microbio 2125 unit 6 part 15 - Rabies

Etiological Agent:

Rabies virus (genus Lyssavirus, family Rhabdoviridae)

Distinguishing characteristics of etiological agent:

Enveloped, bullet-shaped virions;

single-stranded RNA virus (ssRNA);

slow, progressive zoonotic virus

Virulence Factor(s):

Neurotropism (ability to spread along peripheral nerves to the central nervous system), replication in salivary glands enabling transmission

Predisposing Factors:

Exposure to wild or stray animals; unvaccinated domestic animals; bites, scratches, or contact with infected animal droplets

primary reservoirs are wild mammals

Transmission:

Zoonotic transmission via bites, scratches, or inhalation of droplets from infected wild or domestic mammals

Syndrome (signs + symptoms): Prodromal phase

fever, nausea, vomiting, headache, fatigue; burning/tingling at bite site

Syndrome (signs + symptoms): Furious phase

agitation, disorientation, seizures, twitching, hydrophobia

Syndrome (signs + symptoms): Dumb phase

paralysis, disorientation, stupor

Progresses to coma and death

Affected body region/system:

Nervous system (CNS); also affects salivary glands during viral replication

Treatment:

• Passive and active post-exposure immunization

• Infusion of wound with human rabies immune globulin (HRIG) and rabies globulin

• Vaccination with human diploid cell vaccine (HDCV): 6 doses + 2 boosters

Prevention:

• Vaccination of domestic animals

• Elimination of stray animals

• Strict quarantine of potentially exposed animals

• Live oral vaccine in bait for wild animal immunization

Other notes:

Diagnosis in living patients is based on detecting virus in blood; often confirmed at autopsy by presence of Negri bodies in nervous tissue