The viral isolates of a patient with influenza A(H7N9) and an epidemiologically linked market chicken were found to be almost identical, researchers from China reported in The Lancet.
As of Thursday, there have been 109 cases of H7N9 and 22 deaths, according to WHO. There has been no evidence of widespread human-to-human transmission, and officials in China are continuing to monitor the outbreak.
The researchers identified four patients who had contact with poultry 3 to 8 days before the onset of disease. They collected throat and sputum samples from the patients and cloacal swabs of 86 birds from epidemiologically linked wet markets. To identify and subtype the isolates, they performed sequencing, RNA extraction and complementary DNA synthesis on one patient isolate and one chicken isolate.
The H7 was closest to that found in the H7N3 virus from domestic ducks in Zhejiang. The N was closest to that found in the wild bird H7N9 virus in South Korea.
“Interaction between newly established H7 subtypes and other avian influenza viruses, such as the H9N2 subtype, might have resulted in the current H7N9 strain, which has gained some ability to infect human beings,” the researchers wrote. “Further adaptation could lead to less symptomatic infection and more efficient person-to-person transmission.”
Disclosure: The researchers report no relevant financial disclosures.