Effect of indoor residual spraying on sandfly abundance and incidence of visceral leishmaniasis in India, 2016-22: an interrupted time-series analysis and modelling study.
Luc E Coffeng, Sake J de Vlas, Rudra Pratap Singh, Ananthu James, Joy Bindroo, Niteen K Sharma, Asgar Ali, Chandramani Singh, Sadhana Sharma, Michael Coleman
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引用次数: 0
Abstract
Background: Efforts to eliminate visceral leishmaniasis in India mainly consist of early detection and treatment of cases and indoor residual spraying with insecticides to kill the phlebotomine sandfly Phlebotomus argentipes that transmits the causative Leishmania protozoa. In this modelling study, we aimed to estimate the effect of indoor residual spraying (IRS) on vector abundance and transmission of visceral leishmaniasis in India.
Methods: In this time-series analysis and modelling study, we assessed the effect of IRS on vector abundance by using indoor vector-abundance data (from 2016 to 2022) and IRS quality-assurance data (from 2017-20) from 50 villages in eight endemic blocks in India where IRS was implemented programmatically. To assess a potential dose-response relation between insecticide concentrations and changes in sandfly abundance, we examined the correlation between site-level insecticide concentrations and the site-level data for monthly sandfly abundances. We used mathematical modelling to link vector data to visceral leishmaniasis case numbers from the national Kala-Azar Management Information System registry (2013-21), and to predict the effect of IRS on numbers of averted cases and deaths.
Findings: IRS was estimated to reduce indoor sandfly abundance by 27% (95% CI 20-34). Concentrations of insecticides on walls were significantly-but weakly-associated with the degree of reduction in vector abundance, with a reduction of -0·0023 (95% CI -0·0040 to -0·0007) sandflies per mg/m2 insecticide (p=0·0057). Reported case numbers of visceral leishmaniasis were well explained by trends in vector abundance. Village-wide IRS in response to a newly detected case of visceral leishmaniasis was predicted to reduce disease incidence by 6-40% depending on the presumed reduction in vector abundance modelled.
Interpretation: Indoor residual spraying has substantially reduced sandfly abundance in India, which has contributed to reductions in visceral leishmaniasis and related deaths. To prevent the re-emergence of visceral leishmaniasis as a public health problem, surveillance of transmission and sandfly abundance is warranted.
Funding: Bill & Melinda Gates Foundation.
Translation: For the Hindi translation of the abstract see Supplementary Materials section.
期刊介绍:
The Lancet Infectious Diseases was launched in August, 2001, and is a lively monthly journal of original research, review, opinion, and news covering international issues relevant to clinical infectious diseases specialists worldwide.The infectious diseases journal aims to be a world-leading publication, featuring original research that advocates change or sheds light on clinical practices related to infectious diseases. The journal prioritizes articles with the potential to impact clinical practice or influence perspectives. Content covers a wide range of topics, including anti-infective therapy and immunization, bacterial, viral, fungal, and parasitic infections, emerging infectious diseases, HIV/AIDS, malaria, tuberculosis, mycobacterial infections, infection control, infectious diseases epidemiology, neglected tropical diseases, and travel medicine. Informative reviews on any subject linked to infectious diseases and human health are also welcomed.