Science

Chasing typhus in Texas

Researchers expose scourges lurking in the United States

Peter Hotez started the National School of Tropical Medicine to fight neglected diseases in the U.S.
Agapito Sanchez/Baylor College of Medicine

HOUSTON — Raymond Bares owns two Harley-Davidson motorcycles and a small business, Bares Auto Repair, in La Marque near Houston. He rarely catches a cold, so he was dumbfounded by unrelenting fevers in early July. After a few days, Bares went to see a doctor and returned home with antibiotics. The drugs did nothing to lower his temperature, and his head hurt so badly that he began to vomit. He checked into a hospital, where doctors ran tests for HIV, hepatitis C, West Nile fever and other infections. They all turned up negative.

As another week passed, his wife, an administrator at the University of Texas Medical Branch at Galveston (UTMB), asked the doctors she worked with for urgent help. Eventually the story reached Lucas Blanton, a young infectious disease physician at UTMB who studies murine typhus, an ancient bacterial infection no longer thought to plague the United States. Blanton immediately recognized Bares' symptoms and prescribed drugs to treat murine typhus, which is spread by fleas. Within 72 hours, Bares' fever lifted as quickly as it had come.

Murine typhus is one of a handful of diseases now surfacing in Texas, in part because of a cadre of tropical disease specialists trained to spot them. Their sleuthing techniques range from assessing old blood samples to testing insects for parasites. In the past two years, they've uncovered murine typhus, as well as two diseases thought to exist only south of the Mexican border, dengue fever and Chagas' disease, in people who rarely leave the U.S.

Raymond Bares, of La Marque, Texas, was diagnosed with murine typhus, an ancient infection no longer thought to plague the United States.
Raymond Bares, of La Marque, Texas, was diagnosed with murine typhus, an ancient infection no longer thought to plague the United States.
Amy Maxmen

Rather than occurring in dramatic outbreaks, these diseases bubble to the surface slowly and largely slip by unnoticed because few doctors know what they are. Peter Hotez, a tropical disease expert, calls these ailments "neglected" diseases because they are rarely recognized by doctors in the U.S. and, as a result, are underestimated and disregarded by government agencies that fund disease research and surveillance. In 2011, Hotez started the National School of Tropical Medicine at Baylor College of Medicine, in Houston, to fight them.

"I think these diseases have been around for a while," says Hotez. "But no one has been looking."

A comeback

Texas, along with Alabama, Louisiana, Florida and a few other southern states, is particularly vulnerable to neglected diseases because of its proximity to the Mexican border and its tropical climate and high rate of poverty, which leaves people exposed to the outdoors and vulnerable to pests that transmit parasites. Some of these diseases were widespread in the southern U.S. in the first half of the 20th century before public health strategies banished them.

For instance, murine typhus spread to humans via fleas carried by rats that thrived among the busy ports lining Galveston, a small island near Houston. But the epidemic was quashed when the government hired "rat trappers" and dusted large swaths of land with DDT. A national outbreak like that of 1944, in which more than 5,400 people caught murine typhus, has not been seen in the U.S. since. With cases turning up in Galveston, Houston and Austin, researchers say the scourge could be making a comeback. They are exploring whether fleas carrying the typhus bacteria now infest opossums and feral cats.

Domestic cases of Chagas' disease became apparent when blood drives in Houston began to screen for it in 2007. Milton Wright, a retired sheriff at Fort Ben County in Houston, learned he had the disease via a letter asking him to refrain from giving blood again. Additional tests for signs of the parasite that spreads Chagas', Trypanosoma cruzi, confirmed that he was indeed infected. But Wright could not imagine why. A Google search for the disease identified it as a cause of death in Latin America, yet Wright's only trips there were on cruise ships to the Caribbean.

Armed with DDT,
Armed with DDT, "rat trappers" in Galveston, Texas, quashed typhus decades ago.
Blocker History of Medicine Collections, Moody Medical Library

For a moment, Wright thought he might have been infected in the county jail, where many inmates are Latin American immigrants. If that were the case, however, some jail wardens should also have contracted the disease, and they had not.

Recently, researchers at the National School of Tropical Medicine found clues to suggest that Chagas' disease is transmitted within Texas. Not only do the "kissing bugs" that pass T. cruzi on to people live in the state, but 60 percent of those sampled carry the parasite. In addition, veterinarians in Texas frequently see dogs with the disease.

Recently, researchers at the National School of Tropical Medicine found clues to suggest that Chagas' disease is transmitted within Texas. Not only do the "kissing bugs" that pass T. cruzi on to people live in the state, but 60 percent of those sampled carry the parasite. In addition, veterinarians in Texas frequently see dogs with the disease.
Recently, researchers at the National School of Tropical Medicine found clues to suggest that Chagas' disease is transmitted within Texas. Not only do the "kissing bugs" that pass T. cruzi on to people live in the state, but 60 percent of those sampled carry the parasite. In addition, veterinarians in Texas frequently see dogs with the disease.

Chagas' disease can remain hidden because infections remain asymptomatic for decades. The parasites slowly invade heart tissue, causing potentially lethal heart disorders in a third of all people infected. If physicians diagnose an infection early, they can cure it with drugs.

