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Risk factors
By Mayo Clinic staffAnyone can develop encephalitis. Factors that may increase the risk of the condition include:
- Age. Some types of encephalitis are more prevalent or more severe in certain age groups. In general, young children and older adults are at greater risk of most types of viral encephalitis. Encephalitis from the herpes simplex virus tends to be more common in people 20 to 40 years of age.
- Weakened immune system. People who have HIV/AIDS, take immune-suppressing drugs, or have another condition causing a compromised or weakened immune system are at increased risk of encephalitis.
- Geographic regions. Mosquito-borne or tick-borne viruses are common in particular geographic regions.
- Outdoor activities. Outdoor activities or work that results in more exposure to ticks or mosquitoes increases the risk of encephalitis.
- Season of the year. Mosquito- and tick-borne diseases tend to be more prevalent in summer and early fall in many areas of the United States. In warmer areas of the U.S., however, mosquitoes and ticks may be present year-round.
References
- Encephalitis and meningitis fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm. Accessed March 8, 2011.
- Encephalitis. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/sec16/ch217/ch217c.html. Accessed March 10, 2011.
- Johnson RP, et al. Viral encephalitis in adults. http://www.uptodate.com/home/index.html. Accessed March 10, 2011.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Clinical manifestations and diagnosis. http://www.uptodate.com/home/index.html. Accessed March 10, 2011.
- Beckham J, et al. Encephalitis. In: Mandell G, et al., eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2009. http://www.mdconsult.com/books/page.do?sid=1129246002&eid=4-u1.0-B978-0-443-06839-3..00087-4&isbn=978-0-443-06839-3&type=bookPage§ionEid=4-u1.0-B978-0-443-06839-3..00087-4&uniqId=237025740-4. Accessed March 10, 2011.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Pathogenesis and etiology. http://www.uptodate.com/home/index.html. Accessed March 10, 2011.
- Information on arboviral enchephalitides. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvbid/arbor/arbdet.htm. Accessed March 8, 2011.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Treatment and prevention. http://www.uptodate.com/home/index.html. Accessed March 10, 2011.
- Insect repellant use and safety. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm. Accessed March 15, 2011.
- A parent's guide to insect repellent. American Academy of Pediatrics. http://patiented.aap.org/content.aspx?aid=5556. Accessed March 11, 2011.
- Acyclovir. National Center for Biotechnology Medicine. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000533. Accessed March 22, 2011.
- Ganciclovir injection. National Center for Biotechnology Medicine. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000889. Accessed March 22, 2011.
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