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West Nile Virus

Questions and answers about West Nile Virus

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West Nile
Q1:

What is West Nile virus?

A:

West Nile virus is an arthropod-borne virus (arbovirus) most commonly spread by infected mosquitoes.

Q2:

How is West Nile transmitted?

A:

West Nile virus is most commonly transmitted to humans by mosquitoes. Additional routes of human infection have also been documented. It is important to note that these methods of transmission represent a very small proportion of cases:

  • Blood transfusions
  • Organ transplants
  • Exposure in a laboratory setting
  • From mother to baby during pregnancy, delivery, or breastfeeding 

West Nile virus is not transmitted:

  • From person-to-person or from animal-to-person through casual contact. Normal veterinary infection control precautions should be followed when caring for a horse suspected to have this or any viral infection.
  • From handling live or dead infected birds. You should avoid bare-handed contact when handling any dead animal. If you are disposing of a dead bird, use gloves or double plastic bags to place the carcass in a garbage can.
  • Through consuming infected birds or animals. In keeping with overall public health practice, and due to the risk of known food-borne pathogens, always follow procedures for fully cooking meat from either birds or mammals.

Q3:

What are symptoms of West Nile virus?

A:

No symptoms in most people: Most people (70-80%) who become infected with West Nile virus do not develop any symptoms.

Febrile (fever) illness in some people: About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.

Severe symptoms in a few people: Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues).

  • The symptoms of neurologic illness can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis.
  • Serious illness can occur in people of any age. However, people over 60 years of age are at the greatest risk for severe disease. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.
  • Recovery from severe disease may take several weeks or months. Some of the neurologic effects may be permanent.
  • About 10 percent of people who develop neurologic infection due to West Nile virus will die.

Q4:

Where do most cases of West Nile virus occur?

A:

West Nile virus disease cases have been reported from all 48 lower states. The only states that have not reported cases are Alaska and Hawaii. Seasonal outbreaks often occur in local areas that can vary from year to year. The weather, numbers of birds that maintain the virus, numbers of mosquitoes that spread the virus, and human behavior are all factors that can influence when and where outbreaks occur.

Q5:

Who is at risk of serious illness if infected with West Nile virus?

A:

Serious illness can occur in people of any age. However, people over 60 years of age are at the greatest risk for severe disease. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.

Q6:

What is the treatment for West Nile virus?

A:

There are no medications to treat or vaccines to prevent West Nile virus infection. Over-the-counter pain relievers can be used to reduce fever and relieve some symptoms.

People with milder symptoms typically recover on their own, although some symptoms may last for several weeks.

In more severe cases, patients often need to be hospitalized to receive supportive treatment, such as intravenous fluids, pain medication, and nursing care.

Q7:

How can I reduce the chance of getting infected?

A:

The most effective way to avoid West Nile virus disease is to prevent mosquito bites:

  • Use insect repellents when you go outdoors. Repellents containing DEET, picaridin, IR3535, and some oil of lemon eucalyptus and para-menthane-diol products provide longer-lasting protection.
  • Wear long sleeves and pants from dusk through dawn when many mosquitoes are most active.
  • Install or repair screens on windows and doors. If you have it, use your air conditioning.
  • Help reduce the number of mosquitoes around your home. Empty standing water from containers such as flowerpots, gutters, buckets, pool covers, pet water dishes, discarded tires, and birdbaths.

Q8:

Should we be concerned with West Nile virus in the United States?

A:

West Nile virus disease is a nationally notifiable condition. Cases are reported to CDC by state and local health departments using standard case definitions.

Zika Virus

Questions and answers about the Zika Virus

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Zika Virus
Q1:

What is the Zika Virus?

A:

The Zika virus is spread primarily through the bite of an infected mosquito. These are the same mosquitoes that spread other viruses like dengue and chikungunya. Only about one in five people infected with the Zika virus will feel sick. In those that do, symptoms are usually mild and can include fever, rash, joint pain and red eye.

Learn more about symptoms and diagnosis from the Centers for Disease Control and Prevention (CDC).

Q2:

What are symptoms of Zika virus?

A:

Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. 

  • The most common symptoms of Zika are fever, rash, joint pain, or conjunctivitis (red eyes). 
  • Other common symptoms include muscle pain and headache.
  • The illness is usually mild with symptoms lasting for several days to a week.
  • People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected.

