Wikimedia Commons // Public Domain
Wikimedia Commons // Public Domain

7 Questions About the Zika Virus, Answered

Wikimedia Commons // Public Domain
Wikimedia Commons // Public Domain

In just a few weeks, the Zika virus has gone from relative obscurity to a major concern of the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and other giants in global disease control. What’s happening with Zika, and why has it exploded now?

1. WHAT IS ZIKA VIRUS?

Zika is a virus transmitted by mosquitoes. It’s in the same family as several other mosquito-borne viruses that also can cause human disease, including yellow fever, dengue, and chikungunya. There is no treatment or vaccine available.

2. WHAT ARE THE SYMPTOMS OF INFECTION?

Most people who are infected with Zika virus don’t even know it; as many as 80 percent of the cases are asymptomatic. For those who do show symptoms, fever, headache, rash, and joint and muscle aches are the most common signs of infection.

3. HOW DOES THE VIRUS SPREAD?

Zika is an arbovirus—a virus that is “arthropod-borne.” It is transmitted by mosquitoes—most commonly a mosquito called Aedes aegypti. This mosquito lives mainly in tropical areas of the world, including parts of the United States. A. aegypti is well-adapted to live with humans, laying eggs in stagnant water that can be found around homes—old tires, bird baths, cans, or pots. They feed almost exclusively on humans and can be day-biters, so some interventions to keep mosquitoes away, such as bed nets, aren’t as helpful. They also travel well and can spread via boats or potentially airplanes that move around the world.

While A. aegpyti is the main vector for Zika, there is concern that other mosquitoes may be able to transmit the virus. Another invasive mosquito, the Asian tiger mosquito (Aedes albopictus) is a common disease vector. It can spread viruses related to Zika, and was the main vector of a large Chikungunya outbreak in 2006. This mosquito also was involved in a Zika outbreak in Gabon in 2007, but that was a different strain of Zika than the one currently circulating in the Americas. Researchers in Brazil are also testing the possibility that another mosquito species of the Culex family could spread Zika. While A. aegypti is geographically limited, A. albopictus and various species of Culex mosquitoes are more widely distributed, living in colder climates.

Human-to-human transmission is also theoretically possible. There are two reports of Zika virus transmission via sex. One report involved an American who had contracted Zika in Senegal and developed symptoms upon his return to Colorado, and whose wife developed Zika infection after exposure. A second case found Zika virus in the semen of a man in Tahiti long after the virus had been cleared from the blood. However, even if this is possible, it seems to be a rare mode of transmission.

4. WHERE DID IT COME FROM?

We’ve known about Zika since 1947, when it was discovered in a monkey in the Zika forest in Uganda. A year later, the virus was found in a mosquito in the same location, and blood samples from humans showed antibodies to Zika, evidence they had previously been infected with the virus. The first documented human case was identified in Nigeria in 1968. Blood testing in the 1950s and 1960s showed infection with the virus was widespread in humans across Africa and many parts of Asia. The first outbreak of Zika outside of Africa or Asia was on Yap Island in 2007, infecting almost 75 percent of the island’s population of 6900 people. A second outbreak in French Polynesia in 2013–2014 may have infected as many as 19,000 people.

5. HOW WIDESPREAD IS IT?

Zika first appeared in Brazil in mid-2015, possibly introduced from French Polynesia during 2014’s World Cup soccer tournament or other international sporting events. Active transmission of the virus has been confirmed in 22 countries as of January 28. Many of them are popular travel destinations.

Because they are tourist spots, individuals infected during travel have returned home, incubating the virus. Travel-associated cases have been diagnosed in Denmark, Spain, Portugal, Italy, and the United Kingdom. The United States has seen approximately a dozen cases of imported Zika infections. No local spread has been documented in these countries. The WHO has suggested the outbreak could eventually affect up to 4 million people; approximately 1 million have already been infected.

6. WHY IS THIS OUTBREAK SO SERIOUS?

First, the outbreaks are very large and have infected large proportions of the population where they’ve occurred. Because this virus has never been identified in this geographic location before, the population has no immunity to it—meaning everyone is vulnerable.

