Measurement of recent exposure to Phlebotomus argentipes, the vector of Indian visceral Leishmaniasis, by using human antibody responses to sand fly saliva.

Meredith F Clements,Petr Volf,Shyam Sundar,Ingrid Müller,Kamlesh Gidwani,Clive R Davies,Diwakar S Dinesh,Murari Das,Suman Rijal,Vijay Kumar,Matthew E Rogers,Albert Picado,Rajiv Kumar,Jitka Hostomska,Marleen Boelaert,Pradeep Das,Vera Volfova,Gordon Hamilton

doi:10.4269/ajtmh.2010.09-0336

Abstract

Antibody (IgG) responses to the saliva of Phlebotomus argentipes were investigated using serum samples from regions of India endemic and non-endemic for visceral leishmaniasis (VL). By pre-adsorbing the sera against the saliva of the competing human-biting but non-VL vector P. papatasi, we significantly improved the specificity of a P. argentipes saliva enzyme-linked immunosorbent assay. Using this method, we observed a statistically significant correlation between antibodies to P. argenitpes saliva and the average indoor density of female sand flies. Additionally, the method was able to detect recent changes in vector exposure when sera from VL patients were assayed before, during, and after hospitalization and protected from sand fly bites under untreated bed nets. Collectively, these results highlight the utility of antibodies to P. argentipes saliva as an important tool to evaluate VL vector control programs.

Highlights

Visceral leishmaniasis (VL) in the Indian subcontinent, known as kala-azar, is caused by Leishmania donovani
By pre-adsorbing the sera against the saliva of the competing human-biting but non-visceral leishmaniasis (VL) vector P. papatasi, we significantly improved the specificity of a P. argentipes saliva enzyme-linked immunosorbent assay
To investigate whether a human population from an leishmaniasis-endemic region had IgG against salivary gland antigens of the vector sand fly P. argentipes, we measured by enzyme-linked immunosorbent assay (ELISA) the antibody level in sera of 89 adults from India and 12 adults from the United Kingdom

Summary

Introduction

Visceral leishmaniasis (VL) in the Indian subcontinent, known as kala-azar, is caused by Leishmania donovani. In India the main endemic focus is in Bihar State where resistance to the first-line treatment, pentavalent antimonials, is rife; there is no vaccine.[2] In India, Nepal, and Bangladesh, L. donovani is transmitted exclusively by Phlebotomus argentipes, a sand fly that is considered anthroponotic.[3,4] Because VL in the Indian subcontinent cycles predominantly between humans, with no established zoonotic involvement, control strategies have focused on prevention of infection through the promotion of early diagnosis and vector control.[5,6]

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Conclusion