Rabies surveillance in the United States during 2001

Abstract

During 2001, 49 states and Puerto Rico reported 7,437 cases of rabies in nonhuman animals and 1 case in a human being to the Centers for Disease Control and Prevention, an increase of < 1% from 7,364 cases in nonhuman animals and 5 human cases reported in 2000. More than 93% (6,939 cases) were in wild animals, whereas 6.7% (497 cases) were in domestic species (compared with 93.0% in wild animals and 6.9% in domestic species in 2000). The number of cases reported in 2001 increased among bats, cats, skunks, rodents/lagomorphs, and swine and decreased among dogs, cattle, foxes, horses/mules, raccoons, and sheep/goats. The relative contributions of the major groups of animals were as follows: raccoons (37.2%; 2,767 cases), skunks (30.7%; 2,282), bats (17.2%; 1,281), foxes (5.9%; 437), cats (3.6%; 270), dogs (1.2%; 89), and cattle (1.1%; 82). Nine of the 19 states where the raccoon-associated variant of the rabies virus has been enzootic reported decreases in the numbers of rabid raccoons during 2001. Among states with extensive wildlife rabies control programs, Ohio reported (other than rabies in bats) 1 case of rabies in a raccoon that was associated with the epizootic of rabies in raccoons and 1 case in a bovid that was infected with a bat variant of the rabies virus, compared with no cases reported in any terrestrial animals during 2000. Texas reported 1 case associated with the dog/coyote variant of the rabies virus (compared with no cases in 2000) and 20 cases associated with the gray fox variant of the virus (a decrease of 50% from reported cases in 2000). Reports of rabid skunks in Massachusetts and Rhode Island, states with enzootic raccoon rabies, exceeded reports of rabid raccoons for the fifth consecutive year. A similar situation may soon exist in the state of Maine (32 rabid skunks and 34 rabid raccoons during 2001). Nationally, the number of rabies cases in skunks during 2001 increased by 2.7% over those reported in 2000. Texas reported the greatest number of rabid skunks ever documented during a single year by any state, as well as the greatest numerical increase in rabid skunks (778 cases in 2001, compared with 550 in 2000; an increase of 228 cases, or 41.5%) and the largest overall state total of rabies cases (1,043) during 2001. Arizona reported the greatest percentage increase in rabid skunks (247.1%), representing an increase from 17 rabid skunks in 2000 to 59 in 2001. Nineteen of these cases were infected with a bat variant of the rabies virus, documenting a spillover event followed by unprecedented detection of temporal enzootic transmission of a bat variant in a terrestrial species. The number of cases of rabies reported in bats during 2001 (1,281 cases) increased 3.3% and surpassed the previous year's record (1,240 cases) as the largest number of reported cases ever recorded for this group of mammals. Cases of rabies reported in dogs (89) and cattle (82) decreased by 21.9 and 1.2%, respectively; these are the lowest numbers reported for rabid cattle and dogs since the dawn of national rabies record keeping (ca 1938). Cases in cats (270) increased by 8.4% over those reported in 2000, whereas rabies among sheep and goats declined 70%, from 10 cases in 2000 to 3 cases (goats only) in 2001. Rabies among horses and mules declined 1.9% (52 cases in 2000 to 51 cases in 2001). Reported cases of rabies in mongooses in Puerto Rico increased 18.6%, compared with the previous year (70 cases in 2001 from 59 cases in 2000), whereas cases of rabies in dogs declined 15.3% (15 to 13). One case of rabies in a human being reported by California during 2001 was the result of infection with a canine variant of the rabies virus acquired outside the United States.