TY - JOUR
T1 - Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme
AU - Deb, Rinki
AU - Singh, Rudra
AU - Mishra, Prabhas Kumar
AU - Hitchins, Lisa
AU - Reid, Emma
AU - Barwa, Arti Manorama
AU - Patra, Debanjan
AU - Das, Chandrima
AU - Sukla, Indranil
AU - Srivastava, Ashish Kumar
AU - Raj, Shilpa
AU - Mishra, Swikruti
AU - Swain, Madhuri
AU - Mondal, Swapna
AU - Mandal, Udita
AU - Foster, Geraldine
AU - Trett, Anna
AU - Garrod, Gala
AU - McKenzie, Laura
AU - Ali, Asgar
AU - Morchan, Karthick
AU - Chaudhuri, Indrajit
AU - Roy, Nupur
AU - Gill, Naresh K.
AU - Singh, Chandramani
AU - Agarwal, Neeraj
AU - Sharma, Sadhana
AU - Stanton, Michelle
AU - Hemingway, Janet
AU - Srikantiah, Sridhar
AU - Coleman, Michael
PY - 2021/8/9
Y1 - 2021/8/9
N2 - BACKGROUNDIn 2005, Bangladesh, India and Nepal agreed to eliminate visceral leishmaniasis (VL) as a public health problem. The approach to this was through improved case detection and treatment, and controlling transmission by the sand fly vector Phlebotomus argentipes, with indoor residual spraying (IRS) of insecticide. Initially, India applied DDT with stirrup pumps for IRS, however, this did not reduce transmission. After 2015 onwards, the pyrethroid alpha-cypermethrin was applied with compression pumps, and entomological surveillance was initiated in 2016.METHODSEight sentinel sites were established in the Indian states of Bihar, Jharkhand and West Bengal. IRS coverage was monitored by household survey, quality of insecticide application was measured by HPLC, presence and abundance of the VL vector was monitored by CDC light traps, insecticide resistance was measured with WHO diagnostic assays and case incidence was determined from the VL case register KAMIS.RESULTSComplete treatment of houses with IRS increased across all sites from 57% in 2016 to 70% of houses in 2019, rising to >80% if partial house IRS coverage is included (except West Bengal). The quality of insecticide application has improved compared to previous studies, average doses of insecticide on filters papers ranged from 1.52 times the target dose of 25mg/m2 alpha-cypermethrin in 2019 to 1.67 times in 2018. Resistance to DDT has continued to increase, but the vector was not resistant to carbamates, organophosphates or pyrethroids. The annual and seasonal abundance of P. argentipes declined between 2016 to 2019 with an overall infection rate of 0.03%. This was associated with a decline in VL incidence for the blocks represented by the sentinel sites from 1.16 per 10,000 population in 2016 to 0.51 per 10,000 in 2019.CONCLUSIONThrough effective case detection and management reducing the infection reservoirs for P. argentipes in the human population combined with IRS keeping P. argentipes abundance and infectivity low has reduced VL transmission. This combination of effective case management and vector control has now brought India within reach of the VL elimination targets.
AB - BACKGROUNDIn 2005, Bangladesh, India and Nepal agreed to eliminate visceral leishmaniasis (VL) as a public health problem. The approach to this was through improved case detection and treatment, and controlling transmission by the sand fly vector Phlebotomus argentipes, with indoor residual spraying (IRS) of insecticide. Initially, India applied DDT with stirrup pumps for IRS, however, this did not reduce transmission. After 2015 onwards, the pyrethroid alpha-cypermethrin was applied with compression pumps, and entomological surveillance was initiated in 2016.METHODSEight sentinel sites were established in the Indian states of Bihar, Jharkhand and West Bengal. IRS coverage was monitored by household survey, quality of insecticide application was measured by HPLC, presence and abundance of the VL vector was monitored by CDC light traps, insecticide resistance was measured with WHO diagnostic assays and case incidence was determined from the VL case register KAMIS.RESULTSComplete treatment of houses with IRS increased across all sites from 57% in 2016 to 70% of houses in 2019, rising to >80% if partial house IRS coverage is included (except West Bengal). The quality of insecticide application has improved compared to previous studies, average doses of insecticide on filters papers ranged from 1.52 times the target dose of 25mg/m2 alpha-cypermethrin in 2019 to 1.67 times in 2018. Resistance to DDT has continued to increase, but the vector was not resistant to carbamates, organophosphates or pyrethroids. The annual and seasonal abundance of P. argentipes declined between 2016 to 2019 with an overall infection rate of 0.03%. This was associated with a decline in VL incidence for the blocks represented by the sentinel sites from 1.16 per 10,000 population in 2016 to 0.51 per 10,000 in 2019.CONCLUSIONThrough effective case detection and management reducing the infection reservoirs for P. argentipes in the human population combined with IRS keeping P. argentipes abundance and infectivity low has reduced VL transmission. This combination of effective case management and vector control has now brought India within reach of the VL elimination targets.
U2 - 10.1371/journal.pntd.0009101
DO - 10.1371/journal.pntd.0009101
M3 - Article
SN - 1935-2727
VL - 15
SP - e0009101
JO - PLoS Neglected Tropical Diseases
JF - PLoS Neglected Tropical Diseases
IS - 8
M1 - e0009101
ER -