In July, Melissa Nolan Garcia, an epidemiologist at the National School of Tropical Medicine, enrolled Wright and 30 other Texans who similarly learned of their diagnoses through blood drives in a study to assess their heart function and to fill out the profile of a Texan at risk for Chagas'. For example, did many of the people diagnosed hunt or golf in regions where the bug lives?

Researchers in Houston would like to screen people proactively, as opposed to relying on results from blood drives, but budgets for surveillance are tight. Right now, the Centers for Disease Control and Prevention counts 300,000 cases of Chagas' in the U.S., but they acknowledge that the number falls short. "We might hear about individual patients, but that would be a huge underestimate of what's out there," says Monica Parise, chief of the parasitic disease branch at the CDC. The government shutdown has further curtailed the agency's efforts: 70 percent of its staff has been sent home.

Dengue outbreaks

Lucas Blanton tests ticks collected from south Texas for the bacteria that causes epidemic typhus.
Lucas Blanton tests ticks collected from south Texas for the bacteria that causes epidemic typhus.
Amy Maxmen

Dengue fever outbreaks among locals in Brownsville, Texas, piqued the interest of Kristy Murray, an infectious disease specialist at the National School of Tropical Medicine. Murray has traveled to poor, remote villages in southeast Asia to track outbreaks, but she has discovered plenty of mysteries to keep her occupied back in her home state.

The disease, which is spread by mosquitoes, diminished with mosquito control efforts in the early and mid-1900s, as houses were built with better screens, swamps were drained and insecticides dumped across mosquito-ridden regions. A dengue infection causes acute fevers, headaches, back pain and, on rare occasions, death. The risk of death skyrockets if a person is reinfected with another dengue strain.

Feverish patients often leave the hospital without a diagnosis, so Murray decided to revisit blood and spinal fluid samples drawn from these cases in Houston between 2003 and 2005. Nearly 50 samples tested positive for dengue. Most patients presumably recovered from the fever. However, one patient — a 92-year-old woman — died of brain inflammation, the disease's hallmark.

The deceased woman, as well as several others who tested positive, had not left Houston for at least two years before they had the samples taken, indicating that they caught the dengue virus locally. Murray points to a graph in a report showing when the cases occurred. They peak in mid-2003, suggesting that a dengue outbreak might have slipped completely below the radar. What worries her most is that alternative strains in Mexico or Florida could feasibly make it to Texas if an infected person traveled between the two places. "We need to be on guard," she says. "Our biggest bang for the buck would be to focus on dengue with physicians, so that they know how to recognize a case and submit samples for testing."

Lessons from West Nile

Like a growing number of Texans, Milton Wright, here with his wife Miriam, contracted Chagas' disease.
Like a growing number of Texans, Milton Wright, here with his wife Miriam, contracted Chagas' disease.
Amy Maxmen

Murray has watched outbreaks unfold in the U.S. before. In 1999, she was part of the CDC team that discovered crows dropping dead from West Nile virus in New York City. At that time, the virus had never before been seen in the Western Hemisphere. Since then, more than 1,500 Americans have died from West Nile infections.

"The lesson from West Nile is that we should really be looking for diseases that we think are outside of our border," Murray says, adding that detection costs money. "Public health departments have been shrinking because they don’t have the budgets they used to," she says. "With a limited workforce, they focus on disasters as they happen, instead of what might be a problem in the near future."

Umair Shah feels this pressure acutely as director of the Harris County Public Health department, which provides services for 4.1 million people living in Houston and the surrounding areas. He has heard of cases of murine typhus, Chagas' and dengue, but he does not have the resources to intensify surveillance. Since 2010, he says, the department has reduced its staff by 30 percent because of budget cuts.

"The public expects you to just figure it out and be as effective with fewer people," he says, "but that’s a real challenge." Shah says people may have forgotten about the measures that enabled Texas to curb several diseases half a century ago. "A doctor can say, I treated a child who had cancer, and there’s obvious value in that," he says. "But who is the poster child when you prevent a disease in the first place?"

At the National School of Tropical Medicine’s clinic, doctors teach their colleagues how to recognize neglected diseases that are skipped over in medical school. One Friday morning, a clinician shadows a tropical disease doctor as she treats a Cuban patient for leishmaniasis, a parasitic disease that has caused open sores to form on her face. Before the lesson, the young clinician says, she would have wrongly diagnosed the infection as Staphylococcus.

Baylor College of Medicine and Texas Children’s Hospital supported Hotez’ vision for a national school with a 10-year, $20 million start-up package, in hopes of becoming a resource for doctors, scientists and patients across the U.S. The school also houses high-tech laboratories for research into vaccines for neglected diseases that would save lives on a global scale. Finally, Hotez, who left Washington, D.C., for Houston two years ago, has added one final mission for his school: advocacy. He frequently hops on flights to Washington, D.C., where he promotes the message that the United States ignores neglected diseases at its own peril.

If neglected diseases turn out to be as prevalent as Hotez suspects, government agencies might put more money toward surveillance, education and research in the coming years. For now, the scientists in Houston and Galveston are taking the first steps. "Infectious disease programs focus on developing countries instead of pockets of poverty here in the U.S.," says Hotez. "That's where we come in."

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