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Zika Virus Update Archived Discussion Room

Fairfax County, Virginia

Zika Virus Update

Zika virus continues to be a public health concern, especially in light of the Olympic Games in Brazil and the first cases of local transmission in Florida. What does that mean for residents here in Fairfax County? Join a an epidemiologist and a mosquito biologist with the Fairfax County Health Department for an online chat Aug. 8 at 11 a.m. to get your questions answered about Zika virus - where it is spreading, what is known about the virus, and what residents can do to prevent Zika and other mosquito-borne diseases. Submit a question in advance or visit online Aug. 8 to participate.

Barbara Downes : Good morning! This is Barbara Downes and Andy Lima from Fairfax County Health Department. We are happy to be here to answer your questions about Zika Virus.

Anonymous User : How is zika virus disease diagnosed?

Barbara Downes : Preliminary diagnosis is based on the patient’s clinical features, places and dates of travel, and activities. Laboratory diagnosis is generally accomplished by testing blood or urine to detect the virus. See your doctor or other healthcare provider if you develop the symptoms (fever, rash, red eyes, joint pain) and have visited an area where Zika is found or have a history of mosquito bites within 2 weeks of symptom onset. A laboratory test is the only way to confirm a Zika infection.

Anonymous User : I want to travel, but I'm scared about Zika. What should I do?

Barbara Downes :

If you are pregnant or trying to get pregnant the Centers for Disease Control and Prevention (CDC) recommends you do not travel to areas with Zika. If you are trying to get pregnant, talk to you doctor about your travel plans.The most updated map and listing of areas with Zika virus transmission, can be found here:

For everyone else, it is safe to travel to a Zika-affected area, but you should pack to prevent and prevent mosquito bites during and after your trip. Take the following steps to prevent Zika virus while traveling to a Zika-affected area:

Before your trip: Check the CDC webpage for the latest travel notices ( This is a great resource for all you need to know, before you go. Also, pack to prevent—pack your insect repellent, long sleeves, long pants, mosquito nets,  and condoms (if you plan to have sex).

During your trip: Protect yourself from mosquito bites. If possible, stay in places with air conditioning and with window/door screens. Use a bed net if air conditioned or screened rooms are not available of if sleeping outdoors.

After your trip: All travelers returning to the United States from an area with Zika should take steps to prevent mosquito bites for 3 weeks—even if you do not feel sick.

Protect yourself during sex. The amount of time you need to protect yourself during sex depends on whether you or your partner has symptoms and whether you and/or your partner are trying to get pregnant. For specific guidelines—visit the CDC webpage located here:

If at any time you feel sick after you return from your trip, see your doctor.

Anonymous User : There is a lot of information out there about Zika--what are the top 5 things I need to know about Zika virus?

Barbara Downes :

As of 08/08/2016, here are the top 5 things everyone needs to know about Zika:

1. Zika primarily spreads through the bite of an infected mosquito. You can also get Zika through sex ( Many areas in the United States have the type of mosquitoes that can spread Zika virus. These mosquitoes are aggressive daytime biters and can also bite at night. Also, Zika can be passed through sex from a person who has Zika to his or her sex partners.

2. The best way to prevent Zika is to prevent mosquito bites. This can be accomplished by using an EPA-registered repellent, wearing long-sleeved shirts and long pants and removing standing water from around your home.

3. Zika is linked to birth defects, including microcephaly. Doctors have also found other problems in pregnancies and among fetuses and infants infected with Zika virus before birth.

4. Pregnant women should not travel to areas where Zika transmission is occurring.

5. Returning travelers infected with Zika can spread the virus through mosquito bites. During the first week of infection, Zika virus can be found in a person’s blood and can pass from an infected person to a mosquito through mosquito bites. An infected mosquito can then spread the virus to other people. Additionally, all travelers returning to the United States from a Zika affected area should take steps to prevent mosquito bites for 3 weeks upon return (even if you do not feel sick).

Constituent : What is the specific guidance to communities and HOAs with storm water drainage parcels? A lot of these land areas stay wet and marshy and swampy for weeks after a rainfall. Do the Zika mosquitoes live and reproduce in wet parcels like this with periods of rainwater flushing across the land?