In Brazil, there has been an increase in reports of microcephaly in babies. This means that the babies are born with an abnormally small head, and problems with brain development. This has been linked to Zika virus infections in the mother during pregnancy; almost 4000 babies have been diagnosed with the condition since October 2015. A baby born in Hawaii to a mother who had been infected with Zika was also born with microcephaly. As a consequence, the CDC has issued interim guidelines for travel during pregnancy, suggesting that pregnant women do not travel to areas experiencing a Zika outbreak. Other countries experiencing outbreaks have suggested that women delay pregnancy for months or years, until the outbreak subsides—a difficult proposition in an area where many pregnancies are unplanned and access to birth control is limited.

Increases in another neurological condition, Guillain-Barré syndrome, has also been reported in Colombia, and that is thought to be due to Zika virus infections. Though microcephaly has not been reported in association with previous Zika outbreaks, Guillain-Barré syndrome was identified in the 2013 outbreak in French Polynesia.

7. WHAT DON'T WE KNOW ABOUT ZIKA?

A lot. Right now, there appears to be a correlation between microcephaly and Zika infection, but we can’t be 100 percent sure that Zika is causing it—or that there really is an increase in microcephaly cases at all. If Zika is indeed causing microcephaly (and/or Guillain-Barré syndrome), we have no idea how the virus is doing this. Assuming the virus is responsible, we don’t know if infection needs to be in a certain developmental window during the pregnancy, or if the infection would have to be symptomatic in order for microcephaly to result. We have no vaccine or treatment for Zika, though the outbreak has spurred interest in developing them. For now, control efforts are concentrated on mosquito elimination and education of the population about the potential risks of infection.

nextArticle.image_alt|e
iStock
arrow
Health
16 Facts About Migraines
iStock
iStock

Unless you suffer from migraines yourself, you may think that having a migraine means having a really bad headache. But debilitating head pain is only one part of the medical condition called migraine disorder. Other common symptoms are nausea, dizziness, fatigue, sensitivity to light and sound, and even temporary blindness. The symptoms and causes of migraine look different in different patients, and researchers are only now beginning to understand what the condition is and how to treat it. Here are some of the most enlightening facts we know about migraine disorder.

1. IT'S THE THIRD MOST COMMON DISEASE IN THE WORLD.

Even if you don’t suffer from migraine, chances are you know someone who does: The disorder affects 14.7 percent of the population, or one in seven people, around the world. In the U.S. alone, roughly 39 million people are affected by the condition. Chronic migraine (experiencing at least 15 headache days per month over a three-month period, with over half being migraines) is more rare, impacting about 2 percent of the world population.

2. WOMEN SUFFER MORE THAN MEN.

Of the one billion people on Earth who have migraine disorder, three-fourths are women. Medical experts suspect this has to do with the cyclical nature of female hormones. According to research presented earlier in 2018, NHE1, the protein that regulates the transfer of protons and sodium ions across cell membranes, is a crucial component of migraine headaches. NHE1 production likely fluctuates a lot more in women than in men. When scientists looked at the brains of lab rats, they found that NHE1 levels were lowest when estrogen was at its peak. In general, female rats also had four times the amount of NHE1 in their brains as males. If the same holds true for people, that could explain why women are not only more likely to suffer migraines in the first place, but why they experience them more frequently and more intensely, and have more difficulty responding to treatment.

3. MIGRAINE TRIGGERS VARY WIDELY.

For doctors and sufferers, migraine triggers can be a source of confusion. They vary from patient to patient and often come from unexpected sources that have no relation to each other. Stress, too much or too little sleep, dehydration, alcohol, and caffeine are some of the most common triggers. Some people get migraines after eating specific foods, like cheese, and others are sensitive to changes in weather conditions like barometric pressure. Some people manage their migraines by pinpointing and avoiding triggers.

4. FOR SOME, AURAS ARE A WARNING THAT A MIGRAINE IS COMING.

Before the nausea, dizziness, and splitting head pain begin, auras warn some people that a migraine is on its way. Less than 25 percent [PDF] of migraine sufferers experience distorted senses, such as numbness or tingling in the hands or face, or blotches of light or darkness disrupting their vision. Auras usually occur 10 to 30 minutes before the migraine develops and last from five minutes to one hour.

