| This negatively-stained transmission electron micrograph (TEM) revealed the presence of La Crosse (LAC) encephalitis virus ribonucleoprotein particles (RNP). LAC virus is a member of the Bunyaviridae virus family, California serogroup. This is an arbovorus, which means that transmission occurs through the bite of an infected arthropod, which in this case, is the treehole mosquito, Aedes triseriatus. LAC can also be transmitted through the bite of infected vertebrates including chipmunks and squirrels. What is the treatment for LaCrosse encephalitis? There is no specific treatment for LaCrosse encephalitis. Antibiotics are not effective against viruses, and no effective anti-viral drugs have been developed. Therapy is supportive only, directed at relieving the symptoms and preventing complications. How common is LaCrosse encephalitis? During an average year, about 70 cases of LaCrosse encephalitis are reported, most in children under the age of 16 years old. Is LaCrosse encephalitis an emerging infectious disease? Yes. LaCrosse encephalitis virus was first isolated in the United States in 1963. The risk of exposures has been increasing as people move into previously undeveloped areas where the virus lives. | 
