It is a retrospective study conducted in the Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, between the period of September 2014 and April 2016. The records of routine stool examination carried out during the study period, were analyzed. Stool samples received from the patients of different outdoor and indoor wards, presenting with complaints of diarrhoea and other gastrointestinal symptoms such as nausea, vomiting, flatulence, and pain abdomen were included in the study. More than one sample collected from a single patient having same findings were excluded from the study. A total of 968 cases of all age groups including 604 males and 364 females formed the study population. The demographic data of each case, i.e., age and sex along with stool examination findings were noted. All stool samples were tested as per the routine laboratory protocol, which included gross and microscopic examination within one hour of its collection. In gross examination, the colour and consistency of the stool samples, presence or absence of mucus, blood, adult worms, and body segments of the parasites were noted. Stool samples were further examined microscopically in wet mount preparation of normal saline and Lugol’s iodine after concentration, using formol-ether stool concentration technique [29]. The presence of ova, larvae, cysts, and trophozoites of various parasites as well as other intestinal commensals were noted. In 17 cases, additional detection of coccidian parasites were done during the study period, on request from clinicians. Modified ZN staining was done in all these cases [30].

The approval for this study was obtained from the Institute Ethics Committee. 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.

The interpretation and analysis of the data obtained were done using Microsoft Excel. The quantitative data were expressed as percentages in tabular form.

Out of 968 cases, 158 (16.3%) were found to be infected with either a parasite or a commensal or both; 604 samples were from males of which 98 (16.2%) were positive; and among 364 samples from females, 60 (16.5%) were found to be positive. A maximum number of isolates (21.1%) were found in the age group of 31-40 years. Among females, maximum (22.4%) infection was in the age group of 31-40 years, whereas in males (23.8%), it was in the age group of >60 years [Table/Fig-1]. The isolation of protozoans (95.38%) was more as compared to the helminths (4.62%). Entamoeba histolytica (37.57%) was the most commonly detected protozoa, followed by Giardia lamblia (23.12%), Entamoeba coli (22.54%), B. hominis (6.94%), and Iodamoeba butschlii (5.2%). Among helminths, Hymenolepis nana (2.9%) was most commonly detected, followed by Ascaris lumbricoides (1.15%) and hookworm (0.57%) [Table/Fig-2].

Single organism was detected in 144 (91.1%) stool samples each, whereas dual organisms were detected each in 13 (8.2%) samples. In a single case, three organisms were detected [Table/Fig-3].

Coccidian parasites were found in three out of 17 stool samples using modified ZN staining [Table/Fig-4]. The patient who was infected with Isospora belli was suffering from HIV. In other two cases, HIV status was negative. The patient infected with Cryptosporidium sp. was taking antitubercular treatment for pulmonary tuberculosis.

With the regularly changing lifestyles and dietary habits, the incidence of intestinal parasitic infections has upsurged. Many goals are being set from time to time for their control, but due to lack of epidemiological data, it is difficult to accomplish them. As far as Rajasthan is concerned, very few data from different places [24-28] are reported in literature. These studies have not included the intestinal commensals which, besides serving as indicators of the socioeconomic and sanitation conditions of a population, are on the rise causing various opportunistic infections [7,8].

In this study, the intestinal parasites were detected in 16.3% of the cases which is in accordance with earlier studies done in different parts of the state and ranges from 5.2% to 43.6% case [24,25,28]. The study conducted in Udaipur among the individuals of Bhil tribe [27] showed a high isolation rate of about 51.78% as compared to this study. Such differences may occur due to the varied socioeconomic conditions of different communities.

The percentage detection is almost similar in males (16.2%) and females (16.5%) and is in accordance with the findings of Kavathia G et al., [11,12]. In some other studies, detection rate was higher in males [10,18,19] and in some females were found to have predominant infection [13]. Such variations may be due to equal involvement of females in outdoor activities as compared to males nowadays. In various studies, the most common age group involved was 6-20 years [14,18,19,27] as compared to this study, where it is 31-40 years. In a previous study also, the trend of parasitic infection in recent years has shown to predominate among adults as compared to children [9].

In some studies, helminthic infections were found to predominate [14,23] while in this study protozoal infection (95.38%) far more exceeded the helminthic infections (4.62%). Protozoal infections were also predominant in some other studies from Rajasthan [25,27] as well as from different parts of country [11,12,21]. In this study, the most common protozoa isolated was Entamoeba histolytica (37.57%), followed by Giardia lamblia (23.12%) and Entamoeba coli (22.54%). Entamoeba histolytica followed by Entamoeba coli was also found to be the main protozoan in the study conducted among the Bhil tribe in Rajasthan [27] but strikingly, Giardia lamblia was not isolated even in a single case in that study. Entamoeba histolytica followed by Giardia lamblia has also been found as the main protozoan in studies from other parts of India [11,12,21,22], whereas Giardia lamblia followed by Entamoeba histolytica has been found in others [9,14,19]. Although we could find very less helminths, Hymenolepis nana followed by Ascaris lumbricoides was the most common among them, which is in accordance with the study done in Southern Gujarat by Patel MM et al. [14]. In other studies, Ascaris lumbricoides was found to be the most common helminth [9,11,12,19,21,22,31]. Such variations in the parasite prevalence may be accounted to the difference in geographic conditions and cultural practices and food habits in different regions, which further strengthens the need for such type of studies.

Mixed infections in 8.9% samples in this study suggest that parasitic infections do not always exist singly, but protozoal and helminthic infections can coexist. Mixed infections were also found in 13.39% cases in a study from Rajasthan [27] and in 13.4% cases in another study [23].

Among the three stool samples [Table/Fig-4] infected with coccidian parasites, the case infected with Isospora belli was HIV positive, whereas the case infected with Cryptosporidium sp. was suffering from tuberculosis. Intestinal parasitic coinfection with tuberculosis without HIV infection has been studied in the past [32]. Studies also have shown that coccidian parasites infect the immunocompromised patients suffering from HIV [33,34]. The presence of coccidian parasites in two patients not suffering from HIV, stresses on the need for further investigation into their relevance in non-HIV patients.

As this was a retrospective record based study, several demographic data pertaining to the socioeconomic conditions and other risk factors could not be collected. Single stool samples were taken from each patient and also modified ZN staining was not performed on each sample which could have diagnosed additional cases infected with parasites. This study being a hospital based study, cannot determine the true burden of parasitic infections in the community, for which more studies at community and village levels are needed with larger sample size.

Protozoal infections were more prevalent as compared to helminthic infections in the present study group. Intestinal parasitic infection is on the rise among the adult patients and may be caused due to single or multiple parasites, which must be considered while administering treatment to the patients presenting with diarrhoea or other gastrointestinal symptoms. Intestinal commensals too serve as indicators of the socioeconomic and sanitation conditions of a population, so their presence in stool samples must also be taken into account and clinical correlations must be done wherever required. Such types of hospital-based studies are always helpful in accessing the present burden of parasitic infections in patients suffering from gastrointestinal diseases. Our study would surely add to the existing knowledge of parasite prevalence in such type of patients and serve as a measure of their inclination toward the health indicators.