Public Health Response to a Rabid Dog in an Animal Shelter --- North Dakota and Minnesota, 2010

On March 31, 2010, the North Dakota Department of Health (NDDoH) was notified by a local public health department that a stray dog found in rural Minnesota and housed during March 9--20 in a North Dakota animal shelter had been found to have rabies. NDDoH, along with the local public health department, the North Dakota Board of Animal Health (BOAH), the Minnesota Board of Animal Health, and the Minnesota Department of Health, immediately began an investigation to identify persons requiring rabies postexposure prophylaxis (PEP) and to prevent further rabies transmission. This report summarizes the public health investigation, which used animal shelter records and public notification to identify possible human and animal contacts of the rabid dog. Among 32 persons who might have been exposed to the rabid dog at the shelter, 21 persons, including nine shelter employees and one volunteer, received PEP. In accordance with 2009 Compendium of Animal Rabies Prevention and Control guidance (1), the 25 dogs in the shelter with the rabid dog were euthanized. Among 25 other dogs without an up-to-date rabies vaccination that were adopted or claimed from the shelter and might have been exposed, 11 were euthanized, 13 were isolated for 6 months in their owners' homes, and one was unintentionally killed. No additional cases of rabies in dogs or humans had been identified as of December 2010. This event supports consideration of preexposure vaccination of animal shelter employees and highlights the continued importance of routine rabies vaccination of domestic animals.

On March 9, 2010, two stray dogs found by a sheriff's deputy in Marshall County, Minnesota, were brought to an animal shelter in Grand Forks, North Dakota. Marshall County is a rural area of Minnesota, and Grand Forks offers the closest animal shelter. In accordance with animal shelter protocol and city ordinance, the dogs were isolated from other animals in the shelter for 5 days. During this time, the dogs were observed for signs of disease or behavioral abnormalities. Dog A was fearful of shelter staff members and dependent on dog B, which was dominant, aggressive, and larger than dog A. On March 15, after the 5 days of isolation, the two dogs were transferred to the area holding the general shelter population and made available for adoption. Because of its dominant and aggressive temperament, however, dog B was deemed unsuitable for adoption and euthanized on March 19. On March 20, dog A was placed with a foster family in North Dakota. Five days later, the dog was vomiting and had loss of balance. On March 27, the family returned the dog to the shelter, where it was examined by a veterinarian, who noted hyperesthesia, tremors, ataxia, and dilated pupils. Because the differential diagnosis included canine distemper and rabies, the dog was euthanized the same day, and the brain was sent to the state veterinary diagnostic laboratory for testing. Three days later, the laboratory reported that a fluorescent antibody test was positive for rabies virus. CDC confirmed the result and characterized the virus as a North Central skunk rabies virus variant.

The animal shelter that housed the rabid dog takes in approximately 35--40 animals per week and can house up to 125 animals. The shelter is operated by the local humane society and also serves as the city pound, under a contract with Grand Forks. Dogs are kept in kennels constructed with concrete walls to minimize contact between dogs. Dogs are taken out of the kennels on leashes, and employees and volunteers are instructed to prevent contact between dogs. However, shelter employees could not verify that this policy was strictly followed while dogs A and B were at the shelter.

Employees, volunteers, and visitors to the animal shelter could have been exposed to rabies during March 9--20 while either dog was in the shelter (Figure). Dog B was presumed to be rabid, based on the close relationship with dog A and the possibility that they both were exposed to rabies virus at the same time. In addition, anyone in contact with dog A while it was with the foster family during March 20--27 also was at risk. A review of employee records and volunteer logs identified 32 persons who might have been exposed to the dogs at the shelter. Nine animal shelter employees and one volunteer received PEP. Eleven other persons received PEP, including the five members of dog A's foster family and one neighbor child, three members of the family who found dogs A and B in Minnesota, and two children who visited the shelter. In total, 21 persons received PEP. Of the 15 persons whose exposures were documented, all were licked by one of the dogs, and five had open wounds on their hands. As of December, no contacts had developed rabies.

The second phase of the public health investigation involved identifying animal contacts of the dogs. Although the shelter's animal handling policies likely minimized contact among dogs, muzzle-to-muzzle contact could not be ruled out; therefore, BOAH and NDDoH recommended that all dogs present in the shelter from March 9--20 be euthanized. All 25 dogs remaining in the shelter were euthanized. Adoption and claimed pet records were used to identify 37 other dogs that had been in the shelter during March 9--20, including 31 in North Dakota, five in Minnesota, and one in Michigan. Among those dogs, 12 were up-to-date on rabies vaccination, including one in Minnesota and one in Michigan. Of the 25 dogs without documented rabies vaccination, the owners of 11 opted to euthanize them, and the owners of 13 decided to confine their dogs for 6 months of observation. One dog in North Dakota was unintentionally killed before a decision was made. All euthanized dogs tested negative for rabies. No additional cases of rabid animals related to possible shelter exposure had been identified as of December 2010.

