"This study was designed to give us clues about the transmission of H7N9 which has affected some humans in China," said David Kelvin, PhD, a senior scientist at the Toronto General Research Institute and Professor at the University of Toronto. "The animals used in the study had very mild clinical symptoms as a result of their exposure to the virus and it was clear that very close contact was required for transmission. It also appears that this virus in its present form does not transmit very well through the air."
The study, published in Science
, conducted in China at Shantou University with the assistance of Kelvin and Dr. Michael Roehrl, a pathologist at the University Health Network, was started because, as of May 1, over 125 human cases have been confirmed in China with the majority of these people hospitalized and many suffering acute respiratory distress. Over 75% of these people had a history of contact with, or exposure to poultry before becoming ill.
Ferrets and pigs were used in the study and transmission in the ferrets occurred when the animals shared cages and had direct contact with each other but was much reduced if cages were well spaced, which demonstrated that airborne transmission is not a high risk for H7N9 in this animal model.
"This study, while conducted in animal models, tells us that close contact is required for transmission and that health care workers are at risk for transmission as they are in close contact with the individuals," said Kelvin. "It also demonstrated that airborne transmission was very difficult in the animal models, which is likely to be the case in humans as well."