Viral Infections of Nervous System

What causes viral meningitis?

Non enveloped RNA virus part of the enterovirus subgroup

What does viral meningitis infect?

Throat, intestinal epithelium, lymphoid tissues

What is the inflammatory response of viral meningitis?

Fewer neutrophils and more monocytes enter CSF compared to bacterial meningitis

How is viral meningitis spread?

Fecal oral route. Feces of infected individual contain viruses for weeks.

Enteroviruses are stable or unstable in environment?

Stable, can exist in chlorinated pools

Treatment of viral meningitis?

No treatment, recovery within 7-10 days.

How to prevent viral meningitis?

Handwashing, avoid crowded swimming pools. No vaccines.

Which enteroviruses are most commonly associated with viral meningitis?

Coxsackieviruses and echoviruses.

What does "arbovirus" mean?

Arthropod-borne virus.

What is the leading cause of epidemic viral encephalitis in the United States?

West Nile virus.

Which viruses commonly cause epidemic encephalitis in the U.S.?

West Nile, La Crosse, St. Louis encephalitis, Eastern Equine, and Western Equine viruses.

What symptoms suggest viral encephalitis rather than meningitis?

Confusion, seizures, paralysis, and coma.

What cells are infected first after a mosquito bite?

Skin dendritic cells

What are the natural reservoirs for many arboviruses?

Birds and small animals

Why are humans considered dead-end hosts for West Nile virus?

Humans do not develop enough viremia to transmit the virus back to mosquitoes

What virus causes polio?

Poliovirus

What family does poliovirus belong to?

Picornaviridae

How is poliovirus transmitted

Fecal-oral route.

Which nervous system cells are targeted by poliovirus?

Motor neurons.

What is the hallmark symptom of poliovirus infection of the CNS?

Flaccid paralysis due to destruction of motor neurons

What vaccine did Jonas Salk develop?

IPV (Inactivated Polio Vaccine, injected).

What vaccine did Albert Sabin develop?

OPV (Oral Polio Vaccine, live attenuated).

Which vaccine is live attenuated?

Sabin OPV.

Which vaccine is killed/inactivated?

Salk IPV.

What syndrome can occur years after recovery from polio?

Post-polio syndrome.

What is the hallmark symptom of severe polio?

Flaccid paralysis.

Which polio vaccine is currently used routinely in the United States?

IPV

What family does rabies virus belong to?

Rhabdoviridae

What is the shape of rabies virus?

Bullet-shaped.

What is the major reservoir of human rabies in the U.S.?

Bats

What is a classic early symptom of rabies?

Paresthesia (tingling) at the bite site.

How does rabies travel to the CNS?

Retrograde transport through peripheral nerves.

What is hydrophobia?

Painful throat spasms triggered by swallowing liquids.

What are Negri bodies?

Inclusion bodies found in rabies-infected neurons.

What are the two major forms of rabies?

Furious (encephalitic) rabies and paralytic rabies.

What is post-exposure prophylaxis (PEP) for rabies?

Wound washing, human rabies immune globulin (HRIG), and rabies vaccination.

What are the three major stages of rabies?

1. Prodromal stage

2. Neurologic stage

3. Coma/death stage

What occurs during the prodromal stage?

Fever, malaise, headache, muscle aches, sore throat, and paresthesia at bite site.

What occurs during the neurologic stage?

Agitation, hallucinations, confusion, seizures, encephalitis, hydrophobia.

What occurs during the final stage?

Paralysis, coma, respiratory failure, and death.

What are the three components of rabies PEP? Post-Exposure Prophylaxis.

1. Immediate wound washing

2. Human Rabies Immune Globulin (HRIG)

3. Rabies vaccine series

Why does PEP work for rabies?

Rabies usually remains outside the nervous system for an extended period before entering neurons.

What vector transmits La Crosse encephalitis?

Mosquitoes

La Crosse virus is classified as what type of virus?

Arbovirus (arthropod-borne virus).

What does encephalitis mean?

Inflammation of the brain.

What is the direct result of viral encephalitis?

Destruction of brain tissue causing neurologic deficits such as seizures, paralysis, deafness, or mental impairment.