History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include a recent scratch or bite from a known vector in a rabies-endemic country, recent contact with a bat, and occupational or recreational exposure.
hydrophobia
A classic sign of rabies that appears within a few days of disease onset and is identified in about one third of the cases.
Attempting to drink or being presented with liquid to drink produces severe laryngeal or diaphragmatic spasms and a sensation of choking.
Can be elicited by presenting a cup of water to the patient.
One of the most specific signs of the disease.[13]
aerophobia
A classic sign of rabies that appears within a few days of disease onset.
Air blown on the face produces severe laryngeal or diaphragmatic spasms and a sensation of choking.
Can be elicited by fanning the face or placement of nasal cannulae.
One of the most specific signs of the disease.[13]
limb numbness, pain, and paraesthesia
dysphagia
Occurs in 41% of cases.[13]
fever
Always present in rabies infection and appears as part of the prodrome.
The diagnosis of rabies is unlikely unless the patient is at least intermittently febrile.
change in behaviour
Frequently the first sign observed by the family.
Rare in the paralytic form.
agitation and confusion
Usually relapsing/remitting over hours.[13]
Rare in the paralytic form.
hallucination
Frequently seen in patients with encephalitic form.[44]
signs of autonomic instability
rapid progression of symptoms
Rabies progresses rapidly over a period of days.[39] If this progression does not occur, rabies is less likely.
weakness and paralysis
Present in about 16% of cases.[13]
The main feature of the paralytic form.
Other diagnostic factors
common
uncommon
abdominal pain
Reported in 20% of cases diagnosed antemortem. Can be confused with acute abdomen.[39]
insomnia
A non-specific symptom.
seizures
May be seen in pre-terminal phase.[40]
slurred or stuttered speech
Due to neurological deficits.
ataxia
May be accompanied by other motor deficits in atypical cases.[40]
Risk factors
strong
recent scratch or bite from a known vector
The principal vector in developing countries is the dog.
In the US, vectors include bats, raccoons, skunks, foxes, and mongooses.[17] Bats are the major source of infection in the US and the Americas. Over 95% of indigenously acquired cases in the US are caused by bat viruses. Only 55% of patients with a bat rabies virus infection report an antecedent bite from a bat or other physical contact with a bat.[13] About 10% of patients with a bat rabies infection and no known history of bat contact have a recent history of finding bats in the home.[15][32]
In Western Europe, Brazil, and South Korea, rabies has also been maintained in nature by other vectors. Many reservoirs are found in wild carnivora, including coyotes; red, arctic, and grey foxes; jackals; mongooses; raccoons; skunks; and wolves.[18] Bats have also emerged as vectors in some Latin American and European countries, parts of Africa, and Australia. The main vector in Western Europe is the red fox.
A case has been reported in a captive anteater (tamandua). This demonstrates the possibility of rabies translocation by human movement of captive mammals, including species in which rabies has not been previously reported.[26]
travel to/living in rabies-endemic country
occupational or recreational exposure
People at elevated risk for exposure to rabies include: people working with live rabies virus in research or vaccine production facilities; people performing diagnostic testing for rabies in laboratories; people with frequent bat contact; people who interact with animals who could be rabid; people who perform animal necropsies; people whose occupational or recreational activities typically involve animal contact; and selected travellers (depending on occurrence of animal rabies in destination country, availability of treatments, intended activities, and duration of stay). Occupations at higher risk include animal handlers, field biologists, cavers, missionaries, veterinarians, and some laboratory workers.[33]
weak
age <15 years
A disproportionate number of dog bites and 30% to 50% of rabies cases occur in children.[12] Children are also less likely to report contact with a bat or other wild animal.
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