According to CDC, rabies in humans is rare in the United States. There are usually only one or two human cases per year. But the most common source of human rabies in the United States is from bats. For example, among the 19 naturally acquired cases of rabies in humans in the United States from 1997-2006, 17 were associated with bats. Among these, 14 patients had known encounters with bats. Four people awoke because a bat landed on them and one person awoke because a bat bit him. In these cases, the bat was inside the home.
Rabid bats have been documented in all 49 continental states. Hawaii is rabies-free. Bats are increasingly implicated as important wildlife reservoirs for variants of rabies virus transmitted to humans.
Recent data suggest that transmission of rabies virus can occur from minor, seemingly unimportant, or unrecognized bites from bats. Human and domestic animal contact with bats should be minimized, and bats should never be handled by untrained and unvaccinated persons or be kept as pets.
In a 2016 MMWR there was a tragic report of a woman in Wyoming who died of rabies after a bat bite (Harrist A, Styczynski A, Wynn D, et al. Human Rabies — Wyoming and Utah, 2015. MMWR Morbidity and Mortality Weekly Report 2016; 65:529–533. DOI: http://dx.doi.org/10.15585/mmwr.mm6521a1. ) CDC cited as responsible factors a lack of rabies knowledge on the part of the public and inadequate education and coordination from local public health agencies.
A few years ago my own daughter was bitten by a dog wandering in our neighborhood. Within an hour of the incident, I tried to follow up with local agencies (police, animal control, ASPCA) as well as my Westchester County Health Department. I was appalled at the lack of knowledge among officials about rabies exposures and had to strongly advocate for my child to get the evaluation she required. Fortunately, the dog was not rabid. Over the course of a very stressful week, I learned that neither my town nor county had a rabies exposure protocol, and coordination between human and animal health management units was totally lacking.
As travel health nurses we regularly discuss rabies prevention and vaccination for international travel. In my own practice I also use the opportunity to share CDC guidelines for domestic bat exposures. Bats are recognized as a source of rabies in the U.S. as described on the CDC website, http://www.cdc.gov/rabies/bats/contact/index.html.
General guidelines for how to determine if a person should seek medical evaluation after a bat encounter:
- If an adult wakes up with a bat in the room, try to safely capture the bat for examination and seek professional evaluation.
- If a child, asleep or awake, is alone in a room with a bat, professional evaluation is indicated.
- If a bat is observed near a mentally impaired or intoxicated person, seek professional evaluation.
- And of course, if either an adult or child knowingly experiences a bat bite, professional evaluation is warranted.
Keep in mind that a bat bite may not be apparent. Bat bites can be very, very small and often clinicians never locate the actual bite. Post-exposure evaluation and management is based on history, not direct evidence of a bite.
As described in the MMWR notice, and as I have recounted in my own experience, local authorities may not provide accurate follow-up guidance. Encourage your patients to follow-up with their state health department or the CDC to insure that any potential rabies exposure is properly assessed and treated in accordance with the most up-to-date guidelines. If treatment is indicated, but no bite wound can be located, the patient will still require the full post-exposure protocol consistent with their pre-bite status. Assuming no pre-exposure vaccination series, HRIG and four doses of rabies vaccine should be given in accordance with the CDC schedule of 0, 3, 7, and 14. Rather than infiltrate HRIG around the wound, the clinician will administer HRIG at an IM site distant from the vaccine site.
When travel health nurses advise patients about rabies, education about avoidance is foremost. When discussing post exposure care, it is important to include these key messages:
- Thoroughly wash the bite with copious amounts of soap and water as soon as possible. Rabies virus is in saliva and it is important to remove as much saliva as possible.
- Seek evaluation only at a medical facility that meets CDC and WHO standards of care such as a regional medical center. Travelers can contact their embassy for guidance.
- If treatment is received while abroad, get documentation of the name of the treatments and the dates. This is especially important if treatment needs to be completed upon return.
- Ideally start treatment within 24 hours, however, because rabies virus can persist in tissue for a long time before gaining access to a peripheral nerve, a patient who has sustained a bite that is suspicious for rabies should receive full PEP, including HRIG, even if a considerable length of time has passed since the initial exposure. The Annals of Indian Neurology reports a case of rabies incubation delayed 25 years (Shankar, S.A. et al., Rabies viral encephalitis with probable 25 year incubation period! Ann Indian Acad Neurol. 2012 Jul-Sep; 15(3): 221–223 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424805/)
- CDC guidelines for post-exposure medical care are available In the CDC Yellow Book at http://www.cdc.gov/rabies/medical_care/index.html
Although the CE accreditation has expired, CDC offers a training video on “Rabies Post-exposure Prophylaxis Basics” for further learning (http://phpa.dhmh.maryland.gov/training/Pages/rabies.aspx)
Gail Rosselot NP, MS, MPH, FFTM, RCPS (Glas), FAANP, FISTM, FATHNA http://www.nptravelhealth.com