Unique strain of parechovirus causes Australian outbreaks in infants

June 25, 2019

Researchers have unlocked the genetic code of a novel type of parechovirus circulating in Australia every two years and causing severe disease mostly in infants less than three months of age.

In cases tested from an Australia-wide database of the 2017–2018 outbreak, a specific strain of parechovirus type 3 caused serious disease mainly in infants including sepsis-like illness and meningitis.

The study showed the same virus strain has caused at least three outbreaks in Australia in the 2013–2014, 2015–2016 and 2017–2018 seasons.

The number of cases of severe hospitalised parechovirus illness has increased across the three outbreaks, with more than 200 cases in 2017–2018.

The research, published in Scientific Reports, was funded by the National Health and Medical Research Council (NHMRC) of Australia through a Centre of Research Excellence called the Australian Partnership for Preparedness Research on Infectious Diseases Emergencies (APPRISE).

Senior author, Professor Soren Alexandersen, Director of the Geelong Centre for Emerging Infectious Diseases (GCEID, a partnership between Barwon Health, CSIRO and Deakin University) and APPRISE researcher, said the parechovirus strain is evolving between outbreaks.

“The genetic analysis across outbreaks creates a ‘molecular clock’ for us and we have found genetic changes that could indicate the virus is evolving to cause more severe disease.”

“Although this more severe strain of parechovirus has not been reported anywhere else in the world, the genetic changes suggest the virus is also circulating and evolving outside of Australia in between our outbreaks,” Professor Alexandersen said.

The genetic analysis was performed on clinical samples and data brought together by an APPRISE Australia-wide collaborative project aimed at preparing for any future outbreaks.

Co-author, Dr Philip Britton, Senior lecturer at the University of Sydney School of Medicine, said the project also enabled the researchers to design a single database for harmonised collection of information from all of the Australian parechovirus cases from the 2017/18 outbreak.

“We can’t predict the future, but if we were to have another epidemic over the 2019–2020 season, our ability to undertake real-time data collection will allow us to compare the features of a future epidemic with past epidemics to better understand the evolution of this virus that is of clinical and public health significance to Australia.”

“The databases will also allow researchers to better answer important public health questions such as how does the parechovirus spread through communities and what are the major locations and risk factors for transmission.”

Dr Britton said the project networked specialist virology laboratories at GCEID and the Victorian Infectious Diseases Reference Laboratory and major children’s hospitals around Australia – The Children’s Hospital at Westmead, Sydney Children’s Hospital Randwick, Queensland Children’s Hospital, Royal Children’s Hospital Melbourne and Perth Children’s Hospital.

“We hope our work will also lead to greater international collaborations to really understand the global genotypes of this virus and any correlations with the severity of the disease.”

Chamings A, Druce J, Caly L, Yoga Y, Britton PN, Macartney K, Alexandersen S. Evolutionary analysis of human parechovirus type 3 and clinical outcomes of infection during the 2017–18 Australian epidemic. Scientific Reports 9:8906 https://doi.org/10.10

Britton, PN, Jones CA, Macartney K, Cheng AC. Parechovirus: an important emerging infection in young infants. Medical Journal of Australia 208(8):365–369. https://doi.org/10.5694/mja18.00149

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