Viral Encephalitis Overview

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Questions and Answers

What characterizes acute viral encephalitis (AVE)?

Rapid-onset, febrile inflammatory disease (correct)

Chronic inflammation of the brain

Primarily a bacterial infection

Localized infection without fever

Which virus is the most common cause of acute viral encephalitis?

Eastern equine alphavirus

West Nile virus

Herpes simplex virus (HSV) (correct)

St. Louis flavivirus

What is the incidence rate of herpes simplex virus encephalitis in the population?

5 cases per 1 million people per year

1 case per 1 million people per year

10 cases per 1 million people per year

2 cases per 1 million people per year (correct)

Which demographic is most commonly infected by herpes simplex virus encephalitis?

Children and young adults Signup and view all the answers

Which of the following viruses has the highest mortality rate associated with encephalitis?

Rabies rhabdovirus Signup and view all the answers

How does the clinical course of encephalitis differ among age groups?

Infants and elderly patients often have a more serious clinical course Signup and view all the answers

What is often a co-occurring condition with acute viral encephalitis?

Viral meningitis Signup and view all the answers

What is a significant risk associated with untreated acute viral encephalitis?

Permanent damage to the central nervous system Signup and view all the answers

In which year did the largest encephalitis outbreak in U.S. history occur?

2002 Signup and view all the answers

What percentage of all cases of acute viral encephalitis in the United States is attributed to HSV?

10% Signup and view all the answers

What is a primary cause of acute viral encephalitis in the United States?

Poliovirus during epidemic outbreaks Signup and view all the answers

Which viruses are commonly responsible for sporadic encephalitis?

HSV and varicella/zoster Signup and view all the answers

What type of viral encephalitis is caused directly by the invasion of the brain?

Primary encephalitis Signup and view all the answers

How can arboviruses be transmitted to humans?

Insect bites from infected blood-sucking insects Signup and view all the answers

Which of the following is NOT a method of exposure to viruses that can lead to acute viral encephalitis?

Airborne transmission during sleep Signup and view all the answers

Which of the following viruses is associated with epidemic encephalitis in the United States?

Coxsackievirus Signup and view all the answers

What is the primary mode of transmission for viruses causing sporadic encephalitis?

Contact with infected animal saliva Signup and view all the answers

Which of the following options describes a risk factor for infection with viruses causing acute viral encephalitis?

Sharing a classroom with an infected person Signup and view all the answers

What is NOT a typical virus responsible for causing outbreaks of encephalitis?

Influenza virus Signup and view all the answers

Which form of encephalitis can occur at any time of the year and is linked to sporadic cases?

Primary encephalitis Signup and view all the answers

Study Notes

Overview of Acute Viral Encephalitis (AVE)

AVE is characterized by rapid onset, fever, and inflammation of the brain caused by viral invasion or immune reaction.
Infection can be focal (localized) or diffuse (widespread).
Often coexists with viral meningitis and is classified as a neurologic emergency.
While bacterial and fungal infections can also cause encephalitis, viruses are the most common culprits.

Herpes Simplex Virus (HSV) Encephalitis

HSV encephalitis is the most prevalent type of AVE, with an incidence of approximately 2 cases per million people annually.
Accounts for about 10% of AVE cases in the U.S.
Children and young adults are primarily affected, but infants and the elderly may experience more severe outcomes.
In 2002, West Nile virus was responsible for the largest encephalitis outbreak in U.S. history, resulting in 3,800 cases and 225 deaths.

Clinical Implications

Most AVE cases are mild, but some can be life-threatening, leading to permanent central nervous system damage.
Mortality rates vary based on the virus:
- Rabies: nearly 100%
- HSV: 70%
- Eastern equine alphavirus: 35%
- St. Louis flavivirus: 20% in elderly patients

Causes and Risk Factors

AVE can be triggered by various viruses, predominantly:
- Enteroviruses (notably coxsackievirus and echovirus)
- HSV
- Rabies virus (from rabid animal bites)
- Arboviruses, transmitted by insect bites.

Forms of Acute Viral Encephalitis

Two main forms of AVE exist:
- Primary encephalitis: virus directly invades the brain and can occur sporadically or during outbreaks.
- Secondary (postinfectious) encephalitis: follows another viral infection.
Epidemic causes in the U.S. include:
- Arboviruses
- Poliovirus
- Echovirus
- Coxsackievirus
Sporadic causes include:
- HSV
- Varicella/zoster
- Mumps viruses

Pathophysiology and Modes of Transmission

Virus exposure can happen via multiple routes, including:
- Insect and animal bites
- Sexual contact
- Contaminated food or drink
- Inhalation of respiratory droplets from an infected individual
- Skin contact with infected fluids.
Transmission risks are heightened through sharing personal items and close contact in communal settings (households, daycares, classrooms).

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Description

This quiz provides an understanding of acute viral encephalitis, including its definition, symptoms, and its relationship to viral meningitis. Participants will explore the neurological implications and recognize the urgency of this condition. Test your knowledge about this important medical topic!