Despite the Cold Spring, the Mosquitoes will be Arriving

Thursday, May 1, 2014 - 10:14am

It´s Time to Start Thinking about Avoiding Bites and the Risk of West Nile Virus

The good news is that the grass is getting green and the cold weather is likely to finally end soon.  However, when the cold temperatures let up, it will also wake up the now dormant population of mosquitoes.  Once awake, these pests can be extremely annoying, but they also can be carriers of West Nile virus (WNV). 

This disease was first identified in 1937 in the West Nile region of Uganda and slowly moved out of the tropical latitudes, showing up in New York City in 1999.   In nature, WNV cycles between birds and mosquitoes.  Infected birds can carry large amounts of the virus in their blood stream that can be transmitted to mosquitoes during biting; in turn, the bite of an infected mosquito can transmit the disease to humans and other mammals.  But after humans are infected, the disease cannot be transmitted person to person.

Everyone can do something to reduce the impact of WNV:

  • Prevent mosquito bites
  • Report any sick or dead blue jays and crows you see by calling the Dead Bird Hotline at 1-800-433-1610. 

Prevent mosquito bites by:

  • Limiting time spent outside at dawn and dusk, when mosquitoes are most active.
  • Applying insect repellant to exposed skin as well as clothing because mosquitoes may bite through clothing.
  • Making sure window and door screens are in good repair to prevent mosquito entry.
  • Properly disposing of items that hold water, such as tin cans, plastic containers, ceramic pots or discarded tires to prevent mosquito breeding. Turn over wheelbarrows, wading pools, boats and canoes when not in use.
  • Cleaning roof gutters and downspouts for proper drainage.
  • Changing the water in birdbaths and pet dishes at least every three days.
  • Cleaning and chlorinating swimming pools, outdoor saunas, and hot tubs; drain water from pool covers.
  • Trimming tall grass, weeds and vines because mosquitoes use these areas to rest during hot daylight hours.
  •  Landscaping to prevent water from pooling in low-lying areas.

Although your chances of getting bitten by an infected mosquito are small, it is enough of a possibility to recommend that appropriate precautions should be taken. Last year, a total of 4 cases of WNV (2 confirmed and 2 probable) were reported in Dane County during the 2013 mosquito season; a total of 23 cases have been reported in this county since 2002.

Most people infected with the virus will not display symptoms.  For those who do show symptoms, the situation is a bit more serious. They may develop a fever, headache, rash, muscle and joint aches, nausea, vomiting and fatigue that can last a few days. Symptoms may begin three to 15 days after being bitten by an infected mosquito. In rare cases, WNV can cause severe disease including encephalitis and meningitis. Severe symptoms include high fever, muscle weakness, stiff neck, disorientation, mental confusion, tremors, convulsions, paralysis and coma. Older adults and people with compromised immune systems are at an increased risk of severe disease caused by the virus.  There is no specific treatment for WNV infection other than to treat symptoms. If you think you have WNV infection, contact your healthcare provider.

PHMDC (Public Health-Madison and Dane County) continues to maintain partnerships with other City of Madison agencies, six neighboring communities, and the University of Wisconsin campus to implement mosquito larvae monitoring and control activities in the Madison metropolitan area. Last year, almost 9% of the ditches and ponds monitored by PHMDC staff produced high numbers of WNV carrying mosquitoes and were treated with larvicide to prevent them from becoming adult mosquitoes.

While we can´t predict whether this will be a particularly bad summer for mosquitoes, we can be sure that these annoying and sometimes threatening little bugs will be around.   So do your best to minimize getting bitten.

For more information regarding West Nile virus in Wisconsin
For information on WNV and PHMDC´s monitoring efforts
For further background information regarding West Nile virus

For WNV information in Dane County, call PHMDC at (608) 266-4821.



  • Jeff Golden, Public Health Madison Dane County(608) 243-0302
Health & Safety