Intestinal parasitic infections are prevalent worldwide and are one of the major health challenges faced by developing countries due to large population size, poverty, malnutrition, lack of availability of proper sanitation facilities and poor personal hygiene conditions [1,2]. Earlier, these infections were considered to be restricted to the developing countries, but now with the increase in the immigration, cases have been reported from the developed world too.

Worldwide, around 450 million people are infected by the intestinal parasites with a range of 11- 90% being reported in developing countries like India. [3, 4]. Intestinal parasites causing infections belong to the Protozoa and Helminth classes of parasites. Protozoa are unicellular structures transmitted by food and water contaminated with their cysts or oocysts. Most common Protozoa causing intestinal infections are Entamoeba histolytica/dispar, Giardia lamblia, Balantidium coli, Cryptosporodium species, Cyclospora cayetanensis, Cystoisospora belli and Microsporidia species. As per a WHO report, Entamoeba histolytica/ dispar was the third most common protozoa causing intestinal infections [5].

The helminths include Ascaris lumbricoides (roundworm), Ancylostoma duodenale (Hookworms), Trichuris trichiura, Enterobius vermicuralis, Hymenolepis nana and Strongyloides stercoralis. Ascaris lumbricoides and Hymenolepis nana are the most common helminths affecting approximately1 billion people [5]. In recent years, parasitic infections in immunocompromised patients are being increasingly reported. The various immunocompromised conditions associated with the intestinal parasitic infections are HIV/AIDS, Human T-Cell Lymphotropic Virus-(HTLV-1), corticosteroid treatment, malignancy, organ transplantation, malnutrition, hypogammaglobuli-naemia, collagen/ vascular diseases and metabolic disorders.

Coccidian parasites were infrequently reported before the era of AIDS/HIV emergence.

Among the coccidians, Cryptosporidiosis was classified as one of the AIDS defining illnesses [6]. The infection dose of these opportunistic parasites is as low as 10 oocysts [7].

Other than the coccidians, various other parasites reported to cause intestinal infections in immunocom-promised groups are S. stercoralis,

Microscopic examination: Microscopic examination was done for presence of motile trophozites, cyst, oocyst, pus cells and red blood cells.

The methods employed were Direct wet mount (saline/iodine) with and without Concentration technique of Formol ether sedimentation method and special staining like modified Ziehl Neelson stain for oocyst of coccidian parasites.

A total 57 stool specimens were examined from 57 cases during the 6 months duration. Majority of cases were in the age group of 31-40 years (29.82%) followed by 41-50 years (24.56%). In the study, 34 (59.64%) were female and 23 (40.35%) were males with a male-female ratio of 0.67:1.

The prevalence of parasitic infections in patients with diarrhea was 17.54%. Out of these 10 cases, 7 different species of intestinal parasites were identified (Figure 1-6). The Protozoa (70%) were more common than the helminths (30%).

Overall, Cryptosporidium species were the most common observed parasites followed by Isospora species. (Table 1) Among the 10 positive cases, 7 had associated immunocompromised conditions.

Majority of immunocompromised patients had HIV/AIDS (57.14%) followed by ulcerative colitis (28.57 %) (Table 2).

Table-1: Frequency of the parasites isolated.

Table-2: Distribution of parasites in Immunocompromised conditions

Figure-4: Oocysts of Cryptosporidium parvum in Modified Kinyon’s stain (100 X magnification)

Figure-5: Eggs of Hymenolepis nana in saline wet mount (40 X Magnification)

Figure-6: Rhabditiform larvae of Strongyloides stercoralis (Methylene blue stain 100 X magnification)

Many reports elucidate E. histolytica and G. lamblia as the common protozoa [1, 2, 15]. In the present study, among the protozoa as well as when total number of parasites were considered, Cryptosporidium species were the most common 5 (50%) followed by Isospora belli (20%).

The higher percentage of these coccidians can be explained by the fact that the present study group included both immunocompetent and immunocom-promised cases with the higher number of immunocom-promised individuals (70%). Cryptosporidium species were isolated from HIV/AIDS and ulcerative colitis cases whereas Isospora belli from HIV/AIDS. A study by Kaur R et al also reported a high isolation rate of Cryptosporidium species as compared to the other protozoa. [16].

With the advancement in diagnostic and therapeutic medical science come the detrimental effects of introducing various immunocompromised conditions. Over the last two decades, Cryptosporidiosis is being increasingly reported in developed and developing countries. Though, Cryptosporidiosis is one of the opportunistic pathogen in the immunocompromised groups, its infection in the immunocompetent individuals is not uncommon [17]. Various factors contribute towards the ubiquity and pathogenicity of Cryptosporidiosis like zoonotic nature, lack of host specificity, very low infectious dose (< 10 oocysts), oocysts highly resistant to the common disinfectants (chlorine) and discharged in large numbers from severely infected individuals and ability to cause autoinfection [7].

Helminthic infections affect 2 billion of the world’s population with India contributing to nearly 25% of this burden [18]. Though, India is an endemic region for these parasites, only three cases (30%) were observed infected with helminths in the present study, one case each by A. lumbricoides, H. nana and S. stercoralis. This may be due to the fact that the predominantly affected strata in the present study were adults and helminthic infections are more commonly found in children.

Around 85% of studies from different regions of India report that soil-transmitted helminthic infections are common in young children. Also, Delhi state falls in the zone of less than 20% affected region by the helminthes [18]. Furthermore, WHO recommends the Kato-Katz technique as the most reliable, accurate and effective diagnostic tool for the helminths.

A study from Mexico found protozoa like Blastocystis hominis, Endolimax nana and E.histolytica as the parasites in ulcerative colitis patients ⁽²³⁾ whereas a case report has published the occurrence of Giardia in ulcerative colitis [24]. In the present study, the case affected with Strongy-loides larvae had myasthenia gravis along with diabetes mellitus. Few case reports have reported this parasite in these autoimmune conditions. [25, 26, 27].

The most commonly used anti-protozoal drugs are nitroimidazoles like metronidazole or tinidazole, nitazoxanide, trimithoprim- sulfamethoxazole, paramomicin etc while albendazole, mebendazole, pyrantel pamoate etc are the commonly used anti-helminthic drugs. The cases in the present study were mostly treated with metronidazole for protozoal infections and albendazole for helminthic infections.

Among the pathogenic enteric parasites, the protozoans like coccidians predominate. Though the diagnostic technology has evolved with time, it largely depends on conventional methods in resource constraint settings. An accurate diagnosis is of utmost importance as treatment varies as per the infecting parasite. Furthermore, conditions like Cryptosporidiosis should be diagnosed early as they are responsible for relapse as well as exacerbation of symptoms especially in immunocompromised conditions.

Majority of positive cases detected in the present study were affected with some immunocompromised conditions. Thus, in the present study highlights that the occurrence of intestinal parasites is increasing in this group of patients. Many studies have demonstrated the occurrence of these intestinal parasites in HIV/AIDS patients.

The present study reports the existence of these pathogens in various other immunosuppressed conditions like ulcerative colitis, myasthenia gravis etc. The clinical presentation of these intestinal disorders is with non-specific symptoms. Hence, the diagnosis mainly depends on the high clinical suspicion and reliable laboratory techniques requiring expertise.