Clinical signs in animals
All animals exhibit certain neurological signs as a result
of rabies. From species to species these symptoms may differ slightly.
Prodromal stage: After a certain incubation period, the
onset of clinical symtoms follows. During this first stage which usually lasts
for about 1-3 days minor behavioural changes might occur, i.g agressiveness in
tame animals, daytime activities in nocturnal animals, no fear of humans in wild
animals or abnormalities in appetite.
Excitative (furious) phase: Eventually, the prodromal
stage is follwed by a period of severe agitation and agressiveness. The animal
often bites any material. Rabid dogs, for example, may develop a typical high
barking sound during furious rabies. Death may follow convulsions even without
the paralytic stage of the disease.
Paralytic (dumb) phase: This stage is characterized by the
inability to swallow, leading to a typical sign of foaming saliva around the
mouth. Some animals may develop paralysis beginning at the hind extremities.
Eventually, complete paralysis is followed by death.
Clinical signs in humans
It is very difficult to differentiate rabies in humans
from other diseases by clinical examination. In rabies-endemic countries rabies
should always be suspected when neurological symptoms follow an animal bite.
After the incubation period a 2–10 days prodromal period of nonspecific symptoms
is followed. The first clinical symptom is usually neuropathic pain at the wound
site. Further symptoms which may include tiredness, weakness, loss of appetite,
headache, fever and other aches suggest involvement of the respiratory,
gastrointestinal and/or central nervous systems.
During the acute stage of the disease two different forms
may occur. Furious rabies is characterized by hydrophobia or aerophobia,
hyperactivity and fluctuating consciousness. Paralytic rabies runs a less
dramatic course, but the final outcome is the same. Rabies is inevitably fatal
and death occurs during the first seven days of illness without intensive care
due to respiratory failure.