1.11 (0.67–1.83)	0.69	1.38 (0.91–2.07)	0.13	1.24 (0.81–1.91)	0.32

95%CI: Confidence interval at 95%, cOR: Crude odds ratio, aOR: Adjusted odds ratio, HIV: Human immunodeficiency virus

Univariate and multivariate logistic regression analysis was used to identify determinants of HIV and T. pallidum infections among blood donors

*Statistically significant at p < 0.05

Discussion

It is now well-proven that blood transfusion has been saving millions of lives around the globe, but this medical act is also an open window for the acquisition of several life-threatening pathogens, which are big challenges for blood donation systems in African countries. Here, we evaluated the burden and correlates of HBV, HCV, HIV, and T. pallidum among blood donors in Douala, Cameroon.

Characteristics of blood donors

The predominance of males in blood donation was noted in this study, which is consistent with previous studies in Cameroon and outside [17]. This finding is the result of traditional belief-related misconceptions in African settings, as males are thought to be healthier than women [18]. Other specifically female-related factors, such as cyclic blood losses during menstruation, pregnancy, and breastfeeding, also limit participation in blood donation [19].

Blood samples analysed were mainly from replacement donors, and this is consistent with previous investigators who reported high rates of replacement donors in Douala (89.5%) in the Littoral region [13] and Edéa (64.3%) in the east region [20]. In contrast, lower proportions of replacement donors were reported in Ethiopia [21]. Our finding points out that volunteer blood donation is still a big challenge to cover the national blood need, estimated at 400,000 blood bags (https://pnts-minsante.cm/accueil). Thus, it is crucial to promote strategies for ethical, non-remunerated blood donation in the country.

Prevalence of TTIs and co-infections

The overall prevalence of TTIs was 19.6%, which is close to estimates from previous studies in Edéa (21.2%) [13]. In contrast, our prevalence estimate is higher than that of studies conducted earlier in Douala (13.7%) [13], and several settings such as Nigeria (14.9%) [22], in which the same TTIs were targeted. The epidemiology of TTIs is shaped by a cocktail of factors related to the host (e.g., level of immunity, genetic polymorphisms, risk-increasing sexual behaviours), pathogens (e.g., circulating strains), and environment (e.g. control strategies), and spatial- and time-dependent variations could likely explain such discrepancies observed between the above-mentioned prevalence estimates. Differences in study design, sampling statistical fluctuations, and screening assays have also added heterogeneity to estimates.

Co-infections accounted for 3.2% of all infection cases in this study. This finding is not surprising as these pathogens share the same routes of transmission and some risk factors such as the number of sexual partners or resorting to blood transfusion [13]. Again, co-infections are epidemiologically and clinically important, as interactions between different pathogens could be favourable to one another (e.g., increased transmissibility and/or virulence); and thus, complicate the treatment of co-infected individuals because of possible drug-drug interaction-related severe adverse effects. Several systematic reviews found that HCV/HIV co-infected individuals have a higher risk of faster progression to cirrhosis/histological fibrosis, and decompensated liver disease than individuals with HCV infection only [23], thereby suggesting that HIV infection could facilitate HCV infection directly or indirectly.

Determinants of TTIs

Several determinants of TTIs were identified in this study. A higher educational level was associated with a reduced risk of TTIs, and this finding was also reported elsewhere [24]. The positive impact of higher educational levels has also been demonstrated for other common major infectious diseases in Cameroon and the past COVID-19 pandemic [9, 25]. People with higher education are able to better understand health messages from sources of information (i.e. television, radio, health campaigns), and thus, are more willing to change their behaviours, and adopt and/or implement TTIs control strategies. Consisting with previous studies [26], we also found that older donors were more at risk of TTIs. Several observations and assumptions could explain this result. The proportion of individuals with a high educational level was lower among donors aged 35–45 years compared to those aged 18–25 years. As above discussed, a high educational level is a key determinant of awareness and compliance with health prevention strategies.

Students were less at risk of HBV infections in this study, and this finding is supported by that from a previous study conducted in Ethiopia [26]. The Government of Cameroon actively implemented and scaled up national campaigns and awareness strategies towards the prevention of sexually transmitted diseases in youths this last decade. The current awareness strategies exploit a large set of communication tools such as social media and phone applications which are mainly used by youths. Students have access more easily to health messages via these tools than their older peers. Married donors had less chance of being infected with HCV, and this could be due to a limited number of sexual partners as compared to singles.

In this study, being a replacement donor was associated with a reduced risk of HIV infection. Contradictory finding was found among Tanzanian blood donors [27]. We also found that older age was a risk factor for HIV infections, and a similar finding was reported earlier [27]. Also, this is consistent with national epidemiological data that show a higher HIV burden in older individuals, with prevalence ranging from ~ 0.2% in 0–14 years to ~ 3.4% in 15–49 years [28]. It is possible that replacement donors, being family members/relatives of the recipient, are more aware of the infectious risks of blood transfusion, and thus, could adopt better health behaviours towards TTIs to preserve the health of the recipient.

Syphilis risk was strongly associated with poorer educational level and older age. As above discussed, persons with higher educational levels are more aware of health messages and the dangerousness of diseases, and thus, are more likely to adopt good attitudes and behaviours towards the prevention and control of diseases. A similar association between low educational level and increased risk of syphilis was recently found among Chinese blood donors [29]. We found that older donors were more at risk of T. pallidum infection, which is consistent with what is known in the literature [29]. Previous studies reported other determinants of T. pallidum infection in blood donors - e.g. tattoo, multiple sexual partners, occupation, living area, donor type, and razor reuse [30] - which can outline geographical variations in determinants of this infection.

Conclusion

In the present study, we analysed the blood transfusion-associated risk of HBV, HCV, HIV, and T. pallidum pathogens among blood donors in Douala, Cameroon. The results indicated a high prevalence of these pathogens among donors, especially among those aged ≥ 45 years old and with a low educational level. TTIs were mainly represented as single infections, with a few donors carrying multiple infections. Older age was associated with a higher risk of TTIs, while a high educational level and being a family donor were protective factors against TTIs. Similar patterns of association were found between these three determinants and the risk of HIV and T. pallidum. The risk of carriage of multiple pathogen species was reduced in married individuals. It is crucial to improve the awareness of communities towards the promotion of blood bank activity to increase the number of repeated voluntary donors. Taken together, our findings will contribute to the ongoing efforts of the government of Cameroon to improve transfusion-related systems and strategies at both regional and national levels in Cameroon.

Electronic supplementary material

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Abbreviations

95%CI

Confidence interval at 95%

aOR

Adjusted odds ratio

BTC

Blood transfusion centre

COVID-19

Coronavirus disease 2019

cOR

Crude odds ratio

df

Degree of freedom

DLH

Douala Laquintinie hospital

HBV

Hepatitis B virus

HCV

Hepatitis C virus

HIV

Human immunodeficiency virus

MCA

Multiple correspondence analysis

RDT

Rapid diagnostic test

SD

Standard deviation

SPSS

The statistical package for social sciences

TTI

Transfusion-transmittable infection

USA

The United States of America

WHO

World Health Organization

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

Data for this study may be made available on suitable request from the corresponding authors.

Declarations

Competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.