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Edina, Minnesota

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Deer Ticks

Deer ticks transmit agents of three diseases. Lyme disease is still the State's most commonly reported tick-borne disease, but two other diseases - human anaplasmosis and babesiosis - can result from deer tick bites in Minnesota.

Human anaplasmosis and babesiosis can result in serious illness. The elderly or immune compromised are at particular risk for these diseases, which can result in hospitalization or even death.

The high-risk season for Lyme disease, human anaplasmosis, and babesiosis is mid-May through mid-July, and risk is greatest in woody, brushy areas in central and southeast Minnesota.

Personal protection measures including tick repellents and tick checks will reduce disease risk. Early recognition and treatment of these diseases is important.

More information on tick-borne disease epidemiology and diagnosis is available at 651-201-5414 or at www.health.state.mn.us/divs/idepc/dtopics/tickborne/index.html.

West Nile Virus

What is West Nile encephalitis?

  • West Nile encephalitis is a viral disease transmitted to people and horses through the bite of an infected mosquito.
  • West Nile virus (WNV) is maintained in a transmission cycle involving one or more species of mosquitoes and birds. Current research is focusing on which mosquitoes and birds are most important in this cycle.
  • WNV is usually found in Africa and southern Europe. The virus was first reported in North American during a 1999 outbreak of encephalitis in New York City.

How serious is West Nile virus?

  • Most people infected with WNV will have either no symptoms or a very mild illness. A small percentage of people, especially elderly patients, may develop encephalitis (inflammation of the brain). Approximately 10 percent of these encephalitis cases are fatal.
  • Most of the severe human cases of WN encephalitis begin with sudden onset of fever, headache, still neck and vomiting. The illness progresses quickly to include confusion and other mental status changes, altered reflexes, convulsions and coma. There is no treatment for WN encephalitis other than supportive care.
  • Approximately 33 percent of symptomatic horses are put down or die from WNV infections.

What is the risk of a West Nile Encephalitis outbreak in Minnesota?

  • Since 1999, WNV has moved rapidly to 48 states, the District of Colombia, seven Canadian provinces, 24 Mexican states, the Dominican Republic, El Salvador, Jamaica and the Cayman Islands. WNV was first detected in Minnesota July 23, 2002.
  • Since 1999, 16,633 (656 deaths) human WN cases were reported in the United States. There have been 230 (6 deaths) human WN cases in Minnesota residents since 2002.
  • With our abundant mosquito and bird populations, we expect that WNV will become established in MN. Similar to other mosquito-transmitted diseases already established in this area (LaCrosse encephalitis, Western equine encephalitis and Eastern equine encephalitis). WNV will likely cause sporadic illness in humans (especially elderly people) and horses.

What can people do to prevent West Nile Encephalitis?

  • Personal protection measures such as use of mosquito repellents, avoiding outdoor exposures at dusk and dawn (peak feeding time for many mosquitoes) and wearing long-sleeved shirts and long pants can reduce the risk of WN encephalitis.
  • Removal of water-holding containers (mosquito breeding sites) from residential areas will reduce the numbers of several mosquito species.
  • There is a vaccine available for horses to prevent WN encephalitis. Please contact your veterinarian for vaccine recommendations. A human WNV vaccine is still in development.

How do I report a dead bird?

  • Since 2002, the Minnesota Department of Health has used dead bird reporting and virus testing to confirm WNV is widely established. As further reporting and testing would not add to this understanding, MDH has discontinued dead bird reporting efforts. However, the Metropolitan Mosquito Control District is still taking reports of dead birds (Especially American Crows, Blue Jays and Hawks) within the seven-county Minneapolis-St. Paul area to help guide mosquito control efforts within their service area.

For more information, contact the Health Department at 952-826-0370 or visit the Minnesota Department of Health's website at www.health.state.mn.us/divs/idepc/diseases/westnile/index.html.