The incubation period (the time from exposure to symptoms) for Zika virus disease is not known, but is likely to be a few days to a week. See your doctor or other healthcare provider if you are pregnant and develop a fever, rash, joint pain, or red eyes within 2 weeks after traveling to an area with Zika. Be sure to tell your doctor or other healthcare provider where you traveled.

Q3:

How is Zika transmitted?

A:

Zika is primarily spread to people through the bite of infected Aedes mosquitoes. It can also be transmitted from a pregnant mother to her baby during pregnancy, though we do not know how often that transmission occurs.

Learn more about Zika transmission.

Q4:

Can Zika be transmitted through sexual contact?

A:

  • Zika virus can be passed through sex from a person with Zika to his or her partners.
  • Many people infected with Zika virus won’t have symptoms or will only have mild symptoms, and they may not know they have been infected.
  • Zika can be passed from a person before their symptoms start, while they have symptoms, and after their symptoms end.  In one case, the virus was spread a few days before symptoms developed.
  • The timeframes that men and women can pass Zika through sex are different because Zika virus can stay in semen longer than in other body fluids.

>>View the CDC's Interim Guidance for Prevention of Sexual Transmission of Zika Virus

Q5:

Where are people contracting Zika?

A:

People are contracting Zika in areas where Aedes mosquitoes are present, which include South America, Central America and the Caribbean. As the CDC notes, specific areas where the Zika virus is being transmitted are likely to change over time, so please check the CDC website for the most updated information.

Q6:

Who is at risk of being infected?

A:

Anyone who is living in or traveling to an area where the virus is found is at risk for infection.

Q7:

What is the treatment for Zika?

A:

There is no vaccine or specific medicine to treat Zika virus infections.

Treat the symptoms:

  • Get plenty of rest.
  • Drink fluids to prevent dehydration.
  • Take medicine such as acetaminophen to reduce fever and pain.
  • Do not take aspirin or other non-steroidal anti-inflammatory drugs.
  • If you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication.

Q8:

Why are there specific recommendations for pregnant women?

A:

There may be a link between a serious birth defect called microcephaly—a condition in which a baby's head is smaller than expected—and other poor pregnancy outcomes and a Zika infection in a mother during pregnancy. While the link between Zika and these outcomes is being investigated the CDC recommends that you take special precautions if you fall into one of these groups:

If you are pregnant (in any trimester):

  • You should consider postponing travel to any area where the Zika virus is active.
  • If you must travel to an active region, talk to your doctor first and follow the steps to prevent mosquito bites during your trip.

If you are trying to become pregnant:

  • Before you travel, talk to your doctor about your plans to become pregnant and the risks posed from infection.

For more information, please visit the CDC's resources:

Q9:

Should I be concerned if my newborn is affected by the Zika virus?

A:

Families of newborns affected by Zika virus (Zika) may be overwhelmed, worried, and unsure of next steps in caring for their baby.  A baby affected by Zika virus may be born with significant health issues, like microcephaly. Others may not have apparent symptoms at birth, but may develop them over time.

For more information, please visit the CDC web page for Families of Newborns Affected by Zika.

Q10:

What can I do to prevent a Zika infection?

A:

Right now, there is no vaccine to prevent this disease. The best way to prevent diseases by mosquitoes is to protect yourself from getting bitten. Here’s how:

  • Wear long-sleeved shirts and long pants.
  • Stay in places with air conditioning or that use window, door screens, and netting to keep mosquitoes outside.
  • Use Environmental Protection Agency (EPA)-registered insect repellents. All EPA-registered insect repellents are evaluated for safety and effectiveness.
  • Treat clothing and gear with permethrin or purchase permethrin-treated items.
  • Sleep under a mosquito bed net if you are overseas or outside and are not able to protect yourself from mosquito bites.

You can get a more in-depth explanation of prevention measures from the CDC.

Q11:

Should we be concerned with Zika in the United States?

A:

  • The U.S. mainland does have Aedes species mosquitoes that can become infected with and spread Zika virus. 
  • U.S. travelers who visit a country where Zika is found could become infected if bitten by a mosquito.
  • View Zika cases reported in the United States

Florida

The Florida Department of Health has identified two areas of Miami-Dade County where Zika is being spread by mosquitoes. In addition to the previously identified area in the Wynwood neighborhood, there is now mosquito-borne spread of Zika virus in a section of Miami Beach. >>Learn More

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