A new research study conducted by Imperial College London that examines influenza transmission in ferrets suggested that the virus can be transmitted before symptoms of the disease appear.
If the finding applies to humans as well, people can transmit the flu to others before they know that they are infected with the virus, adding a level of complication to containing epidemics. While previous research using mathematical models found that some flu transmission occurs prior to symptoms, this is the first to investigate the study in an animal model, MedicalXpress.com
During the study, ferrets infected with the flu virus were put into contact with uninfected ferrets at different stages after infection. Transmission of the virus occurred prior to the first symptom of fever appearing.
"This result has important implications for pandemic planning strategies," Wendy Barclay, the lead author of the study, said, according to MedicalXpress.com
. "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."
The researchers determined that ferrets could pass on flu to others only 24 hours after becoming infected. The study found that sneezing was not necessary for flu transmission as virus droplets can be expelled during normal breathing.
"Ferrets are the best model available for studying flu transmission, but we have to be cautious about interpreting the results in humans," Kim Roberts, the first author of the study, said, according to MedicalXpress.com
. "We only used a small number of animals in the study, so we can't say what proportion of transmission happens before symptoms occur. It probably varies depending on the flu strain."