Zika Virus: What Happened When

The Puerto Rico Department of Health reports an increase in cases of Guillain-Barre syndrome, a rare autoimmune disorder triggered by some infections, including the Zika virus.

Meanwhile, a separate report out of Maryland indicates that an infected person can share the virus through sex — even if they did not have symptoms.

In a major expansion of an earlier advisory, the Food and Drug Administration recommends that blood banks across the U.S. screen all blood donations for the Zika virus. The recommendation previously only applied to areas with active Zika virus transmission.

Florida officials announced that mosquitoes have started spreading Zika in another part of the Miami area — Miami Beach. The CDC has advised pregnant women to avoid going there, and suggested that couples concerned about exposure to the virus postpone travel to Miami-Dade County. To date, Florida mosquitoes are known to have infected 36 people with the virus.

After a Texas resident returned from a trip to Miami, the traveler tested positive for Zika virus. Health officials believe the traveler picked up the virus in Florida, which would make it the first case linked to travel within the continental U.S.

The CDC advises pregnant women to avoid traveling to Wynwood, the Miami neighborhood where mosquitoes are transmitting Zika virus. Pregnant women who live there should take measures to prevent mosquito bites and be tested for Zika during the first two trimesters. It's believed to be the first time the CDC has told people to avoid travel to an area in the continental U.S. due to an outbreak of infectious disease.

The Florida health department has found 10 more people who likely got Zika virus from local mosquitoes, bringing the total to 14. Gov. Rick Scott asked the CDC to send an emergency response team to help with the investigation and mosquito control, including inspections of pools and other standing water where mosquitoes breed.

"This morning we learned that four people in our state likely have the Zika virus as a result of a mosquito bite," Florida Gov. Rick Scott said at a press conference. "This means Florida has become the first state in our nation to have local transmission of the Zika virus."

Fearing local transmission of the virus, the Food and Drug Administration has asked two South Florida counties, Miami-Dade and Broward, to cease collecting blood donations until they can test each one for the virus.

Until recently, the CDC only considered men capable of transmitting the virus during sex. But since a man in New York City contracted Zika after having sex with an infected woman, the agency now recommends that heterosexual and homosexual couples — especially those with pregnant partners — use condoms or abstain from sex to reduce the possibility of transmission if one of the partners lives in an area with Zika or has recently traveled to one. In another adjustment, the CDC now recommends that clinicians offer a Zika virus blood test to pregnant women up to two weeks after symptoms set in, as well as to at-risk pregnant women who have had no symptoms.

The relative of an elderly man in Utah seems to have contracted Zika from taking care of him. The patient had an unusually high amount of virus in his blood, about 100,000 times what's expected. That could be why, in this rare case, the virus passed through nonsexual contact with a sick person. Another possibility for spread was reported last week, with the first report of a woman passing the virus to a man through unprotected sex. Health officials maintain that infected mosquitoes are by far the main way Zika virus spreads.

After months of debate, Congress missed its deadline to decide about funding the fight against Zika virus. Now, its members are on a seven-week break. The American Medical Association said in a statement that it's "disappointed by Congress' failure to pass legislation before adjourning."

The worst might be over, according to epidemiologists writing in the journal Science. But though cases of Zika virus appear to be declining golbally, the epidemic is far from over. The virus could be a threat in the U.S. for many summers to come.

House lawmakers passed a bill that would give $1 billion to the Zika virus response, about half of what President Obama requested. It will now move to the Senate, where Democrats have declared opposition to the Republican proposal. If more money isn't allocated, funding would be shifted from Obama's health care law and from Ebola virus research and response. The deadline to approve funding is mid-July. Funding is intended to support efforts at home and abroad to research Zika vaccines and tests and to control mosquito populations.

In April, health officials in Puerto Rico started screening blood donations for Zika virus. Out of about 13,000 donations tested since then, 68 have tested positive with a new, highly sensitive assay. Those donations have been removed from the blood supply. One blood center in Houston has voluntarily begun testing blood donations as well. CDC Director Tom Frieden said the blood screening in Puerto Rico offers a concerning glimpse of how the virus is spreading in the territory. "It's possible that thousands of pregnant women in Puerto Rico could become infected with Zika. This could lead to dozens or hundreds of infants being born with microcephaly in the coming year," he said.

The CDC has started reporting birth defects among babies born in the U.S. to women with evidence of past Zika virus infection. They'll also report on birth defects in cases of pregnancy loss. As of June 9, there have been three of each. Two cases of babies born with microcephaly were previously reported in Hawaii and New Jersey. Brazilian officials have confirmed more than 1,400 cases linked to Zika virus.

