Number Of Infected Mosquitoes Research Articles

MATHEMATICAL MODEL OF DENGUE CONTROL WITH CONTROL OF MOSQUITO LARVAE AND MOSQUITO AFFECTED BY CLIMATE CHANGE

Consider a SIR model for the spread of dengue hemorrhagic fever involving three populations, mosquito eggs, mosquitoes, and humans. The parameters of the SIR model were estimated using rainfall data and air temperature for the cities of Pekanbaru and Solok. The main aim of this paper is to determine the effect of mosquito larvae and adult mosquito control on the spread of the dengue virus. Numerical solutions were also presented by using the Runge-Kutta method of order 4. Based on the results, the SIR model was obtained by involving the control parameters of mosquito larvae and adult mosquitoes. Besides, the mosquito population is affected by changes in temperature, rainfall, and fog. Numerical simulations illustrate that the number of infected mosquitoes and infected humans is influenced by the parameters of the percentage of mortality of mosquito larvae and adult mosquitoes.

29791 Bird-delivered ivermectin as a novel urban West Nile virus prevention strategy

ABSTRACT IMPACT: Successful implementation of this control strategy will result in a commercially available ivermectin-treated birdfeed that the public can use to protect themselves from infection with West Nile virus (WNV) by reducing mosquito survival and thereby suppressing WNV transmission around their homes. OBJECTIVES/GOALS: We assessed the efficacy and feasibility of ivermectin (IVM)-treated birds as a mosquito control strategy for local reduction of West Nile virus (WNV) transmission. We conducted a randomized field trial in backyard chickens and developed a mathematical model informed by field data to predict the impact of treated wild birds on transmission. METHODS/STUDY POPULATION: We placed 48 chickens in four treated and four untreated control flocks in backyards coops across Davis, CA and administered IVM daily in feed to treated flocks (Jul-Sep 2019). We assessed entomological indices weekly (i.e. Culex mosquito abundance, WNV infection prevalence, and parity rate) around each coop, monitored serum IVM levels in treated chickens, and tested for WNV antibodies in all chickens. Shifting our focus to wild birds, we developed a spatially-implicit mathematical model of WNV transmission near IVM-treated birdfeeders. Model parameters for bird movement were based on our telemetry of 27 birds in Fort Collins, CO (Aug-Sep 2020). Using the model, we predicted optimal deployment of treated feeders to provide local WNV control. RESULTS/ANTICIPATED RESULTS: WNV seroconversions were reduced in treated vs. untreated flocks, indicating a reduction in WNV transmission intensity at treated coops (P = 0.03). A sustained, but insignificant reduction in number of infected mosquitoes was observed near treated coops (P = 0.59); small sample sizes and below normal WNV prevalence in the study area limited our power. We anticipate that optimal spacing and number of IVM-treated birdfeeders required for effective WNV control in neighborhoods will depend on feeder usage rates by common bird species irrespective of WNV competence; broad availability of IVM-treated bloodmeals to mosquitoes will be more effective in reducing transmission than targeting the few species responsible for viral amplification. DISCUSSION/SIGNIFICANCE OF FINDINGS: IVM is a novel method for controlling zoonotic pathogens in the US and has the potential for targeted mosquito control to reduce pesticide usage. Evaluating spatial deployment of IVM-treated bird feed for local reduction in WNV transmission is a stepping stone to commercial deployment of this WNV control strategy.

Two-sex mosquito model for the persistence of Wolbachia

ABSTRACTWe develop and analyse an ordinary differential equation model to investigate the transmission dynamics of releasing Wolbachia-infected mosquitoes to establish an endemic infection in a population of wild uninfected mosquitoes. Wolbachia is a genus of endosymbiotic bacteria that can infect mosquitoes and reduce their ability to transmit some viral mosquito-transmitted diseases, including dengue fever, chikungunya, and Zika. Although the bacterium is transmitted vertically from infected mothers to their offspring, it can be difficult to establish an endemic infection in a wild mosquito population. Our transmission model for the adult and aquatic-stage mosquitoes takes into account Wolbachia-induced fitness change and cytoplasmic incompatibility. We show that, for a wide range of realistic parameter values, the basic reproduction number,, is less than one. Hence, the epidemic will die out if only a few Wolbachia-infected mosquitoes are introduced into the wild population. Even though the basic reproduction number is less than one, an endemic Wolbachia infection can be established if a sufficient number of infected mosquitoes are released. This threshold effect is created by a backward bifurcation with three coexisting equilibria: a stable zero-infection equilibrium, an intermediate-infection unstable endemic equilibrium, and a high-infection stable endemic equilibrium. We analyse the impact of reducing the wild mosquito population before introducing the infected mosquitoes and observed that the most effective approach to establish the infection in the wild is based on reducing mosquitoes in both the adult and aquatic stages.