Andrew Lima : The Asian Tiger mosquitoes that have the potential to transmit Zika virus in Fairfax County develop exclusively in artificial containers commonly found around the yard, such as birdbaths, buckets, tires, corrugated downspout extensions, tarps, potted plant saucers, and many others.  This species does not occupy stormwater management structures such as retention and detention ponds, ditches, and streams.  However, stormwater management structures could still be potential breeding sites for other types of mosquitoes, such as those that can spread West Nile virus.  If you have questions or concerns about mosquito breeding in those environments, you may contact our Disease Carrying Insects Program at or (703)246-8931

The Health Department’s Zika webpage ( has many resources for HOAs hoping to prevent mosquito-borne diseases this summer.  There we have posted an article for public use that was developed for HOA newsletters about what residents can do to help reduce mosquito populations, which can be found here:  There are three versions (short, medium, and long).  There is also another document that has tips for hiring a pest control professional or doing your own insecticide treatment on your property, found here:

Anonymous User : I'm pregnant, and worried about Zika this summer. How do I keep mosquitoes from biting me?

Barbara Downes :

The best way to prevent Zika is to avoid mosquito bites. During mosquito season, it is recommended that pregnant women take the following steps:
• Choose an EPA-registered insect repellant and use according to the label instructions. Use the repellent day and night because the mosquito species that transmit Zika virus are daytime biters that will also enter buildings and bite at night. When used as directed, EPA-registered insect repellents are safe and effective for pregnant and breastfeeding women.
• Use permethrin-treated clothing
• Cover exposed skin by wearing long sleeves, long pants, and hats
• Sleep indoors in rooms screened windows or air-conditioning, or use a bed net if you sleep in a room that is exposed to the outdoors

Steven Ault : Does Fairfax County and its cities have a map on a webpage of the known distribution of Aedes aegypti and or Aedes albopictus in the county? (Yearly or over last 2 years?). Are the principle Culex species in county also mapped and online? If not, why not? Can the maps be shared with public?

Andrew Lima : The Centers for Disease Control and Prevention have maps that illustrate the approximate potential range for Aedes aegypti (the Yellow Fever mosquito) and Aedes albopictus (the Asian Tiger mosquito) at the following link: Fairfax County does not have county-level maps for these species, or our Culex mosquitoes.  Although we do routine mosquito surveillance throughout the county at 71 different trap locations, these data are only a snapshot of a particular trap site. 

Aedes aegypti, the primary species that is currently spreading Zika, is a tropical and sub-tropical mosquito whose range is generally limited to the Gulf Coast states in the central and southeastern U.S.  Although it has been detected in Fairfax County before, it is rare, since this species is unable to survive our cold winters. Aedes albopictus, the Asian Tiger mosquito, is common and widespread throughout Fairfax County and the state of Virginia, and although this species could potentially spread Zika, it has not yet been proven to do so in the current outbreak.  There are several different Culex species which are routinely found throughout the county. 

Anonymous User : Have mosquitoes carrying the zika virus been found in VA or surrounding areas?

Andrew Lima : Currently, no transmission of Zika by mosquitoes has been detected in Virginia.  All cases of Zika that have been identified in Fairfax County and in Virginia so far have been associated with travel to a Zika-affected area. 

Don't like mosquitoes : There are other mosquito-spread diseases in Virginia. In the past year, how many cases of each of these have we experienced in Virginia or in Fairfax County: - West Nile virus - Eastern Equine encephalitis - La Crosse encephalitis - St. Louis encephalitis? Are Virginia citizens more at risk for those four health concerns, or more at risk for Zika?

Barbara Downes :

Arboviral (short for arthropod-borne) infections can be caused by a number of different viruses that are spread by arthropods such as mosquitoes. These infections generally occur during the warm weather months when mosquitoes are active. The most common arboviruses found in Virginia include West Nile virus, St. Louis encephalitis virus, La Crosse encephalitis virus, and Eastern Equine Encephalitis virus. 
In Fairfax County in 2015 there were 8 confirmed cases of West Nile Virus. For the other viruses, our case numbers have been zero, or a number less than 5 (which is our standard threshold for publicly reporting case numbers). You can find data on reportable diseases, including arboviral disease, in Virginia on the Virginia Department of Health's website at:

West Nile Virus can be found annually in our mosquito population, the other viruses are not as common in our jurisdiction. Zika virus is a concern for public health because it is the only mosquito-borne illness that has been linked to a birth defect in pregnancy. It is also the only one that can be transmitted through sex.

Anonymous User : If you're bitten my a mosquito, should you be worried? If your bitten many times and are able to kill one or two of them for identification purposes, should one be trying to find out if it is the type of insect that carries Zika?

Andrew Lima : It is understandable to be worried about Zika, but it’s important to note that currently, local transmission of Zika by mosquitoes is limited to a relatively small geographic area in south Florida. 

The Fairfax County Health Department has a mosquito surveillance program that collects samples of adult mosquitoes for testing at trap sites throughout the county. Our program is not set up to examine individual mosquitoes submitted by residents.

