Rabies and Zoonotic Risk on Rural and Animal Calls

Why this matters

A zoonotic disease is one that passes from animals to people. Most of them are a nuisance and a few are serious, and one, rabies, is almost always fatal once symptoms start and almost entirely preventable if treatment begins in time. The trap is that the dangerous exposures do not feel dangerous. A bat bite can be smaller than a pinprick and go unnoticed. A tech scratched by a farm cat thinks about the scratch, not the cat. This card sorts the animal exposures field crews actually meet into the ones that need a doctor today and the ones that do not, and explains why. What to do in the first minutes after a bite or bat contact is in The Animal Bite or Bat Contact Response SOP.

Rabies, in the terms you need

Rabies is a virus carried in the saliva and nervous tissue of an infected mammal. It spreads through a bite, or through saliva getting into a scratch, an open wound, the eyes, nose or mouth. It does not spread through petting an animal, touching blood, urine or feces, or being near a rabid animal without contact. Bat guano carries other hazards, but rabies is not one of them.

After exposure the virus travels slowly along nerves, and the delay before symptoms is usually weeks to a few months. That delay is the window. Post-exposure prophylaxis (PEP), a dose of rabies immune globulin around the wound plus a series of vaccine shots over about two weeks, is highly effective when started before symptoms. Once symptoms appear, there is essentially no treatment. Nobody waits to see whether symptoms develop; the decision about PEP is made by a doctor and the local health department, usually within a day or two of the exposure.

Which animals carry it, and where

In the US the virus lives in a few wildlife reservoirs, and which one matters depends on where you work:

• Bats, everywhere in the continental US. Most human rabies cases in recent decades trace to bats.
• Raccoons, along the eastern seaboard and into the Appalachians.
• Skunks, across the north-central and south-central states and in California.
• Foxes, in parts of Alaska, Arizona and Texas, among others.
• Domestic animals catch it from wildlife. Unvaccinated cats are the most common rabid domestic animal in the US, ahead of dogs, which matters on farms where barn cats are rarely vaccinated.

Small rodents and rabbits sit at the other end. CDC notes that squirrels, chipmunks, rats, mice, hamsters, rabbits and hares are almost never found rabid and have not been known to give rabies to people in the US. The exception that catches people: groundhogs (woodchucks) are the rodent most often reported rabid, and a groundhog bite is treated as a real exposure. Any rodent bite still gets washed and reported, and the health department makes the call, but the default answer is different.

Bats need their own rule

A bat's teeth are so small that a bite may leave no mark you can see and may not wake a sleeping person. So CDC's guidance does not wait for a visible bite. A person should get medical advice about PEP when they:

• had direct contact with a bat and cannot rule out a bite or scratch, or
• woke up to find a bat in the room, or
• were in a room with a bat while unable to know whether they were bitten: a sleeping person, an unattended child, or someone intoxicated or mentally impaired.

That last rule is why a bat found in a bedroom is a health department call, not a pest call. Unless the bat can be captured and tested and comes back negative, the people in that room may need treatment. Testing needs the bat's brain intact, so a bat swatted with a shovel or flushed down a toilet takes the cheapest answer off the table.

A tech working an attic or eave is not "sleeping," so seeing bats while awake and untouched is not an exposure. Handling one, being bitten or scratched, or having one land on bare skin is.

Domestic animals: the 10-day rule

When a dog, cat or ferret bites, the health department's usual path is to have the animal confined and observed for 10 days. A dog, cat or ferret that can spread rabies through a bite will show signs of illness within that window, so an animal that stays healthy through it could not have transmitted rabies at the time of the bite, and the bitten person does not need PEP. This is why getting the owner's name and address before you leave a property matters more than anything you do to the wound beyond washing it. An unknown stray that runs off is a different case, and the doctor and health department weigh it with the local rabies picture.