KENDALI OPTIMAL PADA MODEL DINAMIK EPIDEMI DENGUE MENGGUNAKAN MISER3

Dengue fever is an infectious tropical disease caused by the Dengue virus. Dengue haemorrhagic fever constitute a substantial health burden on world's population. In thisresearch, an application of optimal control theory to Dengue epidemics using MISER3 was presented. The dynamic model is described by a set of nonlinear ordinary differentialequations, that depend on the dynamics of the Dengue mosquito, the number of infected individuals, and people's motivation to combat the mosquito. The cost functional dependsnot only on the costs of medical treatment of the infected people but also on the costs related to educational and sanitation campaigns. We observe that with currentcomputational tools it is easy to obtain, in an efficient way, better solutions to Dengue problems, leading to a decrease in the number of infected mosquitoes and individuals inless time and with lower costs.

Dynamics of Dengue epidemics when using optimal control

We present an application of optimal control theory to Dengue epidemics. This epidemiologic disease is important in tropical countries due to the growing number of infected individuals. The dynamic model is described by a set of nonlinear ordinary differential equations, that depend on the dynamics of the Dengue mosquito, the number of infected individuals, and people’s motivation to combat the mosquito. The cost functional depends not only on the costs of medical treatment of the infected people but also on the costs related to educational and sanitation campaigns. Two approaches for solving the problem are considered: one using optimal control theory, the other carried out by first discretizing the problem and then solving it with nonlinear programming. The results obtained with OC-ODE and IPOPT solvers are given and discussed. We observe that with current computational tools it is easy to obtain, in an efficient way, better solutions to Dengue problems, leading to a decrease in the number of infected mosquitoes and individuals in less time and with lower costs.

Bacteria in midguts of field-collected Anopheles albimanus block Plasmodium vivax sporogonic development.

Bacterial infections were investigated in midguts of insectary and field-collected Anopheles albimanus Weidemann from southern Mexico. Serratia marcescens, Enterobacter cloacae and Enterobacter amnigenus 2, Enterobacter sp., and Serratia sp. were isolated in field samples obtained in 1998, but only Enterobacter sp. was recovered in field samples of 1997 and no bacteria were isolated from insectary specimens. These bacteria were offered along with Plasmodium vivax infected blood to aseptic insectary An. albimanus, and the number of infected mosquitoes as well as the oocyst densities assessed after 7d. Plasmodium vivax infections in mosquitoes co-infected with En. amnigenus 2, En. cloacae, and S. marcensces were 53, 17, and 210 times, respectively, lower than in control mosquitoes, and the mean oocyst density in mosquitoes co-infected with En. cloacae was 2.5 times lower than in controls. Mortality was 13 times higher in S. marcensces-infected mosquitoes compared with controls. The overall midgut bacterial infection in mosquito field populations may influence P. vivax transmission, and could contribute to explain the annual variations in malaria incidence observed in the area.

Bacteria expressing single-chain immunotoxin inhibit malaria parasite development in mosquitoes

Single-chain immunotoxins are ideal tools to selectively kill infectious agents. In applying this technology to block transmission of malaria parasites in the mosquito vector, we have constructed a single-chain immunotoxin composed of a single-chain antibody fragment (scFv) directed to Pbs2l on the surface of Plasmodium berghei ookinetes linked to a lytic peptide, Shiva-1. The single-chain immunotoxin was expressed in Escherichia coli, and the protein was purified by a Ni–NTA column. The single-chain immunotoxin was initially shown to exhibit greater killing properties for P. berghei ookinetes in vitro compared with the scFv or synthetic Shiva-1 peptide alone. In an attempt to block malaria transmission by genetically engineered bacteria, recombinant E. coli harboring the single-chain immunotoxin gene were introduced into the mosquito midgut by membrane feeding. The number of infected mosquitoes and their oocyst densities were significantly reduced when the mosquitoes were subsequently allowed to feed on P. berghei-infected mice. These results indicate not only that a single-chain immunotoxin with enhanced parasiticidal activity could form a basis for the development of more effective malaria therapeutic agents, but also that introduction of genetically engineered bacteria into anopheline mosquitoes may offer a practical approach to the regulation of malaria transmission.

Effect of a Cecropin-like Synthetic Peptide (Shiva-3) on the Sporogonic Development of Plasmodium berghei

The effect of a synthetic cecropin-like peptide, Shiva-3, on in vitro ookinete development and on the early sporogonic stages of Plasmodium berghei in the midgut of Anopheles albimanus was investigated. Peptide concentrations of 75 and 100 μM were effective ( P < 0.05) in reducing ookinete production and the number of infected mosquitoes in almost all experiments. These peptide concentrations in the midgut were not toxic for the survival of the mosquitoes. Complete inhibition was obtained if 100 μM Shiva-3 was applied in the first 8 hr of parasite development. The deleterious effect of the peptide on the parasite was effective after exposure for as short as 50 sec and the permanence of free peptide in the mosquito midgut was estimated to be of a minimum of 5 min. These observations indicate the possibility of using Shiva-like peptide genes to engineering malaria-resistant vectors as an alternative in malaria control strategies.