Volume 99, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



In the Indian subcontinent, visceral leishmaniasis (VL) has a strongly clustered distribution. The “index case approach” is promoted both for active case finding and indoor residual spraying (IRS). Uncertainty exists about the optimal radius. Buffer zones of 50–75 m around incident cases have been suggested for active case finding, for IRS the recommendation is to cover a radius of 500 m. Our aim was to establish optimal target areas both for IRS and for (re)active case finding. We plotted incident VL cases on a map per 6-month period (January–June or July–December) and drew buffers of 0 (same household), 50, 75, 100, 200, 300, 400, and 500 m around these cases. We then recorded total population and numbers of VL cases diagnosed over the next 6-month period in each of these buffers and beyond. We calculated incidence rate ratios (IRRs) using the population at more than 500 m from any case as reference category. There was a very strong degree of spatial clustering of VL with IRRs ranging from 45.2 (23.8–85.6) for those living in the same households to 14.6 (10.1–21.2) for those living within 75 m of a case diagnosed, during the previous period. Up to 500 m the IRR was still five times higher than that of the reference category. Our findings corroborate the rationale of screening not just household contacts but also those living within a perimeter of 50–75 m from an index case. For IRS, covering a perimeter of 500 m, appears to be a rational choice.

[open-access] This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


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  1. Bhunia GS, Chatterjee N, Kumar V, Siddiqui NA, Mandal R, Das P, Kesari S, , 2012. Delimitation of kala-azar risk areas in the district of Vaishali in Bihar (India) using a geo-environmental approach. Mem Inst Oswaldo Cruz 107: 609620. [Google Scholar]
  2. Chappuis F, Sundar S, Hailu A, Ghalib H, Rijal S, Peeling RW, Alvar J, Boelaert M, , 2007. Visceral leishmaniasis: what are the needs for diagnosis, treatment and control? Nat Rev Microbiol 5: 873882. [Google Scholar]
  3. Bern C, Courtenay O, Alvar J, , 2010. Of cattle, sand flies and men: a systematic review of risk factor analyses for south Asian visceral leishmaniasis and implications for elimination. PLoS Negl Trop Dis 4: e599. [Google Scholar]
  4. Hasker E, Singh SP, Malaviya P, Picado A, Gidwani K, Singh RP, Menten J, Boelaert M, Sundar S, , 2012. Visceral leishmaniasis in rural Bihar, India. Emerg Infect Dis 18: 16621664. [Google Scholar]
  5. Ostyn B, Gidwani K, Khanal B, Picado A, Chappuis F, Singh SP, Rijal S, Sundar S, Boelaert M, , 2011. Incidence of symptomatic and asymptomatic Leishmania donovani infections in high-endemic foci in India and Nepal: a prospective study. PLoS Negl Trop Dis 5: e1284. [Google Scholar]
  6. Singh SP, 2010. The epidemiology of Leishmania donovani infection in high transmission foci in India. Trop Med Int Health 15 (Suppl 2): 1220. [Google Scholar]
  7. Bern C, 2007. The epidemiology of visceral leishmaniasis and asymptomatic leishmanial infection in a highly endemic Bangladeshi village. Am J Trop Med Hyg 76: 909914. [Google Scholar]
  8. Alvar J, Yactayo S, Bern C, , 2006. Leishmaniasis and poverty. Trends Parasitol 22: 552557. [Google Scholar]
  9. Boelaert M, Meheus F, Sanchez A, Singh SP, Vanlerberghe V, Picado A, Meessen B, Sundar S, , 2009. The poorest of the poor: a poverty appraisal of households affected by visceral leishmaniasis in Bihar, India. Trop Med Int Health 14: 639644. [Google Scholar]
  10. Huda MM, 2012. Active case detection in national visceral leishmaniasis elimination programs in Bangladesh, India, and Nepal: feasibility, performance and costs. BMC Public Health 12: 1001. [Google Scholar]
  11. Hirve S, 2010. Effectiveness and feasibility of active and passive case detection in the visceral leishmaniasis elimination initiative in India, Bangladesh, and Nepal. Am J Trop Med Hyg 83: 507511. [Google Scholar]
  12. Singh SP, 2011. Options for active case detection of visceral leishmaniasis in endemic districts of India, Nepal and Bangladesh, comparing yield, feasibility and costs. PLoS Negl Trop Dis 5: e960. [Google Scholar]
  13. WHO, 2010. Control of the Leishmaniases. Available at: http://apps.who.int/iris/bitstream/10665/44412/1/WHO_TRS_949_eng.pdf. Accessed April 24, 2018.
  14. NVBDCP, 2017. Accelerated Plan for Kala Azar Elimination 2017. Available at: http://nvbdcp.gov.in/Doc/Accelerated-Plan-Kala-azar1-Feb2017.pdf. Accessed April 24, 2018.
  15. Malaviya P, Picado A, Hasker E, Ostyn B, Kansal S, Singh RP, Shankar R, Boelaert M, Sundar S, , 2014. Health & demographic surveillance system profile: the Muzaffarpur-TMRC health and demographic surveillance system. Int J Epidemiol 43: 14501457. [Google Scholar]
  16. Cunningham J, 2012. A global comparative evaluation of commercial immunochromatographic rapid diagnostic tests for visceral leishmaniasis. Clin Infect Dis 55: 13121319. [Google Scholar]
  17. Coleman M, 2015. DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India. Proc Natl Acad Sci USA 112: 85738578. [Google Scholar]
  18. Poche D, Garlapati R, Ingenloff K, Remmers J, Poche R, , 2011. Bionomics of Phlebotomine sand flies from three villages in Bihar, India. J Vector Ecol 36 (Suppl 1): S106S117. [Google Scholar]
  19. Perry D, Dixon K, Garlapati R, Gendernalik A, Poche D, Poche R, , 2013. Visceral leishmaniasis prevalence and associated risk factors in the saran district of Bihar, India, from 2009 to July of 2011. Am J Trop Med Hyg 88: 778784. [Google Scholar]

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  • Received : 27 May 2018
  • Accepted : 28 Aug 2018
  • Published online : 08 Oct 2018

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