Trends and clinico-epidemiological profile of patients with Giardiasis: Five-year experience from a university hospital of northern India

Abstract

Background:

Giardiasis is an important cause of diarrheal disease and is associated with morbidity in children and adults worldwide. We aimed to study the prevalence of Giardiasis, its clinical presentations, seasonal trends in detection, and coinfection with other intestinal parasites along with comparison of fecal antigen and microscopy for the detection of Giardiasis.

Materials and Methods:

It is a retrospective study conducted from Jan. 2017 to Dec. 2021 at our university hospital. Iodine and normal saline mounts and enzyme-linked immunosorbent assay (ELISA) were used for the detection of Giardiasis in stool samples. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of tests were computed.

Results:

Of 8364 patients, 432 (5.2%) had Giardiasis by microscopy and/or ELISA. Giardiasis was more common in males compared to females (318/5613 [5.6%] vs. 114/2751 [4.1%]; P = 0.003) and among those ≤10 y compared to older individuals (102/560 [18.2%] vs. 330/7804 [4.2%]; P <0.0001). Most cases were detected in the month of May to October. The most common clinical presentation was diarrhea (80.1%) and abdominal pain (72.9%) followed by malnutrition (60.2%) and loss of appetite (46.8%). Using microscopy as gold standard, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of ELISA were 95%, 91%, 91%, 95%, and 93%, respectively.

Conclusion:

Awareness and knowledge amongst the primary healthcare professionals and family physicians will help in early diagnosis and treatment of Giardiasis. Fecal antigen detection should be done along with microscopy for detection of Giardiasis.

Introduction

Giardia duodenalis (also known as Giardia lamblia and Giardia intestinalis) is one of the most common intestinal parasites in humans. Globally, about 280 million people suffer from symptomatic Giardia infection annually.[1] Although distributed worldwide, the prevalence of Giardiasis ranges from 20% to 30% in developing countries[2,3,4] compared to 2% to 5% in developed countries.[2,5] Since 2006, it has been included in the World Health Organization’s Neglected Disease Initiative. In India, the prevalence of Giardia varies from 3.8 to 23.5%.[6] Although Giardia infection is more common in children,[7] it is an important cause of diarrhea in adults too. Most studies reported in India focused on children,[8,9] and there are scanty data on Giardia infection in adults from India.

Giardiasis commonly presents as acute or chronic diarrhea, weight loss, abdominal cramp, and malabsorption.[10] Less frequently, in adults, severe illness and/or chronic sequelae occur, including irritable bowel syndrome,[11] chronic fatigue,[12] postinfectious arthritis, or joint pain.[10,13] Failure to thrive and malnutrition are chronic sequelae in infants and children.[14] Early identification of Giardiasis will help in its treatment simply with antigiardial drugs and thus minimize postinfectious and long-term sequelae.[15] Diagnosis of Giardiasis is often made by stool microscopy for the detection of cysts and trophozoites, but it is less sensitive.[16,17] Antigen detection by ELISA is a sensitive and specific method, and is useful for screening a large numbers of specimens in a short time-period.[17,18] It can also detect the antigen of Giardia even in the absence of this parasite in stool sample. Since there are scanty studies on Giardiasis (especially in adults) in India, therefore, we conducted this retrospective study in our university hospital in northern India over a period of five years, with the following objectives: To study,

1. Prevalence of Giardiasis by stool microscopy or ELISA

2. Demographic details and clinical presentation of patients with Giardiasis

3. Seasonal trends in the detection of Giardiasis

4. Comparison of fecal antigen detection with microscopy for detection of Giardia

5. Coinfection of Giardia with other intestinal parasites.

Materials and Methods

Study design and setting

This is a retrospective study conducted in a parasitology laboratory, Department of Microbiology at Sanjay Gandhi Postgraduate Institute of Medical and Sciences, Lucknow, India.

Study duration

The study was undertaken for a period of five years from January 2017 to December 2021.

Sample size and sampling

The records of stool examination of patients of all age groups carried out during the study period were analyzed. Stool samples received from the patients of different outpatient departments and indoor wards, presenting with complaints of diarrhea, which was defined as passage of more than three loose or watery stool per day,[19] and other gastrointestinal symptoms such as abdominal pain, loss of appetite, and weight loss were included in the study.

