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?


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.


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.


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.


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.


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.


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.


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.

Karen Bleier, AFP/Getty Images
Bill and Melinda Gates Will Repay Nigeria's $76 Million Polio-Fighting Loan
Karen Bleier, AFP/Getty Images
Karen Bleier, AFP/Getty Images

Not long after announcing a $100 million donation to find a cure for Alzheimer's disease, Bill and Melinda Gates have agreed to pay off Japan's $76 million loan to Nigeria to stamp out polio, Quartz reports.

Polio has been eradicated in most countries around the world, but it's still present in Nigeria, as well as in Afghanistan and Pakistan. In 2008, according to The Conversation, Nigeria accounted for 86 percent of all polio cases in Africa. This high number was thanks in part to low immunization rates and calls from extremists to boycott polio vaccinations out of fear that they were tainted with anti-fertility steroids.

National and international campaigns were launched to lower polio rates in Nigeria, and in 2014 the nation received the loan from Japan to boost disease-fighting efforts. Progress has been made since then, with no new cases of polio reported in Nigeria in 2017. Two children had contracted polio in 2016, two years after Nigeria's last known case.

Nigeria's loan repayments to Japan were slated to begin in 2018. The Bill & Melinda Gates Foundation agreed to cover the costs after Nigeria met its goal of "achieving more than 80 percent vaccination coverage in at least one round each year in very high risk areas across 80 percent of the country's local government areas," Quartz reports. The loan will be repaid over the next 20 years.

While the Gates Foundation is lending a hand to Nigeria, the Associated Press reports that health officials in Pakistan's eastern Punjab province recently launched a new chapter in the nation's ongoing struggle against the disease. Health workers will engage in a week-long, door-to-door vaccination campaign, though efforts like this are risky due to threats from the Taliban and other militant groups, who view vaccinations as a Western conspiracy and believe they sterilize children. Anti-polio efforts in Pakistan also suffered after the CIA used vaccinations as a cover to get DNA samples from the Bin Laden compound.

[h/t Quartz]

Stones, Bones, and Wrecks
8 Amazing Things Discovered During the Expansion of the London Underground

In 2009, the city of London embarked on a massive infrastructure project: a 73-mile underground railway network called the Elizabeth Line that will ultimately boost urban train capacity by 10 percent. Slated to be up and running by 2018, the undertaking allowed archaeologists to take an unprecedented peek at swathes of subterranean London, and yielded plenty of cool historic treasures from various periods. Here's a small sampling of the finds.


A skeleton belonging to a victim of the Black Plague, unearthed by archaeologists while expanding the London Underground.

While excavating London's Charterhouse Square in 2013, archaeologists unearthed dozens of skeletons. Scientists analyzed the remains and discovered that some of them belonged to victims of the Black Death—a.k.a. bubonic plague—who succumbed to pandemics that swept 14th- and 15th-century England.

Teeth contained traces of DNA from the plague bacterium Yersinia pestis, and radio-carbon dating indicated that the burial ground had been used during two outbreaks of plague, one from 1348 to 1350 and another during the 1430s. The skeletons also showed signs of poor diets and hard lifestyles, which might have been contributing factors for why Londoners were so susceptible to the plague.

But the so-called plague pit didn't just contain those who'd succumbed to disease. Not only were some bodies plague-free, "what they found was, not bodies tumbled together as they'd expected, but rather orderly burials with people laid in rows with their bodies orientated in one direction," historian Gillian Tindall told The Guardian. This suggests not all of them died due to plague but from other, more everyday causes.


An 8000-year-old piece of flint, discovered by archaeologists while expanding the London Underground.

While digging at North Woolrich, in southeast London, archaeologists discovered a Mesolithic-era site along the Thames where early humans are thought to have crafted tools around 8500 to 6000 years ago. The encampment had traces of campfires and flint scatters, and experts recovered 150 pieces of flint, including an 8000-year-old stone tool.

"This is a unique and exciting find that reveals evidence of humans returning to England and in particular the Thames Valley after a long hiatus during the Ice Age," Crossrail lead archaeologist Jay Carver said in a news release. "It is one of a handful of archaeology sites uncovered that confirms humans lived in the Thames Valley at this time. The concentration of flint pieces shows that this was an exceptionally important location for sourcing materials to make tools that were used by early Londoners who lived and hunted on Thames Estuary islands."


