A surge in invasive group A streptococcal reports in Australia has prompted Telethon Kids Institute researchers to call for a unified national public health response, as researchers work on developing a vaccine.
Following a spike in cases of invasive Strep A (iGAS) in Europe last year, Australia has seen a similar surge, with the National Communicable Diseases Surveillance (NCDS) recording 1,184 cases in 2022, prompting Victoria to issue the first advisory notice, with WA, NSW and the ACT issuing notices in January 2023, following a jump in case numbers to 547 during the first quarter of the year.
WA recorded 228 cases in 2022, with 126 confirmed cases already reported in the first half of 2023.
An analysis by the Telethon Kids Institute, published in the Medical Journal of Australia, highlighted that the recent cases could be caused by new strains, relaxed hygiene standards after the pandemic, along with reduced immunity, and noted that the bacteria spread rapidly among household contacts up to 200 times more efficaciously than among the general population – for up to 30 days following exposure.
Lead researcher, Dr Thel Hla from the Wesfarmers Centre of Vaccines and Infectious Diseases, said national differences in the definition of a Strep A infection and the accompanying health advice could have resulted in an underestimate of the true burden of the disease.
“The national surveillance system for Invasive Strep A came into effect fairly recently, in July 2021, to allow us to examine and track patterns of disease, but it is still in its infancy,” Dr Hla said.
“There remains a broad lack of consensus about public health management for invasive Strep A, so there’s an urgent need to synthesise clinical and public health prevention priorities to guide a national public health response.
“This means agreeing on what constitutes a close contact, the types of drugs to administer for treatment and developing national guidelines – this should be a priority while Strep A vaccine development is underway.”
Another key study from Murdoch Children’s Research Institute, published this week in The Lancet Regional Health – Western Pacific, confirmed the spike in cases using data from the Paediatric Active Enhanced Disease Surveillance Network (PAEDS), with the findings revealing the extent of symptoms among children admitted with Strep A.
The contagious bacteria can cause flesh eating necrosis, strep throat, toxic shock, skin infections, acute rheumatic fever, and rheumatic heart disease, with 20% of invasive cases causing death. Necrotising fasciitis, which eats away at the flesh, can have reported death rates as high as 70% to 80%.
While the disease can be treated with penicillin and other antibiotics, deaths and disability still occur, even with treatment, and Murdoch Children’s Professor Andrew Steer said the study found more children were presenting with severe symptoms because of Strep A infections, underscoring the need for a safe and effective vaccine.
Professor Steer and his team are currently testing candidate Strep A vaccines developed by researchers in Australia and overseas in a first of its kind human challenge model, involving 50 participants who will receive either a candidate vaccine or placebo while having Strep A applied to their throats in a controlled environment.
“We hope this research will accelerate the development of a vaccine and move things forward to bigger field trials. With ongoing funding, we can begin to answer some of these complex questions and work towards an effective and accessible Strep A vaccine.”
The Australian Pathogenic Genomic Program is currently building a national Strep A surveillance system with epidemiological data essential to guide future vaccine roll out and treatment measures, but Professor Steer advised that availability will still take years, with clinical trials and regulatory approvals needed.
The team from Wesfarmers also investigated the impact of previous respiratory infections on the risk of Strep A infection, revealing an association for future study.
“Predisposition to iGAS following viral infections such as influenza and varicella zoster virus are well described, and a predisposition to iGAS following COVID infection is plausible, although the association is yet to be fully elucidated,” the authors said.