Cystoisospora belli is an intestinal protozoon distributed worldwide; however, it is a less common cause of protozoal diarrhoea than Toxoplasma and Cryptosporidium [9]. Studies showed that many parasitic infections are prevalent and endemic in Iraq, including Sulaimaniyah; however, research on C. belli infections is limited in Iraq, with no reported data in Sulaimaniyah.
The direct wet mount technique was used in this study. Still, it didn’t reveal any oocyst of C. belli in the examined stool samples of the children, which might be related to the transparent appearance of the oocysts that could be overlooked in direct faecal smears. Diagnosis can be challenging owing to intermittent and low-grade shedding of oocysts that may not be found despite actual infection [10]. However, a modified ZN stain detected a high burden of Cystoisosporiasis (26.92%) in children. This outcome is inconsistent with that found by Abdel-Hafeez et al., 2012 in Egypt (9.7%) [11], Vouking et al., 2014 in Cameron (10.08%), Barcelos et al., 2018 in Brazil (3.8%), Al-Saeed et al., 2019 in Erbil, Iraq (3.8%) [12], Kumar et al., 2017 in India (2%) [13], and Mbae et al., 2013 in Kenya (1.2%) [14]. However, it is in line with that found by Casmo et al., 2018 in Mozambique (25%), but it is lower than that observed by Swathirajan et al., 2017 in India (88.8%) [15]. These variations were referred to the differences in the study area and designs, methods of diagnosis, the season of studies and geographic location and patient populations.
Additionally, microscopical examination in this study showed the presence of other microbial agents rather than C. belli, such as Entamoeba histolytica, monilia, Giardia lamblia, and Entrobius vermicularis. Similarly, other studies found various microbial agents, including Giardia lamblia [12], Ascaris lumbricoides, Entamoeba histolytica, Trichuris trichiura, Giardia intestinalis, Hymenolepis nana, and Schistosoma mansoni [16]. At the same time, the most common protozoan infection in immunosuppressed children was Cryptosporidium parvum (60.2%), Blastocystis hominins (12.1%), Cyclospora caytenensis (7.8%), Entamoeba histolytica (24.6%), and Giardia lamblia (17.6%) [11].
In the current study, age (4–6 years), duration of infection (1–3 days), and type of drinking water (bottled water) (p < 0.05) were considered as the main predisposing and risk factors for development and progression of cystoisosporiasis in diarrheal children and on the other hand, gender, residency, and type of the school had no impact on the development and progression of the disease in children with diarrhoea. Thus, other risk factors for developing intestinal parasites were reported in other studies, such as high waste disposal habits, open field defecation, drinking water sources, and hand washing habit before meals [17].
Cryptosporidium spp., Cyclospora spp., Toxoplasma spp., and C. belli are related taxonomically [3]. Thus, the modified ZN stain revealed the presence of other protozoa, including Cryptosporidium spp., Microsporidia, Cyclospora spp., and Blastocyst hominins. In this regard, Cryptosporidium spp was detected in 34.3% and C. belli in 1.5% of patients with HIV/AIDS in South Ethiopia [18]. In comparison, another study reported Cryptosporidium parvum (43.6%), C. belli (15.5%) and Blastocystis hominis (10.5%) in HIV/AIDS patients in North West Ethiopia [19]. Moreover, Adamu et al., 2006 in Addis Ababa found emerging opportunistic parasites in diarrhoeal children, including Cryptosporidium parvum (8.1%), C. belli (2.3%), Enterocytozoon bieneusi/Encephalitozoon intestinalis (0.5%), Ascaris lumbricoides (0.5%), Trichuris trichiura (0.9%), Giardia lamblia (6.3%), Entamoeba histolytica/ E. dispar (1.4%), Blastocystis hominis (5.9%) and Hymnolepis nana (0.5%) [20].