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Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme

Deb, Rinki, Singh, Rudra, Mishra, Prabhas Kumar, Hitchins, Lisa, Reid, Emma, Barwa, Arti Manorama, Patra, Debanjan, Das, Chandrima, Sukla, Indranil, Srivastava, Ashish Kumar, Raj, Shilpa, Mishra, Swikruti, Swain, Madhuri, Mondal, Swapna, Mandal, Udita, Foster, Geraldine ORCID: https://orcid.org/0000-0002-9769-4349, Trett, Anna, Garrod, Gala, McKenzie, Laura, Ali, Asgar, Morchan, Karthick, Chaudhuri, Indrajit, Roy, Nupur, Gill, Naresh K, Singh, Chandramani, Agarwal, Neeraj, Sharma, Sadhana, Stanton, Michelle ORCID: https://orcid.org/0000-0002-1754-4894, Hemingway, Janet ORCID: https://orcid.org/0000-0002-3200-7173, Srikantiah, Sridhar and Coleman, Michael ORCID: https://orcid.org/0000-0003-4186-3526 (2021) 'Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme'. PLoS Neglected Tropical Diseases, Vol 15, Issue 8, e0009101.

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Abstract

BACKGROUND
In 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.

METHODS
Eight 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.

RESULTS
Complete 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.

CONCLUSION
Through 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.

Item Type: Article
Subjects: WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases
WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries
WA Public Health > Health Administration and Organization > WA 540 National and state health administration
WA Public Health > Sanitation. Environmental Control > General Sanitation and Environmental Control > WA 670 General works
WA Public Health > Housing. Buildings. Public Facilities > WA 795 Housing
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 715 Visceral leishmaniasis
WR Dermatology > Parasitic Skin Diseases > WR 350 Tropical diseases of the skin. Mucocutaneous leishmaniasis. Leishmaniasis
Faculty: Department: Biological Sciences > Vector Biology Department
Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI): https://doi.org/10.1371/journal.pntd.0009101
Depositing User: Mel Finley
Date Deposited: 12 Aug 2021 09:40
Last Modified: 12 Aug 2021 09:40
URI: https://archive.lstmed.ac.uk/id/eprint/18623

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