Summer in South Texas brings with it images of fishing at a nearby lake. Picnics in the park. Swimming at the pool or barbecuing to the sound of cicadas as night falls.
What can mar these picturesque scenes comes in the form of an insect about a quarter-inch long.
The World Health Organization estimates that more than 300 million illnesses are attributable to mosquitoes each year. Malaria alone accounted for 214 million in 2015, and killed 438,000 worldwide.
Then there’s West Nile. Chikungunya. Dengue. Yellow fever. And in 2016, a little-known virus spread by mosquitoes became an international pandemic: Zika.
Last year, the World Health Organization declared Zika a “public health emergency of international concern,” a classification that has only been given four times in the organization’s history. The announcement came after an outbreak of the virus in Brazil in 2015 and an accompanying surge in fetal microcephaly cases. Microcephaly is a neurological condition, usually the result of the brain developing abnormally in utero, in which an infant’s head is significantly smaller than the heads of other children. Severe cases often feature a backward-sloping forehead.
“The information from Brazil was really terrifying,” said Patrick S. Ramsey, M.D., M.S.P.H., professor of obstetrics and gynecology. “They went from 62 cases of microcephaly in the entire country to over 4,500 in one year. And that’s what raised all the flags.”
As summer turned into fall, the virus had spread to 61 countries worldwide. By February 2017, the U.S. had 4,753 known cases in 49 states, all acquired while traveling abroad. Then the virus hit the U.S. mosquito population, with local transmissions in Florida and South Texas.
Then, a stroke of luck. The weather cooled and mosquitoes tapered off.
“We were lucky, because we had a decent freeze and the mosquito population was thought to be largely out of the community at that point,” Dr. Ramsey said. “We did have the cases that were locally transmitted in Brownsville in December, but then the cold weather came in and everything was in a bit of a lull.”
But as temperatures once again rise in Texas, so does the risk of an onslaught. And this year is expected to bring a particularly hot and dry summer, exactly the kind of weather in which Aedes mosquitoes—the type that carry the virus—thrive.
“We’re getting ready for a reactivation of Zika this spring or summer,” Dr. Ramsey said. “We’ll probably have many more cases in Texas than we had last year.”
Already, there have been 10 confirmed cases of Zika in Texas in 2017. The Centers for Disease Control and Prevention is monitoring 250 more pregnant women who have laboratory evidence of Zika infection, and their infants.
In preparation for an increase in high-risk pregnancies linked to Zika, UT Health San Antonio physicians at the Medical Arts & Research Center, in collaboration with University Health System, are building a regional Zika Care Center to provide community and regional providers with ready access to diagnostic testing, surveillance and follow-up for patients exposed to the Zika virus in pregnancy.
“If we have an outbreak in San Antonio, I think there will be some form of mild panic, and we’ll have to deal with that,” Dr. Ramsey said. “We’re getting our clinic systems revved up to the point of having a Zika clinic so we can have all our resources in one spot.”
From unknown to pandemic
Zika made its debut in 1947 in a monkey in the Zika forest of Uganda. There were few human cases, so the virus raised little alarm.
Fast forward 60 years to 2007, when the first outbreak of the virus was recorded in Micronesia, in the Western Pacific Ocean. Within seven years, there were outbreaks throughout the Western Pacific and in Southeast Asia.
In 2015, the first case of Zika was recorded in the Americas. Within a year, it was an epidemic in Brazil.
“Some of the emerging infections are ones that we’re newly discovering, but many of them, like Zika, are those that have been around and it’s now just a new opportunity for them to spread,” said Jason Bowling, M.D., assistant professor of infectious diseases. “It’s interesting that, particularly over the last few years, we’re starting to see these emerging infections become more prominent.”
Zika is transmitted primarily by Aedes aegypti mosquitoes, distinguishable from other mosquitoes by their striped legs.
They live in tropical, subtropical and temperate areas, such as the southern U.S., Puerto Rico and the U.S. Virgin Islands. They live in populated areas because they prefer to feed on people.
“Mosquitoes in general are not good to people or other animals, for that matter,” said Dr. Bowling. “They cause a large amount of death and disease to humans and all other animals because of malaria and all other diseases they transmit. Malaria is probably the biggest one globally, but Zika is now on that list.”
The virus is closely related to the dengue and yellow fever viruses and lives in blood and seminal fluid, so a person infected with the virus can spread it sexually, and pregnant women can transmit the virus to their unborn babies.
