In Texas, Where Mosquitoes Thrive, Tick-Borne Diseases Are Often Overlooked
From Texas Standard:
For some Texans, a mosquito bite can cause more than just an itch. From yellow fever to West Nile virus, there's a long history of mosquito-borne diseases in Texas, some of them causing serious harm or even death.
Ticks, on the other hand, haven't been a major concern in the Lone Star state – until now. The Centers for Disease Control and Prevention reports that instances of tick-borne diseases have more than doubled across the country in recent years, as their geographic reach spreads and new infectious agents are identified.
While working in the Sabine Forest in 2012, Chris Taylor had an experience he'd rather not repeat. He’d finally located a red-cockaded woodpecker, the endangered bird he was searching for. But, instead of being excited, he passed out.
“I leaned up against a tree and sat down watching this woodpecker, and I actually fell asleep against this tree,” he says.
Realizing he was sick, Taylor left the woods, but barely made it back to his hotel.
“I kept falling asleep while I was driving, including at a four-way stop. I remember I woke up to just horns blaring at me,” he says.
After 18 hours of fevered sleep, Taylor says he felt mostly normal for the next week or two. Then, other problems began cropping up, like the feeling that worms were crawling under his skin. Doctors didn’t know what to make of Taylor’s illness, which progressed to migraine-like headaches and more, even though Taylor had told them about a tick bite he suspected might be the cause.
“I knew it had to be associated with that tick bite or the thousands of mosquitoes I had been bitten by, just because the symptoms were just all too strange,” he says.
And he was right. Eventually, Taylor was diagnosed with both Rocky Mountain spotted fever and West Nile virus. What’s more, the delay in his diagnosis could have killed him. Rocky Mountain spotted fever can be fatal and should be treated with specific antibiotics within a few days of showing symptoms.
Today, Taylor takes precaution.
“I bought something called a tick picker, which pretty much just looks like a tablespoon with a little slice cut out of it, and you can get down below their mouthparts and just pop ‘em right off. ... So I keep one of those on my key chain at all times to make sure I don’t get anything again,” he says.
Tick-borne diseases are becoming a bigger problem across the country, and in Texas, says Ben Beard, deputy director of the Division of Vector-Borne Diseases at the CDC.
“Tick-borne diseases are on the increase in the United States. … In fact, in 2017, we had the highest numbers of all the reportable tick-borne diseases reported that year ever in history," Beard says. "In Texas, what we’ve seen has not quite been as dramatic as it’s been in other parts of the United States, but we have seen a pretty steady increase in the key tick-borne diseases there.”
Lyme disease represents the majority of tick-borne illness in the U.S. But that’s not true in Texas, where “spotted fever" diseases are more prevalent – that’s what officials now call Rocky Mountain spotted fever, and its close relatives. The state reported 101 confirmed or probable cases in 2017, up from 34 such cases in 2010.
What’s more, these numbers could grow quickly, says Dr. Lucas Blanton, a researcher at the University of Texas Medical Branch at Galveston's Western Gulf Center of Excellence for Vector-Borne Diseases. Blanton is trying to learn more about the threat of tick-borne illness in Texas, something that is not currently well understood. With funding from the CDC, he and others are studying ticks that live here and the diseases they carry or could acquire under the right circumstances.
One prompt for the research is an alarming epidemic of Rocky Mountain spotted fever that has emerged in northern Mexico. Since 2003, the illness has caused at least 247 deaths in the Mexican state of Sonora, which borders Arizona and New Mexico. In Mexicali, across the border from California, at least 132 deaths have been reported since 2009.
“This has not only been a problem in northern Mexico, but has also occurred in tribal lands of Arizona where there’s been outbreaks of Rocky Mountain spotted fever,” Blanton says.
Elsewhere in the United States, the types of ticks that carry Rocky Mountain spotted fever live in the wild and are mainly encountered by hikers, campers or hunters, Blanton says. But in Mexico and parts of Arizona, the infection has spread to a type of tick called the brown dog tick that lives on dogs and among people, exposing whole families and communities to the disease. Blanton thinks this could happen in Texas, too, especially in communities where dogs roam freely or are not routinely treated with flea and tick medicine.
“I believe the situation in South Texas is it’s the right situation for an outbreak of Rocky Mountain spotted fever, as similar to that what is going on in northern Mexico right now,” Blanton says.
The disease can amplify rapidly under the right conditions, Blanton says. He and his team don’t want to wait for more cases to show up here.
“In the United States, we have a lot more resources to curtail such an outbreak. But, at the same time, in a disease that can be very severe — especially in the very young and in very old — it is something that we can easily prevent if we have more knowledge about the ecology of Rickettsia rickettsii – or the agent that causes Rocky Mountain spotted fever – and the ticks that transmit it in this area,” Blanton says.
At the Mad Island Marsh Preserve along the Texas Gulf Coast, another research team has been studying migratory songbirds and the ticks they carry, also hoping to understand more about how disease vectors may spread. The location provides a critical stopping point for birds traveling north each spring, says Emily Cohen, a research scientist with the Smithsonian Migratory Bird Center involved with the project.
“The coast of the Gulf of Mexico is one of the most amazing places to study bird migration because birds from across all of the winter latitudes from Central America, South America and the Caribbean congregate along the U.S. coastline of the Gulf of Mexico before and after making the flights across the gulf,” Cohen says.
Sarah Hamer, an associate professor with the College of Veterinary Medicine at Texas A&M University, is helping identify and analyze ticks these birds carry. Her team has found that some songbirds do carry non-native species of ticks to Texas shores, some of which are infected with new types of bacteria that could cause human disease.
“Whether or not they may pose a problem for public health or for animal health is yet to be determined, but we know that at least the early stages of an invasion, you know, these birds are bringing in these ticks that are infected with these pathogens,” Hamer says.
Ticks and their diseases are not new. So, why the need for so much study? As the CDC’s Ben Beard explains, understanding vector-borne diseases is complicated and can be a moving target.
“As time passes, we realize that what we know in one location is not always the same in another location because the ecology is a lot different. You know, the temperature, the rainfall, the vegetation patterns and all those things are different,” Beard says.
Human activity, like global commerce and international travel, along with land use patterns and climate change, can spread or force pathogens and vectors to new areas. So, what was true before may no longer be true.
“In public health, we’re dealing with all of those issues at the same time. The lack of basic knowledge, the fact that situations are changing and that they’re very unique from one location to the next,” Beard says.
In the meantime, here’s what you can do to protect yourself: wear bug repellent and check for ticks after being outdoors, especially in woods, shrubs and tall grasses; remove ticks completely if found; treat pets with flea and tick medicine; and, finally, if you think you might be infected, see a doctor right away. Early treatment for tick-borne disease is key.
Support for Texas Standard’s ”Spotlight on Health” project is provided by St. David’s Foundation.
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