If you’ve heard about the Zika virus and are wondering what it is, you’re not alone. Cases of this emerging infectious disease are soaring in the Americas and “spreading explosively,” according to World Health Organization (WHO) Director-General Margaret Chan, MD. Several states are reporting cases of U.S. travelers bringing the infection back with them, and health officials in Texas have confirmed a case of sexual transmission of the virus.
For most people, the Zika virus causes only a brief, mild flu-like illness. But in pregnant women it has been linked to an alarming increase in the rate of the birth defect known as microcephaly — a debilitatingly small head and brain size. The clusters of birth defects linked to the Zika virus are an international public health emergency, according to the WHO. Dr. Chan characterizes the situation as an “extraordinary event and a public health threat to other parts of the world.”
The Centers for Disease Control and Prevention (CDC) posted a travel alert advising pregnant women to delay travel to areas where Zika is active. The travel alert list continues to expand and now includes 30 countries or territories, most of them in the Americas
The CDC’s newest guidelines recommend that pregnant women coming back from these areas get tested for Zika if they have symptoms. Two pregnant women in Illinois tested positive for the virus after recent travel, reports the Illinois Department of Public Health. In addition, the CDC advises men who have a pregnant partner to use condoms if they live in or travel to areas with Zika infection.
A baby born recently with microcephaly in Oahu, Hawaii, had been infected with Zika, according to a press release from the Hawaii Department of Health, and the child’s mother had previously lived in Brazil — a Zika hot zone with up to 1.3 million cases of infection.
With the 2016 summer Olympic Games coming up in Rio de Janeiro, public health experts are worried that the virus may spread far beyond Latin America. The World Health Organization expects Zika to spread to all but two countries in the Americas: Canada and Chile.
Given the possible link to birth defects, preventing the spread of Zika is critical, especially for women in their childbearing years.
Here are the facts about the Zika virus:
1. The Zika virus is carried by mosquitoes and people, but usually spread by mosquitoes. Zika is an RNA virus related to the West Nile, yellow fever, and dengue viruses, and caused by the bite of the Aedes mosquito. These viral diseases have mosquitoes as their vector — the bug or organism that transmits an infection — and are generally not passed from person to person, explains Peter Jay Hotez, MD, PhD, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston.
“A person bitten by a mosquito that has the virus then becomes viremic. They get bitten by another mosquito, which then passes the virus along,” Dr. Hotez says.
The virus can also be sexually transmitted. A person in Texas became infected after having sex with someone who had traveled abroad, according to local health officials. Condom use can protect you against infection. If you are pregnant and your partner has been exposed to mosquitoes in regions that have Zika, you should talk with your doctor.
2. Symptoms of Zika virus infection are usually mild. Eighty percent of people who become infected never have symptoms. In those who do, the most common Zika virus symptoms are fever and rash; it can also cause muscle and joint pain, headache, pain behind the eyes, and conjunctivitis (itchy, red eyes), according to the World Health Organization (WHO). Health experts at the WHO Regional Office for the Americas note that symptoms generally last two to seven days. No effective treatment is available for Zika infection, but over-the-counter fever or pain medication can be helpful for symptom relief.
3. Unborn babies are most at risk from Zika virus complications. When pregnant women are infected with Zika, the unborn child is at risk, says Hotez. “We’re seeing illness when it strikes women who are pregnant, and it’s producing a horrific effect of microcephaly,” he says. “We don’t know when in pregnancy the consequences are greatest.” Microcephaly may cause mental retardation, as well as delays in speech, movement, and growth, according to the Mayo Clinic.
Healthcare workers in Brazil were stunned to learn that, throughout all of 2015 and up to the present, there have been more than 4,000 total new microcephaly cases that were suspected to be caused by Zika — more than 20 times higher than the numbers in prior years.
4. There’s no vaccine to protect against the Zika virus. “There’s going to be a need to accelerate a Zika vaccine,” says Hotez. “I think the world got caught by surprise at the congenital infections. Now there’s going to be a lot of interest in a vaccine for women of reproductive age, like the rubella vaccine [to prevent birth defects].” Rubella vaccination is now mandatory for children and is a recommended vaccine for adults; it helps prevent miscarriage in pregnant women, and heart problems, blindness, and hearing loss in newborns.
5. Zika began in Africa and spread rapidly. The virus, originally named ZIKV, was first discovered in 1947 in a rhesus macaque in the Zika forest in Uganda. Researchers there found that it lived in mosquitoes, and they learned through experimentation that it could also infect mice.
Outbreaks were reported from 1951 to 1981 throughout Africa and Asia, and in 2007 in Polynesia where 73 percent of the population were infected. But since the first cases were discovered in Latin America in 2014, the virus has quickly spread. In December 2015, the Pan American Health Organization/World Health Organization (PAHO/WHO) recommended Latin American countries start gearing up to screen for Zika and prepare for demands on the healthcare systems due to the severe health problems it’s causing in newborns.
6. Zika has reached Puerto Rico’s mosquitoes and may keep traveling north.“Puerto Rico has reported the first locally-acquired Zika virus case in the United States,” says Benjamin Haynes, a CDC spokesperson. The case was reported in December 2015.
“I think we have to proceed along a worst-case scenario that the Gulf Coast is at risk. We’re vulnerable,” says Hotez. “I’m not an alarmist. But I am worried about a Zika outbreak on the Gulf Coast.” That includes areas around Houston, New Orleans, and Tampa-St. Petersburg, Florida, which are all potential hot zones for tropical diseases because mosquitoes thrive there.
7. U.S. travelers are bringing the viral disease back with them. These imported cases happen when a person is infected elsewhere and then visits or returns to the United States. “The first travel-associated Zika virus disease case among U.S. travelers was reported in 2007,” says Haynes. “From 2007 to 2014, a total of 14 returning U.S. travelers had positive Zika virus testing performed at the CDC.” He adds that in all of 2015 and in 2016 to date, at least eight U.S. travelers have tested positive for the Zika virus. “The CDC is still receiving specimens for Zika virus testing from returning U.S. travelers who became ill in 2015 or 2016,” he cautions, which means the counts could get higher.
8. Travelers probably won’t bring infected mosquitoes along with them. “It’s extremely unlikely that mosquitoes would be carried back to the United States by citizens traveling abroad,” says Jim Fredericks, PhD, chief entomologist and vice president of technical and regulatory affairs for the nonprofit National Pest Management Association in Fairfax, Virginia. “As adults, mosquitoes are a relatively fragile insect that doesn’t travel very well. In addition, since only a fraction of the total mosquito population in Zika-endemic areas carries the virus, it’s even less likely for an infective mosquito to be brought back alive,” he says. The bigger concern is that a person infected with the virus could pass it along to local mosquito populations.
9. You can help prevent Zika infection by using insect repellents. Travelers going to areas with current Zika outbreaks can take steps to avoid catching the virus. “The best way to avoid mosquito bites is to use a repellent containing at least 20 percent DEET, picaridin, oil of lemon-eucalyptus, or IR3535 when venturing outdoors, especially near dawn and dusk when mosquitoes are most active,” says Dr. Fredericks. “Whenever possible, it also makes sense to wear long sleeves and pants when outside during these times,” he says.
10. Mosquito control can help prevent Zika. Controlling the insect vector by cutting down on mosquito breeding is one way to prevent spread of this and other mosquito-borne viruses. Breeding sites include water-filled habitats like plant containers and toilets inside the home, and puddles, birdbaths, and pooled water outdoors. Chemical pesticides can kill mosquitoes, but use them carefully to prevent contamination that could be harmful to your health, notes the CDC.