About 80 percent of those infected are asymptomatic or have mild symptoms such as fever, rash, joint or muscle pain, conjunctivitis and headaches, although there has been a corresponding increase in Guillain-Barré syndrome in adults in areas affected by Zika. Those affected with the disorder, in which the body’s immune system attacks part of the peripheral nervous system, have weakness and abnormal sensations in the legs, arms and upper body. When severe, the person is almost totally paralyzed.
But in most cases, Zika goes unnoticed. For those who do experience symptoms, they last about a week, even though the virus can remain in bodily fluid for eight weeks in women, and up to six months in men.
And this presents the biggest challenge, Dr. Bowling said. Most people won’t know they’re infected and won’t take care to prevent transmission by using bug sprays with DEET to keep mosquitoes away or by using prophylactics during sex.
“One of the risks is that people like to travel, particularly young healthy people of reproductive age,” Dr. Bowling said. “So while in San Antonio we may not have Zika in our mosquito pools, we obviously have a lot of people who travel. We’re a military city. We have a young healthy population, and they don’t have to travel far to get to areas with Zika.”
And the toll the virus takes on unborn babies is devastating.
“When it hits you, it’s like a bolt of lightning that will ruin your kid’s life before it is even born,” said Sidney Atkinson, M.D., associate professor of pediatrics and division chief for child neurology, developmental pediatrics, and genetics and metabolic disorders.
No vaccine, no treatment
Unknowns are the biggest drivers of fear, Dr. Bowling said. And there is much that is still unknown about Zika.
“What are the risks to older children? What about kids playing in the backyard? Are they at risk? We don’t know,” Dr. Ramsey said. “Or what about a baby who is 2 months old and gets bitten by a mosquito that is carrying the Zika virus? What is the risk to that child? We just don’t know yet.”
But every new case brings new discoveries.
“Unfortunately, it takes numbers of people who are infected to see what will happen and get a better sense of this virus,” Dr. Bowling said. “But that’s not reassuring.”
Scientists are looking to Brazil and French Polynesia for answers.
“Some of the earliest data is from Brazil,” Dr. Ramsey said. “They had around 100 women with Zika who were pregnant when they were exposed to the virus. And of those women, only about 28 percent of them had any ultrasound findings that would suggest problems. Those were women who were definitely infected. Then of those, the babies with severe microcephaly were 19 percent. So that gives us some reassurance that even if you get infected, it’s not 100 percent [that the baby will be infected].”
In French Polynesia, located in the South Pacific, one out of every 100 Zika-infected mothers has a child with microcephaly.
“That one in 100 number is scary,” Dr. Atkinson said. “Depending on how widespread Zika becomes, it could be that a lot more local babies will be [infected than originally thought].”
To date, there have been 1,367 pregnancies in the U.S. with laboratory evidence of Zika virus infection. That includes those that ended in a live birth, miscarriage, stillbirth or termination, according to the CDC. Of the live births, 58 babies had birth defects. Seven pregnancies with birth defects were lost.
Probably the greatest risk to fetuses is in the first trimester, Dr. Ramsey said. The virus appears to attack the immature neurons in the fetal brain, which are abundant in the first months of pregnancy. This leads to congenital Zika syndrome, characterized by the presence of severe microcephaly where the skull has partially collapsed, decreased brain tissue with a specific pattern of brain damage, damage to the back of the eye, joints with limited range of motion and too much muscle tone restricting body movement soon after birth.
“Microcephaly is such a short word for what it does to your brain,” Dr. Atkinson said. “Microcephaly is really bad because it means the brain did not form. Think of all the things that we do that depend on the brain—eating, rolling over, breathing, all of those things are disordered in children with microcephaly. Some can have microcephaly and can have basic skills, but at the more severe end of the spectrum, kids never learn to sit up, never learn to roll over, never learn to crawl or walk, never learn to talk.
“Children often die in the first decade of life because the brain is so malformed and they can’t do anything. They can’t protect themselves in any way. That’s the kind of thing that we’re worried about with Zika.”
Before Zika entered the U.S., the number of babies born with microcephaly was small, two babies for every 10,000 live births. That translates to between 400 and 800 each year, and between two to five babies born in San Antonio with the disease. Even though Dr. Atkinson predicts only a slight increase, about 1 percent, in Zika cases locally, he said he’s bracing for the worst. He is part of an expert-action team at UT Health San Antonio assembled to manage children with congenital Zika syndrome.
