This is a guest blog from one of our partners at USF Health. Lindsay Maggio, MD, MPH, is Assistant Professor at the College of Medicine, Obstetrics and Gynecology at the University of South Florida. She earned a Master of Public Health from the University of Massachusetts, Amherst, and her medical degree from Rutgers University.
What is Zika virus and how is it transmitted?
Zika virus is a Flavivirus, which is the same class of virus as yellow fever, dengue and West Nile virus. Zika is transmitted by the bite of an infected mosquito. The most common mosquito that is transmitting this virus is the Aedes aegypti, however the Aedes albopictus has also been found to transmit the Zika virus. These mosquitoes bite predominantly during the day, but also bite at dawn and dusk. These mosquitos live around households and lay their eggs in domestic water-holding containers.
Recently, it has been discovered that this virus can also be transmitted sexually, from infected and symptomatic males to their partners. There is also sufficient evidence that perinatal transmission from a mother to her unborn fetus can occur.
Is this a new virus?
Zika virus was first discovered in 1947 in a monkey in Uganda. The first reported cases in human were in 1953 in Nigeria. Since 2007, this virus has spread eastward, from Africa and Asia, to Micronesia then French Polynesia, and most recently, in 2015, the virus was spread to the Central and South America. For a complete up-to-date map of areas with ongoing active Zika virus transmission, visit the Center for Disease Control and Prevention (CDC) website: http://www.cdc.gov/zika/geo/.
What is the Zika virus infection?
Of those infected with Zika virus, only 20% will become symptomatic. The most common symptoms include a rash, fever, red eyes, and joint pain. Other symptoms associated with this infection include muscle pain, headaches, eye pain, itching, and vomiting. Zika virus is believed to have an incubation period of 3-14 days. The illness itself lasts for 4-7 days, with the virus remaining in the blood stream for 7-11 days.
If I am pregnant or trying to get pregnant, can my fetus become infected?
Zika virus can cause a perinatal infection. The most common findings we are seeing in fetuses infected with Zika virus include microcephaly (small head size), other brain and central nervous system abnormalities (intracranial calcifications, eye abnormalities, ventriculomegaly [increased fluid in the brain]), and fetal growth restriction. This congenital syndrome is also associated with miscarriage and stillbirth.
When is my fetus at risk for getting this infection?
Most of the current evidence suggests that pregnancies exposed to the virus during the first trimester have the greatest risk of perinatal transmission. Transmission rates are still unknown at this time, however there are some reports that up to 30% of infected mothers will have infected fetuses. It is also unknown if transmission rates are higher if the mom has symptoms of infection compared to those that are asymptomatic. There have also been reports of transmission around the time of delivery of 2 newborns. One newborn was unaffected and the other had a mild rash and a low platelet count.
There have not been any reports of newborns acquiring this infection from breast milk. One study has found virus particles in breast milk, however, they were unable to culture the virus. Experts believe, at this time, that the benefits of breast feeding outweigh the potential risk of transmission.
Is there a treatment for this infection?
Currently there is no treatment for Zika virus infection. Most healthy people will have mild self-limited infections and not require any supportive care other than Tylenol for the pain and fever. This virus has been associated with Guillian-Barré syndrome. This syndrome is a progressive paralysis that is also associated with other viral illnesses. The incidence of this syndrome appears to increase with increasing age.
The National Institutes of Health (NIH) is working on vaccine development at this time and increased funding has been requested from the US government to better study this virus and the effects of this illness as well as on efforts at vaccination. At this time, however, there is no vaccine available.
What can I do to prevent getting this infection?
Avoiding exposure to this virus is the first step in prevention. If you are pregnant or are attempting pregnancy, you should avoid any trips to areas of active Zika virus transmission. If you have recently travelled to an area with ongoing infection, attempting pregnancy should be delayed at least 8 weeks. There is no evidence that Zika virus will cause a congenital infection after the virus has been cleared from your blood. If your male partner has travelled and has no symptoms of Zika infection, then it is advised to wait 8 weeks. If he has symptoms consistent with Zika infection, then you are advised to wait 6 months before attempting conception.
Currently, there have been no cases of transmission here in the US. All infections have been in people that have travelled to countries with ongoing infection. The mosquitos that transmit the infection, however, are native to the US, and there is a possibility that virus transmission could occur in this country. Preventing mosquito bites is important in preventing this infection. Using the US Food and Drug Administration (FDA) recommend mosquito repellants is a safe way to prevent bites. The use of these repellents, including DEET, Picaridin, IR3535, and oil of lemon eucalyptus are safe for pregnant women to use. They have not been associated with any birth defects. Their use should be as described on the packaging.
Sexual transmission Prevention
All cases of sexual transmission have occurred from a symptomatic male partner. If your male partner has travelled to an area of active virus transmission, and you are pregnant, either abstain from intercourse, or use a condom correctly and consistently to prevent sexual transmission.
What should I do if I think I have been exposed to Zika virus and/or have the infection?
If you have travelled to an area of active transmission or have had intercourse with someone who has travelled and you have symptoms of Zika infection, talk with your doctor. If the symptom onset was under 7 days, a blood and urine test can be performed looking specifically for the virus. All of the testing is being conducted by the Florida Department of Health with the CDC. If the symptoms were in the last 12 weeks an antibody test can be performed. This test is not as specific and can be positive in those with a history of dengue or other flaviviruses. A second test must be performed to determine if you did have Zika virus. Sometimes this test can be equivocal.
If you are pregnant and have travelled to an area with active transmission, and you are asymptomatic, talk to your doctor about possible testing of your blood. Additionally, if you are asymptomatic or symptomatic, you will need to have a detailed ultrasound of your fetus and possibly additional ultrasounds to monitor for any signs of congenital Zika infection.
Where can I find more information on Zika virus?
The CDC website has a wealth of information that is updated frequently and can be found: http://www.cdc.gov/zika. Local information in the state of Florida can be found on the Department of Health website which is also updated frequently: http://www.floridahealth.gov/diseases-and-conditions/zika-virus/.