Avian flu is back, and this is proving that it also can be lethal to humans.
In early February, Chinese scientists reported the first human death associated with a new bird flu virus, H10N8. The virus showed a disturbing ability to replicate in humans. The infected person, a woman from Nanchang City in China, died nine days after contacting the virus, despite antibiotic and antiviral treatment.
Dr. Yuelong Shu from the Chinese Centers for Disease Control and Prevention, Beijing, said the following:"A genetic analysis of the H10N8 virus shows a virus that is distinct from previously reported H10N8 viruses having evolved some genetic characteristics that may allow it to replicate efficiently in humans. Notably, H9N2 virus provided the internal genes not only for the H10N8 virus, but also for H7N9 and H5N1 viruses.”
“The pandemic potential of this novel virus should not be underestimated,” the medical team wrote in The Lancet.
The patient had visited a live poultry market, but stayed only for about five minutes and didn’t handle any birds herself. The birds in the market were examined, and no flu virus was found. Analysis in the Lancet paper showed a genetic similarity of haemagglutinin genes in wild birds.
A group of scientists publishing in early March in the online journal PLoS One identified 116 avian flu strains in wild birds. “This is roughly twice the number that were found in domestic birds, and more than 10 times the number found in humans,” according to a news release on the report.
Last year an H7N9 avian flu strain caused a deadly human outbreak in China. The strain had never before caused disease in humans. So far there have been more than 300 clinical cases of H7N9, and 33 percent of people who contracted the virus died. To date, more than 380 people have died from the H5N1 strain, which first wreaked havoc in 2003.
When avian flu jumps from its bird hosts to humans it can usually be traced to contact with domestic poultry. Although avian flu often originates in wild birds, “it is the mixing of viruses among poultry, pigs, and people that substantially heightens the disease risk in humans,” the PLoS One press release says.
“Mallards carry the highest number of strains at 89 and ruddy turnstones were second with 45. The more a strain was shared across wild bird types, the more likely it was to be found in domestic birds, a risk factor for spillover events,” the scientists found.
Another report published in mid-March in The Lancet shows how critical it is to begin treatment early. The researchers found that the antiviral drug Tamiflu reduced the risk of death in adults who had contracted the H1N1 flu virus. People treated with neuraminidase inhibitors (NAIs) like Tamiflu were 25 percent less likely to die from the disease.
The authors of The Lancet study suggested that to maximize survival, ideally NAIs should be started within two days of symptoms developing. They noted that the risk of death was halved when victims started treatment within 48 hours of symptom onset compared with later treatment, or no antiviral treatment. Conversely, each day that a victim delayed starting antiviral treatment after two days from illness onset the risk of death rose roughly 20 percent, compared with starting treatment within two days of onset.