Let me get the obvious out of the way – I’ve never seen a case of rabies. In fact, in the county in which I work there has not been a case of rabies in over 60 years. But, you will all see children bitten by some sort of creature. So, when should we worry about rabies? Which animals are high risk? How do I know what to give and when to give it? Read on and learn more!
What does rabies actually look like in a human?
Bad. It looks bad. And it’s almost uniformly fatal. Most patients die within 2 weeks after onset of coma. Here are some specifics:
Prodrome (up to one week)
Non-specific symptoms, including fever, chills, malaise, myalgia, nausea, vomiting, headache, photophobia and a lot more. Patients can have paresthesias radiating from the wound site as well as localized pain due to the wound response and local injury. These are somewhat specific for rabies actually.
Encephalitic rabies (80%)
“Furious” rabies presents with fever, hydrophobia (pathologic fear of drinking water!), pharyngeal spasms (triggered after a draft of air), facial grimace (opisthotonos) and hyperactivity later leading to paralysis, coma and death
Paralytic rabies (20%)
Ascending paralysis – kind of like Guillain-Barré syndrome. Initially patients develop flaccid paralysis most prominent in the bitten limb then it spreads. Patients have fasciculations and DTRs are lost.
How does one make the diagnosis?
It’s hard and you need a high index of suspicion, which is the most important thing in the ED really. techniques include immunofluorescent antibodies of skin samples, virus isolation from saliva or anti-rabies antibodies in the CSF.
How is it treated?
Since most of you will never see rabies I’ll keep this part brief – It’s hard and requires ICU level management with induction of coma and multiple parallel therapies. I’ve linked to an article below that describes the Milwaukee protocol. For the more “human” side of things you should listen to the RadioLab episode on this topic. it’s excellent!
OK, how about prophylaxis? That’s what I’ll do in the ED anyway.
Most of your patients have never been vaccinated against rabies, so this is the immediate Day Zero regimen.
Rabies Immune Globulin (RIG)
Dose 20 units/kg . As much of the full dose as feasible should be infiltrated around the wound(s). Give the remaining IM at a separate site.
Human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV) 1 mL, IM (deltoid) – on days 0, 3, 7 and 14. I like to remember these dates as first half score tallies from an American Football game.
Previously vaccinated patients shouldn’t get RIG, and then get the vaccine on days zero and 3. Patients with immune compromise get five doses of vaccine on days 0, 3, 7, 14, and 28. Also, check out this algorithm to help decide when to employ post-exposure prophylaxis.