Influenza-related muscle pain cases no cause for alarm

5 September 2011

5 September 2011

A rise of influenza B in the community may be to blame for a cluster of cases in Melbourne of flu-related myositis (muscle inflammation and pain), an expert says.

Calf muscle cramps are a well-recognised complication of the B strain of flu, said Professor Robert Booy, head of clinical research at the National Centre for Immunisation Research and Surveillance, Sydney.

A school in the bayside suburb of Sandringham has reported 8 cases of children with the flu experiencing myositis, prompting a public advisory in a bid to allay parental concerns that their children were temporarily unable to walk.

"I’m not surprised ... influenza B normally comes late in the winter," Professor Booy said.

"Myositis ... is transient, and you generally get good recovery within a week or 2 – the problem is that pain in the calves prevents walking, but, as best we know, you recover well."

Latest National Communicable Diseases Surveillance data shows pandemic A (H1N1) influenza (swine flu) has accounted for most influenza transmission this year, with influenza B also circulating (Australian influenza report, 6-19 Aug 2011).

Professor Booy said he expected cases of influenza to tail off within the next few weeks, along with the arrival of warmer weather.

"Some people [with myositis] have an associated [infection-like] syndrome ... but it almost always occurs on its own without any serious complication," he said.

Last Reviewed: 5 September 2011
Reproduced with kind permission from Medical Observer.

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References

1. Australian Government Department of Health and Ageing. Communicable diseases surveillance. Australian influenza report 2011 - current report: 6-19 August 2011. http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-surveil-ozflu-flucurr.htm (accessed Sep 2011).
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