Parasitology

Research Article

Spatial analysis of Leishmania donovani exposure in humans and domestic animals in a recent kala azar focus in Nepal

BASUDHA KHANALa1, ALBERT PICADOa3, NARAYAN RAJ BHATTARAIa1a2a5, GERT VAN DER AUWERAa2, MURARI LAL DASa1, BART OSTYNa4, CLIVE RICHARD DAVIESa3, MARLEEN BOELAERTa4, JEAN-CLAUDE DUJARDINa2a5 c1 and SUMAN RIJALa1

a1 B.P. Koirala Institute of Health Sciences, Dharan, Nepal

a2 Department Molecular Parasitology, Institute of Tropical Medicine Antwerp, B-2000 Antwerpen, Belgium

a3 Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E7HT, UK

a4 Department of Public Health, Institute of Tropical Medicine, Antwerp, B-2000 Antwerpen, Belgium

a5 Department of Biomedical Sciences, University of Antwerp, Antwerpen B-2080, Belgium

SUMMARY

Visceral leishmaniasis (VL) is a major public health problem in the Indian subcontinent where the Leishmania donovani transmission cycle is described as anthroponotic. However, the role of animals (in particular domestic animals) in the persistence and expansion of VL is still a matter of debate. We combined Direct Agglutination Test (DAT) results in humans and domestic animals with Geographic Information System technology (i.e. extraction maps and scan statistic) to evaluate the exposure to L. donovani on these 2 populations in a recent VL focus in Nepal. A Poisson regression model was used to assess the risk of infection in humans associated with, among other factors, the proportion of DAT-positive animals in the proximities of the household. The serological results showed that both humans and domestic animals were exposed to L. donovani. DAT-positive animals and humans were spatially clustered. The presence of serologically positive goats (IRR=9·71), past VL cases (IRR=2·62) and the proximity to a forest island dividing the study area (IRR=3·67) increased the risk of being DAT-positive in humans. Even if they are not a reservoir, domestic animals, and specially goats, may play a role in the distribution of L. donovani, in particular in this new VL focus.

(Received December 14 2009)

(Revised February 04 2010)

(Accepted March 01 2010)

(Online publication May 12 2010)

Correspondence:

c1 Corresponding author: Department Molecular Parasitology, Institute of Tropical Medicine Antwerp, Nationalestraat 155, B-2000 Antwerpen, Belgium. Tel: +3232476355. Fax: +3232476359. E-mail: jcdujardin@itg.be

Footnotes

† Clive Richard Davies passed away in March 2009.

‡ B. K. and A. P. contributed equally to the paper.

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