Newer Approaches for Malaria Vector Control and Challenges of Outdoor Transmission

The effective and reliable management of malaria vectors is still a global challenge. Recently, it has been noted that the first vaccine against Plasmodium falciparum malaria, RTS,S/AS01 showed only transient protection, particularly in infants, and rapid resistance has been developing to artemisinin-based drugs. Therefore, the control of malaria mosquito vectors according to strategies of integrated vector management (IVM) is receiving emphasis. A rather wide number of novel mosquito control tools have been tested, including attractive toxic sugar baits, eave tubes, nano-synthesized pesticides loaded with microbial- and plant-borne compounds, biocontrol agents with little non-target effects, new adult repellents, oviposition deterrents, and even acoustic larvicides. However, their real-world applications remain limited. Most National Malaria Control Programs in Africa still rely on indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) to reduce malaria incidence but generally have insufficient impact on malaria prevalence. Here, we focus on facts, trends, and current challenges in the employment of the above-mentioned vector control tools in the fight against malaria. We emphasize the needs for better vector control tools used in IVM to overcome the challenges posed by outdoor transmission and growing levels of insecticide resistance, which are threatening the efficacy of LLINs and IRS

Invasion, establishment, and spread of invasive mosquitoes from the Culex coronator complex in urban areas of Miami-Dade County, Florida

Species from the Culex coronator complex are Neotropical species and potential vectors of Saint Louis and West Nile viruses. Culex coronator was first described in Trinidad and Tobago in the early twentieth century and since then it has invaded and has been reported established in most countries of the Americas. Species from the Culex coronator complex were first detected in the United States in the state of Louisiana in 2004 and were subsequently detected in Florida in 2005, reaching Miami-Dade County in 2008. We hypothesize that species from the Cx. coronator complex are adapting to urban environments in Miami-Dade County, Florida, and are becoming more present and abundant in these areas. Therefore, our objective was to investigate the patterns of the presence and abundance of species from the Cx. coronator complex in the urban areas of Miami-Dade County. Here we used weekly data comprised of 32 CDC traps from 2012 to 2020 and 150 BG-Sentinel traps from 2016 to 2020. A total of 34,146 female mosquitoes from the Cx. coronator complex were collected, 26,138 by CDC traps and 8008 by BG-Sentinel traps. While the number of CDC traps that were positive was relatively constant at 26–30 positive traps per year, the number of positive BG-Sentinel traps varied substantially from 50 to 87 positive traps per year. Furthermore, the heat map and logistic general linear model for repeated measures analyses showed a significant increase in both the distribution and abundance of mosquitoes from the Cx. coronator complex, indicating that these species are becoming more common in anthropized habitats being able to thrive in highly urbanized areas. The increase in the distribution and abundance of species from the Cx. coronator complex is a major public health concern. The ability of species from the Cx. coronator complex to benefit from urbanization highlights the need to better understand the mechanisms of how invasive vector mosquito species are adapting and exploiting urban habitats

Urbanization favors the proliferation of Aedes aegypti and Culex quinquefasciatus in urban areas of Miami-Dade County, Florida

Urbanization processes are increasing globally. Anthropogenic alterations in the environment have profound effects on biodiversity. Decreased biodiversity due to biotic homogenization processes as a consequence of urbanization often result in increased levels of mosquito vector species and vector-borne pathogen transmission. Understanding how anthropogenic alterations in the environment will affect the abundance, richness, and composition of vector mosquito species is crucial for the implementation of effective and targeted mosquito control strategies. We hypothesized that anthropogenic alterations in the environment are responsible for increasing the abundance of mosquito species that are adapted to urban environments such as Aedesaegypti and Culexquinquefasciatus. Therefore, our objective was to survey mosquito relative abundance, richness, and community composition in Miami-Dade County, Florida, in areas with different levels of urbanization. We selected 24 areas, 16 remote areas comprised of natural and rural areas, and 8 urban areas comprised of residential and touristic areas in Miami-Dade County, Florida. Mosquitoes were collected weekly in each area for 24 h for 5 consecutive weeks from August to October 2020 using BG-Sentinel traps baited with dry ice. A total of 36,645 mosquitoes were collected, from which 34,048 were collected in the remote areas and 2,597 in the urban areas. Our results show a clear and well-defined pattern of abundance, richness, and community composition according to anthropogenic modifications in land use and land cover. The more urbanized a given area the fewer species were found and those were primary vectors of arboviruses, Ae.aegypti and Cx.quinquefasciatus

