Rabies Virus - Research Paper Example

The RNP complex along with the the viral RNA is comprised “of the proteins L (transcriptase), N (nucleoprotein), and NS (transcriptase-associated)” (Rupprecht). “These aggregate in the cytoplasm of virus-infected neurons and compose Negri bodies, the characteristic histopathologic finding of rabies virus infection. The M (matrix) and G (glycoprotein) proteins are associated with the lipid envelope. The G protein forms the protrusions that cover the outer surface of the virion envelope and is the only rabies virus protein known to induce virus-neutralizing antibody” (Rupprecht).

Rabies virus can be either the fixed type or street (wild type) (Rupprecht). Incubation period In dogs, the incubation period is usually 3-6 weeks but it may range from 10 days to a year. In man, the incubation period is usually from 1-3 months though it may be as short as 10 days or as long as 3 years. Incubation period is usually short in persons bitten on the face or head and long in those bitten on the legs. Incubation period is shorter in children. (Ananthnarayanan) Reservoirs of infection and host range The rabies virus infects a wide range of hosts, including dogs and cats, raccoons, coyotes, skunks, foxes, bats, and human beings.

Any warm-blooded animal can be infected with rabies; however, some animals like wolves, foxes, and coyotes are more susceptible (Ananthnarayanan) Transmission About 99.8% of reported cases of rabies are due to bites of animals. The “other forms of transmission that have been reported includes contamination of mucous membranes, faulty vaccines, corneal transplants, and aerosol transmission” (Rupprecht) Signs and symptoms Rabies virus affects primarily the central nervous system, and causes an acute infection.

In humans, there are five clinical stages: “the incubation period, prodrome, acute neurologic period, coma, and death” (Rupprecht) The prodromal period usually lasts from 2 to 10 days and clinical symptoms are first noticed during this stage. The symptoms may include fever, general malaise, fatigue, cough, sore throat, dyspnea, nausea, vomiting, anorexia, dysphagia, abdominal pain, diarrhea, irritability, vertigo, headache, anxiety, nervousness and apprehension (Rupprecht). Some significant features like “insomnia, nightmares, depression, increased agitation, photophobia, priapism, and increased libido, may also occur” (Rupprecht).

In that case, it suggests the presence of psychiatric disturbances encephalitis, or other brain abnormalities (Rupprecht). A pathognomonic feature in the acute neurologic period is difficulty in drinking together with intense thirst. Attempts to drink brings painful spasms of pharynx and larynx, producing choking that patients later develop a dread for even the sight or sound of water (hydrophobia) (Scheld & Whitley) In the acute neurologic period, the disease is categorized as dumb rabies if paralysis is the main clinical feature and as furious rabies if the symptom of hydrophobia is the main clinical feature.

Both types of rabies may show signs like “focal and generalized convulsions, muscle fasciculations, hyperventilation, paresthesia, hypersalivation and nuchal rigidity” (Rupprecht) After the acute neurologic period ends, the patient may develop a rapid, irregular type of breathing. Very soon, paralysis and coma develops. Unless ventilator support is instituted, the patient may