Abstract
The elimination of infectious diseases requires reducing transmission below a certain threshold. The Visceral Leishmaniasis (VL) Elimination Initiative in Southeast Asia aims to reduce the annual VL incidence rate below 1 case per 10,000 inhabitants in endemic areas by 2015 via a combination of case management and vector control. Using a previously developed VL transmission model, we investigated transmission thresholds dependent on measures reducing the sand fly density either by killing sand flies (e.g., indoor residual spraying and long-lasting insecticidal nets) or by destroying breeding sites (e.g., environmental management).Model simulations suggest that elimination of VL is possible if the sand fly density can be reduced by 67% through killing sand flies, or if the number of breeding sites can be reduced by more than 79% through measures of environmental management.These results were compared to data from two recent cluster randomised controlled trials conducted in India, Nepal and Bangladesh showing a 72% reduction in sand fly density after indoor residual spraying, a 44% and 25% reduction through the use of long-lasting insecticidal nets and a 42% reduction after environmental management.Based on model predictions, we identified the parameters within the transmission cycle of VL that predominantly determine the prospects of intervention success. We suggest further research to refine model-based predictions into the elimination of VL.
Highlights
Visceral leishmaniasis (VL), known as Kala-azar, is a vector-borne parasitic disease that almost always ends in death if untreated [1]
The basic reproduction number of VL under the conditions observed in the KALANET project without any vector control measures was estimated as R0 = 4.71 ( = median pre-study R0)
A reduction of sand fly density by reducing the sand flies’ longevity has a different effect on Re than a reduction by means of breeding site control, even if both measures lead to the same sand fly density: N If the sand flies’ life expectancy is reduced, our analyses suggest that elimination can be achieved by reducing the sand fly density by 67%, which is a reduction of approximately twothirds
Summary
Visceral leishmaniasis (VL), known as Kala-azar, is a vector-borne parasitic disease that almost always ends in death if untreated [1]. Leishmania chagasi/ infantum in the New or parts of the Old World or Leishmania donovani in other regions of the Old World, occurs through the bite of an infected sand fly and leads to a spectrum of outcomes ranging from asymptomatic infection to active disease. In the latter case, progressive clinical manifestations, including prolonged fever, weight loss, hepatosplenomegaly and anaemia, result in suppressed immune responses and death [2]. There, VL is caused by L. donovani and transmitted by the female sand fly Phlebotomus argentipes in an anthroponotic cycle [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
