By now you’ve heard that we have another reason to hate mosquitoes. They carried and transmitted yellow fever in decades past, and have never stopped being responsible for the itchy, red welts we get after forgetting to layer on repellent and sit next to the citronella candle while we’re camping. More recently, they’ve been singled out as the main culprits behind spreading the Zika virus, a disease that can cause serious health issues and made many worried about traveling to the Olympic games in Rio — or anywhere else in South and Central America.
In February, the World Health Organization (WHO) declared Zika a public-health emergency of international concern, a rare designation that has only recently been extended to the Ebola outbreak in 2014, the H1N1 flu epidemic of 2009, and the polio outbreak in Syria in 2014.
For most adults who contract Zika, the effects are generally mild. However, the quick spread to most of the Americas — and its link to some serious health complications — has many health experts concerned. “The level of alarm is extremely high,” Margaret Chan, WHO’s director-general, said in Geneva in January, according to The Atlantic.
If you haven’t taken the time to brush up on your knowledge of Zika and how to protect yourself, here are the most important things to know about the disease and how it could affect you or your family members.
1. It’s been around for a while
Though Zika captured the international health spotlight only recently, the disease was identified by scientists in 1947, BBC reports. At that time, it was only present in monkeys living in Uganda in the namesake Zika forest. The first human case was found in Nigeria in 1954, and there have been outbreaks on a much smaller scale throughout Africa, Southeast Asia, and the Pacific Islands.
The largest outbreak up until this point was in French Polynesia from 2013 to 2014, the WHO reports. During that time, roughly 30,000 people were infected, and doctors began to see an increase in certain neurological disorders. WHO experts believe a traveler from French Polynesia brought the disease to Rio de Janeiro in Brazil, now the epicenter of the disease in the latest (and largest) outbreak. Within one year of hitting Brazil (thought to be in January 2015), the virus had spread throughout all of South and Central America, including the Caribbean.
2. It spreads through mosquitoes — and sex
Often, Zika is spread when a mosquito bites an infected person, then bites someone else, transferring the disease through the bloodstream. According to the WHO, Zika is spread through the Aedes mosquitoes, which live primarily in the Americas. They’re nicknamed the “gothic cockroaches” of the mosquito family, since they’re attracted to black things (like suitcases piled in closets or discarded tires). Shadowy, damp places are their ideal breeding ground. But they can multiply pretty much anywhere, making their proliferation difficult to control. Essentially, they’re the rabbits of the insect world that no one wants.
This particular type of mosquito bites during the early morning, late afternoon, and dusk, meaning good repellents are often more effective than mosquito nets at night.
While mosquitoes are typically ground zero for the disease, cases throughout the Western Hemisphere have spread through sexual transmission as well. To prevent further spreading, some health organizations are recommending using a condom for a month after returning home from visiting an area where Zika is a problem, and for up to six months if you show symptoms of the disease.
3. Zika symptoms only last about a week
For most people, Zika symptoms include a fever, rash, joint pain, and/or red eyes. Some people have complained of muscle soreness and headaches as well. According to the Centers for Disease Control and Prevention (CDC), symptoms are only likely to persist for a few days or up to a week.
There is no vaccine or treatment for Zika, though you should still see a doctor if you develop these symptoms after traveling to a country with known Zika outbreaks. Zika is likely only present in your bloodstream for about a week, though there is evidence to suggest it could remain in semen for up to two weeks. (Hence the advice to have protected sex for a month or longer, to be on the safe side.)
Though most symptoms are mild, the WHO concluded in March 2016 there is a “scientific consensus” (though not a proven link) to causing Guillain-Barré syndrome, which can cause tingling in certain parts of the body and can lead to temporary paralysis and trouble breathing at its worst. People who contract Guillain-Barré syndrome are rare, but a growing number of people in Zika zones have been diagnosed with the issue.
4. The largest concern is birth defects
The WHO has also concluded there is “scientific consensus” the Zika virus can cause birth defects, though scientists are still trying to discover the probability of such defects after being bitten by a mosquito. So far, scientists aren’t sure if being infected during a certain period of pregnancy makes a difference.
One of the most common birth defects associated with Zika is microcephaly, when the infant’s head is smaller than normal. This often signifies an underdeveloped brain, which can vary in severity. Microcephaly isn’t from Zika alone; it affects 25,000 children born in the U.S. each year, according to BBC. It can also be caused from outbreaks of rubella and from substance abuse during pregnancy.
The CDC and WHO strongly advise pregnant women to either abstain from sexual activity or have protected sex during their pregnancies if their partner has traveled to an area where the Zika virus is present. However, there is no evidence that Zika can affect the health of a fetus if it’s conceived after the virus has been cleared from the blood. The CDC further recommends that women with Zika should wait eight weeks before trying to become pregnant and men with Zika should wait up to six months after symptoms began before attempting to father a child. If you have additional questions, the CDC provides several checklists of items to discuss with your doctor.
5. Infections in the U.S. are minimal
A map from the CDC shows Zika has spread far and wide across the Americas, but so far is contained to small areas within the United States.
As of the beginning of August 2016, just six cases acquired locally have been reported, though some cases have been reported in numerous states after traveling to other infected areas. The CDC has identified one neighborhood in Miami that’s been impacted, recommending certain precautions there and in nearby areas. Wear insect repellent and long sleeves, and engage in protected sex if you (or your partner) are pregnant or might become pregnant.
For up-to-date information about Zika in the United States, check out the CDC’s case counts here.