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Mosquito Awareness

West Nile & Zika Virus Information

West Nile Virus - What You Need to Know

What is West Nile Virus (WNV)?

West Nile Virus (WNV) is a potentially serious illness. Experts believe it is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. It can infect humans, birds, horses and some other mammals. In a small number of people infected by the virus, the disease can be serious, even fatal.

How is WNV spread?

  • WNV is most often spread to humans by the bite of an infected mosquito that gets infected by biting a bird that carries the virus. Horses and other mammals bitten by mosquitoes that carry the virus can also become infected. Whenever mosquitoes are active, there is a risk of getting WNV. The risk is highest from late July through September.
  • In a very small number of cases, WNV has been spread through blood transfusions, organ transplants, breastfeeding and during pregnancy from mother to baby.
  • WNV is not spread through casual contact such as touching or kissing a person with the virus.

What are the symptoms of West Nile Virus?

If symptoms develop, they usually appear 3 to 14 days after the bite of an infected mosquito.

  • Serious Symptoms in a Few People. About one in 150 people infected with WNV will develop severe illness. Symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.
  • Milder Symptoms in Some People. Up to 20% of the people who become infected display symptoms such as fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days; though, even healthy people have been sick for several weeks.
  • No Symptoms in Most People. Most people (80%) infected with WNV do not have any symptoms.

What is the treatment for WNV?

There is no treatment for WNV infection. Illness may last weeks to months, even in healthy persons. In more severe cases people may need hospital care for supportive treatment such as intravenous fluids, help with breathing, or nursing care.

What should I do if I think I have WNV?

Milder WNV illness usually improves without medical attention. A person may choose to see their doctor. Seek medical attention immediately if symptoms of severe WNV illness develop, such as unusually severe headaches or confusion. Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers who develop symptoms that could be WNV are encouraged to see their doctor.

What is the risk of getting sick from WNV?

  • People over 50 years of age at higher risk of severe illness. People over the age of 50 are more likely to develop serious symptoms of WNV if they do get sick and need to take special care to avoid mosquito bites.
  • Being outside means you're at risk. Avoid mosquito bites when outside working, playing or relaxing.
    Risk of infection through medical procedures is very low. All donated blood is checked for WNV before being used. The risk of getting WNV through blood transfusions and organ transplants is very small, and should not prevent people from having surgery. If you have concerns, talk with your doctor.
  • Pregnancy and nursing do not increase the risk of becoming infected with WNV. The risk that WNV may pass to a fetus or an infant through breastmilk is still being evaluated. Talk with your doctor if you have concerns.

How can West Nile Virus be prevented?

The best way to avoid WNV infection is to prevent mosquito bites:

  • Use insect repellent. The Centers for Disease Control and Prevention (CDC) recommends the use of insect repellents containing active ingredients registered with the U.S. Environmental Protection Agency (EPA). Always follow manufacturer's directions carefully.
  • Be careful using repellant on the hands of children because repellents may irritate the eyes and mouth.
  • Wear protective clothing such as long sleeved shirts and pants.
  • Limit outdoor activity from dusk to dawn when mosquitoes are most active.
  • Avoid areas where mosquitoes may be present (i.e. shaded and wooded areas).
  • Maintain window and door screens to keep mosquitoes out of buildings.
  • Get rid of mosquito breeding sites by emptying standing water that collects in birdbaths, boats, buckets, tires, unused pools, roof gutters and other containers.

Zika Virus - What You Need to Know

What is Zika virus (Zika)?

Zika is a disease caused by the Zika virus that is spread to people mainly from the bite of an infected Aedes species mosquito. About one in five people infected with Zika will get sick. The illness is usually mild with symptoms lasting for several days to one week. Most people will not realize they have been infected.

What are the symptoms of Zika virus?

The most common symptoms of Zika virus are fever, rash, joint pain, or conjunctivitis (red eyes). Symptoms typically begin two to seven days after being bitten by an infected mosquito.

How is Zika virus transmitted?

Zika is mainly transmitted through the bite of an infected Aedes mosquito. A mosquito becomes infected from biting a person already infected with the disease. Infected mosquitos can then spread Zika to other people through bites. Transmission may also occur from a pregnant mother to her baby during pregnancy or around the time of birth.

Spread of the virus through blood transfusion and sexual contact has been reported. Centers for Disease Control and Prevention (CDC) recommends that men who have traveled to an area of active Zika virus transmission and who have a pregnant partner not engage in sexual activity without taking appropriate precautions such as using condoms for the duration of the pregnancy. For more information about how Zika is transmitted, click here.

How can Zika virus be prevented?

There is no vaccine to prevent Zika. The best way to prevent diseases spread by mosquitoes is to avoid being bitten. The following can help protect you and your family from mosquito bites:

  • Use Environmental Protection Agency (EPA)-registered insect repellant. All EPA-registered insect repellants are evaluated for safety and effectiveness.
    • Always follow the product label instructions.
    • Do not use insect repellant on babies younger than 2 months of age.
    • Do not apply insect repellant on a child's hands, eyes, mouth, cut or irritated skin.
    • Adults: spray insect repellant on your hands and then apply to a child's face.
  • Wear protective clothing such as long-sleeved shirts and pants.
  • Avoid outdoor activities during daylight for about two hours after sunrise and several hours before sunset.
  • Protect yourself from mosquito bites at night in well-lit areas.
  • Avoid areas where mosquitoes may be present, including indoor areas.
  • Maintain window and door screens to keep mosquitoes out of buildings. Do not prop open doors.
  • Get rid of mosquito breeding sites by removing standing water in and around your home:
    • Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, roof gutters, or trash containers.

How is Zika virus diagnosed?

If you have recently traveled to areas with local Zika transmission and you develop symptoms (fever, rash, joint pain, red eyes), consult a healthcare provider immediately. Currently, Zika testing is coordinated with the CDC and your healthcare provider.

What is the treatment for Zika virus?

  • There is no vaccine or specific medicine to treat Zika virus infections. Instead, you can treat the symptoms by:
  • Getting plenty of rest.
  • Drinking fluids to prevent dehydration.
  • Taking medications such as acetaminophen to reduce fever and pain.
  • Talking to your healthcare provider before taking additional medication if you are taking medicine for another medical condition.
  • Do not take aspirin or other non-steroidal anti-inflammatory drugs without consulting a healthcare provider.

Who is at risk of Zika virus infection?

Anyone without prior exposure to the virus and who lives in or travels to an area where local transmission has been reported may become infected. For a complete list of countries and territories with Zika virus activity, click here.

How does Zika virus infection affect pregnant women and unborn babies?

Information about the link between Zika and poor birth outcomes is evolving. Reports of a serious birth defect of the brain called microcephaly (a condition in which a baby's head is smaller than expected when compared to babies ofthe same sex and age) and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant have occurred. Until more information is known, CDC recommends the following special travel precautions:

  • Women who are pregnant (in any trimester):
    • Consider postponing travel to any area where Zika virus transmission is ongoing.
    • If you must travel to one of these areas, talk to a health care provider first and strictly follow steps to avoid mosquito bites during your trip.
  • Before traveling, women who are trying to become pregnant or thinking about becoming pregnant should talk to a healthcare provider about the risks of Zika virus infection.

For up-to-date information regarding CDC's Zika virus travel restrictions, click here, or contact Oakland County Health Division's Nurse on Call at 800-848-5533 or by email at For up-to-date information about pregnancy and Zika virus, click here.