Scientists in Colombia tracking thousands of pregnant women found that if a woman was infected with Zika during the third trimester, her baby wasn't likely to be born with severe birth defects. As they wrote in The New England Journal of Medicine, none of the 600 women who experienced Zika symptoms during the third trimester gave birth to babies with brain abnormalities.

WHO says that "cancelling or changing the location of the 2016 Olympics will not significantly alter the international spread of the Zika virus." The announcement came a day after 150 scientists wrote this in an open letter to the organization: "It is unethical to run the risk" of delivering the virus via attendees to poor countries where the virus could become endemic. Who is right? NPR's Michaeleen Doucleff finds that according to one estimate, there would be at most 16 cases of Zika among Olympic attendees.

While Congress continues to fight over whether and how much to fund Zika preparedness, state and local health departments scramble to fill the gaps. "It is not a question of whether babies will be born in the United States with Zika-related microcephaly. It is a question of when and how many," says Ron Klain, former White House Ebola response coordinator. Rep. Tom Cole of Oklahoma tells All Things Considered that the current House funding package, which is one-third of the president's request, is enough for now.

Researchers in Brazil studying 40 infants born with microcephaly found that 22 had eye abnormalities, including some in small optic nerves and a very sensitive part of the retina responsible for color vision. They write in JAMA Ophthalmology that mothers with symptoms of Zika during the first trimester were more likely to give birth to children with eye abnormalities.

There are 56 species of mosquitoes flying around Harris County, Texas. But entomologists there hunt only for the big three — the ones that carry West Nile virus, St. Louis encephalitis, dengue, chikungunya and now Zika. Dozens of scientists and technicians are already setting traps and testing species to see which viruses are present and where it makes sense to spray pesticides. In New Jersey, inspectors are scouting out the bugs in marshes.

That brings the U.S. total to about 280 U.S. women affected by Zika, including more than 120 in U.S. territories. NPR's Michaeleen Doucleff explains where in the country pregnant women should take precautions. The CDC says there's no sign people have gotten Zika from mosquitoes in the continental U.S.

The virus continues its trip around the globe. The World Health Organization confirms that the strain of the virus found in Cape Verde, off the northwest coast of Africa, is the same one that's circulating in the Americas. It was probably imported from Brazil. Dr. Matshidiso Moeti, WHO regional director for Africa, says the virus is now "on the doorstep of Africa."

Scientists agree that the Zika virus can, in rare cases, trigger a disease called Guillain-Barre syndrome. We follow two people who went through the sudden traumatic illness. While there's a high recovery rate, patients with GBS often require intensive hospital care to survive weeks of paralysis.

Scientists say they may know how the virus damages the brains of infected fetuses. By testing mice, they found that the virus is particularly attracted to brain cells, which it can infect and turn into virus-making factories. But those particular cells are also the ones responsible for building a large portion of the brain.

One year ago, Brazil confirmed its first case of Zika virus. "As far back as 1952, [scientists] speculated that Zika and other newly discovered African viruses might have effects on the central nervous system or produce congenital changes in the foetus if pregnant women were infected. But that was pure speculation. For all practical purposes, Zika looked like a medical curiosity that posed little, if any, threat to public health," says a World Health Organization report on what's been learned in the past year. An accompanying timeline traces the virus's path since 1947.

The New York City Department of Health announces that it will donate 1 million free condoms to Puerto Rico, in an attempt to reduce the spread of Zika there through sex. There are over 3.5 million people in Puerto Rico.

A 70-year-old man died in Puerto Rico of complications due to the Zika virus, health authorities announced. After a rare immune reaction to the virus that prevented his blood from clotting, he experienced internal bleeding and died in February.

Anxiety about the potential spread of Zika is growing in Gulf Coast states. In places like Houston, it's causing some tough choices for pregnant women and those considering conceiving. A special clinic has opened to counsel women who have traveled to Zika-affected areas.

A Dallas man passed the virus to his partner after a trip to Venezuela. The case confirmed something researchers suspected for a long time: that vaginal sex isn't the only way the virus can get around.

Yes, the Zika virus is causing birth defects in the infants of some women who were infected during pregnancy. After months of hesitation, a CDC review published Wednesday in the New England Journal of Medicine concludes there's a causal relationship.

President Obama will sign a bill that would offer incentives to drug companies to develop vaccines and treatment for the Zika virus. "In some ways, it's akin to passing out umbrellas in advance of a hurricane," says White House press secretary Josh Earnest. Congress is "two months late and $1.9 billion short," he says, referring to its failure to come through with emergency funding requested by the Obama administration.

