GAINESVILLE – In the battle against vector borne disease, mosquito control using insecticides is an essential tool. But what happens when that tool starts to fail, and how do you know it? Insecticides are regularly used by public health agencies to reduce populations of blood-sucking mosquitoes. Effective control programs are important to public health because, in addition to posing a nuisance, mosquitoes can also spread diseases to humans. Insecticide resistance, where mosquitoes adapt to survive exposure to commonly-used chemicals, has become an increasingly pressing issue for many health agencies, undermining mosquito control efforts. New research by the Quantitative Disease Ecology and Conservation (QDEC) Lab Group at the University of Florida, the Center for Research on Health in Latin America (CISeAL) at Pontificia Universidad Católica del Ecuador (PUCE), the Institute for Global Health and Translational Science at SUNY Upstate Medical University, Escuela Superior Politécnica del Litoral (ESPOL), and the Universidad Técnica de Machala is the first attempt to investigate seasonal and geographic variations of mosquito insecticide resistance in southern coastal Ecuador, a region where mosquito control is key to stopping the spread of serious diseases like Zika and dengue fever. The study was funded by the U.S. Centers for Disease Control and Prevention (CDC). The team of researchers used both genetic screening and pesticide assays to evaluate insecticide resistance in mosquitoes collected in urban locations at different seasons. Differences in the resistance status of mosquitoes to the insecticides commonly used by the local health ministry were found both across collection seasons and across the four cities in the study area. Detected resistance to Malathion, deltamethrin, and alpha-cypermethrin was particularly high in the port city of Machala, which has a long history of dengue outbreaks and insecticide use. Information on insecticide resistance status, patterns, and timing will help local public health professionals design sustainable mosquito control programs that will continue to be effective in the fight against disease.

Read Seasonal and geographic variation in insecticide resistance in Aedes aegypti in southern Ecuador, at PLoS Neglected Tropical Diseases.

La Resistencia a los Insecticidas Amenaza el Control de las Enfermedades Transmitidas por Mosquitos en Ecuador

GAINESVILLE – En la batalla contra las enfermedades transmitidas por vectores, el uso de insecticidas para el control de mosquito es una herramienta esencial. Pero ¿qué sucede cuando esa herramienta comienza a fallar y cómo lo sabe? Las agencias de salud pública utilizan regularmente los insecticidas para reducir las poblaciones de mosquitos que chupan la sangre. Los programas de control efectivos son importantes para la salud pública porque, además de ser una molestia, los mosquitos también pueden transmitir enfermedades a los humanos. La resistencia hacia los insecticidas, donde los mosquitos se adaptan para sobrevivir a la exposición a sustancias químicas de uso común, se ha convertido en un problema cada vez más urgente para muchas agencias de salud, desfavoreciendo los esfuerzos de control de mosquitos. Una nueva investigación realizada por el Grupo de Laboratorios de Ecología y Conservación de Enfermedades Cuantitativas (QDEC) en la Universidad de Florida, el Centro de Investigación para la Salud en América Latina (CISeAL) en la Pontificia Universidad Católica del Ecuador (PUCE), el Instituto de Salud Global y la Ciencia Traslacional en la Universidad Médica del Estado de SUNY, la Escuela Superior Politécnica del Litoral (ESPOL), y la Universidad Técnica de Machala es el primer intento en investigar las variaciones estacionales y geográficas sobre resistencia a insecticidas en mosquitos en la costa sur de Ecuador, una región donde el control de mosquitos es clave para detener la propagación de enfermedades graves como el Zika y el Dengue. El estudio fue financiado por los Centros para el Control y la Prevención de Enfermedades (CCPEEU). El equipo de investigación usó tanto análisis genético como los ensayos de pesticidas para evaluar la resistencia a insecticidas en los mosquitos recolectados en áreas urbanas, en diferentes estaciones. Diferencias en el estado de resistencia en mosquitos a los insecticidas comúnmente utilizados por el ministerio de salud local, se encontraron tanto en las diferentes temporadas de recolección, como en las cuatro ciudades dentro del área de estudio. La resistencia detectada al malatión, la deltametrina, y la alfa-cipermetrina fue particularmente alta en la ciudad portuaria de Machala, que tiene una larga historia de brotes de dengue y uso de insecticidas. La información sobre el estado de resistencia hacia insecticidas, los patrones y el tiempo ayudará a los profesionales de la salud pública local a diseñar programas sostenibles de control de mosquitos que continuarán siendo eficaces en la lucha contra la enfermedad.

Lee Seasonal and geographic variation in insecticide resistance in Aedes aegypti in southern Ecuador, en PLoS Neglected Tropical Diseases.