A bawdy Victorian chamber pot, discovered by archaeologists while excavating future London Underground sites.

While excavating the Stepney Green station in East London, archaeologists came across a 19th-century cesspit dating to sometime after 1850. The waste hole was filled with tobacco pipes and fragments of pots, including a raunchy Victorian chamber pot. It was once likely kept under a bed, and allowed for its owner to do their business in private during the evening hours.

The pot's bottom contains a cartoon of a grimacing man, encircled by the phrase "Oh what I see/I will not tell." Witty cursive lines once covered the exterior of the broken vessel. Archaeologists were able to decipher one line, which read "… when you in it want to p-s/ Remember they who gave you this."


A Tudor-era bowling or skittles bowl, discovered by archaeologists while excavating future sites for the London Underground's expansion.

In addition to the aforementioned cesspit, excavations at Stepney Green also revealed a 15th-century Tudor manor house, complete with moat. Originally home to a rich family named Fenne, it was once called King John's Court or Palace, and later became known as the Worcester House after its owner the Marquis of Worcester.

In 2013, archaeologists excavated the home's foundations, moat, and boundary walls. Inside the moat they discovered a wooden ball made from willow, which was likely either used for bowling or skittles, a European lawn game. Other recovered items included fine glassware, tableware, and cooking and storage vessels, all of which were buried when the moat was either destroyed or filled in.


55-million-year-old amber, retrieved by engineers while expanding the London Underground

Slated to open in late 2018, London's new Canary Wharf business district station is located deep below a mixed-use development called Crossrail Place. While tunneling at Canary Wharf was too deep to disturb any buried relics, engineers were still able to retrieve a piece of 55-million-year-old amber from nearly 50 feet below the site's dock bed before construction began. It's the oldest amber to have ever been found in London, and is also notable considering that amber isn't often found in the UK to begin with.

Amber, or fossilized tree resin, takes millions of years and proper burial conditions to form. These preserved relics often contain prehistoric plants and creatures, suspended in the clear material. Experts said they plan to analyze the Canary Wharf amber to learn more about prehistoric environmental conditions and vegetation. The fossil also contained bubbles of trapped gas, which scientists said might yield new scientific insights about global warming.


A rare Roman medallion dating back to 245 CE, found by archaeologists during the London Underground expansion.

Archaeologists excavating Crossrail's Liverpool Street site discovered more than 100 mostly-copper Roman coins, along with a handful of silver currency. They ranged in date from 43 CE, during the reign of Emperor Claudius, to 348 CE.

One of the most exciting discoveries among these coins was a rare bronze medallion that was issued to mark the New Year in 245 CE. Presented by Emperor Phillip I (also called Philip the Arab) to a high-ranking government official, it's only the second example of its kind that's ever been found, according to The Guardian.

"You wonder how it got there, who brought it with them, and then how did they lose it—were they heartbroken?" speculated Jackie Keily, a curator at the Museum of London who organized an exhibition of 500 Crossrail artifacts in 2017.


A Roman skull, uncovered by archaeologists during the expansion of the London Underground.

In 2013, Crossrail workers found Roman pottery and around 20 Roman skulls while working on the Liverpool Street station site. Other Roman skulls had been found in the area, along the historic River Walbrook, and some speculated that they belonged to rebels led by the Iceni warrior-queen Boudicca, who revolted against the Roman Empire during the 1st century CE. But since the newly unearthed skulls were found in sediment that had accumulated in a bend of the river, archaeologists believe that they likely washed out of an eroded Roman cemetery long ago. Moreover, the skulls appear to date to after the uprising.


The gravestone of plague victim Mary Godfree, discovered at Liverpool Street in London during the Crossrail excavations.

On September 2, 1665, a girl named Mary Godfree succumbed to the plague—one of 95 people from the same church parish who died from the disease that day. She was remembered solely by a line in a burial register until October 2015, when archaeologists discovered her limestone burial stone while excavating the new Liverpool Street Crossrail station site.

The area was originally home to the historic New Churchyard burial ground, also called the Bedlam burial ground. There, archaeologists discovered a mass grave, along with the remnants of 10 stone markers. Godfree's headstone didn't mark the presence of her actual grave, as the headstone had been removed sometime during the 18th century and reused in the foundation of a wall. Still, it revealed new insights into how and where the rediscovered Londoner was buried, and what burial conditions were like during the Great Plague.


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