Virus Transmission Precedes Flu Symptoms

The flu virus can be transmitted ahead of its symptoms showing, according to the results of new research carried out in the UK.

Based at Imperial College London, the researchers involved found the advance flu virus transmission scenario true for ferrets. If it's also the case for humans, this could radically alter the way flu is diagnosed and treated in the future.

Prior flu infection knowledge is crucial in epidemic response planning but this is the first study to highlight the potential for the symptoms to lag behind actual person-to-person transmission.

Flu Transmission

Led by Professor Wendy Barclay, the Imperial College London researchers used ferrets to study the flu transmission issue since, compared to humans, the way they contract and react to flu is pretty similar.

So, healthy ferrets were exposed to ferrets suffering from flu. Fever - the first flu symptom to materialise - showed itself after the flu had spread from one ferret to another, no matter whether the animals were right next to each or some space apart.

It took an average of just 24 hours for the flu to be transmitted, while the fever didn't show itself for another 13 hours and sneezes weren't recorded until 11 hours after that.

Flu Virus Symptoms

The result firms up what was previously thought: sneezes don't necessarily spread flu and typical breathing patterns are enough to send the virus into the air and into another subject.

"This result has important implications for pandemic planning strategies", Barclay explained in an Imperial College London press release on the flu virus symptoms and transmission study.

"It means that the spread of flu is very difficult to control, even with self-diagnosis and measures such as temperature screens at airports. It also means that doctors and nurses who don't get the flu jab are putting their patients at risk because they might pass on an infection when they don't know they're infected."

Flu virus image copyright US Centers for Disease Control and Prevention - Courtesy Wikimedia Commons