In last week’s Morbidity and Mortality Weekly Report, the CDC revealed, in 2011, La Crosse Virus (LACV) surpassed West Nile Virus (WNV) as the leading cause of tick–borne disease among children.
In 2011, only 12 out of 712 confirmed WNV infections occurred in children and teens. In contrast, LACV infections were responsible for 123 out of 130 cases in young Americans. The data for LACV also shows a 73 percent increase in neuroinvasive infections since 2010. However, LACV resulted in only one fatality, as compared to 43 for WNV.
LACV disease occurs primarily in the upper Midwestern states (Minnesota, Wisconsin, Iowa, Illinois, Indian and Ohio) and the mid-Atlantic and southeastern states (West Virginia, Virginia, Kentucky, North Carolina, and Tennessee) from late spring into early fall.
Most people infected with LACV will never exhibit any symptoms. For those who do, initial signs include fever, headache, nausea, vomiting and tiredness. LACV may become dangerous if neuroinvasive symptoms arise. More severe forms of LACV disease often involve encephalitis, which may cause seizures, coma, and even paralysis. Although rare, LACV disease may lead to permanent disability or death. Children under the age of 16 are particularly vulnerable to this severe form. Currently, there is no specific treatment for infections of LACV; healthcare workers can only provide care based on symptoms.
To avoid infection with LACV, reducing exposure to mosquitoes is key. The CDC recommends applying repellent that contains DEET, picaridin, or IR3535. For a more natural alternative, oil of lemon eucalyptus has also proven effective. Additional suggestions include wearing protective clothing and installing or repairing screens.