Vector control by insecticide‐treated nets in the fight against visceral leishmaniasis in the Indian subcontinent, what is the evidence?

Ostyn, Bart; Vanlerberghe, Veerle; Picado, Albert; Dinesh, Diwakar Singh; Sundar, Shyam; Chappuis, François; Rijal, Suman; Dujardin, Jean‐Claude; Coosemans, Marc; Boelaert, Marleen; Davies, Clive R.

doi:10.1111/j.1365-3156.2008.02110.x

Cited by 71 publications

(94 citation statements)

References 50 publications

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“…It has been demonstrated historically in Bangladesh, India, and Nepal that IRS, but not long-lasting insecticide nets, is effective in reducing P. argentipes populations, and that this IRS subsequently reduces the number of cases of VL (8,9,14). This finding is also supported by recent collections of P. argentipes outdoors and associated with cattle sheds using CDC light traps (32), where a large proportion of the sand flies had fed on humans, suggesting endophilic and exophagic behaviors (32,33).…”

Section: Discussionmentioning

confidence: 99%

“…Although the current data on sand fly resistance are limited, a review of resistance in the region clearly shows that DDT resistance in sand flies has been regularly reported in India since the 1990s (8). There are also sporadic reports of low levels of deltamethrin resistance in sand flies; however, because none of the studies applied the same standardized protocol, it is difficult to map overall trends in resistance prevalence.…”

Section: Significancementioning

confidence: 99%

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DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India

Coleman

Foster

Deb

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Indoor residual spraying (IRS) is used to control visceral leishmaniasis (VL) in India, but it is poorly quality assured. Quality assurance was performed in eight VL endemic districts in Bihar State, India, in 2014. Residual dichlorodiphenyltrichloroethane (DDT) was sampled from walls using Bostik tape discs, and DDT concentrations [grams of active ingredient per square meter (g ai/m 2 )] were determined using HPLC. Pre-IRS surveys were performed in three districts, and post-IRS surveys were performed in eight districts. A 20% threshold above and below the target spray of 1.0 g ai/m 2 was defined as "in range." The entomological assessments were made in four districts in IRS and non-IRS villages. Vector densities were measured: pre-IRS and 1 and 3 mo post-IRS. Insecticide susceptibility to 4% DDT and 0.05% deltamethrin WHO-impregnated papers was determined with wild-caught sand flies. The majority (329 of 360, 91.3%) of pre-IRS samples had residual DDT concentrations of <0.1 g ai/m 2 . The mean residual concentration of DDT post-IRS was 0.37 g ai/m 2 ; 84.9% of walls were undersprayed, 7.4% were sprayed in range, and 7.6% were oversprayed. The abundance of sand flies in IRS and non-IRS villages was significantly different at 1 mo post-IRS only. Sand flies were highly resistant to DDT but susceptible to deltamethrin. The Stockholm Convention, ratified by India in 2006, calls for the complete phasing out of DDT as soon as practical, with limited use in the interim where no viable IRS alternatives exist. Given the poor quality of the DDT-based IRS, ready availability of pyrethroids, and susceptibility profile of Indian sand flies, the continued use of DDT in this IRS program is questionable.leishmaniasis | elimination |

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Section: Discussionmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India

Coleman

Foster

Deb

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…The potential of insecticide-treated nets (ITNs) to control leishmaniasis has recently been reviewed (Ostyn et al 2008). There are no published studies of ITNs as an intervention against ZVL, though some efficacy against AVL in Sudan has been demonstrated (Ritmeijer et al 2007).…”

