Saturday could be Waco’s first triple-digit day this summer. You may be looking to one of the area’s lakes or rivers for relief, but is it safe to take the plunge?
Many Wacoans associate open-water swimming with Naegleria fowleri, commonly known as the brain-eating amoeba. Infections are almost always lethal but extremely rare, affecting fewer than 10 Americans per year.
Still, the protozoa has engrained itself in the area’s collective consciousness after claiming a surfer at BSR Cable Park in 2018 and a 10-year-old girl near Lake Whitney the year after, the pathogenic equivalent of lightning striking the same place twice.
The Waco area offers swimming beaches at Lake Waco and the Tonkawa Falls swimming hole at Crawford, now closed because of water quality concerns with low flow. And this past weekend, hundreds of athletes swam in the Brazos River downtown as part of the annual TriWaco Triathlon.
Swimming in nature is always a matter of personal risk tolerance, but local water and health experts offer a host of practical tips to manage the risk of waterborne illnesses.
What are amoebas?
Amoebas are tiny, single-celled organisms present in soil and water across the world, the vast majority of which are harmless to humans. Naegleria fowleri is among the widespread species and is most prevalent in warm, fresh water, including hot springs and rivers and lakes in the summer months.
That’s where it tends to come into contact with humans. Naegleria fowleri is not a risk if ingested, but if it enters the nose, the amoeba can reach the brain and begin to consume brain tissue.
Even in Texas, which has seen the most brain-eating cases in the country, the chance of infection is exceedingly rare. The Centers for Disease Control and Prevention has counted just 40 cases across the state since 1937 and 173 cases nationwide during that time. Cases are overwhelmingly concentrated among children and young adults and tend to spike in July and August.
How can you manage risk?
There’s good news for the amoeba-anxious: The most effective safeguards come down to a few simple rules of thumb (or nose), experts told the Waco Bridge.
“There’s things that one can do to minimize their exposure like not allowing water up the nose to prevent that brain-eating occurrence,” said Kristina Mena, chair of UT Health Houston’s Department of Environmental and Occupational Health Sciences.
Mena advised the 2016 Rio Olympics on mitigating water quality hazards for athletes.
Other simple precautions include:
- A nose clip for swimming,
- Holding your nose when jumping into water,
- Avoid immersing your head in water, especially when temperatures are high, and
- Avoid stirring up sediment, which can disperse amoebas into the water.
What other pathogens should I watch for?
Brain-eating amoebas are like shark attacks — terrifying, random and extremely rare — but Waco-area swimmers are more likely to encounter parasites and bacteria originating from feces.
“Wildlife has always done their business out on the landscape,” said Tiffany Malzahn, chief environmental officer for the Waco-based Brazos River Authority. Faulty septic tanks and sewer mains also pose risks, especially after heavy rains.
With feces come pathogens primarily affecting the human gut, including Escherichia coli, Cryptosporidium, Shigella and Giardiasis. Transmission usually occurs through consuming polluted water, most often in summer and early fall. Infections in healthy adults are not typically life-threatening, though E. coli and Cryptosporidium can be for children, the elderly or immunocompromised.
“The most prevalent waterborne illnesses in McLennan County are Shigella and Cryptosporidium,” said Fannie Parker, senior epidemiologist at the Waco-McLennan County Public Health District.
The county averages about 30-35 cases of Cryptosporidium and 10 cases of Shigella a year, Parker said. Most of those cases, however, were linked to foods washed in contaminated water, not recreation, according to the health district.
Texas Shigella and Cryptosporidium cases arising from recreation are rare in general, according to CDC data and local sources. Between 1971 and 2023, there were only 124 combined cases in the state and one hospitalization, according to the health district.
Experts gave several tips for managing risk and exposure:
- Wait 7-10 days after a heavy rainstorm before entering water.
- Avoid warm, stagnant water.
- Do not enter fresh water with an open cut or wound, or after surgery.
- Larger water bodies and rivers are better at diluting contaminants than smaller ones.
Are water bodies tested for these organisms?
The Brazos River Authority regularly tests area rivers for E. coli and non-organic pollutants, which are sent to the Texas Commission on Environmental Quality. Malzahn said E. coli is a useful proxy for several common pathogens originating from feces. At the same time, E. coli is one of the few pathogens for which rapid, affordable testing exists, she said.
But most microorganisms are resistant to regular monitoring and require hours of manual microscopy, including Naegleria fowleri, she said. Meanwhile, the health district publishes online notices if more than three people become ill from the same source.
The Brazos emerges as swim venue
Waco also conducts freshwater testing ahead of major aquatic events hosted on the Brazos River.
Events such as the Ironman Triathlon and the Beast of the Brazos open-water swim competition see anywhere from several hundred to 2,500 swimmers in the river, said Mike Vogelaar, executive director of the Greater Waco Sports Commission.
He’s not aware of anyone who has been sickened by a waterborne illness at a Waco open-water event — and some contestants have ingested plenty of river water, he said.
“Open water swimming is an incredibly safe activity if it’s well planned and the participants respect the environment,” Vogelaar said. “So the biggest risks aren’t mysterious illnesses but issues like weather, water conditions and people swimming beyond their ability.”
When those out-of-towners come to compete, they often ask him why there aren’t more people enjoying the Brazos.
“I think the river has just had this stigma over the years,” Vogelaar said.
But he is noticing a steady change in sentiment.
“For the most part, conditions are great for recreational use in all the bodies of water here,” he said.
