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The virus replicates in muscles at the bite site, then spreads via peripheral nerves to the spinal cord and up into brain tissue. It can follow along nerves going to salivary glands, from which it can be transmitted in a bite. Bites on the face are associated with the highest rates of infection and death, and on legs the lowest.
The medical stages of rabies in humans roughly divide into four. The first is nonspecific, like so many other viral illnesses, and lasts about one to four days with fever, headache, feeling rotten, muscle aches, sore throat, cough, etc. A curious feature more peculiar to rabies is shooting pains and muscle twitching at the bite site, affecting about 50 percent to 80 percent of those infected.
The second, or brain infection, phase is what gives rabies (Latin for rage or fury) its name. The person becomes excessively agitated, confused, combative, hallucinatory, alternating with periods of clear thinking (sure sounds like a parent discussing the fate of the family flivver-car last night with teen offspring).
A host of other nervous system symptoms can occur, such as seizures or violent back spasms. An odd feature here is extreme sensitivity to light, loud noise, touch or even gentle breezes that can trigger muscle spasms.
The third stage, characterized by hydrophobia (fear of water, and actually a misnomer) is the hallmark of rabies. It overlaps and blends with the second. It is the painful, violent, involuntary contraction of the diaphragm and swallowing and breathing muscles when trying to drink liquids, seen in about 50 percent of those infected. The combination of excessive salivation and spasms of swallowing muscles during attempts to drink or eat create the “foaming at the mouth” image. (Picture yourself when you first heard about the car at the dinner table.)
The fourth stage is lapsing into coma, paralysis and death from breathing failure.
The average survival after symptom onset is four days, maximum 20.
A known variation from these patterns in 20 percent of patients is called “dumb (silent) rabies.” In these cases, the rage and hydrophobia are missing. Instead, there is an ascending paralysis, like Guillaine-Barre syndrome. This occurs mostly after a vampire bat bite.
The diagnosis of rabies is difficult. There is little to distinguish rabies clearly from other viral brain infections. The most helpful point is the history of exposure. The incubation period from infection to symptoms is highly variable. It may be from one to three months, with a range of seven days to more than a year.
Even with only zero to five human cases reported each year in the U.S., it is still worthwhile preventing one of the most grisly deaths known. There have been only a handful of patients who have survived rabies with intensive life support once it has begun.
It is wise to agree to rabies immunizations if there is any thought you may have it incubating. It could keep you from becoming literally rabid and dead, which is otherwise inevitable.
In contrast, your teenager’s demise is unlikely, even after your rabid phase, mostly because of the laws.