Anthropogenic changes and associated impacts on vector-borne diseases

Urbanization impacts the community composition, abundance, and richness of mosquitoes. As urbanization processes increase globally, it is important to better understand the biodiversity loss caused by anthropogenic changes and associated impacts on vector-borne diseases. Mosquito surveillance and control are key for reducing the risk of mosquito-borne pathogen transmission

Increasing Complexity Threatens the Elimination of Extra-Amazonian Malaria in Brazil

Extra-Amazonian malaria has been reported to be endemic in Brazil since the end of the 19th century. Currently, only a few cases are reported annually. However, recent findings of unexpected Plasmodium infections with uncertain transmission cycles in the Extra-Amazonian region could pose a threat to the malaria elimination agenda in Brazil

Impact of population displacement and forced movements on the transmission and outbreaks of Aedes-borne viral diseases: Dengue as a model

[Display omitted] •Population displacement and forced human movements impact the spatiotemporal epidemiology of dengue.•Risk mapping of transmission “hotspots” in displacement settings is needed for better multi-sectoral prevention and control.•Phylogenetic analysis of virus isolates in outbreaks is needed to understand the impact of dengue in displacement settings.•The changing landscape of how displaced populations are infected with dengue is challenging to public health policymakers. Population displacement and other forced movement patterns following natural disasters, armed conflicts or due to socioeconomic reasons contribute to the global emergence of Aedes-borne viral disease epidemics. In particular, dengue epidemiology is critically affected by situations of displacement and forced movement patterns, particularly within and across borders. In this respect, waves of human movements have been a major driver for the changing epidemiology and outbreaks of the disease on local, regional and global scales. Both emerging dengue autochthonous transmission and outbreaks in countries known to be non-endemic and co-circulation and hyperendemicity with multiple dengue virus serotypes have led to the emergence of severe disease forms such as dengue hemorrhagic fever and dengue shock syndrome. This paper reviews the emergence of dengue outbreaks driven by population displacement and forced movements following natural disasters and conflicts within the context of regional and sub-regional groupings

A molecular surveillance-guided vector control response to concurrent dengue and West Nile virus outbreaks in a COVID-19 hotspot of Florida

Simultaneous dengue virus (DENV) and West Nile virus (WNV) outbreaks in Florida, USA, in 2020 resulted in 71 dengue virus serotype 1 and 86 WNV human cases. We hypothesized that we would find a number of DENV-1 positive mosquito pools, and that the distribution of these arbovirus-positive mosquito pools would be associated with those neighborhoods for which imported DENV cases have been recently reported in 2019 and 2020. We collected and screened Aedes aegypti, Ae. albopictus, Anopheles crucians, Culex coronator, Cx. nigripalpus, and Cx. quinquefasciatus mosquitoes from Miami-Dade County (Florida) for DENV and WNV by rRT-qPCR. Spatial statistical analyses were performed to capture positive mosquito pool distribution in relation to land use, human demography, environmental variables, mosquito trap placement and reported human travel associated DENV cases to guide future mosquito control outbreak responses. A rapid screen of 7,668 mosquitoes detected four DENV serotype 2 (DENV-2), nine DENV-4 and nine WNV-positive mosquito pools, which enabled swift and targeted abatement of trap sites by mosquito control. As expected, DENV-positive pools were in urban areas; however, we found WNV-positive mosquito pools in agricultural and recreational areas with no historical reports of WNV transmission. These findings demonstrate the importance of proactive arbovirus surveillance in mosquito populations to prevent and control outbreaks, particularly when other illnesses (e.g., COVID-19), which present with similar symptoms, are circulating concurrently. Growing evidence for substantial infection prevalence of dengue in mosquitoes in the absence of local index cases suggests a higher level of dengue endemicity in Florida than previously thought. This research was supported in part by U.S. Centers for Disease Control and Prevention (CDC) grant 1U01CK000510-03, Southeastern Regional Center of Excellence in Vector Borne Diseases Gateway Program