Seasonal Variation in the Prevalence of Sand Flies Infected with Leishmania donovani

Abstract

BackgroundVisceral Leishmaniasis (VL) is a life threatening neglected infectious disease in the Indian subcontinent, transmitted by the bite of female sand flies. Estimation of the infectivity in the vector population, collected in different seasons, may be useful to better understanding the transmission dynamics of VL as well as to plan vector control measures.MethodologyWe collected sand flies from highly endemic regions of Bihar state, India for one year over three seasons. The species of the sand flies were confirmed by species-specific PCR-RFLP. Leishmania donovani infection was investigated in 1397 female Phlebotomus argentipes using PCR, targeting the Leishmania specific minicircle of the kDNA region. Further, the parasitic load in the infected sand flies was measured using quantitative PCR.ConclusionThough sand flies were most abundant in the rainy season, the highest rate of infection was detected in the winter season with 2.84% sand flies infected followed by the summer and rainy seasons respectively. This study can help in vector elimination programmes and to reduce disease transmission.

Temporal distribution and behaviour of sand flies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus of the Kani Tribe settlements in the Western Ghats, India

“…Dhanda and Modi (1971) from Aurangabad district, Maharashtra and Joseph (1981) from Kala azar affected areas of northern districts of Bihar and Tiwary et al (2013) from VL endemic areas of Muzaffarpur in Bihar, India substantiated that sand flies were abundant with a single peak in monsoon month of October. In the present investigation, sand flies including P. argentipes were found prevalent throughout the year, with two peaks, a minor peak in June/July which was in the south-west monsoon period and a major peak in October, in northeast monsoon season, where there was no winter season, however, the month the period between December and February were relatively cooler in this region.…”

Progress in the Mathematical Modelling of Visceral Leishmaniasis

“…Similarly, on the ISC, Picado et al (2010a) argue that IRS should be carried out in Feb/March and August/September based on seasonal patterns observed in their sandfly density studies in India and Nepal. However a study in Bihar, India which examined sandfly infection as well as density found that whilst abundance was highest during August/September, prevalence in sandflies was greatest in November/December (Tiwary et al, 2013). Such results warrant further investigation into the seasonality in all endemic regions, especially when planning the timing of vector interventions such as IRS.…”

Risk of vector‐borne diseases for the EU: Entomological aspects – Part 1

“…were 1.0 % (4/384) in summer 0.8 % (5/591) in the rainy season, and 2.8 % (12/422) in winter (Tiwary, Kumar et al 2013 (Guimaraes, Costa et al 2014). …”