Data collection

Demographic details and clinical information for each patient were retrieved from patients’ medical records and were entered in a predesigned performa.

Sample processing and reporting guidelines

Microscopy was performed as soon as possible, preferably within one hour. Both iodine and normal saline mounts were prepared as per standard method. With the help of an applicator stick, one part of the stool sample was emulsified in a drop of saline on a clean, dry slide and in a drop of Lugol’s iodine. These were covered with coverslips and observed under low power of light microscope for the detection of cysts and trophozoites of Giardia. In bright-field microscopy, cysts of Giardia appear ovoid to ellipsoid in shape and usually measure 10–12 μm in length and 4–6 μm in width. Immature and mature cysts have 2 and 4 nuclei, respectively [Figure 1a]. Trophozoites are pear-shaped, bilaterally symmetric, measuring 12 to 15 μm and contain two anteriorly placed nuclei and eight flagella [Figure 1b].

Figure 1.

(a) Iodine mount showing cysts of Giardia intestinalis and (b) trophozoite of Giardia intestinalis (×40)

Antigen test for the detection of Giardia in stool samples was performed by a commercially available ELISA kit (NovaTec Immunodiagnostic GMBH ELISA kit, Germany) in a subset of patients as per manufacturer’s instructions.

Data analysis

The Statistical Package of Social Sciences, version 23 (SPSS-23, IBM, Chicago, USA), was used for statistical analysis. Categorical data were analyzed using Fisher’s exact test with a 95% confidence interval. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated as per standard formulae. P values less than 0.05 were considered significant for all statistical analysis.

Ethical issues

The study protocol was approved by Institutional Ethics Committee (IEC code: 2013-32-IMP-EXP/179). The individual consent was not obtained from each case as this was a retrospective study, and tests were carried out in the microbiology laboratory as a routine procedure.

Results

Prevalence and clinico-demographic details of patients with Giardiasis

Over a five-year period, 432 (5.2%) patients were positive for Giardia either on stool microscopy or ELISA. Mean age of the patients was 32.33 ± 16.49 years (range: 1-74 years). Giardiasis was more common in males as compared to females (P = 0.003) and is significantly associated with age group ≤10 years (P <0.0001), but no association with other age groups was seen in the study [Table 1]. The most common clinical presentation in the study patients was diarrhea and abdominal pain followed by malnutrition and loss of appetite [Figure 2].

Table 1.

Demographic details of study population

Characteristics	Total patients screened	Patients positive for Giardia (Microscopy±ELISA)	P
Overall cases	8364	432 (100%)	-
Gender
Male	5613	318 (73.6%)	0.003
Female	2751	114 (26.4%)
Age (years)
≤10	560	102 (23.6%)	<0.0001
11-20	1280	82 (19%)	Not significant
21-30	1876	78 (18.1%)
31-40	2109	75 (17.3%)
41-50	1642	56 (13%)
>50	897	39 (9%)

Figure 2.

Clinical presentations of patients of Giardiasis in the study

Seasonal trends in the detection of Giardiasis

All the data were categorized on a monthly basis to assess any possible seasonality in Giardia prevalence. Giardiasis was found to be prevalent throughout the year, but during this course of study, it was little higher in premonsoon, monsoon, and postmonsoon season especially from the month of May to October [Figure 3].

Figure 3.

Seasonal trend of Giardiasis in the study

Comparison of fecal antigen detection and microscopy for detection of Giardiasis

Using microscopy as gold standard, sensitivity, specificity, positive, and negative predictive value and diagnostic accuracy of ELISA were 95%, 91%, 91%, 95%, and 93%, respectively [Table 2].

Table 2.