Top officials with the Obama administration announce that they'll redirect $589 million toward the Zika virus response. Most of that money was to be used to deal with the Ebola virus.

When a disease breaks out, scientists from wealthy countries tend to swoop in, take samples and then head back to the lab, rarely sharing their results with anyone for months, if ever. But, as NPR's Nurith Aizenman reports, scientists working on the current Zika outbreak are trying to nip "parachute research" in the bud by sharing more, and sharing faster. A lab at the University of Wisconsin, Madison is publicly sharing its findings in real time, including ultrasounds from infected monkeys.

The World Health Organization says there's scientific consensus that the Zika virus is responsible for causing birth defects. In northern Brazil, epidemiologists with the CDC finish gathering blood samples from 600 families. They want to know what the risk is to a woman infected with Zika that her child will have birth defects.

After a vacation to Mexico, Guatemala and Belize, a couple from Washington, D.C., learned that their fetus had severe brain abnormalities. They decided to end the pregnancy. The case, published in The New England Journal of Medicine, gave hints at how Zika infects a fetus — and at how women may be able to find out earlier whether babies will have birth defects.

Couples are wondering what to do if they want to get pregnant but are worried about the Zika virus. Here's what the Centers for Disease Control and Prevention says about how to minimize the risk of microcephaly in future pregnancies:

— If you're a man and you were diagnosed with Zika virus (or you even just had symptoms of the virus) wait at least six months before having unprotected sex with a female partner. If your female partner is already pregnant, use condoms or abstain from sex until the baby is born.

— If you're a woman who was diagnosed with Zika or had the symptoms, wait at least two months before trying to get pregnant.

— The CDC also advises that people who had even a chance of being exposed to the virus during travel or through sex wait at least a couple of months before trying to get pregnant.

It's still not confirmed that infection with Zika virus causes microcephaly, but there's increasing evidence that it can.

A test called the Trioplex determines in one go if a person has dengue, chikungunya or Zika virus in the blood. It's been used in San Juan, Puerto Rico, to test pregnant women in the territory. Now that the Food and Drug Administration has granted emergency use authorization, it can also be used by qualified labs in other parts of the U.S. But as Shots has reported, this kind of test (RT-PCR) is conclusive only if a patient is tested within a week of infection with Zika virus.

Looking back at a Zika outbreak in French Polynesia, researchers writing in The Lancet estimate that the risk of having a baby born with microcephaly was about 1 per 100 in women infected with Zika virus during their first trimester of pregnancy. The usual rate of microcephaly there had been about 1 in 5,000 newborns. "There's something different about the way these babies cry," writes Rob Stein after a visit to a hospital in Recife, Brazil.

It's pretty simple to figure out if someone has an active Zika infection with a blood test. But people tend to clear the virus out of their bodies quickly, and that's when it can get complicated. Shots picks apart what the current host of tests can accomplish. In San Juan, Puerto Rico, the CDC is unrolling a test called the Trioplex that can determine in one go if a person had dengue, chikungunya or Zika virus.

Shipments of blood from the continental U.S. arrive in Puerto Rico. The U.S. Department of Health and Human Services is funding the shipments so that patients in Puerto Rico in need of blood transfusions don't have to worry that they'll accidentally get Zika from an infected donor.

Preliminary results from a study of 42 pregnant women in Brazil suggest Zika can cause a whole spectrum of complications — not just microcephaly — in the fetuses of women infected while pregnant. In another study, Colombian researchers found that three newborns tested positive for Zika, one diagnosed with microcephaly and two with abnormal brains, Nature News reports. The research isn't peer-reviewed or published, so we can't vouch for it. Studies of babies in Brazil have made similar findings, but these cases may be the first Zika-related birth defects in Colombia. NPR's Nurith Aizenman has reported: "If there really is a link, Colombia is where the next surge in birth defects could be."

Republican congressmen question the need for $2 billion requested by the Obama administration to fight Zika. At the same hearing, Dr. Jeanne Sheffield, director of the division of maternal-fetal medicine at Johns Hopkins University School of Medicine, says it's likely that about a month after infection with Zika, women can conceive without worrying about the virus's effect on the fetus. "It's about the only good news here," she says. Public Health Canada recommends couples wait at least two months after infection with Zika virus to conceive. Also: WHO summarizes its latest guidance for pregnant women. The FDA adds corneas, bone, skin, heart valves, stem cells, cord blood, placenta, semen and oocytes to the list of donated human materials that need to be screened for Zika virus before being transplanted in a patient.