Section: Insecticide-treated Netsmentioning

confidence: 99%

Transmission, reservoir hosts and control of zoonotic visceral leishmaniasis

2009

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S U M M A R YZoonotic visceral leishmaniasis (ZVL) caused by Leishmania infantum is an important disease of humans and dogs. Here we review aspects of the transmission and control of ZVL. Whilst there is clear evidence that ZVL is maintained by sandfly transmission, transmission may also occur by non-sandfly routes, such as congenital and sexual transmission. Dogs are the only confirmed primary reservoir of infection. Meta-analysis of dog studies confirms that infectiousness is higher in symptomatic infection ; infectiousness is also higher in European than South American studies. A high prevalence of infection has been reported from an increasing number of domestic and wild mammals ; updated host ranges are provided. The crab-eating fox Cerdocyon thous, opossums Didelphis spp., domestic cat Felis cattus, black rat Rattus rattus and humans can infect sandflies, but confirmation of these hosts as primary or secondary reservoirs requires further xenodiagnosis studies at the population level. Thus the putative sylvatic reservoir(s) of ZVL remains unknown. Review of intervention studies examining the effectiveness of current control methods highlights the lack of randomized controlled trials of both dog culling and residual insecticide spraying. Topical insecticides (deltamethrin-impregnated collars and pour-ons) have been shown to provide a high level of individual protection to treated dogs, but further community-level studies are needed.

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“…Indoor Residual Spraying (IRS) Vector control by IRS using DDT or pyrethroid insecticides is a key component of national VL control campaigns, with mixed success in reducing infection incidence via purposeful IRS against Leishmania vectors, or as a benefit of the spraying campaigns against malaria vectors (Alexander and Maroli, 2003;Ostyn et al, 2008). IRS is effective against adult vectors that blood-feed indoors (endophagic) or rest indoors between blood-feeding and searching for an oviposition site (endophilic).…”

Section: Vector Controlmentioning

confidence: 99%

Progress in the Mathematical Modelling of Visceral Leishmaniasis

Rock¹,

Quinnell²,

Medley³

et al. 2016

Advances in Parasitology

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The leishmaniases comprise a complex of diseases characterised by clinical outcomes that range from self-limiting to chronic, disfiguring and stigmatising, to life-threatening. Diagnostic methods, treatments, and vector and reservoir control options exist, but deciding the most effective interventions requires a quantitative understanding of the population level infection and disease dynamics. The effectiveness of any set of interventions has to be determined within the context of operational conditions, including economic and political commitment. Mathematical models are the best available tools for studying quantitative systems crossing disciplinary spheres (biology, medicine, economics) within environmental and societal constraints.In 2005, the World Health Assembly and government health ministers of India, Nepal, and Bangladesh signed a Memorandum of Understanding to eliminate the life threatening form of leishmaniasis, visceral leishmaniasis (VL), on the Indian subcontinent by 2015 through a combination of early case detection, improved treatments, and vector control. The elimination target is <1/10,000 population at the district or subdistrict level compared to the current 20/10,000 in the regions of highest transmission.Towards this goal, this chapter focuses on mathematical models of VL, and the biology driving those models, to enable realistic predictions of the * Corresponding author Email address: orin.courtenay@warwick.ac.uk (Orin Courtenay)Preprint submitted to Advances in Parasitology July 18, 2016 best combination of interventions. Several key issues will be discussed which have affected previous modelling of VL and the direction future modelling may take. Current understanding of the natural history of disease, immunity (and loss of immunity), as well as stages of infection and their durations are considered particularly for humans, but also for dogs. Asymptomatic and clinical infection are discussed in the context of their relative roles in Leishmania transmission, as well as key components of the parasite-sandfly-vector interaction and intervention strategies including diagnosis, treatment and vector control. Gaps in current biological knowledge and potential avenues to improve model structures and mathematical predictions are identified. Underpinning the marriage between biology and mathematical modelling, the content of this chapter represents the first step towards developing the next generation of models for VL.

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Vector control by insecticide‐treated nets in the fight against visceral leishmaniasis in the Indian subcontinent, what is the evidence?

Cited by 71 publications

References 50 publications

DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India

DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India

Transmission, reservoir hosts and control of zoonotic visceral leishmaniasis

Progress in the Mathematical Modelling of Visceral Leishmaniasis

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