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- Title
Incidence of Symptomatic and Asymptomatic Leishmania donovani Infections in High-Endemic Foci in India and Nepal: A Prospective Study.
- Authors
Ostyn, Bart; Gidwani, Kamlesh; Khanal, Basudha; Picado, Albert; Chappuis, François; Singh, Shri Prakash; Rijal, Suman; Sundar, Shyam; Boelaert, Marleen
- Abstract
Incidence of Leishmania donovani infection and Visceral Leishmaniasis (VL) was assessed in a prospective study in Indian and Nepalese high-endemic villages. DAT-seroconversion was used as marker of incident infection in 3 yearly surveys. The study population was followed up to month 30 to identify incident clinical cases. In a cohort of 9034 DAT-negative individuals with neither active signs nor history of VL at baseline, 42 VL cases and 375 asymptomatic seroconversions were recorded in the first year, giving an infection∶disease ratio of 8.9 to 1. In the 18 months' follow-up, 7 extra cases of VL were observed in the seroconverters group (N = 375), against 14 VL cases among the individuals who had not seroconverted in the first year (N = 8570) (RR = 11.5(4.5<RR<28.3)). Incident asymptomatic L. donovani infection in VL high-endemic foci in India and Nepal is nine times more frequent than incident VL disease. About 1 in 50 of these new but latent infections led to VL within the next 18 months. Author Summary: Visceral Leishmaniasis is well known as a public health problem in North-Indian Bihar state and adjacent districts in Nepal, with about 300.000 new cases per year. As not all infections with L.donovani lead to disease, the impact of control programs should not only be measured in numbers of VL cases, but also in number of new infections. So far there have been little or no data on the infection∶disease ratio for this region, and the evolution of these latent infections. Using DAT seroconversion as a marker of infection, we found incident asymptomatic infection to be nine times more frequent than incident VL disease in high-endemic villages in India and Nepal, and about 1 in 50 of these latent infections lead to VL in the next 18 months, while over 80% turn seronegative again within a year. Asymptomatic DAT-positivity detected through screening in a person with no history of VL, and especially in case of documented recent seroconversion, is a risk factor for ultimately developing VL. Further studies on transient and persistent asymptomatic L. donovani infection are needed to better understand their immunological patterns and serokinetics, their level of infectivity, and their potential for later progression to VL.
- Subjects
NEPAL; INDIA; LEISHMANIA donovani; HIV seroconversion; LATENT infection; VISCERAL leishmaniasis; LONGITUDINAL method; INFECTION
- Publication
PLoS Neglected Tropical Diseases, 2011, Vol 5, Issue 10, p1
- ISSN
1935-2727
- Publication type
Article
- DOI
10.1371/journal.pntd.0001284