Researchers are working furiously to determine whether the Zika virus now spreading in Latin America is responsible for a spike in cases in Guillain-Barre syndrome, a condition that can cause temporary paralysis. Scientists studying patients from a 2013 outbreak in French Polynesia argue that a link can already be established. NPR's Nurith Aizenman visits patients with Guillain-Barre syndrome in Colombia, where scientists are also trying to confirm the link.

NPR's Rob Stein comes eye to eye with frozen tubes of Zika virus held by a researcher in Recife, Brazil. He also follows CDC investigators as they go door to door looking for new moms. They're trying to figure out if the virus is really causing microcephaly, a birth defect that leaves babies with abnormally small heads and damaged brains.

The U.S. territory is reporting at least 117 cases of Zika virus, including five pregnant women. The island's government is working to get screens on more windows. Emergency crews hunt for the mosquito that reproduces in piles of old tires, open containers and even flower vases — before the rainy season hits. "We have to do what we didn't do for 30 years in 45 days," Dr. Johnny Rullan, Puerto Rico's former secretary of health, tells NPR.

Caribbean islands St. Vincent and the Grenadines and St. Maarten join the list of destinations where Zika virus transmission is ongoing. That makes 36 countries and U.S. territories with a CDC Zika virus travel notice — just in time for spring break.

The Summer Olympics will be held Aug. 5-21 in Rio de Janeiro. If you'll be pregnant then, the CDC recommends not going. For those who choose to go anyway, it offers a list of precautions and health phrases in Portuguese, like "fwee pee-KAH-doo poor pare-nee-LONE-goo," or "I have been bitten by mosquitoes."

Nine women are confirmed to have been infected with Zika while pregnant. Of the nine cases, two babies were born healthy, and one was born with severe microcephaly. Two women had miscarriages, two had abortions, and the remaining two pregnancies appear to be continuing normally. The women had all traveled to places where Zika virus transmission is ongoing, including Mexico, Puerto Rico and American Samoa. The CDC recommends that all pregnant women who have recently traveled to such places be screened for the virus. Ten more possible cases of Zika virus in pregnant women are currently being investigated.

Breast-feeding is really important for mothers and children. There's no evidence that a mother — even one who is sick with Zika — can transmit the virus to a child through her milk, according to new guidance from WHO.

Health officials in Florida report 32 cases of Zika virus, all acquired during travel. That includes three pregnant women. Gov. Rick Scott requested 250 more Zika antibody tests from the Centers for Disease Control and Prevention. "I would like to bet money on the fact that we will see locally acquired cases," Dr. Amy Vittor, an internist and public health researcher who studies tropical diseases at the University of Florida, tells NPR's Greg Allen. But the state is unlikely to see the scale of the Zika outbreaks now sweeping through the Caribbean and Latin America, in part because residents have far less exposure to mosquitoes. A British company, Oxitec, awaits FDA approval to test how well genetically modified mosquitoes can reduce the populations of Aedes aegypti in the Florida Keys.

Tourism officials in Puerto Rico worry that the Zika virus could cause a slump in tourists. But in Colombia, the worry is more about people coming into the country — people from Venezuela crossing the border for medical care on the other side, and potentially bringing the virus with them.

The Centers for Disease Control and Prevention confirmed two cases of Zika virus in U.S. women who had no risk factors for the illness except one: They had slept with their male partners, who had recently traveled to countries with ongoing transmission and who reported having Zika-like symptoms. Twelve other possible cases of sexual transmission from men to women are being studied. The CDC recommends that men who could have been exposed to Zika either use condoms during sex with a pregnant partner or abstain from sex for the rest of the pregnancy.

Media coverage has centered on the virus's potential effect on babies, but it may also be causing an illness in adults. Guillain-Barre syndrome is a condition where a person's immune system starts to attack nerves. It can be triggered by exposure to a number of viruses and bacteria and can cause temporary or permanent paralysis. Colombia has seen about 100 cases suspected of being linked to Zika, three times more than the usual rate.

"Some men in Brazil see a child with special needs as a woman's problem and promptly leave their partner," reports NPR's Lulu Garcia-Navarro. One psychologist predicts that some children with microcephaly will be abandoned and end up in state institutions. In Colombia, where the Zika virus hit later, maternity wards are bracing for the possibility that they, too, will see an increase in microcephaly in coming months.

