The death of a rabid captive deer, an adult doe, was reported initially in August 2007 at farm A; during October 2007–January 2008, three buck fawns from this farm also died of rabies (). In April 2008 and December 2009, two adult does died of rabies at farm B and farm C, respectively (). Lastly, during July 2010, one adult doe, followed by 4 buck fawns, died at farm D (). All reported cases were laboratory confirmed, and diagnostic testing detected a rabies virus variant associated with raccoons.
Rabies deaths among captive deer at 4 farms in Lancaster and Chester counties, Pennsylvania, USA, 2007–2010.
We conducted a case–control study among deer farms in Pennsylvania. A case farm was defined as a registered deer farm with >1 laboratory-confirmed case of rabies in a deer. A control farm was defined as a registered deer farm that did not report any laboratory-confirmed rabies in deer. Ten control farms were chosen by referral from farmers and from the Pennsylvania Deer Farmers Association website. Control farms were limited to the affected counties and 1 noncontiguous county to account for local ecologic diversity. Four farms (farms A–D) met the case definition. Staff from the Centers for Disease Control and Prevention, state and local health departments, and the Pennsylvania Department of Agriculture conducted site visits to each affected farm. A standardized questionnaire was administered in person or by telephone to all study farms during August 2–5, 2010. Proportions were compared with Fisher exact test by using SAS version 9.2 (SAS Institute Inc., Cary, NC, USA).
Farmers’ ages, levels of education, and number of years farming did not differ between case and control farms (). Control farms tended to be larger than case farms (27.4 vs. 15.3 acres; odds ratio [OR] 0.99, 95% CI 0.95–1.03) with more deer per acre (36.8 vs. 34.7; OR 0.99, 95% CI 0.96–1.04), although neither difference was significant (). Farming practices did not differ between case and control farms (). Trough and bottle feeding of deer were common practices, and most (71%) farms reported using sweet deer feed containing molasses, which might attract rabies reservoir species, such as raccoons. Deer were moved infrequently between pens, and few outside deer were brought onto the farms (mean 2.5 deer/year); however, interstate travel of deer was reported. Most (71%) farms reported vaccinating deer against at least 1 disease, but deer were vaccinated on case farms only in response to previously rabid deer (). A low perceived risk for rabies was cited as the primary barrier to rabies vaccination among control farms. In contrast, witnessed contact between deer and rabies reservoir species was relatively common (43% of farms reported contact with skunks, and 36% reported contact with raccoons) ().
Characteristics and practices of farms with rabid deer, Pennsylvania, USA, 2007–2010
Rabies knowledge, exposures, and health-seeking behavior among deer farmers, Pennsylvania, USA, 2007–2010
Each of the 4 deer farmers from case farms received rabies PEP because of exposures to the rabid deer. Potential sources of exposure were common. All deer farmers reported bare skin contact with animal saliva, 50% reported being scratched by an animal, 29% reported being bitten by an animal, and 29% reported bare skin contact with animal tissue (). Case farms had significantly higher self-reported knowledge about rabies, probably because of their direct experience with the disease (). However, knowledge of rabies among control farms was low (90% of farmers reported knowledge as basic), and none of the farmers indicated that they should wash with soap and water if potentially exposed to the rabies virus ().