Summer is here and with it comes the busiest time for animal bite and bat exposure reports to Public Health. Every year about half of all the animal bite and bat exposure reports occur between June and September, largely due to an increase in bat activity during that time. As of July 15, 2007, this year Public Health has received 327 reports of humans bitten by or exposed to bats and other animals where potential rabies exposure may have occurred.

Although rare, rabies still occurs in humans in the U.S. and is almost uniformly fatal. One to two deaths each year are attributed to rabies, and there may be additional deaths due to rabies that go undiagnosed. In Washington State , the most recent human cases (in 1995 in Lewis County and in 1997 in Mason County ) were both due to infection with bat rabies strains.

Rabies and bats

Bats are the primary reservoir for rabies in Washington State ; 7 percent of bats tested in Washington State between 2000 and 2006 were positive for rabies. However, the actual proportion of bats that are rabid is likely to be lower than this because healthy, non-rabid bats are not likely to be captured and tested. Two bats have tested positive for rabies so far this year in King County .

Rabies and wild terrestrial animals

No rabies cases have been identified in wild terrestrial animals in Washington in the past 60 years. However, there is currently no systematic surveillance for rabies among wild animals in our state - only animals involved in human exposures are tested. Sporadic rabies in skunks and foxes have occurred in recent years in Idaho , Oregon and British Columbia . Furthermore, spill-over of bat rabies into terrestrial animals (skunks) leading to a sustained epizootic has been documented in Arizona . Although the risk of rabies from terrestrial animals in Washington is low, without a good surveillance system it is possible for rabies to be present or emerge without detection. Therefore, after consultation with the CDC, Public Health continues to recommend rabies post-exposure prophylaxis (PEP) for persons bitten or scratched by raccoons and other terrestrial carnivores when the animal is not available for rabies testing.

Rabies and foreign travel

While the majority of cases that required rabies PEP were exposed in King County , 14% were exposed while traveling abroad. The foreign exposures included monkeys and dogs. Follow-up for cases exposed in other countries can be complex for many reasons: rabies PEP initiated outside the U.S. may include the administration of biologics that are not approved by the U.S. Food and Drug Administration (such as vaccines of nerve tissue origin); the schedule or dosage for PEP may differ from recommendations in the U.S.; and rabies immune globlulin (RIG) is not always available. In these situations, Public Health provides recommendations for PEP on a case-by-case basis.

Tetanus prophylaxis in wound management

Adults 19-64 years of age who require a tetanus toxoid-containing vaccine as part of wound management should receive Tdap instead of Td if they previously have not received Tdap. If Tdap is not available or was administered previously, Td should be administered. Adults who have never received tetanus and diphtheria toxoid-containing vaccine should receive a series of three vaccinations. The preferred schedule is a dose of Tdap, followed by a dose of Td >4 weeks later, and a second dose of Td 6 to 12 months later. Tdap can substitute for Td for any one of the three doses in the series.

Prevention of rabies

Many animal bites and rabies exposures can be avoided. Health care providers can help educate their patients about reducing the risks associated with wild and domestic animals:

• Teach children never to approach or handle unfamiliar animals, wild or domestic, even if they appear friendly.
• Do not handle or feed wild animals.
• Avoid attracting wild animals by tightly covering garbage cans and compost bins tightly, and keeping pet food and food scraps indoors.
• Never adopt or “rescue” wild animals or bring them into your home.
• Keep windows and doors closed, or use tightly-fitting screens over open windows and doors.
• When traveling abroad, avoid contact with animals and be especially careful around dogs in developing countries. Rabies is common among dogs and other animals in parts of Asia, Africa, and Latin America . If planning a trip for an extended period or involving increased exposure to animals, pre-exposure prophylaxis with rabies vaccine maybe recommended.  Be sure to seek medical care promptly if bitten by an animal when abroad.
• Keep rabies vaccinations up to date for all dogs, cats, and ferrets.

Additional information on rabies decision trees for assessing the need for PEP is available at: www.metrokc.gov/health/providers/epidemiology/rabies/ and www.cdc.gov/mmwr/PDF/rr/rr4801.pdf.