Objective—To describe surveillance trends and epidemiologic
features of rabies in bats in the United
States, focusing on 3 bat species primarily associated
with variants of the rabies virus that affect humans.
Procedure—Data on rabies for bats identified to
species and reported by state laboratories from 1993
to 2000 were analyzed, focusing on silver-haired,
eastern pipistrelle, and Brazilian free-tailed bats.
Categoric variables were derived from other provided
Results—Data were reported from 37 states during
the study interval; complete species-specific data
were not reported by any state for the entire interval.
Bats primarily associated with rabies virus variants
affecting humans were more likely to yield positive
test results for rabies (22.7%), compared with all
other bats (5.5%) in most seasons and from most
regions of the United States. However, certain other
bat species had higher percentages of positive
results. Risk of positive results was highest in the fall
and highest among bats originating in the southwestern
Conclusions and Clinical Relevance—Increased
risk of rabies among certain groups of bat species
was consistently found across seasons and most
geographic regions of the United States. Results
were in general agreement with those of previous
studies conducted within smaller geographic regions.
There are ongoing efforts to improve surveillance of
rabies in bats, although surveillance is incomplete in
some regions. (J Am Vet Med Assoc 2003;222:
Summary—During 2003, 49 states and Puerto Rico reported 7,170 cases of rabies in nonhuman animals and 3
cases in human beings to the CDC. This represents a 10% decrease from the 7,967 cases in nonhuman animals and
3 cases in human beings reported in 2002. More than 91% (n = 6,556) were in wild animals, and 8.6% (614) were
in domestic species (compared with 92.5% in wild animals and 7.4% in domestic species in 2002). The relative contributions
of the major groups of animals were as follows: 2,635 raccoons (36.7%), 2,112 skunks (29.4%), 1,212 bats
(16.9%), 456 foxes (6.4%), 321 cats (4.5%), 117 dogs (1.6%), and 98 cattle (1.4%). Compared with cases reported
in 2002, the number of cases reported in 2003 decreased among all reporting groups with the exception of cats,
dogs, equids, and swine. Ten of the 19 states with enzootic rabies in raccoons, the District of Columbia, and New
York City reported decreases in the numbers of rabid raccoons during 2003. Tennessee reported 4 cases of indigenous
rabies in raccoons during 2003, becoming the 20th state where rabies in raccoons is known to be enzootic.
On a national level, the number of rabies cases in skunks during 2003 decreased by 13.2% from those reported
in 2002. Texas again reported the greatest number (n = 620) of rabid skunks during 2003, as well as the greatest
overall state total of rabies cases (909). As in 2002, Texas did not report any cases of rabies associated with the
dog/coyote variant of the rabies virus, but did report 61 cases associated with the gray fox variant of the virus (compared
with 65 cases in 2002). The 1,212 cases of rabies reported in bats during 2003 represented a decline of nearly
12% from the previous year's record high of 1,373 cases for this group of mammals. Cases of rabies reported in
foxes and raccoons declined 10.2% and 8.9%, respectively, during 2003. Rabies among sheep and goats decreased
from 15 cases in 2002 to 12 cases in 2003, whereas cases reported in cats, dogs, and equids increased 7.4%,
18.2%, and 8.6%, respectively. In Puerto Rico, reported cases of rabies in mongooses and dogs decreased 26.9%
and 35.7%, respectively, from those reported in 2002.
Three cases of rabies in human beings were reported in California, Virginia, and Puerto Rico during 2003. The
Virginia case was the first reported occurrence of rabies in a human being infected with the raccoon rabies virus
variant; however, the exposure history was unknown. The California and Puerto Rico cases were the result of infections
with bat and dog/mongoose rabies virus variants, respectively, and each patient had a history of a bite.
Summary—During 2005, 49 states and Puerto Rico reported 6,417 cases of rabies in nonhuman animals and 1 case in a human being to the CDC, representing a 6.2% decrease from the 6,836 cases in nonhuman animals and 8 cases in human beings reported in 2004. Approximately 92% of the cases were in wildlife, and 8% were in domestic animals. Relative contributions by the major animal groups were as follows: 2,534 raccoons (39.5%), 1,478 skunks (23%), 1,408 bats (21.9%), 376 foxes (5.9%), 269 cats (4.2%), 93 cattle (1.5%), and 76 dogs (1.2%). Compared with numbers of reported cases in 2004, cases in 2005 decreased among all groups, except bats, horses, and other wild animals. Decreases in numbers of rabid raccoons during 2005 were reported by 10 of the 20 eastern states in which raccoon rabies was enzootic and decreased overall by 1.2%, compared with 2004.
On a national level, the number of rabies cases in skunks during 2005 decreased 20.4% from the number reported in 2004. Once again, Texas reported the greatest number (n = 392) of rabid skunks and the greatest overall state total of rabies cases (741). Texas reported no cases of rabies associated with the dog/coyote rabies virus variant and only 8 cases associated with the Texas gray fox rabies virus variant (compared with 22 cases in 2004). The total number of cases of rabies reported nationally in foxes decreased 3.3%, compared with those reported in 2004. The 1,408 cases of rabies reported in bats represented a 3.5% increase over numbers reported in 2005. Cases of rabies in cats, dogs, cattle, and sheep and goats decreased 4.3%, 19.2%, 19.1%, and 10%, respectively, whereas cases reported in horses and mules increased 9.3%. In Puerto Rico, reported cases of rabies in mongooses increased 29.8%, and rabies in domestic animals decreased 37.5%.
One case of human rabies was reported from Mississippi during 2005. This case was submitted by the state to the CDC's unexplained deaths project and diagnosed as rabies retrospectively.