Sensitivity and specificity of diagnostic techniques

	ELISA		Total number
	Positive	Negative
Microscopy (Reference method)
Positive	373 (TP)	20 (FN)	393
Negative	40 (FP)	431 (TN)	471
Total number	413	451	864
Sensitivity (%) [95%CI]	94.91% (92.25-96.86%)
Specificity (%) [95%CI]	91.51% (88.62-93.86%)
Negative predictive value (%) [95%CI]	90.31% (87.38-92.62%)
Positive predictive value (%) [95%CI]	95.57% (93.35-97.06%)
Diagnostic accuracy	93.06% (91.15-94.66%)

TP positive in both microscopy and ELISA; FP positive in microscopy but not in ELISA; FN negative in microscopy but positive in ELISA; TN negative in both ELISA and microscopy

Coinfections with other intestinal parasites

Coinfection of Giardia with other intestinal parasites was observed in 15.5% (67/432) cases. Coinfection with Entamoeba spp. and Cryptosporidium spp. was found in 9% (39/432) and 6.5% (28/432) cases, respectively.

Discussion

In the present study, the prevalence of Giardiasis was 5.2%, but this was lower than that in the study by Nitin et al. from Lucknow, who have showed 22% Giardia spp. in their study.[6] A study conducted by Yadav et. al. in a tertiary care hospital of New Delhi, India, and prevalence of Giardia among patients with diarrhea was found to be 2%.[4] In a study from our institute among patients with malabsorption syndrome, we found prevalence of Giardiasis as 5%.[20] High prevalence of Giardiasis ranging from 2% to 50% has been reported from studies from southern India.[8,21,22] Overcrowding, poor sanitation, contaminated drinking water, and poor personal hygiene could be the cause of high prevalence rate of Giardiasis in the study population.[23] The results may be different due to the different study area, sample size, age group, etc., in our study.

We found that a most of the patients with Giardiasis were males and Giardiasis was significantly associated with age ≤10 years. Earlier studies have reported that male gender and young age are more susceptible for both asymptomatic and symptomatic Giardiasis.[7,24] Higher outdoor activity and more environmental exposure in males than females may be the cause of higher rate of Giardiasis in them.[24] In the present study, more cases of Giardiasis were detected higher in premonsoon, monsoon, and postmonsoon season especially from the month of May to October, which is consistent with the previous studies[1,25] and may be attributed to fecal-oral transmission of Giardiasis.

In resource limited countries, most common method employed to detect Giardiasis in stool is microscopy, but it requires trained personnel and has low sensitivity due to intermittent excretion of Giardia cyst or trophozoites in stool.[17,26,27] Using microscopy as gold standard, the sensitivity and specificity of ELISA is in accordance with previous studies where sensitivity varied between 95% and 100% and specificity over 90%.[16-18] In the present study, ELISA detected Giardia in 40 additional samples that were negative on microscopy. Twenty samples were negative by ELISA though positive on microscopy. Possible explanation of this could be low concentration of parasitic load in stool as Giardia antigen can detect only when the cyst or trophozoites concentration is above 5 × 10³ and 2 × 10⁴ per ml of diluted stool samples, respectively. Alternately, it could be due to degradation of epitope region or elution of Giardia antigen as ELISA detects only soluble or free floating antigen, not associated with Giardia cyst wall or trophozoites.[28]

The present study shows coinfection of Giardia with Entamoeba spp. and Cryptosporidium spp., which is in resonance with previous studies.[26,29] The possible reason for coinfection may be that the parasite derives some advantage from the presence of other diarrhea-causing pathogens in the host, or vice versa.

Strengths and limitations of the study

The present study is one of the few studies where Giardia infection is described in both children and adult patients along with demographic details, clinical presentations, seasonal trends, and coinfections with other intestinal parasites. However, we could not do genotyping of the Giardia among patients due to retrospective nature of the study.

Conclusion

This study will help the primary healthcare professionals and family physicians to get adequate knowledge about the significance and diagnosis of Giardiasis in both children and adults. Trends suggest that differences in exposures by sex and age group are important to the epidemiology of Giardiasis. Furthermore, investigation into the risk factors of at community level will support prevention and control efforts. Fecal antigen detection should be done along with microscopy for the detection of Giardiasis.

List of abbreviations

Abbreviation	Definition
ELISA	Enzyme-linked immunosorbent assay
SPSS	Statistical Package for the Social Sciences

Financial support and sponsorship

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest

There are no conflicts of interest.