The much anticipated part 2 on rabies.
Onto the actual important part of this POTD: Rabies post-exposure prophylaxis (PEP). Who gets it and how?
Who: UptoDate keeps recommending contacting local health officials for recommendations which, less face it, generally isn’t happening.
- Anyone with a known or likely exposure to rabies defined as…
o Bite or saliva-containing scratch from an animal with rabies
o An open wound or mucus membrane exposure to saliva, CSF, or CNS tissue from an animal with rabies
- Empirically to anyone with suspected exposure (pretty open-ended)
- Exposure of keratinized skin to saliva, blood, feces DOES NOT count as an exposure
For domesticated animals
- High risk: undocumented vaccination status, aggressive behavior
- If animal (dog, cat, ferret) able to be observed/quarantined for 10 days, can hold off PEP until end of 10-day period
o Animals almost universally show signs within 10 days of rabies
For wild animals
- High risk: bat, raccoon, skunk, fox
o Start PEP, discontinue if animal able to be tested promptly and is negative
- Low risk: squirrel, chipmunk, mouse/rat, rabbit/hare
o Do not start PEP
How: There are 2 components, (1) the rabies vaccine and (2) rabies immune globulin (RIG)
1) Rabies vaccine – administered 1mL IM specifically in the deltoid region (not gluteus muscle, risk of sciatic damage/lower response to vaccine). Has a very specific dosing schedule
a. If patient has received pre-exposure prophylaxis: 2 doses, Day 0 and Day 3
b. If patient unvaccinated: 4 doses, Days 0, 3, 7, and 14
i. If immunosuppressed, a 5th dose is given on Day 28
c. Day 0 is first day that rabies vaccine is given
d. It can be helpful to write the dosing schedule on the discharge papers for future providers (speaking from experience)
2) RIG – only indicated if patient has not received pre-exposure prophylaxis
a. 20 U/kg – as much as possible infiltrated around the wound with the rest delivered IM in the opposite deltoid of the vaccine arm.
b. If no obvious wound, place all IM
PEP should be given regardless of delay from time of exposure
Are there any adverse events with vaccination? Depends on the vaccine…
- Usually local skin reactions (pain, redness, swelling, induration) with possible mild systemic symptoms (fever, headache, GI symptoms)
- Hypersensitivity or anaphylaxis can switch to a different vaccine formulation if possible
- Counseling should be given on these symptoms to prevent patient non-compliance with future doses
FAQ
1) What if they patient doesn’t closely follow the dosing schedule?
Small deviations aren’t that important, and doses should be administered at the same intervals. For example, if day 7 dose is actually given on day 10, then the next dose should be scheduled on day 17 (or 7 days later), etc.
For more significant delays… consult ID? Seriously though, it likely involves antibody testing and titers, while attempting to follow the initial dosing patient was started on (maybe requires ID follow-up).
2) What if patient received different formulations of rabies vaccine?
Just give them what you have and have them follow-up with their PCP or clinic for antibody titers. Theoretically the vaccines are interchangeable but not ideal.
3) What if the patient is pregnant?
Not a contraindication, no evidence associated with fetal abnormalities or adverse pregnancy outcomes.
4) If RIG was not initially administered? Like if a traveler returns from a foreign country and needs to have their scheduled doses at specifically YOUR emergency department
RIG can be administered on return if less than 7 days from initial vaccine administration. RIG should not be administered afterwards because it interferes with the normal immune response that the vaccine causes.
Last, but not least, general wound care like irrigation should always be performed along with tetanus. Antibiotics are a more nuanced discussion, and possibly a POTD for another day (although I lean towards providing a course for patients with animal bites in general).
TL; DR – and considerations for a busy, NY ED
- If there was an exposure (actual bite, found in room with a bat) and patient is concerned – give PEP. No serious adverse events.
- PEP = vaccines in a specific dosing regimen (0, 3, 7, 14, and maybe 28) and RIG (20U/kg) around the wound and the rest IM
- Please write the dosing schedule with dates on the discharge papers. This makes this patient encounter incredibly easy for your fast track resident.
This is likely more than you ever wished to know about rabies. I learned a lot, like next time Mak needs the rabies vaccine I’ll make sure to give it in his arm instead of his butt.
https://www.uptodate.com/contents/treatment-of-rabies?topicRef=8328&source=see_link
https://www.uptodate.com/contents/rabies-immune-globulin-and-vaccine?topicRef=8328&source=see_link