Rabies is a viral disease that affects the central nervous system and is transmitted through the bite or scratch of an infected animal. It is almost always fatal once symptoms appear. However, rabies can be prevented through prompt treatment after exposure and by vaccinating pets and managing wildlife populations. Though rabies has been brought under control throughout much of the United States, the disease remains endemic in wildlife in most areas. Only one state in the U.S. has successfully eliminated rabies – Hawaii.
Background on Rabies in the United States
Rabies has been present in America since colonial times. In the late 19th and early 20th centuries, dog-transmitted rabies caused thousands of human deaths each year in the U.S. However, starting in the 1940s, laws mandating dog vaccination and leash control dramatically reduced this threat. From 1960 to 2018, only 125 human rabies deaths were reported in the U.S., with most contracted from bat exposures.
Wildlife – especially raccoons, skunks, foxes, and bats – now account for the majority of reported rabies cases. The number varies year to year but averages around 5,000-7,000 annually. Rabid wildlife pose a risk to humans and pets in most regions. Trends show the raccoon rabies virus variant spreading up the Eastern U.S. in the 1970s-1990s. Separate wildlife rabies strains also moved westward.
Rabies-Free States
Despite endemic rabies in surrounding states, four states have managed to secure rabies-free status through aggressive control measures:
- Hawaii
- Oregon (west of the Cascades)
- Northern Minnesota and North Dakota
- Parts of Texas along the Mexico border
However, only Hawaii has maintained its rabies-free standing and requires quarantine for imported dogs and cats. The other areas remain at risk for periodic reintroductions or further spread.
Hawaii’s Rabies Prevention Program
Hawaii is the only state in the U.S. to have eliminated rabies viruses from all animal populations. This required a strict quarantine program and limitations on importation of mammals.
History of Rabies and Quarantine in Hawaii
Rabies likely arrived in Hawaii in the early 19th century via infected dogs on ships. Epidemics occurred in the 1840s and early 1900s. To control spread, Hawaii enacted a strict 120-day quarantine on all imported dogs and cats in 1897. From 1947-1957, over 200 rabies cases occurred in quarantined pets, confirming the need for this policy.
The last rabies case in a dog indigenous to Hawaii occurred in 1958. Hawaii was declared rabies-free in 1961. But quarantine remains critical to prevent re-establishment of the virus from infected pets. Over the decades, Hawaii has adjusted its program to balance rabies prevention with facilitating pet travel.
Hawaii’s Current Residential Dog & Cat Quarantine Policies
All dogs and cats imported into Hawaii must meet one of the following quarantine requirements:
- 5 Day Or Less Program: The pet must have a current rabies vaccination and blood test showing sufficient rabies antibodies before arrival. No quarantine is required if the pet meets all criteria.
- 120 Day Quarantine: Pets without proper documentation and rabies protection undergo a 120 day quarantine in Honolulu or the island of arrival. Fees apply.
- Guide/Service Dogs: Guide and service dogs from the continental U.S. qualify for a 30 day in-home quarantine when meeting specific requirements.
Pets transiting Hawaii on way to another destination do not require quarantine if they remain leashed, muzzled or caged during their stopover. Some other exceptions may apply.
Impact and Benefits
While burdensome to pet owners, Hawaii’s stringent import controls have protected residents, pets, and wildlife from rabies re-establishment for over 60 years. Hawaii saves an estimated $500,000 per year on rabies prevention and control costs compared to other states. Rabies vaccinations are not routinely required for cats or dogs in Hawaii like they are elsewhere.
The quarantine program also allows Hawaii to remain free of other diseases spread by introduced mammals such as leptospirosis, ehrlichiosis, heartworm, and external parasites.
Why Rabies Persists in Other States
Eliminating rabies from terrestrial wildlife populations has proven very difficult across the continental U.S. Several key factors account for why rabies remains endemic:
Wide Distribution of Rabies Virus Variants
Multiple distinct rabies virus variants associated with different reservoir species circulate across the U.S. Even if one variant is controlled, others can reintroduce the disease:
- Bat rabies – present across the U.S.
- Raccoon rabies – eastern and southeastern states
- Skunk rabies – midwestern and western states
- Fox rabies – Texas, New Mexico, Arizona
- Mongooses – Puerto Rico
Spread Among Wild Animals
Rabies transmits efficiently between wild animals, especially among carnivores and bats. Control is challenging as population densities are high over large areas. Vaccine programs for wildlife are limited or ineffective.
Spillover into Pets and People
Rabid wild animals periodically interact with pets and humans, resulting in bites/exposures. Lack of consistent rabies vaccination for dogs and cats can allow spillover then spread through domestic animals.
Reintroduction from Outside Areas
Mobile wildlife like bats, foxes, and raccoons can periodically reintroduce rabies into controlled zones by migrating from remote rabies-endemic regions. Imported rabid pets also pose a risk.
Approaches for Eliminating Rabies from Continental U.S.
While daunting, eliminating rabies from the continental U.S. may be possible through commitment to expanded programs proven to control the virus:
Wildlife Rabies Control Methods
- Oral Rabies Vaccines (ORV): Distribution of oral baits with rabies vaccines has succeeded in eliminating fox and raccoon rabies from parts of Canada and France. ORV shows promise but is costly over large rural areas of the U.S.
- Population Reduction: Selective culling of rabies reservoir species like raccoons and foxes has been utilized but is controversial and marginally effective.
- Contraceptives: Immunocontraceptives are under study to reduce raccoon densities and rabies transmission.
- Trap-Vaccinate-Release: Trapping wild animals to vaccinate against rabies has had localized success but is labor intensive.
Domestic Animal Programs
- Stringent pet vaccination and leash laws.
- Stray animal control and shelter policies.
- Identification and sterilization programs.
- Quarantine of imported animals.
Public Health Measures
- Rabies education on risks and prevention.
- Prompt postexposure treatment when warranted.
- Surveillance and testing of suspect animals.
Adequate funding, interagency coordination, and public compliance would be critical for success. But a coordinated long-term initiative could feasibly eliminate terrestrial rabies from the U.S. over the next 50-100 years.
Conclusion
Rabies remains endemic in wildlife across most of the United States, except for Hawaii which uniquely enforced strict animal quarantine and import controls starting nearly a century ago. Eliminating rabies from the continental U.S. would require substantial, targeted investment and policies over decades. However, the goal of becoming a rabies-free nation in the future may be achievable through a strategic One Health approach, building on proven tactics like oral immunization, responsible pet ownership laws, and public education.