(California encephalitis, La Crosse encephalitis,
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California serogroup viruses including California
encephalitis, Keystone, La Crosse, Jamestown Canyon, snowshoe hare, and
trivittatus are all mosquito-borne arboviral infections. In the United
States, La Crosse virus (LACV) is the most common of the California
serogroup viruses. Both LACV and Jamestown Canyon virus (JCV) infections
have been reported in Wisconsin. People infected with California
serogroup viruses may have no apparent symptoms. Some people have
symptoms of illness that may range from mild fever to encephalitis or
La Crosse encephalitis disease mostly occurs in the
Midwestern, mid-Atlantic, and southeastern states of the United States.
LACV was first isolated in1963 in children from La Crosse, Wisconsin.
From 2002 to 2008, 68 cases of La Crosse encephalitis (average 10
cases/year) were reported in Wisconsin. Initial symptoms of illness may
include fever, headache, nausea, vomiting, and tiredness. Some people
may develop severe neuroinvasive disease (disease that affects the
nervous system). Severe symptoms often involve encephalitis (an
inflammation of the brain) and can include seizures, coma, and
paralysis. Historically, most of the LACV infections in Wisconsin have
been reported in children less than 16 years old; however, recent
surveillance data show that both adults and children can become ill with
La Crosse encephalitis.
Jamestown Canyon virus was first recognized as causing
human illness in 1980 and occurs throughout temperate climate regions of
North America. JCV infections have been rarely reported in Wisconsin,
but because of the unavailability of a commercial test to detect the
virus, the infection may be unrecognized and under reported.
|Wisconsin acquired diseases
||Travel related diseases
La Crosse encephalitis
infections fact sheet (PDF, 16 KB) Hmong
(PDF, 14 KB) Spanish (PDF,
Data and statistics
California serogroup viruses data
Some tips to protect yourself:
- Use effective mosquito repellant and apply according to the label
- Wear long-sleeved shirts, long pants, socks, and shoes.
- Mosquitoes may bite through thin clothing, so spraying clothes
with a repellent containing permethrin or DEET will give extra
protection. These repellants are the most effective and most studied.
- Avoid being outside during times of high mosquito activity,
specifically around dawn and dusk.
- Keep window screens repaired so that mosquitoes cannot enter your
- Dispose of discarded tires, cans, or plastic containers left
outside that may contain standing water.
- Drain standing water from pool or hot tub covers.
- Turn over plastic wading pools and wheel barrows when not in use.
- Change the water in bird baths, pet dishes and wading pools every
- Keep drains, ditches and culverts clean of trash and weeds so
water will drain properly.
- Clean gutters to ensure they drain
For more information,
Using Insect Repellants Safely - CDC
Information for health professionals
This is a Wisconsin Disease Surveillance Category II disease:
the patient's local public health department electronically, through the Wisconsin
Electronic Disease Surveillance System
(WEDSS), by mail or fax using an Acute and Communicable Disease Case
Report F44151 (PDF,
167 KB) or by other means within 72-hours upon recognition of a
Communicable Disease Reporting webpage.
Wisconsin case reporting and public health follow-up
diseases EpiNet (PDF, 52 KB)
case report form (PDF, 46 KB)
2013 Arbovirus management protocol (PDF, 372 KB)
- Specimens should be tested using an arbovirus panel because arboviruses
have similar clinical symptoms and serologic testing often results in
cross-reactive antibodies among agents. Positive arbovirus specimens
tested by a commercial laboratory should be forwarded to the Wisconsin
State Laboratory of Hygiene (WSLH) for confirmatory panel testing (WNV,
SLE, LAC, EEE, and WEE). Due to unavailability of a commercial test for
Jamestown Canyon virus (JCV), the WSLH will forward JCV testing requests
to the CDC.
- Additional laboratory guidance
Local Health Departments - Regional offices - Tribal agencies
Diep Hoang Johnson
Vectorborne Disease Epidemiologist
Wisconsin Division of Public Health
Bureau of Communicable Diseases and Emergency Response
(Phone 608-267-0249) (Fax 608-261-4976)
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November 04, 2013