What Is the Zika Virus, and Why Should I Care?

Zika is exploding across the Americas and slowly creeping across the globe, too, with documented cases in 24 countries by the end of January and more to come.
Publish date:
February 1, 2016
diseases, Public Health

The name might sound a little strange, but the virus is quite serious. Zika is exploding across the Americas and slowly creeping across the globe, too, with documented cases in 24 countries by the end of January and more to come. Officials estimate that as many as four million people may become infected with Zika before the outbreak is resolved, and it is definitely at pandemic status.

Until last week, though, you might not have even heard of it (though the current outbreak started to pick up steam in late 2015).

What exactly is Zika, and should you be worried?

The short answer: Zika is a virus originating in the tropics that causes mild fever and some associated symptoms. Even if you personally don't get sick, Zika poses a risk to the general population, and like many other viruses, it always has the possibility of evolving into something more aggressive. If it does, the ease with which it spreads could be a significant problem.

This virus, carried by mosquitoes and also transmissible through blood transfusions and labor, as well as through the placenta — more on that in a moment — appears to have originated in Uganda, where the first specimens were identified in 1947 by researchers at the Yellow Fever Institute. It's related to yellow fever as well as dengue, Japanese encephalitis, and West Nile, and only about 20 percent of infected people actually develop symptoms, but that doesn't make it less serious.

No fatalities have been linked to Zika yet, with most patients who do develop symptoms report experiencing mild fever, rash, joint pain, eye irritation, and headaches. After a few days of not feeling very well, the infection passes. While infected, regardless as to whether people have visible symptoms, they can in turn pass the virus on to others, and after they recover, the virus can leave an unpleasant legacy behind.

While researchers haven't definitively declared a casual relationship, they strongly suspect that Zika infection during pregnancy could cause microcephaly in some infants. You may not have heard of microcephaly until last week either, because it's fairly rare — around two to 12 in 10,000 births according to statistics, which are a little imperfect.

Babies born with this congenital abnormality have smaller heads than would be expected for their developmental age, and they typically also have smaller, less-developed brains. It can cause a variety of impairments including intellectual and cognitive disabilities, blindness, balance problems, feeding difficulty, developmental delays, and seizures.

The level of support a child with microcephaly requires varies, depending on the degree of impairment. Some children may have mild disabilities, but go on to live active adult lives, fully engaged with their communities. Others may have significant anomalies that make it difficult to perform tasks of daily living, to learn, or to develop — they'll have to work with aides for their rest of their lives and they may have trouble communicating.

Doctors monitoring births in Latin America, where the disease started propagating, have made a disturbing finding: In Zika-associated cases, microcephaly tends to be more severe. Especially in instances where mothers are exposed during the first trimester — when some may not have even realized they were pregnant. Furthermore, they're finding that in some cases babies thought to be at risk for microcephaly because of Zika infection are born with head sizes within expected ranges, but later go on to develop brain lesions and other health problems, so issues associated with Zika will likely keep growing.

Developing fetuses aren't the only ones at risk of long-term complications from Zika. In adults, some cases of Guillain-Barré, a rare neurological disorder seen in about one of every 100,000 people, appear to be linked with the virus. People with this neurological disorder experience an abnormal immune response, with the immune system attacking the critical myelin sheath in the peripheral nervous system, which interferes with the transmission of signals along the nerves. They develop numbness, tingling, and other problems, and can in extreme cases experience paralysis. At times, the condition is so severe that patients cannot breathe on their own, and may need to use a ventilator. Plasma exchange and physical therapy can help patients recover, but some may experience lasting health problems.

Currently there's no vaccination available for Zika, and there's also no cure. The best approach is prevention, and tackling mosquitos is a considerable challenge, especially in the tropics, where they're numerous and aggressive, and many homes don't necessarily have architectural elements designed to keep them out, like window screens. The CDC recommends wearing full-length pants and sleeves, applying insect repellent while outdoors, using air conditioning instead of open windows, and utilizing insect nets and screens. Sleeping under a mosquito net is particularly important — in fact, a number of charitable organizations coordinate campaigns to send inexpensive but highly effective nets to African nations where malaria is an endemic problem, and if Zika keeps spreading, such initiatives may also be important for the prevention of this disease as well, though it's caused by mosquitos that are primarily active during the day.

All told, this makes for a dangerous combination, as in a population where people can be silent carriers and no one can be treated, the disease can quickly hop around and cause lasting health effects. That's good reason to be seriously concerned, and world health officials definitely are, warning that the virus is "spreading explosively," two words you do not want to hear when it comes to infectious disease. The Centers for Disease Control and Prevention have actually issued a travel advisory, warning about Zika in Central and South America, parts of Africa, and parts of Southeast Asia — like many tropical viruses, it tends to be endemic, and spread, in a band across the equator.

Pregnant people — or those planning to become pregnant — should definitely stay out of areas with ongoing Zika outbreaks, and herein lies the additional rub. Some governments are advising citizens to avoid pregnancy until the outbreak is resolved, which doesn't do much for people who are already pregnant, but also comes with a serious problem.

In Latin America, where the virus is really flourishing, access to contraceptives is severely limited, as is access to abortion — in essence, the government is telling people to practice abstinence for the duration of the pandemic.

Notably, no advisories have recommended that men consider using condoms for the protection of their partners, despite the fact that not using a condom can both cause pregnancy and may serve as a vector for disease transmission.

In and of itself, Zika is dangerous. But it's also serving as a dry run. The catastrophic Ebola epidemic of 2014 and 2015 showed that the global public health community is not prepared for a widespread pandemic, and the response to Zika will demonstrate how much public health officials have learned, if any. The best way to contain an outbreak is to respond extremely rapidly with a coherent framework that will help epidemiologists, health care providers, and officials quickly deal with the situation. Ebola provided many instructive lessons on the subject, as it was the first time some agencies and governments had encountered any kind of outbreak on that scale.

Zika is not going to be the last rapidly spreading pandemic. Viruses and humans have lived together for a very long time, and periodically a virus roars out of the background to flood through human populations. In a globally connected world, the effect of viral spread will be intensified — maybe it will be the next flu season or the resurgence of another existing virus, maybe it will be an entirely new virus.

No matter what it is, the global health community must have a system in place to deal with these threats, and that's one of the reasons it's so critical to care about Zika. Whether you're infected or not, whether you're pregnant or not, whether you spread it to others or not, whether you develop Guillain-Barré or not, you're a part of the global community, and without adequate containment of such viruses now and in the future, you could be in the crosshairs next time.

Image credit: Day Donaldson/CC