New knowledge on rheumatic fever leads to call for more screening

Important new findings about the causes of rheumatic fever could help prevent it, and head off the resulting heart damage dealt to scores of children each year, experts say - but only if they lead to broader surveillance and vigilance.

A team of medical experts from New Zealand and Australia have found skin infections are likely a significant cause of rheumatic fever.

The researchers looked at almost two million throat and skin swabs over eight years, and found that streptococcus bacteria detected on both the skin and the throat indicate a higher risk of developing rheumatic fever.

It was already known that rheumatic fever can develop after strep throat, however the team found the risk was even higher when patients had the bacteria on the skin, which held a five-fold risk.

The data has just been published in the BMJ Global Health.

Public health expert Professor Michael Baker, one of the study's authors, said the findings are a world first, and offer a step forward in understanding a "terrible disease of poverty".

The new knowledge means an overhaul is needed for the national rheumatic fever strategy, he said.

Rheumatic fever has been mostly wiped out in developed countries, but continues to cause problems in New Zealand, where public health experts say the number of people affected - particularly children, is 'a national shame'.

Rheumatic fever is more common in Māori and Pasifika, and can cause permanent damage to the heart, as well as affecting the joints, brain and skin.

Up to 800 people are hospitalised each year because of rheumatic heart disease, and 150 to 200 die from it.

"The study is really throwing up findings that challenge everything that we are doing to prevent acute rheumatic fever in New Zealand [and] our current programme. So really we need to sit down and go through it very carefully and redesign it," Baker said.

"This research collectively does identify a new direction in identifying rheumatic fever, we would like to now hold a large trial in Auckland in children."

Australasian College for Emergency Medicine president Dr John Bonning said rheumatic fever is an autoimmune condition, but it is poorly understood how it develops after strep infections.

"It attacks the heart valves and it makes the valves function poorly. It puts them into heart failure and causes ongoing issues.

"They frequently will require surgery and life-long medication, and this is young people, this is not something that you really expect to do in a teenager and a 20-year-old."

The study was a useful prompt to take skin conditions seriously, Bonning said, and doctors needed to be vigilent about taking swabs from at-risk populations.

The study showed that Pacific Islanders under 20 who had a positive sample for streptococcus on the skin had a seven-fold higher risk of developing rheumatic fever than the rest of the population, and Māori under 20 with a positive skin test had a five-fold higher risk.

And it also threw doubt on the value of using oral antibiotics as a strep throat treatment to prevent acute cases of rheumatic fever. The research team found routine antibiotic treatment following a strep throat diagnosis did not lower the risk of getting the autoimmune condition.

However Bonning said that while antibiotics are widely overprescribed, they should still be seriously considered in cases where people have a strep infection and are from an at-risk population.

Baker said the new findings also present a message to parents; go and see a doctor if a child has a skin infection.

"The problem is you can't tell what a skin infection is simply from looking at it, it really is a matter of taking skin infections really seriously and getting them checked out," Baker said.

The study was done by researchers from the University of Melbourne, University of Otago, University of Auckland and the Southern DHB.

In 2019 a University of Auckland study found children diagnosed with scabies, another skin condition, were more likely to develop rheumatic fever.