FAQ: Rising rabies exposure calls put PEP decisions back in focus

World Rabies Day, observed this past Monday, September 28, arrives on the heels of a Health Alert Network (HAN) advisory issued earlier this month by the Centers for Disease Control and Prevention (CDC). The advisory followed a 17% increase in calls to the agency this summer about potential human rabies exposures in the US. Rabies remains nearly universally fatal once the virus reaches the central nervous system, making prompt recognition of exposures and timely PEP the only reliable defense.

Related: Essential advice from a rabies expert

Rodney E. Rohde, PhD, SV/SM/MB(ASCP)CM, FACSc, university distinguished and regents' professor and chair of the Medical Laboratory Science Program in the College of Health Professions at Texas State University, cautions that the rise reflects more reported exposures and more PEP use rather than evidence of a sustained increase in human rabies disease. Drawing on his conversations with Contagion and dvm360, the following FAQ outlines what clinicians and veterinarians need to know about exposure assessment, wound care, PEP administration, and cross-disciplinary collaboration with public health.

Rohde offered insights around rabies and treatment. Here are some highlights from the 2 conversations:

Does the CDC advisory mean human rabies cases are increasing in the US?

Not necessarily. The CDC's advisory was prompted by a 17% increase in calls this summer about potential human exposures. Rohde emphasizes the distinction: "What we're actually seeing is more reported human exposures, not necessarily yet evidence of a sustained increase in human rabies disease." The measurable change so far is primarily in rabies exposures and the use of PEP.

What should patients do immediately after a potential exposure?

Rabies is transmitted primarily through a bite and, less commonly, a scratch that introduces infected saliva into broken skin or mucous membranes. Patients should wash and irrigate the wound thoroughly with soap and water right away, which reduces the amount of virus at the site, and then contact a health care provider. Rohde stresses that rabies is a medical emergency and that patients should never wait for symptoms to develop, because once the virus enters the brain the disease is fatal; only 1 person in recorded history has survived clinical rabies without having received PEP. He also warns against patients deciding on their own that an animal "looked fine," since the appearance of an animal is not a reliable indicator of infection.

Which animals should clinicians consider when assessing rabies risk?

Any warm-blooded mammal can acquire rabies. In the US, bats are the top concern because contact often goes unnoticed, and bat-associated rabies has caused human deaths. Raccoons, skunks, foxes, and feral cats are also important sources. Rohde notes that clinicians should think beyond these traditional reservoirs: a widely reported North Carolina case involved 3 unvaccinated baby goats at a petting zoo that were laboratory-confirmed with rabies after likely exposure to a skunk, triggering a large human exposure investigation. Livestock and pets are not primary reservoirs, but unvaccinated animals can become infected from wildlife and then expose people. Variant typing of a confirmed animal can identify the likely wildlife source.

What does the current PEP regimen involve?

PEP depends on the patient's vaccination status. Unvaccinated individuals receive a 4-dose vaccine series on days 0, 3, 7, and 14, along with human rabies immune globulin (HRIG). Individuals who were previously vaccinated or are receiving pre-exposure prophylaxis (PrEP) receive 2 vaccine doses given 3 days apart, without HRIG. HRIG is given only once, at the start of the PEP course, to provide immediate antibodies until the vaccine produces an immune response. Per the CDC, HRIG should never be administered in the same syringe or at the same anatomical site as the first vaccine dose. Rohde notes that outdated stories of "30 shots in the stomach" can discourage people from reporting exposures; today's regimen is a few injections in the arm, comparable to a flu or tetanus shot, given over roughly 2 to 4 weeks.

How should clinicians assess exposure risk, and which patients need an adjusted approach?

Rohde recommends recognizing the exposure and assessing risk quickly. Clinicians should check local epidemiology with public health authorities, take a travel history, and determine whether saliva reached broken skin or mucous membranes through a bite or scratch. When in doubt, he advises leaning conservative and starting the vaccine series. Immunocompromised patients may need a fifth vaccine dose on day 28, followed by a check of their antibody response.

What role do veterinarians and public health departments play?

Veterinarians are a first line of defense alongside physicians. Rohde advises keeping domestic animals and livestock appropriately vaccinated, since vaccination creates a barrier between wildlife, domestic animals, and people; goats, for example, may be vaccinated less often than cattle, horses, or pigs. Veterinarians should watch for early potential exposures and work closely with public health authorities, which are often the best source of information on regional hotspots and can support prompt, evidence-based decisions. Accurate risk assessment by veterinarians and physicians protects both animals and people while helping avoid unnecessary PEP, which can be expensive and difficult to obtain.