5. SYMPTOMS CAN INCLUDE TEMPORARY BLINDNESS …

Unlike migraine with aura, retinal migraine is limited to one eye. Symptoms range from seeing twinkling stars to partial or complete loss of vision. The same eye is almost always affected, and the person typically regains their sight after 10 to 20 minutes.

6. … AND LOSS OF LIMB FUNCTION.

One of the rarest, and scariest, subtypes of migraine is hemiplegic migraine. People with this variant can experience weakness, numbness, tingling, or loss of motor function in parts of one half of their body, including their arm, leg, or face. Though sensations usually dissipate within 24 hours, they can last anywhere from one hour to several days. Sometimes they’re accompanied by typical migraine symptoms, such as head pain, but they can also occur on their own.

7. KIDS GET MIGRAINES TOO.

Migraine isn’t just a problem for adults—up to 10 percent of all school-aged kids are affected by the disorder, with reported cases coming from children as young as 18 months. According to the documentary Out of My Head (2018), migraine is the third most common reason for child emergency room visits. The symptoms of migraine in kids are similar to what’s seen in older patients: They may experience intense head pain, sick feelings, distorted vision, and sensitivity to sound and light. The major differences are that child migraines often develop suddenly and are shorter than they are in adults. In children, it’s not uncommon for the nausea and abdominal pain to feel worse than the actual headaches. Just as some sufferers don’t experience their first episodes until after puberty, some children with migraine grow out of it. According to one study, migraine symptoms disappeared completely in 23 percent of former child sufferers by age 25.

8. MIGRAINE MAY BE HEREDITARY.

For most people with migraine disorder, it runs in the family. Anywhere from 80 to 90 percent of migraine sufferers report having at least one family member who has it as well. If one parent has migraine, there’s a 50 percent chance their child will eventually have to live with migraine—and that risk shoots up to 75 percent when both parents have the condition.

9. MANY VETERANS RETURN HOME WITH MIGRAINES.

Genetics isn’t the only factor that contributes to someone’s chance of having migraine disorder. One study found that after a 12-month deployment in Iraq, 36 percent of veterans exhibited symptoms of migraine. The cause often stems from head or neck trauma sustained from explosions, falls, or other accidents during their service. While post-traumatic migraine goes away in most patients within a few months, in some cases it can develop into a chronic condition.

10. MIGRAINE IS LINKED TO THE "SECOND BRAIN" IN YOUR GUT.

In addition to the part of our nervous system that responds to outside stimuli, humans have an enteric nervous system: the part responsible for regulating digestion. Some medical experts believe that migraine is closely tied to this “second brain.” People with migraine are twice as likely to have IBS as people with tension headaches. Abdominal migraine, where the pain is concentrated in the stomach rather than the head, is one form the condition takes. It's most often seen in children, but it can affect adults as well.

11. DESPITE THE HIGH COST OF MIGRAINE DISORDER, RESEARCH IS UNDERFUNDED.

In 2017, the National Institutes of Health invested $22 million in migraine research. Asthma research received $286 million, breast cancer $689 million, and diabetes $1.1 billion.

12. THE DISORDER COSTS US UP TO $13 BILLION ANNUALLY.

Though migraine isn't life-threatening like these other conditions, it is widespread enough to have a negative impact on society as a whole. Workers with migraine often end up taking a lot of time off from their jobs, which can cost their employers. According to Out of My Head, it’s estimated that 113 million work days are missed annually due to migraine, adding up a to $13 billion loss.

13. MIGRAINE MAY HAVE INSPIRED PARTS OF ALICE IN WONDERLAND …

In the famous children’s book, Alice drinks a liquid that makes her grow many times her size and eats a cookie that shrinks her to tiny proportions. Migraine sufferers may recognize themselves in these passages. Possible symptoms of the disorder include micropsia and macropsia, or perceiving objects to be much smaller or larger than they really are. Some theorize that Alice in Wonderland author Lewis Carroll suffered migraines and wrote his experiences into his story. The book’s connection to migraine is so famous that today the related symptoms are commonly known as Alice in Wonderland Syndrome.

