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Viruses and bacteria carried by mosquitoes and sometimes ticks are some of the most common causes of
encephalitis throughout the world. Most people who are
bitten by infected mosquitoes do not develop any symptoms or develop only a
mild flu-like illness. For those who do develop encephalitis, symptoms may
develop within a few days or up to 2 weeks after the mosquito bite occurred,
depending on which virus the mosquito was carrying.
caused by mosquito-borne viruses is spread by the bite of an infected mosquito.
It also may be transmitted through blood transfusions and breast-feeding. There
is no proof that it can be passed from one person to another through casual
contact or from an animal to a person.
The mosquito-borne viruses
that cause encephalitis cannot be destroyed with antiviral or other medicines.
Treatment for these types of encephalitis focuses on reducing symptoms and
providing supportive care while the body heals.
If you have signs of encephalitis caused by bacteria, your doctor will prescribe antibiotics. This type of encephalitis is more common during tick season.
Types of encephalitis include:
Most cases of mosquito-borne encephalitis occur during
the warmest months of the year, when mosquitoes are most active. In areas that
are warm year-round, people may get encephalitis throughout the year.
Rocky Mountain spotted fever can cause encephalitis in some cases. It happens mostly in North, Central, and South America. In the United States, it is most common in the area between North Carolina and Oklahoma. This type of bacterial encephalitis is caused by a tick bite.
Other Works Consulted
Jubelt B (2010). Viral infections and postviral syndromes. In LP Rowland, TA Pedley, eds., Merritt's Neurology, 12th ed., pp. 156–185. Philadelphia: Lippincott Williams and Wilkins.
Ropper AH, Samuels MA (2009). Acute encephalitis section of Viral infections of the nervous system, chronic meningitis, and prion diseases. In Adams and Victor's Principles of Neurology, 9th ed., pp. 716–723. New York: McGraw-Hill.
October 26, 2011
E. Gregory Thompson, MD - Internal Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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