Increased temperatures, humidity and rainfall create the right conditions for a number of summer bugs that can have an impact on your health.
But according to local and state data, the summer illnesses that are making headlines this year are less of a concern in South Texas and Bexar County than others that are lesser-known.
Dr. Heather Yun, a local infectious diseases physician who sits on the board of the Infectious Diseases Society of America, explained best practices to keep yourself protected both from the illnesses making headlines as well as the more unique threats that exist locally.
Cyclosporiasis and cryptosporidium
The U.S. is currently experiencing a significant outbreak of cyclosporiasis, a stomach bug that causes diarrhea and is caused by the parasite cyclospora.
“It’s transmitted by what we affectionately refer to in infectious disease as ‘fecal-oral transmission,’ which means quite literally, we encounter these pathogens by ingesting small quantities of sewage,” Yun said.
U.S. officials believe the outbreak is traced to contaminated produce. The main culprit so far has been iceberg lettuce from Taylor Farms, which has since been recalled. But officials are still tracking down other potential sources, including other fresh produce like berries, salad mixes and herbs.
Cyclosporiasis is not new, but outbreaks to this magnitude are uncommon in the U.S.
There have been more than 11,500 cases of the disease confirmed or suspected so far this summer, according to the U.S. Centers for Disease Control and Prevention, making it the largest outbreak on record. The majority of those cases are in the Midwest and Northeast, especially Indiana, Kentucky, Michigan, Ohio and West Virginia.
As of July 13, DSHS has reported 68 cases in Texas, which is not outside the range for typical cases around this time of year.
The same is true for San Antonio. The city has reported 15 cases of cyclosporiasis as of July 21, according to San Antonio Metropolitan Health District, similar to what the area has seen around this time of the year in past years.
Most people who get cyclosporiasis recover from the illness without medical treatment, though specific treatment does exist for those whose illnesses are more severe. Just like with any other bug that causes diarrhea, the main risk is dehydration.
On whether you should avoid buying certain produce, Yun said it’s largely a personal decision. If you’re immunocompromised, older or have young children, it might be worth taking some precautions. That could include washing produce more thoroughly, cooking produce or making temporary changes to your grocery list.
“It’s a tough thing to tell healthy people just don’t eat produce all summer,” she said.
Despite the headlines, there’s another disease that causes similar symptoms and is found more commonly in South Texas: cryptosporidiosis, caused by another parasite known as cryptosporidium.
This is most often encountered at water parks, swimming pools and bodies of water. Texas sees more than 800 cases every year on average. San Antonio sees 92 cases every year on average, according to Metro Health data from 2016-2024.
“This is another diarrhea parasite that’s pretty common here, and we see it every summer more commonly than cyclospora,” Yun said. “It doesn’t take very much at all — you get one mouthful of the river, and you very well may get cryptosporidium.”
Alpha-gal syndrome and murine typhus
Something else you may be hearing about more often is the tickborne allergy known as alpha-gal syndrome, a potentially life-threatening red meat allergy that can be obtained from the bite of lone star ticks.
Lone star ticks are named for the star-shaped white marking on their backs, not after Texas, where the bug is relatively uncommon.
More than 110,000 suspected cases of alpha-gal syndrome were identified between 2010 and 2022 in the U.S. But cases are not nationally notifiable to CDC, so the actual number is unknown. As many as 450,000 people may be affected.
Tickborne diseases, however, are quite uncommon in Texas compared to the Northeast and Midwest, which offer more favorable climates and larger populations of animals that carry the bugs.
However, South Texas is home to a unique flea-borne disease known as murine typhus. The disease is caused by a bacterium carried by infected fleas that can be transmitted to humans.
“South Texas is actually really unique for murine typhus,” Yun said. “We have this more than any place else really in the world, and we see this every spring and summer as the flea populations here increase.”
Common carriers of infected fleas include rats, opossums, cats, dogs and other small mammals. Symptoms of the disease include fever, headache, chills, weakness, nausea and vomiting, body aches and rash. It can be serious, resulting in hospitalization, if not treated.
Over 6,700 cases of flea-borne typhus were reported between 2008 and 2023. Roughly 70% of the cases resulted in hospitalization and 14 fatalities were attributed to the disease, according to the Texas Department of Health and Human Services. Bexar County saw a significant number of these cases.
Metro Health reported 853 cases of typhus from 2016 through 2024.
“Most of the stories that we encounter with this in South Texas have something to do with feral cats that someone is feeding on their porch, or cats that are going in and out of the house and interacting with opossums, or there’s a crawl space under the house where maybe rats and possums go, and then the fleas come in and bite people in the summer,” Yun said.
Yun advised residents who have outside pets to keep up with flea prevention. It’s also important to address a rodent infestation or any small mammals living under your home, she said.
Of course, there’s also the ever-present threat of mosquito-borne diseases like West Nile Virus. Metro Health has detected WNV in three mosquito traps this summer, including in southwest and northwest San Antonio.
The single most important thing you can do to keep mosquitoes away is eliminating stagnant water around your home, especially dirty water, where mosquitoes reproduce.
If you have to be outside, especially during peak mosquito activity hours at dawn and dusk, wear long sleeves and pants or spray yourself with insect repellent.