The Asian Tiger mosquito, which has the potential to transmit Zika here in Fairfax County, is not the species that is currently driving most of the transmission around the world.  However, it is a common backyard mosquito whose larvae develop exclusively in artificial containers that can be found around the yard.  As such, your best bet for prevention is to: 

-Wear long-sleeved shirts and long pants
-Use EPA-registered insect repellents
-Use permethrin-treated clothing
-Stay and sleep in screened-in or air-conditioned rooms
-Avoid or limit outdoor activities during peak mosquito times (dusk and dawn)

Preventing mosquitoes around the home is also important:
-Eliminate standing water from containers in yards (including bird baths, flower pots, buckets) to stop mosquito breeding.
-Use EPA-registered larvicides to control mosquitoes in containers that cannot be emptied, such as watering troughs, ornamental ponds or unmaintained swimming pools.
-Use insecticides to control adult mosquitoes around the yard.

Anonymous User : Can repellent be used on kids? Is there any type that you recommend?

Barbara Downes :

Yes, always follow instructions when applying insect repellent to children. The American Academy of Pediatrics recommends using DEET for infants and children 2 months of age and older. Do not use insect repellent on babies younger than 2 months old and do not apply insect repellent onto a child’s hands, eyes, mouth, and on cuts or irritated skin. For best application practices, adults should spray insect repellent onto your hands and then apply to a child’s face. Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.

In addition to applying insect repellant, protect your child by dressing them in clothing that covers their arms and legs. If needed, cover their crib, stroller and baby carrier with mosquito netting if planning to spend a lot of time outdoors where mosquitos may be present.

Rachel : With the new reports in Florida and if it reaches Fairfax County, would there be any plans for potential eradication? If so, what would that entail?

Andrew Lima : It is unlikely that we could ever eliminate mosquitoes entirely. However, our Disease Carrying Insects Program practices integrated pest control, which emphasizes a variety of means to reduce mosquito populations. Some of those activities include:

-Education about mosquito bite prevention (Wearing long-sleeved shirts and long pants, using EPA-registered insect repellents, using permethrin-treated clothing staying and sleeping in screened-in or air-conditioned rooms, and avoiding or limiting outdoor activities during peak mosquito times.
-Source reduction (elimination of containers holding water)
-Larval mosquito control (application of a bacterial pesticide that kills mosquito larvae in the water)
-Mosquito surveillance (trapping adult mosquitoes and testing them for diseases such as West Nile and Zika)
-Adult mosquito control (application of a liquid pesticide to vegetation where it will kill adult mosquitoes that land on the vegetation for 2 to 3 weeks, or until the next significant rainfall)

In response to local transmission of Zika by mosquitoes (such as that seen in Florida), all of the same activities listed above would be conducted to reduce the risk of further transmission. This might occur in areas where mosquito or human surveillance indicates the presence of Zika virus.

Mosquitoes bug me : Bug sprays for human skin contain anywhere from 2% - 40% deet. What is the recommended percentage of deet that is safe for human adults? What is the recommended percentage of deet that is safe for human infants and children?

Barbara Downes : The most important thing when applying any repellent is to read and follow the label directions, as this will help you use the product with the highest level of safety and effectiveness. Lower concentrations of DEET are just as effective as higher concentrations, however the duration of protection increases with concentration. A low concentration may provide 1 to 2 hours of protection, whereas a higher concentration may last for 6 to 8 hours. For application and reapplication rates, please follow the label directions. The American Academy of Pediatrics recommends for children 2 months of age and older, the use of up to 30% DEET.

Harry Lenclair : Thank you for this opportunity. In past years there was noted concern by the FC Health & Others about "standing water". Residents were encouraged to report areas with water accumulation to the County. I have not seen such concern this year and I have reported one area of standing water to the Health Department on their e-mail. No response was received and no action was taken to remove standing water. WHY is "standing water" no longer a concern?

Andrew Lima : The Health Department does still routinely respond to inquiries about standing water, and this remains a major part of our outreach platform.  We apologize if you didn't get a response from our email, but would encourage you to resubmit your concern or contact us directly to report standing water at (703) 246-8931. 

The Health Department inspects some county- owned and maintained stormwater structures such as retention and detention ponds for mosquitoes.  The mosquitoes that have the potential to transmit Zika in Fairfax County develop exclusively in containers of standing water that are found around our homes. At citizen’s request, we can also inspect private property to help identify and eliminate standing water.  Residents who would like assistance in identifying ways that they can reduce mosquitoes around their home can also call us at (703) 246-8931.   

Barbara Downes : Thank you for the opportunity to answer your questions on Zika virus. For additional information on Zika or mosquito prevention please visit the Fairfax County Health Department website at

Have a safe and healthy summer.