Human case of H7N9 in China linked to outbreaks at poultry farm
An epidemiological link has been identified between a human case of influenza A(H7N9) virus and a Chinese poultry farm, which yielded positive samples for H7N9 and H9N2 viruses, according to recent findings.
Researchers characterized a case of influenza A that occurred in 2014 in Changchun, Jilin Province, northeastern China. The patient was a 50-year-old man who owned a small farm in that region. The man, who had no history of underlying medical conditions, presented at the Jilin University Third Hospital with an isolated fever on Feb. 15, and subsequently returned to the hospital on Feb, 16, 17, and 19 due to ongoing febrility.
Pneumonia was ruled out through radiographic imaging, and the patient was treated with IV azithromycin and xiyanping, a traditional Chinese medicine. On Feb. 19, the man presented to Jilin University First Hospital, at which time throat swab samples were collected. The samples were assayed at the local and provincial CDC facilities, and were found the same day to be positive for H7N9 virus the same day. The test results were confirmed the following day by CDC China. The patient underwent a regimen of oseltamivir (Tamiflu, Genentech) 150 mg twice-daily and methylprednisolone (80 mg twice daily), and received oxygen via nasal cannula. The patient recovered and was released from the hospital March 7.
The patient reported that he did not have contact with any poultry other than at his own facility. Between August 2013 and February 2014, the patient had added seven groups of birds to his farm, equaling approximately 1,100 birds from eight source locations. The birds coexisted on the egg production warehouse, which was rarely cleaned and never disinfected. The patient saw to the care of the birds daily and did not utilize personal protective gear.
The initial onset of disease occurred among a group of 280 birds brought to the farm in October 2013, culminating in the death of many of these birds over the next 3 months. A second outbreak was seen with the addition of 290 birds on Feb. 10 and 12. After this time, extensive illness occurred in the bird population. By Feb. 15, the date of the onset of the human case-patient’s symptoms, more than 100 birds had died.
The local, provincial and national CDCs subsequently initiated investigations and sampling of the patient’s farm and associated poultry suppliers. Tests were conducted at public health laboratories of 85 poultry and environmental samples taken from the farm. Real-time PCR (RT-PCR) revealed that 19 of these samples were positive for both H7N9 and H9N2 viruses. One sample tested positive only for H7N9, and three tested positive only for H9N2. Of 374 samples collected from various suppliers, four specimens from one distributor tested positive by RT-PCR for the influenza A H9 subtype.
According to the researchers, these findings emphasize the importance of increased virus surveillance in China, as well as improved sanitation practices at farms.
“Public health measures taken to contain the outbreak of H7N9 virus infection have thus far focused on live poultry markets, but our findings suggest that small-scale farms may be another source,” the researchers wrote. “Inadequate cleaning and disinfecting, a lack of personal protective equipment, and the commingling of bird species found on this farm are common in small-scale poultry farms. These factors enable evolution of novel avian influenza viruses and spread of H7N9 virus.”
Disclosure: The researchers report no relevant disclosures.