Texas strep outbreak deadly but beaten
Proven antibiotics overcome resistance fears
Cases of virulent Group A streptococcus began appearing in Texas before last Christmas, grew steadily throughout the beginning of the year in the Austin, Houston, and San Antonio areas, and by the beginning of March they were deemed a bona fide outbreak by epidemiologists at the Centers for Disease Control and Prevention in Atlanta.
By mid-March, new cases were waning and state health department and CDC officials were confident enough to say the outbreak was beaten, but not before more than 100 infections were documented - more cases than the state normally reports in a year - and two dozen people had died.
Along the way, health officials were vexed as cases of Group A strep, easily killed by penicillin as common "strep throat," showed up as both a virulent Group A strain and as cases of the more dangerous M1 variety. M1 strep was blamed for nearly a dozen cases of necrotizing fasciitis.
"Group A strep doesn't change, but you either have M1 or not, and there are different clones of M1," says Benjamin Schwartz, an epidemiologist with the CDC's National Center for Infectious Diseases.
As the relatively short but anxious treatment battle was waged, health officials were relieved that the outbreak, while difficult to subdue, eventually was quelled. Beta-lactams proved successful against the Group A cases, while clindamycin wore down the cases of toxic shock and necrotizing fasciitis. Schwartz says health officials weighed the possibility of treatment with the IV immuno glob ulin known as IVIG for the cases of M1, as Canadian studies have shown that the treatment, combined with antibiotics, has decreased mortality by 50%.Why and how remain a mystery
And while some pediatric infections were blamed on the strep's ability to attack through chicken pox sores, officials still aren't sure how or why the outbreak occurred.
"The issue is different types [of infection] circulating over time, and not one becoming another, and how populations become susceptible to a particular strain. We think it just represents a virulent strain passing through a community," Schwartz says. "This was an outbreak. We compared rates of diseases between this year and last and compared microbiology lab work."
Health officials note that both Group A strep and chicken pox peak in the winter and spring months, making that combination the likely suspect for the passage among infected children to adults, but that's largely guesswork.
Schwartz says similar outbreaks have occurred around the country over the past few years, which has led to better detection and reporting but wasn't an issue in the Texas cases. He adds that follow-up investigation into the outbreak will include more study on whether antibiotic resistance was a factor, but right now officials don't believe a super Group A strep bug is out there.