According to the World Health Organization (WHO), the Zika virus is an "extraordinary event" that is "spreading explosively" through the Americas. The WHO has deemed this an international public health emergency as the virus, and its suspected link to birth defects, could potentially result in as many as 4 million infections by the end of this year.
What is Zika? Where did it come from?
Zika is a disease caused by the Zika virus. It is spread to people through mosquito bites.
Zika was first identified in Africa in 1947. Since then there have been sporadic cases identified in Africa and Asia. In 2007 cases began to be found in Southeast Asia and the Western Pacific.
In May 2015, local transmission of Zika virus was found in Brazil. Since then a serious outbreak of Zika virus transmission has occurred in Brazil and many other countries in South America, Latin America, and the Caribbean have reported cases of Zika virus.
How does Zika virus spread?
The main method of Zika virus to spread to humans is through the bite of an infected Aedes species mosquito. These mosquitos live and breed around natural and artificial bodies of water. They tend to bite during daytime and can be found both indoors and outdoors around homes or other buildings.
Zika virus is also potentially spread from pregnant mothers to babies during pregnancy. Zika virus has been found in infants born to mothers with Zika virus infection during pregnancy.
Zika virus does not typically spread directly from person to person. Isolated cases of sexual transmission have occurred. The most recent case was reported on February 2, 2016, in Dallas, Texas, in which a patient contracted Zika infection after having sexual contact with an ill individual who had recently returned from a country where Zika is present.
Direct person-to-person spread of Zika is still very uncommon. Zika has not been shown to spread by casual contact such as shaking hands, hugging, or kissing, nor through the air, through food, or through water.
Where is Zika virus found?
Prior to 2015, Zika virus was found in areas of Africa, Southeast Asia, and the Pacific Islands. In May 2015, the virus was found to be transmitted locally in Brazil. By January 20, 2016, locally transmitted cases have been reported in Puerto Rico and 19 other countries in South America, Latin America, and the Caribbean.
The vast majority of cases of Zika virus infection diagnosed in the United States have been in persons who recently traveled to a country with active Zika transmission, and that appears to be the case with a patient in Philadelphia who recently traveled to the Caribbean.
There have not been any signs of local transmission by Aedes mosquitoes in our area or any part of the United States.
Travelers going to areas with active Zika transmission should continue to use mosquito repellents judiciously and pregnant women should consider postponing travel to an area with Zika transmission if possible. Anyone who has traveled to an area with Zika virus transmission and gets sick within 2 weeks of returning should contact their doctor. Symptoms of Zika virus infection are fever, rash, muscle or joint aches, conjunctivitis, and headache. Severe illness requiring hospitalization is uncommon and deaths are very rare.
How do you diagnose Zika virus?
Zika virus should be suspected in patients with the above symptoms who traveled to areas with Zika transmission within 2 weeks of symptom onset.
Testing of blood/serum samples of patients suspected of having Zika can be done through the Centers for Disease Control & Prevention (CDC). The specific test ordered is dependent on how soon after symptom onset the sample is drawn.
Because of the similar geographic distribution and symptomatology, patients with suspected Zika infection should also be evaluated for possible dengue & chikungunya infection.
What are the treatment options for Zika infection?
Currently there are no specific antiviral treatments for Zika. The majority of patients with symptomatic disease will improve within one week. Treatment is usually supportive and includes rest, fluids, analgesics for pain, and antipyretics for fever.
Patients with suspected or confirmed Zika infection should be protected from further mosquito exposure to prevent other mosquitos from being infected and to reduce the risk of local transmission.
Patients with suspected or confirmed Zika do not need to be isolated from other people.
How can you prevent Zika infection?
There is no vaccine to prevent Zika infection at this time.
The best way to prevent Zika virus infection is to prevent mosquito bites:
- Wear long sleeve shirts and long pants.
- Stay in places with air conditioning or use window & door screens to keep mosquitos outside.
- Sleep under a mosquito net if you are outside or can’t keep mosquitos outside.
- Use an EPA-approved insect repellent to keep mosquitos from biting.
- Use permethrin to treat clothes/gear to help keep mosquitos away.
Further information on mosquito avoidance is available from the CDC (PDF).
People engaging in any sexual activity while traveling to places with Zika virus transmission, or with partners who have recently traveled to these places should ensure proper use of condoms to prevent potential sexual transmission.
What are the risks of Zika infection during pregnancy?
Current evidence suggests that infection during pregnancy is similar to that of the general population. No evidence exists to suggest that pregnant women are more susceptible to infection or get more severe disease.
There are reports of congenital microcephaly (infants born with smaller than normal heads) in infants born to mothers who were infected with Zika virus during pregnancy. The Zika virus has been found in infants born with congenital microcephaly but it is not yet know if the Zika virus itself is the cause or if there are other factors involved, such as infection with other organisms, nutrition, or other environmental factors.
Further studies and investigation into the possible link between Zika and congenital microcephaly are ongoing.
Because of potential sexual transmission, pregnant women whose partners have recently come from a country with Zika virus transmission should ensure proper use of condoms with any sexual activity.
Are there any restrictions on travel?
At this time the CDC has issued an “Alert-Level 2” warning for travel to areas with active Zika transmission. This means people traveling to these areas should practice enhanced precautions to prevent mosquito bites.
Because the link between Zika virus infection during pregnancy and serious birth defects, including congenital microcephaly, is still not clear the CDC has recommended that women who are pregnant (in any trimester) consider postponing travel to any area where Zika virus transmission is ongoing. If a pregnant woman must travel to these areas, consultation with her physician is recommended. Women who are trying to get pregnant that travel to these areas should also consult with their physician prior to travel.
Is it safe to get pregnant after traveling to a place with Zika transmission?
Zika virus usually remains in the blood of an infected individual for about a week. Zika virus has been found in semen for up to two weeks. There is no evidence that the virus causes infections in a baby that is conceived after the virus is cleared from the blood. There is currently no evidence to suggest that Zika virus infection poses a risk of birth defects in future pregnancies.
Where can more information be found?
The CDC has a webpage at http://www.cdc.gov/zika/index.html with further information on Zika-affected areas, transmission, prevention, diagnosis, and special consideration for pregnant women infected with Zika.
- Hennessey M, Fischer M, Staples JE. Zika Virus Spreads to New Areas — Region of the Americas, May 2015–January 2016. MMWR Morb Mortal Wkly Rep 2016;65:55–58. DOI: http://dx.doi.org/10.15585/mmwr.mm6503e1
- Zika-affected Areas http://www.cdc.gov/zika/geo/index.html
- Petersen EE, Staples JE, Meaney-Delman, D, et al. Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016. MMWR Morb Mortal Wkly Rep 2016;65:30–33. DOI: http://dx.doi.org/10.15585/mmwr.mm6502e1