Every year, thousands of children in the U.S. are infected with strep throat, but some children are hit with the painful bacterial infection over and over again. Now, a study by researchers at the La Jolla Institute for Immunology provides details on why repeat infections occur.
“It’s been a longstanding medical mystery,” said Shane Crotty, Ph.D, a professor with the Institute's Vaccine Discovery Division. “We figured that it must be a difference in the immune system or the immune response.”
Crotty said most children develop a protective immunity to the infection, caused by the A Streptococcus bacteria. Signature symptoms of the illness include swollen tonsils, red or white spots and a fever. The infection is typically treated with antibiotics.
“So the antibiotics will clear the infection, but in your average person they’ll also develop antibodies,” Crotty explained.
But not everybody shares that same protective immune response. Some children carry a gene that prevents them from developing immunity to the strep bacteria, he said.
“The key finding here is that we've got evidence that recurrent tonsillitis or recurring strep throat is a genetic susceptibility disease and it’s tied to the bacteria actually targeting the immune system,” Crotty said.
Susceptible children often have their tonsils removed to help prevent further infections. The lymph-node-like structures on each side of the back of the throat are a breeding ground for strep bacteria. Tonsil tissue played a valuable role in the research.
“We developed a test to be able to measure strep specific responses within the tonsil,” said Jennifer Dan, M.D., Ph.D, a clinical associate who studied tonsil samples of more than 100 San Diego children who each experienced the infection an average of a dozen times.
Dan said recurring strep throat is a major concern because it can lead to serious complications if it is not treated, including rheumatic fever or rheumatic heart disease.
“Rheumatic heart disease is a big problem in third world countries,” Dan said. “It’s one of the primary causes of early heart failure in young adults. So it’s something that the World Health Organization is trying to eliminate.”
The study, published in the Science Translational Medicine could pave the way for a vaccine, said Crotty.
“The way the bacteria is targeting the immune system provides an idea for a vaccine where you can block that activity of the bacteria,” Crotty said. “So if you can block that activity with a vaccine, it might actually be able to stop strep throat in general.”
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