Characterizing the Epidemiology of Bluetongue Virus Serotype One in South Louisiana.
In November 2004, bluetongue virus (BTV) serotype 1 was detected for the first time in the U.S. from a hunter-killed deer in the marsh area of the Atchafalaya Delta in St. Mary Parish, LA. Subsequent serum surveys of three cattle farms further inland from the area where the deer was shot found bluetongue virus serotype 1 positive cattle on two of the three farms. The purpose of this study was to determine potential BTV vectors in the area where BTV-1 positive animals were detected and compare different trapping techniques for capturing specimens of the genus Culicoides. The study was conducted from January 2006 through November 2007. Seven sites were established in the immediate area (marsh) where the deer was found and miniature CDC light traps were deployed once per month at each site. At each of the three cattle farms, two CDC light traps (one with and one without dry ice) were deployed twice per month. In 2007, New Jersey traps with incandescent bulbs or black light bulbs were compared to CDC traps baited with dry ice. Specimens of 10 different species of Culicoides were captured at the farms and specimens of 7 of these 10 species were caught in the Atchafalaya Delta marsh area. In the entire study, 8,179 ceratopogonids were captured including 5,068 of the genus Culicoides. CDC light traps baited with dry ice caught significantly more flies than traps without dry ice. Infrared reverse transcriptase polymerase chain reaction was performed to screen for BTV in 275 pools representing 2,504 specimens collected at the farms. All positive samples were sequenced for serotype determination. Five pools out of 275 (1.8%) were positive for BTV. Pools of four species of Culicoides were found to be positive: C. crepuscularis, C. debilipalpis (2 pools), C. haematopotus, and C. furens. The amplicons of the positive specimens were sequenced and found to be identical to either BTV-17 or BTV-13. Since we did not detect BTV-1 in any biting midges, future studies will be necessary to establish the epidemiology of bluetongue virus serotype 1 in south Louisiana.
Advisor:Wayne Kramer; Kevin Macaluso; Lane Foil
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Date of Publication:07/09/2008