The current study investigated the prevalence of Cryptosporidium infections in Qatar and compared the diagnostic performance of four diagnostic techniques for detection of Cryptosporidium in human stool samples. Our results showed that the prevalence of cryptosporidiosis in Qatar was relatively higher (17.5%) compared to previous reports (15.1% and 4.5%) (30, 31). In this study, the incidence of Cryptosporidium infection was higher in males (61.0%) as reported in previous studies (32, 46). In a study from Saudi Arabia, Hawash et al. (2014). linked the higher incidence of cryptosporidiosis in males to the direct contact with farm animals (38). In contrast, other studies showed a higher Cryptosporidium infection rates in females who had a direct contact with animals (47, 48). These conflicting findings may be influenced by local factors and require further investigation.
Our study also revealed that children under five years had twice the rate of infection as older children (5–10 and 10–20 years). This finding is in agreement with studies from Qatar and abroad (4, 28, 30, 46, 52–55). In our study, the incidence of Cryptosporidium among Qatari citizens (61.0%) was higher than other expatriates (39.0%) as reported in a previous local survey (30).
The PCR method was the most sensitive method compared to the other three diagnostic techniques used in this study. PCR detected the highest positive samples 36/205 (17.5%) compared to direct microscopy, MKS and ICT,12 (6.0%),15(7.3%) and 31(15.0%), respectively. This result was in accordance with previous studies (28, 34, 38, 56, 57).
Direct microscopy and MKS showed the lowest sensitivity rates among the four methods tested with 33.0%, and 41.7%, respectively. On the other hand, both methods showed 100% specificity (Table 1). The sensitivity of both techniques can be improved by testing multiple samples. Reports have shown that the probability of detecting parasites in a single stool specimen may be as low as 50 to 60.0%, whereas it can reach to > 95.0% if three stool samples are tested (58, 59). These findings are similar to those reported in previous studies (46, 51, 53).
The ICT method proved to be more beneficial in our study than the direct microscopy and MKS and showed a sensitivity of 86.0%. The improved sensitivity of the ICT might be due to its ability to detect lower levels of Cryptosporidium oocysts, which can be challenging with direct microscopy. This might occur possibly after an anti-parasitic treatment (38). It is worth noting that the kit used in our study specifically targets C. parvum, which is the predominant species in Qatar (30). This specificity likely contributes to the high sensitivity observed with the ICT method in our study. These findings are in agreement with previous studies (46, 60, 61). However, a lower sensitivities and specificities of ICT were reported in previous studies where similar and different kits were used (38, 62).
The prevalence of Cryptosporidium was found to be increasing during the winter and rainy seasons. This was similarly observed in previous studies from Qatar (30), Kuwait (63), Saudi-Arabia (50) and Sub-Saharan Africa (4).These regions share similar climatic conditions, suggesting that environmental factors, such as increased rainfall and lower temperatures, may contribute to the increased prevalence during winter and rainy seasons. However our findings are discordant with another study from Saudi Arabia where the highest rates of Cryptosporidium infection were detected during the fall and spring seasons (47). Another study from Jordan showed that the highest prevalence of Cryptosporidium was reported in the warm months from May to September (51).
The most common risk factors associated with Cryptosporidium infection world-wide are the direct contact with domestic animals, lack of breastfeeding, and environmental factors, such as unsafe sources of water, malnutrition, and immunosuppression (1, 64, 65). Ahmed et al. (2020). reported the prevalence of cryptosporidiosis in the GCC region and found that the most vulnerable groups to were children under 5 years and immunocompromised individuals (28). Ahmed et al. also showed that expatriates workers were the source of imported Cryptosporidium infection via food handling and poor hygiene (28). However, high prevalence of Cryptosporidium in a study from Kuwait has been linked to consumption of contaminated water in winter desert camps where a large numbers of water storage tanks were used (63). In Qatar, no seasonal studies conducted to determine the relationship between meteorological and other factors e.g. water contamination, animals contact etc. for transmission of Cryptosporidium in Qatar. However, expatriates from regions with a high rate of parasitic infections, such as Southeast Asia and North and sub-Saharan Africa, may be a possible source of Cryptosporidium transmission in Qatar (30, 32).
Currently, a wide range of commercial multiplex PCR assays have been developed to overcome the limitations of conventional microscopic and staining techniques used for detection of parasites in stool sample (66, 67). These PCR assays offer several advantages over traditional methods. Firstly, they provide increased sensitivity and specificity, particularly in populations with low rate of parasitic infections, Allplex™ GI-Parasite Assay showed high sensitivity 96.5% and specificity 98.3% (41). Secondly, the possibility of multiplex PCR assays allows the detection of various organisms and species using multiplex gene targets. Additionally, these assays enable the detection of bacterial and viral co-infections within the same test panel, providing a comprehensive diagnostic solution for patients with mixed infections (68).
However, PCR assays may have some limitations in detecting some protozoan parasites (e.g. Cystoisospora belli) in stool samples (42). Furthermore, the availability of marketed multiplex PCR assay that target helminths parasites and worms, such as Allplex™ GI-Helminth Assay, is currently limited (42). Therefore, when selecting the most appropriate assay, it is crucial to consider several factors, including the laboratory workflow, test performance, and the specific patient population to be tested (44).