Detection of Cryptosporidium Species in Human Diarrhoeic Stools Using Different Diagnostic Methods at Federal Medical Centre, Yenagoa, Bayelsa State, Nigeria

Abstract

Cryptosporidiosis is an important cause of diarrhoeal illness, particularly in young children and people with impaired immunity. Laboratory diagnosis may be difficult when microscopy is used alone because Cryptosporidium oocysts can be overlooked or confused with similarly sized material. This study compared conventional microscopy, coproantigen enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) for the detection of Cryptosporidium in diarrhoeic stool specimens collected at Federal Medical Centre, Yenagoa, Bayelsa State, Nigeria. A total of 138 participants, aged 6 months to 60 years, were recruited from the Emergency Clinic, General Outpatient Department and Medical Outpatient Department. Fresh stool specimens were divided into three portions for microscopic examination, coproantigen ELISA and PCR. Microscopy included direct saline and Lugol's iodine preparations, formol-ether concentration and modified Ziehl-Neelsen (MZN) staining. ELISA was performed with a commercial Cryptosporidium coproantigen kit, while DNA was extracted and amplified using Cryptosporidium-specific primers. Cryptosporidium was identified in 26 (18.8%) samples by microscopy, 29 (21.0%) by ELISA and 34 (24.6%) by PCR. Using PCR as the reference method, microscopy had 70.6% sensitivity, 98.1% specificity and 91.3% accuracy. ELISA showed 85.3% sensitivity, 100% specificity and 96.4% accuracy. Cryptosporidium-positive participants were predominantly from rural areas and many reported contact with domestic or farm animals. The findings indicate that PCR provided the highest detection rate, whereas ELISA offered a practical compromise between diagnostic performance and laboratory requirements. In settings where molecular facilities are unavailable, ELISA can complement microscopy for routine diagnosis.