Symptoms and Outcomes

Incubation period from five to 15 days. It can cause seizures and, in some cases, coma and paralysis. Most patients recover, but some have cognitive and neuro-behavioral problems that require therapy. There is no cure.

Who's at Risk?

The most severe cases are often found in children under 16. It strikes boys 5-9 in particular.

Severe neurological cases occur, mainly in pre-school age children. Seldom fatal, but prolonged hospitalization and adverse events, including personality changes, may occur.

Treehole mosquito
Treehole Mosquito

Behaviors of Mosquitoes that Carry It

La Crosse Encephalitis (LACV) is transmitted by infected eastern treehole mosquitoes. The virus can be transmitted by the infected female to her eggs, so that emerging adults may already by infected and ready to transmit the virus.

Incidence

LACV incidence map

Resources

IndeOnline.com Massillon OH Family warns of dangerous mosquito virus after rare diagnosis Oct 7, 2018 https://www.indeonline.com/news/20181007/stark-family-warns-of-dangerous-mosquito-virus-after-rare-diagnosis  La Crosse encephalitis, a rare and dangerous virus, is on the increase.  (See link for story of one family’s experience, symptoms, more.)  Transmitted by infected eastern treehole mosquitoes, it has a 5-15-day incubation period, with most severe cases often found in children under 16.  It can cause seizures and, in some cases, coma and paralysis. It strikes boys 5-9 in particular.  Though most patients recover, it can cause cognitive and neuro-behavioral problems that require occupational therapy.  There is no cure, however, symptoms are treatable. Severe neurological cases occur, mainly in pre-school age children. They are seldom fatal, but prolonged hospitalization and sequelae including personality changes, may occur.  The virus can be transovarially transmitted by the infected female to her eggs, so that emerging adults may already be infected and ready to transmit the virus. See a summary of LACV, its epidemiology, geographic distribution, and clinical characteristics at https://www.cdc.gov/lac/tech/epi.html

CDC Emerging Infectious Diseases Epidemiology of La Crosse Virus Emergence, Appalachia Region, United States Nov, 2016 La Crosse encephalitis is a viral disease that has emerged in new locations across the Appalachian region of the US. …We conclude that other factors, including different invasive mosquitoes, changes in climate variables, or changes in wildlife densities, should be considered as …explanations for recent increases in La Crosse encephalitis. https://wwwnc.cdc.gov/eid/article/22/11/16-0308_article

CDC Morbidity and Mortality Report Spatially Associated Coincident and Noncoincident Cases of La Crosse Encephalitis — North Carolina, 2002–2017 Oct 5, 2018 …Persons living at the residence of a patient with a newly identified case of LACV disease or in an area where the virus is known to occur should be advised of the risk and measures to reduce risk, such as using Environmental Protection Agency–registered and recommended insect repellents.  https://www.cdc.gov/mmwr/volumes/67/wr/mm6739a8.htm?s_cid=mm6739a8_e