Patient Education
The World Health Organization has declared the Zika virus an international public health emergency, prompted by growing concern that it could cause birth defects. As many as four million people could be infected by the end of the year. Officials at the Centers for Disease Control and Prevention have urged pregnant women against travel to about two dozen countries, mostly in the Caribbean and Latin America, where the outbreak is growing.
The infection appears to be linked to the development of unusually small heads and brain damage in newborns. Some pregnant women who have been to these regions should be tested for the infection, the agency said. Here are some answers and advice about the outbreak.
What is the Zika virus?
The Zika virus is a mosquito-transmitted infection related to dengue, yellow fever, and West Nile virus. Although it was discovered in the Zika forest in Uganda in 1947 and is common in Africa and Asia, it did not begin spreading widely in the Western Hemisphere until last May, when an outbreak occurred in Brazil. Until now, almost no one on this side of the world had been infected. Millions of people in tropical regions of the Americas may now have been infected. Yet for most, the infection causes no symptoms and leads to no lasting harm. The scientific concern is focused on women who become infected while pregnant and those who develop a temporary form of paralysis after exposure to the Zika virus.
How does the virus spread?
Zika is spread by mosquitoes of the Aedes genus, which can breed in a pool of water as small as a bottle cap and usually bite during the day. The aggressive yellow fever mosquito, Aedes aegypti, has spread most Zika cases, but that mosquito is common in the United States only in Florida, along the Gulf Coast, and in Hawaii - although it has been found as far north as Washington, D.C., in hot weather. The Asian tiger mosquito, Aedes albopictus, is also known to transmit the virus, but it is not clear how efficiently. That mosquito ranges as far north as New York and Chicago in summer.
Can the Zika virus be sexually transmitted?
Yes, but it rarely happens. Based on a few reports, the C.D.C. issued tentative new guidelines suggesting that pregnant women avoid contact with semen from men who have recently returned from areas with Zika transmission. Men returning from these regions should consider using condoms.
How might Zika cause brain damage in infants?
The possibility that the Zika virus causes microcephaly - unusually small heads and damaged brains - emerged only in October, when doctors in northern Brazil noticed a surge in babies with the condition. It may be that other factors, such as simultaneous infection with other viruses, are contributing to the rise; investigators may even find that the Zika virus is not the main cause, although right now circumstantial evidence suggests that it is. It is not known how common microcephaly has become in Brazil’s outbreak. About three million babies are born in Brazil each year. Normally, about 150 cases of microcephaly are reported, and Brazil says it is investigating nearly 4,000 cases.
What countries should pregnant women avoid?
About two dozen destinations mostly in the Caribbean, Central America, and South America. The Pan American Health Organization believes that the virus will spread locally in every country in the Americas except Canada and Chile.
How do I know if I’ve been infected? Is there a test?
It’s often a silent infection, and hard to diagnose. Until recently, Zika was not considered a major threat because its symptoms are relatively mild. Only one of five people infected with the virus develop symptoms, which can include fever, rash, joint pain, and red eyes. Those infected usually do not have to be hospitalized. There is no widely available test for Zika infection. Because it is closely related to dengue and yellow fever, it may cross-react with antibody tests for those viruses. To detect Zika, a blood or tissue sample from the first week in the infection must be sent to an advanced laboratory so the virus can be detected through sophisticated molecular testing.
I’m pregnant and I recently visited a country with the Zika virus. What do I do?
Some women should get blood tests, and just about all should get ultrasound scans. On Jan. 19, the C.D.C. issued interim guidelines for women in that situation and for their doctors. The guidelines are complex — and may change. In general, they say that pregnant women who have visited any area with Zika transmission should consult a doctor. Those who have had symptoms of infection like fever, rash, joint pain, and bloodshot eyes during their trip or within two weeks of returning should have a blood test for the virus. Under the C.D.C’s testing algorithm, pregnant women who have been to affected regions - whether they have symptoms or not, and whether they have negative or positive blood tests - should eventually have an ultrasound scan to see if their fetuses are developing microcephaly or calcification of the skull. Unfortunately, an ultrasound usually cannot detect microcephaly before the end of the second trimester. Some women also should have an amniocentesis to test the fluid around the fetus for the Zika virus. But amniocentesis involves piercing the amniotic sac with a long needle through the abdomen; it is slightly risky for the fetus and is not recommended before 15 weeks gestation.
Is there any advise by The Indian Medical Association?
The Indian Medical Association has issued an advisory asking pregnant women to avoid visiting Latin America. India has the diagnostic kits but treatment still eludes the world.
Is there a treatment?
No. The C.D.C. does not recommend a particular antiviral medication for people infected with the Zika virus. The symptoms are mild - when they appear at all - and usually require only rest, nourishment, and other supportive care.
Is there a vaccine? How should people protect themselves?
There is no vaccine against the Zika virus. Efforts to make one have just begun, and creating and testing a vaccine normally takes years and costs hundreds of millions of dollars. Because it is impossible to completely prevent mosquito bites, the C.D.C. has advised pregnant women to avoid going to regions where Zika is being transmitted and has advised women thinking of becoming pregnant to consult doctors before going. Travelers to these countries are advised to avoid or minimize mosquito bites by staying in screened or air-conditioned rooms or sleeping under mosquito nets, wearing insect repellent at all times, and wearing long pants, long sleeves, shoes, and hats.