A short Intro to Rabies Pathophysiology and Treatment

Rabies is a condition caused by virus rabies virus. This virus belong to family of virus Rhabdoviridae and genus lyssavirus.  It is RNA virus and bullet shaped.

Rabies is the condition in which the rabies virus cause encephalitis.

Mood of Transmission

Mood of transmission is mainly from biting of animal which is infected or carrier. Zoonotic disease of warm blooded animals (dogs, cats, foxes and other wild animals).

1. 1  Bites by animals is the main reason.
2. 2)      Non Bite exposure is due to the fluid aerosols contact which come in contact with wound on the skin and other mucosal tissues.
3. 3)      Human to human transmission may occur but is very rare.

Pathogenesis : Incubation period 20-90 day.

1. Stages
2.      In first stage the virus inoculation through bite.
3.       Replication state characterized by replication of virus in muscles.
4.    Axonal transport to the CNS from the muscles. At this stage rabies become fetal up to 100 % mortality rate.

1. 5. Replication in the CNS and encephalitis. And spread to the sensory nervous form CNS.

Clinical Manifestation

In prodromal period when the virus enter the CNS. The duration of this period is 2-10 days.

In prodromal period symptoms include

Malaise, anorexia, headache, fever, chills, pharyngitis, vomiting, nauseas, anxiety, paresthesia at bite site, diarrhea, agitation, mild to moderate depression.

Acute Neurologic Period

In acute phase the clinical symptoms start to appear, like spasms, agitations, generalized convulsions, hydrophobia, agoraphobia, paralysis may occur and coma. And death due to spasms of respiratory failure.

Diagnosis

• Diagnosis made on the symptoms of disease after current or past bite.
• Rabies virus finding in the cutaneous nervous by fluorescent antibody.
• PCR detection of rabies virus in saliva, bites site tissue, cerebrospinal tissues, and brain tissues often postmortems.
• Blood gas analysis: - respiratory alkalosis resulting from hyperventilation.
• Hematology: - Normal to elevated with 6-8% atypical monocytes.
• MRI :- Nonspecific damage to the brain.
• EEG:- Non specific pathogenic findings.
• Negri Bodies which are the Ribonucleic bodies found in the various cells. Extrapyramidal cells. Purkenjee cells.

Treatment

• No post infection treatment after the virus has caused meningitis .  Just symptomatic approach. Neuromuscular relaxant, Benzodiazepines to prevent CNS complications.
• After exposure Anti Rabies vaccine is recommended which include 5 doses. At 0,3,7, 14 and 28^th day of the treatment.
• Wound is usually not stitched because the virus may reside there in the stitched wounds.  Wound is washed directly with soap if emergency treatment or first aid is not available.