14. … AND PLAGUED A FOUNDING FATHER.

Another famous person from history who likely suffered from migraines was Thomas Jefferson. His symptoms could last for weeks and often appeared during stressful times in his life. There was even an episode that coincided with one of the most important nights of his political career. One night in June 1790, he invited Federalist Alexander Hamilton and Republican James Madison to his home for a dinner party in the hopes of getting his peers to agree on a location for the new U.S. capital. Despite dealing with lingering head pain from a migraine, he successfully brokered the compromise that landed the capital at its current spot on the Potomac River between Maryland and Virginia. In return, Madison agreed that he would not block Hamilton's plan for the federal government to take on state war debt, thus helping establish the young nation's credit.

15. MIGRAINE IS LINKED TO DEPRESSION.

In the U.S., up to 40 percent of people with migraine also have depression. Risk of anxiety, bipolar disorder, and panic disorder are also higher in migraine sufferers. Researchers are still figuring out the connections between mental illness and migraine. While the anticipation of painful symptoms can cause depression and anxiety in some people, experts believe that mental illness is often more than just an effect of living with migraine. The production of the brain chemical serotonin is involved in both migraine and depression. That’s why tricyclic antidepressants designed to increase serotonin levels are sometimes prescribed to treat migraine.

16. A NEW SHOT CAN TREAT MIGRAINE.

Many migraine therapies from the past few decades have been the result of trial and error. Medications designed to treat other conditions, such as antidepressants, epilepsy medicine, and botox, have all been prescribed to migraine sufferers, with mixed results. Earlier in 2018, the first-ever shot made to treat migraines specifically secured FDA approval. The shot, which blocks a peptide linked to migraine, is taken once a month and can improve symptoms or completely eliminate them in some cases. Before the new injection came along, the only other migraine-specific medications patients had to choose from were triptans, which stimulate the neurotransmitter serotonin. They can't prevent migraine, but they can help dampen symptoms by reducing inflammation and constricting blood flow. According to Out of My Head, triptans were first approved more than two decades ago—so new medication options are long overdue.

nextArticle.image_alt|e
iStock
arrow
Health
Canine Flu is On the Rise: Here's What You Should Know
iStock
iStock

It's been eight years since the World Health Organization announced the end of the swine flu pandemic, and now the condition is back in the news for infecting a different type of host. As Live Science reports, the H1N1 virus is mixing with canine flu to create new strains that could potentially spread to people.

Dog flu has been around for a couple of decades, but the two main canine strains, H3N8 and H3N2, have never been contracted by humans. According to a new study published in mBio, some dogs in the Guangxi region of China were found carrying H1N1, the flu strain at the root of the swine flu outbreak. Researchers also discovered three entirely new flu strains that were a combination of H1N1 and regular dog flu viruses.

The unrecognized flu strains are the most troubling discovery. As the flu travels between species, it mingles with viruses that are already there, creating a level of genetic diversity that leaves our immune systems, which are best equipped to fight strains they've already been exposed to, vulnerable. The swine flu epidemic of 2009 started in a similar way, when H1N1 jumped from birds to pigs, and eventually to people.

But the new report isn't a reason to banish your pet to the doghouse next time she seems under the weather. The virus samples were collected from dogs in China between 2013 and 2015, and in the years since, zero humans have caught influenza from dogs (though dog flu has started spreading to cats). If the virus continues mutating to the point where it can infect humans, both the CDC and U.S. Department of Agriculture will take action. But for now, the CDC states that canine flu viruses "pose a low threat to people."

Canine flu may not be dangerous to humans yet, but it can still be stressful for dog owners if their pet comes down with a case. Ask your vet about getting your dog vaccinated, and if you see your dog coughing, sneezing, and acting less energetic than usual, make an appointment to get him checked out as soon as possible. If he does have the flu, he can be treated with plenty of rest and hydration.

[h/t Live Science]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios