Experimental Transmission of West Nile Virus by Culex nigripalpus from Honduras
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD VIROLOGY DIV
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Due to concerns regarding the geographic spread of West Nile virus WNV to Central America, we evaluated the potential for Honduran Culex nigripalpus Theobald to transmit this virus. We tested individual mosquitoes captured in Olancho Province, Honduras, in September 2003. Mosquitoes were fed upon 2- to 4-day-old chickens previously inoculated with a New York strain Crow 397-99 of WNV. Infection rates in Cx. nigripalpus ranged from 81-96 after feeding on chickens with viremias between 106.3 and 107.4 plaque-forming units PFUml of blood. Development of a disseminated infection was directly correlated with holding time after the infectious blood meal, as 74 of the mosquitoes tested 20 d after the infectious blood meal had a disseminated infection as compared to 42 of the mosquitoes tested 14 d after feeding on the same viremic chicken. Nearly all 86 of Cx. nigripalpus with a disseminated infection that fed on susceptible chickens transmitted virus by bite. In addition, 8 57 of 14 Cx. nigripalpus with a disseminated infection transmitted virus when tested by a capillary tube feeding assay. Based on its efficiency of viral transmission in this study and its role in the transmission of the closely related St. Louis encephalitis virus in the southeastern USA, Cx. nigripalpus should be considered a potentially important vector of WNV in Honduras and the rest of Central America.
- Medicine and Medical Research