rabies
Fatal , acute viral encephalomyelitis *
Onset : * sense of apprehension
* headache , fever , malaise
* indefinite sensory changes often
referred to the site of animal bite
*excitability & aerophobia (are frequent symptoms ) .
Laboratory diagnosis
**Antemortum
Skin biobsy
Flourescent antibody technique ( for viral Ag detection )
Corneal impression
Saliva smear for FAT ( less reliable )
The disease progress to :
paresis or paralysis
Spasm of swallowing muscles lead to fear of water (hydrophobia ), photophobia (fear of light ), tremors , spasm
Delirium , convulsions
Without medical intervention : the usual duration is 2-6 days
Death is often due to respiratory paralysis .
Postmortum :
Biopsy of brain and sellers stain for Negri bodies
FAT
Infectious agent
,Rabies virus, a rhabdovirus of the genus Lyssavirus
Occurrence : worldwide , with an estimated 35,000 – 40,000 deaths a year , almost all in developing countries .
Rabies is a disease
primary of animals .
Reservoir :
Many wild & domestic canidae including
dogs, cats,monkeys, foxes, wolves , jackals ,racoons
& other biting mammals
In developing countries , dogs remain the reservoir .
Mode of transmission
Virus laden saliva of a rabid animal is introduced by a bite or scratch
Transmission from
person to person ( theorotically possible since the saliva of infected person contain virus )
Organ ( corneal) tranceplant taken from persones have rabies
airborne spread ( lab & caves).
Incubation period
Usually 3-8 wks , depends on the severity of the wound , site of the wound in relation to the richness of the nerve supply . & its distance from the brain . Amount & strain of virus introduced , protection provided by clothing & other factors .
Period of communicability
In dogs & cats , usually for 3-7 days before
onset of clinical sign & throughout the course of the disease .
Susceptibility & resistance
All mammals are susceptible to varying degrees , which may be influence by the virus strain .
Methods of control
A- Preventive measures :
1- immunize all dogs ,collect & euthanized ownerless animal and strays. Immunized all cats.
Educate pet owner & public that restrictions for dogs and cats are important , also animals with strange acting or sick animal of any spp , domestic or wild, may be dangerous & is necessary to report such animals & animals that have bitten a person or other animal
2- maintain active surveillance for rabies in animals .
3- observe for 10 days any healthy appearing dogs or cat known to have bitten a person . If the biting animal were infective at the time of the bite , signs of rabies will usually follow within 4-7 days , with change in behavior and excitability or paralysis , followed by death .
.
In the case of bites by
normal behaving , very valuable pet or zoo animal , it may appropriate to consider post exposure prophylaxis for the human victim , and , instead of sacrificing the animal , hold it in quarantine for 3-12wks .