Continued investigation of hemorrhagic disease virus vectors on Texas ranches

Epizootic hemorrhagic disease (EHD) is the most important and common viral disease of white-tailed deer in the United States, and outbreaks occur every year in parts of the southeast. EHDV was first reported in Texas in 1966 in a captive white-tailed deer and a bighorn sheep, but both wild and domestic ruminants can be infected by this arthropod-borne pathogen. In order to collect and identify biting fly vector(s) of epizootic hemorrhagic disease virus (EHDV) suspected of causing debilitation and death in white-tailed deer in Texas, we set out CDC miniature light traps equipped with CO2 source around likely Culicoides breeding areas on Texas ranches where deer losses due to EHD have been reported. Traps were set out in the evening and collected the next morning over a 5 month period, beginning in Spring, 2008. Counts and species identifications have been made for over 3,000 adult female Culicoides collected from 2 of the larger collection sites in the San Angelo, Texas, area. At least 12 different species are represented. The majority of the specimens were collected during the late spring and early fall months (37% and 36%, respectively). Only 28% of the total flies were collected during the months of June and July, most likely due to the very dry environmental conditions during that time.