Reported by

K Kruger, T Miller, MPH, M Feist, North Dakota Dept of Health; S Keller, DVM, B Carlson, DVM, North Dakota State Board of Animal Health; R Klockmann, Grand Forks Public Health Dept. S Schwabenlander, DVM, Minnesota Board of Animal Health; J Scheftel, DVM, Minnesota Dept of Health. C Rupprecht, VMD, PhD, Div of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Diseases; JR Cope, MD, B Petersen, MD, EIS officers, CDC.

Editorial Note

The case described in this report demonstrates the risk for rabies virus transmission from domestic animals and the importance of vaccination and stray animal control programs in decreasing that risk. In the United States, such programs have succeeded in eliminating the canine rabies virus variant and decreased the number of laboratory-confirmed cases of rabies in dogs from 6,949 in 1947 to 75 in 2008 (1,2). Nevertheless, reintroduction of the canine rabies virus variant remains a threat, as illustrated by the importation of a rabid dog from Iraq in 2008 (3). In addition, rabies virus in indigenous wildlife reservoirs throughout the United States can be transmitted the virus to unprotected domestic animals, as probably occurred in the case described in this report.

Vaccination and animal control programs are the best strategies to protect against rabies and the resulting public health consequences. Rabid domestic animals have the potential to affect public health resources substantially. For example, the total cost to respond to a single rabid dog in California in 1980 was estimated to be $105,790 (4). A similar situation in 1994 involving a single rabid kitten purchased from a pet store led to a total of 665 persons receiving PEP at an estimated overall cost of $1.5 million (5). The identification of a rabid animal in any such public setting should prompt an immediate response to investigate potential exposures and institute prevention and control efforts to protect the health of the public.

Rabies virus is transmitted by bites from a rabid animal or by saliva or other potentially infectious material (e.g., neural tissue) that is introduced into fresh, open cuts in skin or onto mucous membranes (6,7). Activities such as petting an animal; contact with the blood, urine, or feces of an animal; or contact of saliva with intact skin are not exposures and therefore do not require PEP (6,7). Development of a standardized risk assessment with strict application of these exposure definitions might decrease the number of persons receiving PEP in any rabies exposure situation, including this one, in which all exposures of persons receiving PEP were not documented fully. In addition, preexposure prophylaxis for animal shelter workers or other persons whose activities bring them into frequent contact with potentially infected animals should be considered, in accordance with Advisory Committee on Immunization Practices recommendations (6). Preexposure prophylaxis consists of 3 doses of vaccine administered on days 0, 7, and 21 or 28 (6,7). Although the initial cost can be a concern, preexposure prophylaxis decreases costs for PEP after a subsequent exposure by obviating the need for rabies immunoglobulin, reducing the number of vaccine doses from 4 to 2, and decreasing the number of visits to a health-care provider. Preexposure prophylaxis also might help protect persons from unrecognized exposures or offer partial immunity when PEP is delayed.

Several measures should be instituted in animal shelters and other public settings where humans are exposed to animals to decrease the risk for rabies virus transmission and to facilitate the epidemiologic investigation of identified cases. First, all domestic animals should be vaccinated against rabies, in accordance with guidelines (1,8). Second, animals without documentation of vaccination against rabies should be kept separate from the public, wildlife, and other animals to prevent transmission of the virus (5,8). In this case, 36 dogs had to be euthanized because employees and volunteers might not have consistently followed the shelter's policy of preventing muzzle-to-muzzle contact between dogs. Third, each facility should maintain adequate records, including rabies vaccination certificates, animal source documentation, and adoption and sales records, to facilitate the investigation of any possible exposures. Strict adherence to these recommendations will protect humans from exposures and also can protect animals involved with an exposure from being euthanized.

Acknowledgments

This report is based, in part, on contributions by staff members of the Grand Forks Public Health Dept, A Moen, Circle of Friends Humane Society, S Hansen, J Hargreaves, DO, Altru Health System, Grand Forks, North Dakota; L VanderBusch, T Hardy, North Dakota Dept of Health; and L Orciari, MS, and P Yager, Div of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Diseases, CDC.

References

1. CDC. Compendium of animal rabies prevention and control, 2008: National Association of State Public Health Veterinarians, Inc. (NASPHV). MMWR 2008;57(No. RR-2).
2. Blanton JD, Robertson K, Palmer D, Rupprecht CE. Rabies surveillance in the United States during 2008. J Am Vet Med Assoc 2009;235:676--89.
3. CDC. Rabies in a dog imported from Iraq---New Jersey, June 2008. MMWR 2008;57:1076--8.
4. CDC. The cost of one rabid dog---California. MMWR 1981;30:527.
5. CDC. Mass treatment of humans exposed to rabies---New Hampshire, 1994. MMWR 1995;44:484--6.
6. CDC. Human rabies prevention---United States, 2008: recommendations of the Advisory Committee on Immunization Practices. MMWR 2008;57(No. RR-3).
7. CDC. Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: recommendations of the Advisory Committee on Immunization Practices. MMWR 2010;59(No. RR-2).
8. CDC. Compendium of measures to prevent disease associated with animals in public settings, 2009: National Association of State Public Health Veterinarians, Inc. (NASPHV). MMWR 2009;58(No. RR-5).

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