Skin infections confirmed as a cause of rheumatic fever

Researchers at the University of Otago have made a major breakthrough in further understanding acute rheumatic fever, showing that skin infections are likely to be a significant cause of the disease.

Acute rheumatic fever is a cause of serious heart disease, particularly for Māori and Pacific children and young people; indeed, New Zealand has one of the highest rates of rheumatic fever seen in a high-income country. It has long been recognised that rheumatic fever is a complication of group A Streptococcus (GAS) pharyngitis, commonly known as ‘strep throat’; however, new research published in BMJ Global Health indicates that Streptococcus skin infections can also trigger the disease.

“Because acute rheumatic fever is an uncommon disease and few countries have comprehensive linked health data, no previous study has been able to quantify the rheumatic fever risk following a laboratory-confirmed infection,” said Otago researcher Professor Michael Baker.

The study used data on almost 1.9 million throat and skin swabs processed in the Auckland region over an eight-year period, which were linked to hospitalisation data to identify rheumatic fever cases, as well as prescribing data to identify if cases were dispensed antibiotics. The risk of rheumatic fever increased five-fold in the eight- to 90-day period following collection of both a GAS-positive strep throat swab and a GAS-positive skin swab, compared with negative swabs. Māori and Pacific children had the highest risk of developing rheumatic fever following collection of a GAS-positive swab.

“This study is a major breakthrough in understanding the causes of acute rheumatic fever,” Prof Baker said.

“It is the world’s first study to confirm that the risk of rheumatic fever rises after a GAS skin infection in a similar way to how it does after a GAS sore throat.”

Prof Baker said the study’s findings have huge implications for the prevention of acute rheumatic fever, which has until now been largely focused on diagnosing and treating GAS throat infections. “While treating GAS sore throats should remain a key strategy in the prevention of rheumatic fever,” he said, “a new focus should also be placed on addressing GAS skin infections to help reduce the risk of rheumatic fever in New Zealand and internationally.”

New Zealand has a high incidence of skin infections, with markedly higher rates in Māori and Pacific children compared with children of other ethnicities. Prof Baker said, “Health professionals caring for children at risk of rheumatic fever need to treat skin infections with the same level of intensity as throat infections, while a key message for the public is that skin infections matter and need to be treated promptly.”

Co-researcher Dr Julie Bennett said the study team is now planning a trial of intensive skin infection treatment to see if this can reduce the risk of developing rheumatic fever. She also revealed that dispensing a course of oral antibiotics, which is the routine treatment for children following a strep throat diagnosis, was not associated in the study with a reduced risk of developing rheumatic fever.

“This is a worrying finding,” she said. “It suggests that we need to find more effective ways of treating these infections.”

Image credit: ©stock.adobe.com/au/TOM ANG

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