Which animals serve as reservoirs for rabies?

Updated: Jun 21, 2019
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Human rabies reflects the prevalence of animal infection and the extent of contact this population has with humans. Less than 5% of cases in developed nations occur in domesticated dogs; however, unvaccinated dogs serve as the main reservoir worldwide. Undomesticated canines, such as coyotes, wolves, jackals, and foxes, are most prone to rabies and serve as reservoirs. These reservoirs allow rabies to remain an indefinite public health concern, and ongoing public health measures are critical to its control.Animal-control and vaccination strategies currently supersede postexposure prophylaxis in preventing the spread of rabies. Through such programs, rabies has been eliminated in some parts of the United States, as well as several nations.

Terrestrial rabies in the United States is most common in raccoons on the eastern coast and in skunks, foxes, coyotes, and dogs on the Texas-Mexico border. Canine rabies, and to a lesser extent, bat rabies are significant problems in Mexico and around the world. (Opossums are rarely infected and are not considered a likely risk for exposure.)

The only rodent in the United States that can carry rabies long enough to transmit it to humans is the groundhog. Other small rodents (eg, squirrels, chipmunks, rats, mice) and lagomorphs (eg, rabbits, hares) usually die before being able to transmit rabies virus to humans, and human disease has not been documented from these mammals.

Domestic animals usually succumb to the virus strain predominant in their geographic region. Other cases have been associated with dog or animal bites in travelers returning from abroad, especially in countries where wild canine rabies is endemic. In other countries, canines are the most common source of rabies. Other animals, such as mongooses, jackals, ferrets, and domestic farm animals, may be common sources. Human-to-human transmission has only occurred with corneal and other organ transplants. [2, 3] Transmission of virus in saliva through mucous membranes, open wounds, or scratches is possible but rarely documented.

Rabies continues to adapt to new hosts and evolve transmissibility in previously “dead-end” hosts. In Arizona 2001, a mutated bat strain was confirmed to have developed both pathogenicity and transmissibility in both foxes and skunks, which previously were not seriously affected or contagious upon infection. Human encroachments into natural areas, as in suburban development, have been associated with the spread of rabies strains in the past. [8]


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