About Zika Virus
Zika virus disease (Zika) is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito. The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito. 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. Once a person has been infected, he or she is likely to be protected from future infections.
Zika virus was first discovered in 1947 and is named after the Zika forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands. Zika outbreaks have probably occurred in many locations. Before 2007, at least 14 cases of Zika had been documented, although other cases were likely to have occurred and were not reported. Because the symptoms of Zika are similar to those of many other diseases, many cases may not have been recognized.
In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil and on Feb 1, 2016, the World Health Organization (WHO) declared Zika virus a public health emergency of international concern (PHEIC). Local transmission has been reported in many other countries and territories. Zika virus likely will continue to spread to new areas.
- Most people infected with Zika virus won’t even know they have the disease because they won’t have 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 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 healthcare provider if you are pregnant and develop a fever, rash, joint pain, or red eyes within 2 weeks after traveling to a place where Zika has been reported. Be sure to tell your health care provider where you traveled.
- The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito.
- 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.
- Zika virus usually remains in the blood of an infected person for about a week but it can be found longer in some people.
- Once a person has been infected, he or she is likely to be protected from future infections.
- The symptoms of Zika are similar to those of dengue and chikungunya, diseases spread through the same mosquitoes that transmit Zika.
- See your healthcare provider if you develop the symptoms described above and have visited an area where Zika is found.
- If you have recently traveled, tell your healthcare provider when and where you traveled.
- Your healthcare provider may order blood tests to look for Zika or other similar viruses like dengue or chikungunya.
- There is no vaccine to prevent or medicine to treat Zika virus.
- Treat the symptoms:
- Get plenty of rest.
- Drink fluids to prevent dehydration.
- Take medicine such as acetaminophen (Tylenol®) or paracetamol to reduce fever and pain.
- Do not take aspirin and other non-steroidal anti-inflammatory drugs (NSAIDS) until dengue can be ruled out to reduce the risk of bleeding.
- If you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication.
- If you have Zika, prevent mosquito bites for the first week of your illness.
- During the first week of infection, Zika virus can be found in the blood and passed from an infected person to a mosquito through mosquito bites.
- An infected mosquito can then spread the virus to other people.
Through mosquito bites
Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (A. aegypti and A. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses.
- These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases. They prefer to bite people, and live indoors and outdoors near people.
- Mosquitoes that spread chikungunya, dengue, and Zika are aggressive daytime biters. They can also bite at night.
- Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.
From mother to child
- A mother already infected with Zika virus near the time of delivery can pass on the virus to her newborn around the time of birth.
- A pregnant woman can pass Zika virus to her fetus during pregnancy. We are studying the adverse pregnancy and infant outcomes associated with Zika virus infection during pregnancy.
- To date, there are no reports of infants getting Zika virus through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika virus is found.
Through sexual contact
- Zika virus can be spread by a man to his sex partners.
- In known cases of likely sexual transmission, the men had Zika symptoms, but the virus can be transmitted before, during, and after symptoms develop.
- In one case, the virus was spread a few days before symptoms developed.
- The virus is present in semen longer than in blood.
Through blood transfusion
- As of February, 1, 2016, there have not been any confirmed blood transfusion transmission cases in the United States.
- There have been multiple reports of blood transfusion transmission cases in Brazil. These reports are currently being investigated.
- During the French Polynesian outbreak, 2.8% of blood donors tested positive for Zika and in previous outbreaks, the virus has been found in blood donors.
- Anyone who lives in or travels to an area where Zika virus is found and has not already been infected with Zika virus can get it from mosquito bites. Once a person has been infected, he or she is likely to be protected from future infections.
Areas with active mosquito-borne transmission of Zika virus
- Prior to 2015, Zika virus outbreaks occurred in areas of Africa, Southeast Asia, and the Pacific Islands.
- In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infections in Brazil.
- Currently, outbreaks are occurring in many countries.
- Zika virus will continue to spread and it will be difficult to determine how and where the virus will spread over time.
- Local mosquito-borne transmission of Zika virus has been reported in the Commonwealth of Puerto Rico, the US Virgin Islands, and America Samoa.
*Territories of the United States are sub-national administrative divisions overseen by the US federal government.
- No local mosquito-borne Zika virus disease cases have been reported in US states, but there have been travel-associated cases.
- With the recent outbreaks, the number of Zika cases among travelers visiting or returning to the United States will likely increase.
- 80% of cases will not be diagnosed.
- These imported cases could result in local spread of the virus in some areas of the United States.