One state in Brazil stopped using a chemical to treat drinking water, after a report from Argentina suggesting that it — and not the Zika virus — could be the cause of microcephaly. Another rumor is that genetically modified mosquitoes are behind Brazil's recent problems. But international health experts say the evidence continues to pile up against Zika. For now, the virus is guilty until proven innocent.

The U.S. Food and Drug Administration recommends that blood banks not take donations from people who have traveled in the past four weeks to places with active Zika virus transmission. Researchers meeting at the National Academy of Sciences name some top priorities: to improve testing methods; develop animal models of the disease; and understand which animals might still host the virus once the current outbreak wanes in humans.

The Aedes aegypti mosquito is the dog of the mosquito world. "It loves us. It loves our cities. It loves our blood. It functions very well with us," says Marten Edwards, an entomologist at Muhlenberg College. Many countries are stepping up use of insecticides, as seen at left in Managua, Nicaragua. The CDC's Dr. Tom Frieden told lawmakers Wednesday that studies are underway to test which insecticides work best. And as NPR's Goats and Soda blog found in a review of repellents, people could also consider stocking up on perfume from Victoria's Secret.

"There really hadn't been any work done in about 40 years on Zika virus in animals," says Dr. Michael Diamond, an infectious disease specialist at Washington University in St. Louis. "We need vaccines, we need therapies, we need diagnostics. We need to know how this virus works."

That's how much the Obama administration says it plans to ask Congress for to fight the Zika virus. Dr. Anne Schuchat with the Centers for Disease Control and Prevention says the organization has shipped antibody tests to state health departments to test pregnant women who traveled to Zika-affected areas. "But it's important to say we don't have unlimited quantities right now," she says. And "the test isn't perfect."

The Centers for Disease Control and Prevention puts its emergency operations center on the highest level of activation to respond to the Zika outbreak. Officials say they're confident they could quickly contain any outbreaks in the United States. David L. Heymann, chairman of the World Health Organization emergency committee on the virus, tells NPR the main focus now is on clarifying the link between Zika and babies born with small heads and brains.

Brazilian health officials say they have detected live virus in the urine and saliva of people sick with the virus. In the past, researchers isolated live virus from urine and semen. While authorities in Brazil recommended that women not kiss or share silverware with strangers, U.S. health authorities caution that the discovery of virus in bodily fluids does not mean it can spread through exchanging them. Still, the CDC suggests that men who have recently returned from areas where Zika is active use condoms during sex, especially with a pregnant partner. Mosquito bites remain the primary transmission route.

Health officials in Dallas County, Texas, say a local patient acquired Zika virus in the U.S. through sex with a person who had recently returned from Venezuela. Shots reports that the virus is thought to have been transmitted through sex before, though rarely.

Dr. Margaret Chan, director-general of the World Health Organization, declares the strong association between Zika virus and microcephaly a public health emergency of international concern. She says it will take international coordination to improve mosquito control and speed up the development of tests that detect the virus.

"Out of an abundance of caution," the Centers for Disease Control and Prevention advises pregnant women to postpone traveling to areas with active Zika virus transmission. Pregnant women who choose to travel, it says, should take steps to avoid being bitten by mosquitoes.

Countries across Latin America and the Caribbean urge women to put off pregnancy to reduce the risk of babies being born with microcephaly. NPR's Lulu Garcia-Navarro reports from a clinic in Brazil offering women seeking fertility treatment the option to freeze their eggs or an embryo at no additional cost because of the new guidelines due to the Zika outbreak. The virus's link to birth defects reignites debate about abortion in several countries.

The Pan American Health Organization warns of a possible connection between Zika virus and an increase in neurological syndromes. "Although neither event establishes a causal relation with Zika virus, the hypothesis cannot be discarded," the PAHO report says. During a past outbreak in French Polynesia, 42 patients were confirmed to have Guillain-Barre syndrome out of about 9,000 suspected cases.

The Pan American Health Organization asks member nations to report unusual patterns in the health of newborn babies. Researchers at the Osvaldo Cruz Institute in Brazil report detecting signs of the virus in the amniotic fluid of two pregnant women whose fetuses were diagnosed via ultrasound with microcephaly.

A sharp increase in the number of babies born with small heads is reported in a part of Brazil that noted an outbreak in Zika virus infections months before. The state of Pernambuco used to register 10 cases of microcephaly per year. In 2015, there were over 140 cases.

Named after the forest in Uganda where it was discovered in 1947, the Zika virus has sickened people on multiple continents since then. But past outbreaks have not been connected to birth defects or to increased rates of a neurological condition called Guillain-Barre syndrome.