 

Media contact: Mike Ryan Simonovich

 

Aedes control – image courtesy Mr. Dany Krom

GAINESVILLE, FL – New research co-authored by UF Geography’s Dr. Sadie Ryan and Ms. Cat Lippi sheds light on the climate suitability for Aedes aegypti and Aedes albopictus mosquitos and transmission rates of Zika, chikungunya, and dengue fever.

The study, published in PLOS Neglected Tropical Diseases compares new data driven models of Zika, chikungunya, and dengue fever transmission to real world measurements of human infections caused by bites from Aedes aegypti and Ae. Albopictus mosquitoes. These models confirm that temperature is the single most important factor for predicting the rate and geographic spread of epidemics of these mosquito-borne diseases. Temperature influences transmissibility in many ways – affecting the lifespan of an individual mosquito, and determining biting frequency and the reproductive rate of the virus within the mosquito.

The collaborative research team includes experts in epidemiology, public health, ecology, mathematical modeling, and geography, and was funded by a grant from the National Science Foundation’s Ecology and Evolution of Infectious Disease program (NSF-DEB 1518681).

Image courtesy PLoS Neglected Tropical Diseases
Image courtesy PLoS Neglected Tropical Diseases

KRACALIK, MORRIS, BLACKBURN – Cholera in Cameroon, 2000-2012: Spatial and Temporal Analysis at the Operational (Health District) and Sub Climate Levels

Moise C. Ngwa, Song Liang, Ian T. Kracalik, Lillian Morris, Jason K. Blackburn, Leonard M. Mbam, Simon Franky Baonga Ba Pouth, Andrew Teboh, Yang Yang, Mouhaman Arabi, Jonathan D. Sugimoto, John Glenn Morris Jr.

Article first published online: 17 NOV 2016 PLoS Neglected Tropical Diseases

DOI: 10.1371/journal.pntd.0005105

ABSTRACT:

Cholera was first reported in Cameroon in 1971. From 2000–2012, Cameroon reported on average 3,344.2 cases per year. When we divided the country into its four climate subzones (Sudano-Sahelian, Tropical Humid, Guinea Equatorial, and Equatorial Monsoon), there were very different patterns of spatial clustering of health districts with elevated attack rates, as well as differing sets of ecological determinants of cases counts. In the northern Sudano-Sahelian climate subzone, reported cases tended to occur between July and September, during the rainy season; whereas, the southern Equatorial Monsoon subzone reported cases year-round, with the lowest burden during the same rainy season. As cholera displays different epidemiological patterns by subzone, a single approach to controlling cholera for the whole nation does not appear to be viable. Additional prospective epidemiological studies are needed to further elucidate subzone-specific determinants of cholera burden, in order to provide sufficient evidence-based guidance for the formulation and assessment of regionally tailored intervention strategies.

Read the full publication at PLoS Neglected Tropical Diseases

BARRO, BLACKBURN – Redefining the Australian Anthrax Belt: Modeling the Ecological Niche and Predicting the Geographic Distribution of Bacillus anthracis

Alassane S. Barro, Mark Fegan , Barbara Moloney, Kelly Porter, Janine Muller, Simone Warner, Jason K. Blackburn

Article first published online: 09 JUN 2016 PLoS Neglected Tropical Diseases

DOI: 10.1371/journal.pntd.0004689

ABSTRACT: The ecology and distribution of B. anthracis in Australia is not well understood, despite the continued occurrence of anthrax outbreaks in the eastern states of the country. Efforts to estimate the spatial extent of the risk of disease have been limited to a qualitative definition of an anthrax belt extending from southeast Queensland through the centre of New South Wales and into northern Victoria. This definition of the anthrax belt does not consider the role of environmental conditions in the distribution of B. anthracis. Here, we used the genetic algorithm for rule-set prediction model system (GARP), historical anthrax outbreaks and environmental data to model the ecological niche of B. anthracis and predict its potential geographic distribution in Australia. Our models reveal the niche of B. anthracis in Australia is characterized by a narrow range of ecological conditions concentrated in two disjunct corridors. The most dominant corridor, used to redefine a new anthrax belt, parallels the Eastern Highlands and runs from north Victoria to central east Queensland through the centre of New South Wales. This study has redefined the anthrax belt in eastern Australia and provides insights about the ecological factors that limit the distribution of B. anthracis at the continental scale for Australia. The geographic distributions identified can help inform anthrax surveillance strategies by public and veterinary health agencies.

Read the full publication at PLoS Neglected Tropical Diseases