West Nile virus in mosquitoes of northern Ohio, 2003.
ABSTRACT From June 19, 2003 to August 18, 2003, we surveyed the mosquitoes of Oberlin, OH, for West Nile Virus (WNV) infection using reverse transcriptase-polymerase chain reaction. A total of 12,055 mosquitoes, representing 17 species or species groups and 4 genera, were collected in gravid traps at seven sites throughout the city, with Culex pipiens/restuans being the most abundant and showing the highest minimum infection rate (MIR) of 0.78. This represents a decrease in WNV enzootic activity from the previous year. Both Cx. pipiens/restuans abundance and MIR increased significantly with date. However, we found no correlation between Cx. pipiens/restuans abundance and MIR.
Article: The Impact of Weather Conditions on Culex pipiens and Culex restuans (Diptera: Culicidae) Abundance: A Case Study in Peel Region[show abstract] [hide abstract]
ABSTRACT: Mosquito populations are sensitive to long-term variations in climate and short-term variations in weather. Mosquito abundance is a key determinant of outbreaks of mosquito-borne diseases, such as West Nile virus (WNV). In this work, the short-term impact of weather conditions (temperature and precipitation) on Culex pipiens L.-Culex restuans Theobald mosquito abundance in Peel Region, Ontario, Canada, was investigated using the 2002–2009 mosquito data collected from the WNV surveillance program managed by Ontario Ministry of Health and Long-Term Care and a gamma-generalized linear model. There was a clear association between weather conditions (temperature and precipitation) and mosquito abundance, which allowed the definition of threshold criteria for temperature and precipitation conditions for mosquito population growth. A predictive statistical model for mosquito population based on weather conditions was calibrated using real weather and mosquito surveillance data, and validated using a subset of surveillance data. Results showed that WNV vector abundance on any one day could be predicted with reasonable accuracy from relationships with mean degree-days >9°C over the 11 preceding days, and precipitation 35 d previously. This finding provides optimism for the development of weather-generated forecasting for WNV risk that could be used in decision support systems for interventions such as mosquito control.Journal of Medical Entomology 03/2011; · 1.76 Impact Factor
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ABSTRACT: Temporal changes in the abundance Culex restuans and Culex pipiens were monitored in east-central Illinois for over a decade using infusion-baited oviposition traps. The 2 species typically exhibited a seasonal shift in relative abundance with a mean crossover date (when the proportion of egg rafts from both species is equal) of August 10 or 11, depending on leap year, with a 95% confidence interval of +/- 10.7 days. The date of crossover was linearly related to the date of last spring frost and occurred on average about 123 days after the last spring frost. Despite the predictability of crossover, the weekly pattern in the proportion of Cx. pipiens before and after crossover varied considerably, even between years with similar crossover dates. After West Nile virus became established in our area, we found that transmission based on Culex from gravid traps did not increase until Cx. pipiens abundance increased in oviposition traps. Infection rates peaked within the half-month period after crossover. The peak in Cx. pipiens abundance in oviposition traps during this 3-year period was between the 2nd half of August and the end of September. A higher magnitude of transmission in 2002 coincided with warmer temperatures during July and August and an extended period in which the 2 Culex species were in relatively equal abundance.Journal of the American Mosquito Control Association 10/2006; 22(3):390-400. · 0.91 Impact Factor
Article: Survey of Aedes triseriatus (Diptera: Culicidae) for Lacrosse encephalitis virus and West Nile virus in Lorain County, Ohio.[show abstract] [hide abstract]
ABSTRACT: From June through September 2003, we conducted a survey of female Aedes triseriatus (Say) for infection with La Crosse encephalitis virus (family Bunyaviridae, genus Orthobunyavirus, LACV) and West Nile virus (family Flaviviridae, genus Flavivirus, WNV) at three locations in Lorain County, Ohio. To determine infection rate and seasonal variation of both viruses in the Ae. triseriatus population, Ae. triseriatus were collected weekly by using gravid traps and CO2-baited CDC light traps and tested for virus by using reverse transcriptase polymerase chain reaction. In total, 170 pools comprised of 2,143 females were tested for LACV, of which seven were positive; the maximum likelihood estimate of infection rate combined throughout the season was 3.22/1,000. None of 170 pools comprised of 2,158 females tested for WNV were positive. LACV-positive pools were detected between late July and early September.Journal of Medical Entomology 06/2006; 43(3):589-93. · 1.76 Impact Factor