“It’s not great frequency, it’s the severity that is the problem,” he said. “I think that there is going to be a rate of hurt children and it breaks my heart that it is going to happen, but it’s not going to be with such frequency that we’re going to have an epidemic like polio.”
Maternal-fetal medicine doctors at UT Health’s Women’s Health Center at the MARC specialize in high-risk pregnancies in partnership with University Hospital System. They now have an established Zika policy and standard procedures in place for screening for Zika, and implementation of testing strategies once there is a patient identified who may be at risk.
“We’re also educating the community,” Dr. Ramsey said. “We’re getting information out about what the risks are, the algorithm we’re using at University Hospital and here, and we’re sharing that with other hospital systems so they can implement something similar so we have better testing.”
Shrinking world, growing risk
Before Zika, there was Ebola. Before Ebola, there was West Nile. And don’t forget the H1N1 swine flu. Over the past few years, there have been a number of infectious diseases that have caused worldwide havoc. Health officials benefitted from that.
“Nobody saw Zika coming,” Dr. Ramsey said, but “we responded extremely briskly to Zika. Within two months of this starting to raise concerns, the CDC, the American College of Obstetrics and Gynecology, and the Society of Maternal Fetal Medicine all had consistent guidelines that were released. And we’re doing that at the local level, too.”
Dr. Ramsey has been working with those entities, as well as the Texas Department of State Health Services, to strengthen communication about Zika and perinatal risks to providers and patients. He’s working to improve access to Zika testing for obstetric providers and preparing new testing guidelines.
He’s also working closely with the CDC’s Zika response team to brace for a widespread outbreak in the state this summer.
“I think they’re preparing for the worst,” Dr. Ramsey said.
Students have also responded. Even as fall gave way to winter and the mosquito population died away for the season, students and faculty with the Center for Medical Humanities & Ethics began meeting with community members on San Antonio’s South Side in the country’s first Community Health Club. The program works to bring health education and behavioral changes to communities around the world. The club’s first subject: Zika.
Students also conducted a community needs assessment and shared local and regional information with obstetric providers and patients in Bexar County and surrounding areas. That student-led project will expand to the three largest obstetric delivery counties in South Texas: Cameron, Hidalgo and Nueces.
“I want to get out there and make sure the hospitals know how they should be approaching this, what the risks are and that we’re here to help,” Dr. Ramsey said.
In UT Health San Antonio labs, researchers Xiangzhi Meng, M.D., Ph.D., assistant professor of research, and Yan Xiang, Ph.D., associate professor, both in the Department of Microbiology, Immunology and Molecular Genetics, have made an infectious cDNA clone of Zika. This allowed them to create a Zika virus that expresses a green fluorescent protein so the researchers can easily monitor the infection of cells.
“This is an important and unique tool for us to use in studying the Zika virus,” Dr. Meng said. “It can also be used in screening for drugs against Zika virus.”
Meanwhile, scientists around the globe continue to work on a vaccine. While it typically takes a decade to develop a vaccine, researchers are pushing to have a Zika vaccine available by 2018. Already, several potential vaccines are undergoing clinical trials. Until a viable vaccine is found, approved and distributed, prevention and knowledge are the only defenses.
“The risk [of congenital Zika syndrome] is very small, but if it happens to you it’s absolutely devastating,” Dr. Atkinson said. “So I would caution people to be very thoughtful about mosquito bites and where you are going to be and when you are going to go outside when you are pregnant.”
The world is a smaller place now than it was decades ago, with travel becoming faster and easier, Dr. Bowling said. That has quickened the spread of disease, too.
“We are seeing diseases in one continent quickly popping up on another continent,” he said. “I think Ebola made it really hit home that things in Africa can come here, too. Africa is only a 16-hour plane flight away, and there are planes going there every day. We have to be cognizant of different infections and vector-born diseases all around the world.”
No one is immune to Zika, but that shouldn’t keep people from enjoying the warm days of summer and spring, he said. So go on that camping trip. Take a cruise to a tropical island. Go fishing at the lake.
“You don’t want to scare people—you want to empower them. And information is helpful for that,” Dr. Bowling said. “People are still going to travel and they should. We don’t want to paralyze people with fear, but they should all take precautions to protect themselves.”