Application of PCR techniques utilizing sputum and urine for monitoring Wuchereria Bancroft infection in Malindi District, Kenya
Kagai, Jim Mwaniki
MetadataShow full item record
Lymphatic filariasis is caused by Wuchereria bancrofti, Brugia malayi, and B. timori, and afflicts humans. The disease is prevalent in tropical countries, where 128 million are infected and 1.1 billion are at risk of being infected. Over 30% (38.4 million) of the people affected by lymphatic filariasis worldwide live in Africa. In Kenya, the disease is common in the coastal province where 2.5 million people live. The nocturnal W bancrofti is the causative agent for lymphatic filariasis in Africa. These parasites are transmitted by mosquito vector, for which 77 species have been identified. The species belong to the genera, Anopheles, Culex, Aedes, and Mansonia. Specific and sensitive diagnosis of W bancrofti infections has been one of the main challenges in filariasis research. To date, this objective has been hampered by absence of microfilariae in the later stages of the disease, inconveniences of nocturnal behaviour of the parasites, lack of a sensitive diagnostic method, and safer and easier sample collection procedures for mass diagnosis. In 1998 the World Health Organization, identified lymphatic filariasis as one of the diseases that can be eradicated. Several endemic countries including Kenya have put in place elimination programs. However, no surveillance methods have been identified for monitoring W bancrofti infections during and after elimination programs. In this study, two PCR assays were applied to detect W bancrofti infections in Mpirani location of Malindi district, coast province, Kenya. The traditional method utilizing examination of night blood for the presence of microfilaria under the microscope, and the immunochromatographic test (lCT), were also performed on the same samples. The positivity of W bancrofti infection was found to be 22.0 % (67/304) and 38.8% (119/304) respectively by microscopy and ICT, whereas sputum and urine PCRs positivity were, respectively, 42.8% (130/304) and 36.2% (110/304). The sensitivity and specificity of the PCR sputum assay was 97.5% and 92.4% respectively compared to 96.1% and 94.5% ofPCR urine assay. Positive predictive values were 89.2% and 90.0% for PCR assay for sputum and urine respectively. Negative predictive values were 98.3% and 97.9% for sputum and urine respectively. Accuracy was 94.4% in PCR assay for sputum and 95.1% in case of urine. The study concludes that these PCR assays demonstrate great potential for consideration in both diagnosis and epidemiological studies of W bancrofti infections. The study also recommends more studies in the use of urine in particular for surveillance of effectiveness of lymphatic filariasis programs.