Human to Human Transmission of H7N9 Bird Flu Possible But Unlikely, Says Research

By Carol Wickenkamp
Carol Wickenkamp
Carol Wickenkamp
August 7, 2013 Updated: June 28, 2015

The bad news is that the new avian influenza virus, H7N9, can pass from human to human; the good news is that it probably won’t, say researchers in UK.

Referencing recent Chinese research tracking down the deadly new virus’s method of transmission, researchers in UK say that though the research shows the virus, which emerged in this spring, is capable of human to human infection, that’s not so unusual in avian viruses.

In fact, it isn’t surprising to find some transmission of H7N9 from human to human, and the Chinese research done in Jiangsu “does not necessarily indicate that the virus is on course to develop sustained transmission among humans”, explain authors James Rudge and Richard Coker from the London School of Hygiene and Tropical Medicine in the Aug. 6 issue of BMJ.

The Chinese testing was carried out by Qi and colleagues at the laboratories of Jiangsu Province Center for Disease Control and Prevention, where researchers contacted and interviewed victims of the H7N9 virus, their families, and health care workers in order to piece together a coherent picture of the infection’s path.

They found that because most of the flu patients had a history of visiting live poultry markets or had some other contact with poultry a week to ten days prior to the onset of illnesses, indications were that the person contracted the flu from contamination in the environment or directly from the infected poultry.

But their research did establish firm evidence of human to human transmission, the first clear evidence that the novel flu virus could be transmitted from person to person.

Working with the case of a 60 year old man who contracted and died from a severe respiratory illness and his caregiver, a 32 year old daughter who also became fatally infected, the researchers determined that the daughter likely contracted the fatal flu from her father, not from poultry.

The father, they determined, was probably infected in a live poultry market near his home and his daughter most likely contracted the disease while caring for him before he was admitted to the hospital.

A video abstract of the Chinese epidemiological research shows the methodology as well as environmental sampling and specimen collection and other aspects of the research.

Humans seemed to be more susceptible to the H7N9 virus than the H5N1 virus, say the researchers, but concluded that transmissibility was limited and non-sustainable.

The authors write: “So does this imply that H7N9 has come one step closer towards adapting fully to humans? Probably not. Crucially, there is still no evidence of sustained transmission among humans—all 43 close contacts of these two patients, including a son in law who also helped care for the father, tested negative for infection.”

Carol Wickenkamp
Carol Wickenkamp