Influenza-related muscle pain cases no cause for alarm
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.