Models of effectiveness of interventions against malaria transmitted by Anopheles albimanus

Abstract

Background Most impact prediction of malaria vector control interventions has been based on African vectors. Anopheles albimanus , the main vector in Central America and the Caribbean, has higher intrinsic mortality, is more zoophilic and less likely to rest indoors. Therefore, relative impact among interventions may be different. Prioritizing interventions, in particular for eliminating Plasmodium falciparum from Haiti, should consider local vector characteristics. Methods Field bionomics data of An. albimanus from Hispaniola and intervention effect data from southern Mexico were used to parameterize mathematical malaria models. Indoor residual spraying (IRS), insecticide-treated nets (ITNs), and house-screening were analysed by inferring their impact on the vectorial capacity in a difference-equation model. Impact of larval source management (LSM) was assumed linear with coverage. Case management, mass drug administration and vaccination were evaluated by estimating their effects on transmission in a susceptible-infected-susceptible model. Analogous analyses were done for Anopheles gambiae parameterized with data from Tanzania, Benin and Nigeria. Results While LSM was equally effective against both vectors, impact of ITNs on transmission by An. albimanus was much lower than for An. gambiae . Assuming that people are outside until bedtime, this was similar for the impact of IRS with dichlorodiphenyltrichloroethane (DDT) or bendiocarb, and impact of IRS was less than that of ITNs. However, assuming people go inside when biting starts, IRS had more impact on An. albimanus than ITNs. While house-screening had less impact than ITNs or IRS on An. gambiae , it had more impact on An. albimanus than ITNs or IRS. The impacts of chemoprevention and chemotherapy were comparable in magnitude to those of strategies against An. albimanus . Chemo-prevention impact increased steeply as coverage approached 100%, whilst clinical-case management impact saturated because of remaining asymptomatic infections. Conclusions House-screening and repellent IRS are potentially highly effective against An. albimanus if people are indoors during the evening. This is consistent with historical impacts of IRS with DDT, which can be largely attributed to excito-repellency. It also supports the idea that housing improvements have played a critical role in malaria control in North America. For elimination planning, impact estimates need to be combined with feasibility and cost-analysis. Electronic supplementary material The online version of this article (10.1186/s12936-019-2899-3) contains supplementary material, which is a...

Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity

“…The parameterization of the model for predicting impacts on VC of pyrethroid sensitive An. gambiae is described in detail elsewhere [15]. House entry depends on insecticide content (but not on the integrity of the LLINs).…”

“…A discrete-time mathematical model of malaria in mosquitoes [14] was used to make predictions of the impact of a LLIN on VC of the mosquito population as a function of the standardized active ingredient content, and the holed area of the LLIN. Previously published parameters were used to obtain estimates of VC from a model of the feeding cycle for Anopheles gambiae sensu stricto (s.s.) in the absence of intervention [15,16]. This model captures the reduction in VC by LLINs as increases in mortality at different stages of the feeding cycle and extension of the duration of the cycle as a result of deterrence.…”

“…The variance component analysis was carried out using a restricted maximum likelihood (REML) algorithm in the R variance component analysis (VCA) package. The mathematical model of Chitnis et al [14] was implemented in R as described previously [15].…”

Effects of seasonality and land use on the diversity, relative abundance, and distribution of mosquitoes on St. Kitts, West Indies

“…Aedes aegypti was the only species to be captured during every trapping month. Only four Anopheles albimanus , the main vector of malaria in the Caribbean [ 43 ], were caught across the entire survey period. Finally, due to specimen damage during capture and transport to the laboratory, a small proportion of Aedes spp.…”

Risk Factors for Malaria Infection and Seropositivity in the Elimination Area of Grand’Anse, Haiti: A Case–Control Study among Febrile Individuals Seeking Treatment at Public Health Facilities

“…albimanus bites, whereas house screening could be a very effective intervention in Grand'Anse if people are inside during peak biting periods. 35 Entomological data collected in the current case-control study describing indoor and outdoor vector density and blood meal analysis will be detailed in a separate publication (Joseph et al, in preparation).…”