Human-to-human bird flu transition
For the first time, a report has been published on the transition of novel avian influenza A (H7N9) virus from person-to-person in Eastern China.
Avian influenza A was recently identified in the region and by June 30, 2013, 133 cases had been reported, resulting in 43 deaths.
In most cases, those who have contracted the virus appear to have recently visited live poultry markets or had contact with live poultry in the seven to 10 days before the onset of illness.
Researchers studied a recent family cluster of the virus in a father and daughter, to find out whether or not it can pass from person to person, and how efficiently it spreads.
The first patient, a 60-year-old man, was a frequent visitor of live poultry markets and he became ill in March this year, five to six days after his last exposure to poultry.
Shortly after this, on March 24, the patient's 32-year-old daughter contracted the virus, despite having had no known exposure to poultry. She had, however, given direct bedside care to her father in the hospital.
Both patients later died of multi-organ failure and two virus strains were isolated from each patient which were almost genetically identical - suggesting the virus passed from father to daughter.
Public health officials interviewed and tested 43 people who had been in close contact with the patients. A son-in-law who had helped to care for the father had mild illness but all contacts tested negative for the H7N9 virus.
Samples were also taken from poultry cages and water at two local poultry markets, as well as swans from the residential area. One strain of the virus was isolated but it was genetically different to the strains isolated in the patients.
Whilst acknowledging some study limitations, authors of the report, which has been published in the British Medical Journal, say the most likely cause of the family cluster of H7N9 is that the virus passed from the father to the daughter.
However, researchers stress that the virus' ability to transmit from person-to-person is "limited and non-sustainable".
Similarly, James Rudge and Richard Coker from the London School of Hygiene and Tropical Medicine, based in Bangkok, said a limited ability to spread between humans is "not surprising and does not necessarily indicate that the virus is on course to develop sustained transmission among humans."
Despite this, they note that particular traits of the virus are of concern and the study "does provide a timely reminder of the need to remain extremely vigilant: the threat posed by H7N9 has by no means passed."
Click here to read the full report.
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