The other animal-borne risks on rural calls

• Ringworm is not a worm. It is a fungal skin infection that spreads from cats, kittens, calves, horses and dogs by touch, and from contaminated bedding, fences and tools. It looks like an itchy, scaly ring on the skin, often on forearms, within about a week or two of contact. It is treatable with antifungals, and it is the reason not to pick up the barn kitten with patchy fur.
• Q fever is a bacterial infection carried in the birthing fluids, placenta and dried dust of barns where sheep, goats and cattle give birth. It is breathed in, not touched, so the exposure is sweeping or working in a dusty lambing or calving barn. It shows up as flu-like illness, sometimes with pneumonia.
• Leptospirosis comes from animal urine in water and wet soil and enters through cuts and the eyes, nose and mouth. It belongs on farms with standing water and on any flooded site; see related: Floodwater Exposure for Any Trade.
• Salmonella and E. coli ride on poultry, including backyard chickens, and on manure. The protection is handwashing before eating, drinking or smoking, and not eating in a barn.
• Psittacosis comes from dried droppings of pet birds and poultry, inhaled. It sits beside the attic-droppings infections; see related: Bird and Bat Droppings and Histoplasmosis.

The protective habits are few and cheap: do not handle animals you do not need to touch, wear gloves where you handle anything an animal has lived in, wash hands with soap before eating, keep a respirator for dusty barn and animal-housing work, and cover cuts before you go in.

A worked example: one week, four exposures, four answers

A rural shop's techs report four animal contacts in one week. The owner sorts each against the rules above.

Monday, a bat in the nursery. A homeowner tells the tech that a bat was flying in the room where her two-year-old was napping alone. The tech, wearing leather gloves, traps it under a plastic container against the wall, slides cardboard underneath and tapes it shut without touching the bat, then tells the homeowner to call the health department now. The answer: the child was an unattended sleeping person in a room with a bat, so the child needs medical evaluation; the contained bat means testing may settle it. If the bat had flown out the door, the child would likely be advised to start PEP, because a bite cannot be ruled out. The tech's own exposure: none, because he never touched it with skin.

Tuesday, a squirrel scratch. A tech removing a dead nest from an attic gable gets scratched by a live squirrel. Squirrels are on CDC's almost-never list. The answer: wash the scratch with soap and water, report it to the office, and call the health department, which in most places will say no PEP is needed. A doctor still sees the scratch if it gets red or swollen, because an animal scratch can carry an ordinary bacterial infection regardless of rabies.

Wednesday, a groundhog bite. A tech working on a well pump in a field is bitten through his jeans by a groundhog he did not see. Groundhogs are the rodent exception. The answer: wash with soap and running water for about 15 minutes, same-day medical evaluation, health department report, and treat it as a potential rabies exposure. Wednesday and Tuesday look alike, a rodent and a wound, and resolve oppositely because of which rodent it was.

Friday, an itchy ring. A tech who spent last week's farm call petting a barn kitten with patchy fur notices a scaly, itchy ring on his forearm. The answer: not urgent, not rabies. See a doctor or pharmacist for a fungal infection, keep it covered at work, and wash the work shirt he wore that day.

The failure version of this week is the shop that treats all four alike. Treat them all as nothing and the groundhog bite goes unreported, which is the one that could kill. Treat them all as emergencies and the crew stops reporting scratches because each one costs an afternoon in urgent care.

When to see a doctor, and what to bring

See a doctor the same day for any bite or scratch from a bat, raccoon, skunk, fox, groundhog, or any other wild carnivore; any bite from a dog, cat or ferret you cannot identify; and any bat contact or bat-in-the-room situation above. Bring the animal type, the location, the owner's details if it was a pet, whether it was captured, and the time.

For the slower infections, ringworm, Q fever, leptospirosis, psittacosis, the issue is not urgency but remembering to mention the animal. A tech who sees a doctor two weeks later with a fever and does not mention the calving barn gets treated for the flu. Tell the doctor where you worked. See related: The Tech Got Sick Two Weeks After the Attic Job.

Pre-exposure vaccination is a two-dose rabies vaccine series that CDC's advisory committee recommends for people whose work brings frequent risk, such as wildlife control workers who handle bats. It does not replace treatment after an exposure; it simplifies it. For most trades it is not needed. For a pest or wildlife control tech who handles bats regularly, it is worth a conversation with an occupational medicine clinic.

References

• CDC, Rabies: exposure assessment, bats, and post-exposure prophylaxis guidance
• CDC Advisory Committee on Immunization Practices, rabies vaccine recommendations (2022)
• CDC, Q fever, leptospirosis and ringworm information pages
• See related: The Animal Bite or Bat Contact Response SOP
• See related: Bats in Attics and the Maternity Season