Evaluation of the OnSite (Pf/Pan) rapid diagnostic test for diagnosis of clinical malaria.

BACKGROUND: Accurate diagnosis of malaria is an essential prerequisite for proper treatment and drug resistance monitoring. Microscopy is considered the gold standard for malaria diagnosis but has limitations. ELISA, PCR, and Real Time PCR are also used to diagnose malaria in reference laboratories, although their application at the field level is currently not feasible. Rapid diagnostic tests (RDTs) however, have been brought into field operation and widely adopted in recent days. This study evaluates OnSite (Pf/Pan) antigen test, a new RDT introduced by CTK Biotech Inc, USA for malaria diagnosis in a reference setting. METHODS: Blood samples were collected from febrile patients referred for malaria diagnosis by clinicians. Subjects were included in this study from two different Upazila Health Complexes (UHCs) situated in two malaria endemic districts of Bangladesh. Microscopy and nested PCR were considered the gold standard in this study. OnSite (Pf/Pan) RDT was performed on preserved whole blood samples. RESULTS: In total, 372 febrile subjects were included in this study. Of these subjects, 229 (61.6%) tested positive for Plasmodium infection detected by microscopy and nested PCR. OnSite (Pf/Pan) RDT was 94.2% sensitive (95% CI, 89.3-97.3) and 99.5% specific (95% CI, 97.4-00.0) for Plasmodium falciparum diagnosis and 97.3% sensitive (95% CI, 90.5-99.7) and 98.7% specific (95% CI, 96.6-99.6) for Plasmodium vivax diagnosis. Sensitivity varied with differential parasite count for both P. falciparum and P. vivax. The highest sensitivity was observed in febrile patients with parasitaemia that ranged from 501-1,000 parasites/µL regardless of the Plasmodium species. CONCLUSION: The new OnSite (Pf/Pan) RDT is both sensitive and specific for symptomatic malaria diagnosis in standard laboratory conditions.

Diversity of anopheline species and their Plasmodium infection status in rural Bandarban, Bangladesh.

BACKGROUND: Historically, the Chittagong Hill Tracts (CHT) of Bangladesh was considered hyperendemic for malaria. To better understand the contemporary malaria epidemiology and to develop new and innovative control strategies, comprehensive epidemiologic studies are ongoing in two endemic unions of Bandarban district of CHT. Within these studies entomological surveillance has been undertaken to study the role of the existing anopheline species involved in the malaria transmission cycle throughout the year. METHODS: CDC miniature light traps were deployed to collect anopheline mosquitoes from the sleeping room of the selected houses each month in a single union (Kuhalong). Molecular identification was carried out for available Anopheles species complexes. Circumsporozoite proteins (CSP) for Plasmodium falciparum, Plasmodium vivax-210 (Pv-210) and Plasmodium vivax-247(Pv-247) were detected by Enzyme-linked immunosorbent assay (ELISA) from the female anopheline mosquitoes. To confirm CSP-ELISA results, polymerase chain reaction (PCR) was also performed. RESULTS: A total of 2,837 anopheline mosquitoes, of which 2,576 were female, belonging to 20 species were collected from July 2009-June 2010. Anopheles jeyporiensis was the most abundant species (18.9%), followed by An. vagus (16.8%) and An. kochi (14.4%). ELISA was performed on 2,467 female mosquitoes of 19 species. 15 (0.6%) female anophelines belonging to eight species were found to be positive for Plasmodium infection by CSP-ELISA. Of those, 11 (0.4%) mosquitoes were positive for P. falciparum and four (0.2%) for Pv-210. No mosquito was found positive for Pv-247. An. maculatus (2.1%, 2/97) had the highest infection rate followed by An. umbrosus (1.7%, 2/115) and An. barbirostris (1.1%, 2/186). Other infected species were An. nigerrimus, An. nivipes, An. jeyporiensis, An. kochi, and An. vagus. Out of 11 P. falciparum CSP positive samples, seven turned out to be positive by PCR. None of the samples positive for Pv-210 was positive by PCR. In terms of abundance and incrimination, the results suggest that An. maculatus, An. jeyporiensis and An. nivipes play important roles in malaria transmission in Kuhalong. CONCLUSION: The findings of this study suggest that even in the presence of an insecticide impregnated bed-net intervention, a number of Anopheles species still play a role in the transmission of malaria. Further investigations are required to reveal the detailed biology and insecticide resistance patterns of the vector mosquito species in endemic areas in Bangladesh in order to assist with the planning and implementation of improved malaria control strategies.

Evaluation of rK-39 strip test using urine for diagnosis of visceral leishmaniasis in an endemic area in Bangladesh.

Diagnosis of visceral leishmaniasis (VL) by demonstration of parasites in tissue smears obtained from bone marrow, spleen or lymph nodes is risky, painful, and difficult. The rK-39 strip test is widely used for the diagnosis of VL using blood/serum samples in endemic countries. The aim of the study was to evaluate the rK-39 strip test using urine sample as a non-invasive means for the diagnosis of VL. The rk-39 strip test was performed using urine from 100 suspected VL cases along with 25 disease control (malarial febrile cases) and 50 healthy control (from endemic and non-endemic areas). All the VL suspected cases were positive with the rK-39 strip test using serum. The sensitivity and specificity of the rK-39 strip test using urine samples was 95% and 93.3%, respectively, compared to serum based rK-39 test. The findings suggest that the urine based rK-39 test could be a practical and efficient tool for the diagnosis of VL patients in rural areas, particularly where resources are limited.