Evaluation of prevalence and risk factors associated with Cryptosporidium infection in rural population of district Buner, Pakistan

Abstract

Background: Cryptosporidium spp are important intestinal protozoan parasites that cause diarrhea in humans, domestic and wild animals. Its infection remains a main public health concern however, the epidemics in human being is still unclear, particularly in developing countries. There are several factors that may enhance the spreading of this parasite in human population especially in young children.

Methodology: A questionnaire was designed to obtain the demographic and clinical data from the participants. A total of 425 stool samples were collected from suspected children (aged 3-10 years) in different hospitals and villages. The initial screening was performed with modified Ziehl Neelsen (mZN) staining technique followed by polymerase chain reaction (PCR). Several potential risk factors were also assessed through the obtained information from suspected individuals.

Results: Out of all 425 collected samples, 127 were observed positive by mZN with a prevalence of 29.88% (127/425). The 127 mZN positive samples together with 50 mZN negative samples were processed for molecular analysis through PCR assay. Among them, 71 out of 127 mZN positive samples and 4 out of 50 mZN negative samples were found positive by PCR. The molecular analysis showed that Cryptosporidium parvum was the main cause of infection in children. The results revealed that individuals exposed to diarrhea were more likely to be infected with Cryptosporidium infection while several environmental factors may also play a key role in spreading of this parasite.

Conclusions/significance of the study: The current high prevalence of Cryptosporidium infection may be due to the lack of awareness and routine based testing in identification of this parasite in District Buner. Further studies are required to determine the importance of Cryptosporidium infection in this area as well as across the country and to find out the possible risk factors that may be associated with the occurrence of this protozoan. There is, however, an urgent need for laboratory-based observational studies to develop a more dynamic estimate of the cryptosporidial disease burden in the region.

Fig 1. Geographical representation of District Buner (KP Pakistan), and sampling sites (highlighted).

Fig 2

Where (a, b) shows the Cryptosporidium spp oocysts positive smear observed as thick walled spherical structures and stained pink-red color and (c, d) negative smear with pink stained hollow structures.

Fig 3. The graph shows the association between prevalence (%) of Cryptosporidium infection among studied participants (n = 425) and average rainfall (mm) recorded during the study.

Fig 4. The PCR product (556 bp) after amplification of 18S rRNA gene of C. parvum.

Lane-M: Marker (Fermentas, Germany), Lane-N: negative control and L1-L10: C. parvum positive samples.