A surge in severe cases of group A streptococcal disease has prompted Australian health authorities to raise awareness of the potentially deadly illness.
"Strep A", as it is colloquially called, has been around for a very long time.
It mostly presents as a mild illness that many people recover from without ever seeing a doctor, infectious diseases consultant and Telethon Kids Institute executive director Jonathan Carapetis said.
However, a rise in the rarer, life-threatening version of the disease known as invasive strep A is causing concern.
So what is the illness, why is the invasive version so serious, and what could be behind the rise?
What is strep A?
Strep A disease is caused by bacteria known as group A streptococcus.
It is a common infection that can cause sore throats, scarlet fever or impetigo, otherwise known as school sores.
In less common cases, it can become a serious illness requiring hospitalisation — invasive group A streptococcus, also known as invasive strep A or iGAS.
Indicators of the severe illness include fever, a fast heart rate, cold hands and feet or a mottled look to the skin, difficulty waking or increased lethargy or confusion.
Symptoms to look out for in young children that may indicate severe illness include irritability, difficulty waking, high-pitched crying, refusal to eat/feed, fewer or no wet nappies or decreased urination, cold or mottled limbs, and difficulty breathing.
Young children and the elderly are most at risk of infection.
"People haven't been aware of it as perhaps they should be," Professor Carapetis said.
"It's just as severe as meningococcal."
People most at risk are those over 65 or under five, pregnant and post-partum women, Aboriginal and Torres Strait Islander people, intravenous drug users and immunocompromised people.
Why have severe cases been increasing?
There were surges of the disease in the 90s and early 2000s, but the latest rise, Professor Carapetis said, was "very dramatic".
National data prior to 2022 is patchy, as invasive strep A only became a notifiable condition last year.
However, records kept by the federal health department show the number of cases rose sharply in 2022.
The trend looks to be continuing into 2023, with more cases reported so far this month than in all of January 2022.
The World Health Organization has also documented a rise in a number of countries around the world.
There are at least three hypotheses as to why strep A cases are surging, according to the University of Queensland's Mark Walker:
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COVID-19-induced lockdowns throughout 2020 and 2021 insulated the population against all infectious bugs, including strep A.
The lack of low-grade infection could mean peoples' immunity to the bug is now lower, so when they do contract it, they are more likely to get sick. -
The resurgence of viral infections following lockdowns has meant that when some people have caught strep A, they have caught it off the back of a viral infection.
Catching strep A on top of a background viral infection can make a person more susceptible to the disease. -
It is thought there could be new, more aggressive variants of strep A coming into Australia from other countries, such as the UK or China.
Professor Walker believes this is part of the problem, but the extent of it will only be known in a couple of years after immunity to the new bugs has built up in the child population.
Despite the surge, health authorities say the overall risk of invasive strep A to the community remains low.
How dangerous is invasive strep A?
Professor Carapetis said invasive strep A had a high death rate.
"Usually between seven and 20 per cent of cases that get the nasty strep infection will end up dying," he said.
An alert issued last month by Victoria's hospital safety watchdog, Safer Care Victoria, said during 2022, 42 cases of invasive strep A infections were detected at the Royal Children's Hospital (RCH) and Monash Children's Hospital.
Two Victorian children died with the illness last year.
Is there a vaccine?
There will be, but it's not ready yet. Professor Carapetis is co-director of the Australian Strep A Vaccine Initiative (ASAVI), which is among other bodies globally working towards a vaccine.
"Within three years, we will have a vaccine actually in a trial in kids to see if we can prevent strep infection," he said.
"If it works, then, hopefully, [after a few years] we'll have the opportunity for all kids and potentially other high-risk groups to receive it. That would be the game changer.
"It's a bit like meningococcal disease — there’s lots of stuff we can do to treat strep A but the nasty one, it can just come out of the blue and you won’t know it and the only way we can be sure of preventing that will be to get a vaccine."
The hope is that in the near future, a vaccine against strep A will become part of the national vaccination schedule, just like the meningococcal vaccine.
How is strep A treated?
The most important thing with invasive strep A is to get in "very, very early", Professor Carapetis said.
Most doctors will start by prescribing broad-spectrum antibiotics and then after a blood test confirms strep A, they will hone in on it with penicillin.
