Blood samples hint at silent H7N9 in poultry workers
Aug 12, 2013
A serology study in a Chinese province hit hardest by novel H7N9 influenza found evidence of asymptomatic or mild infections in poultry workers, further strengthening suspicions that poultry are the source of the outbreak.
The study focused on members of the general public, poultry workers, and patients with lab-confirmed H7N9 infections in Zhejiang province, which has recorded 45 cases during the outbreak thus far. The Chinese researchers published their findings in the Aug 9 early online edition of the Journal of Infectious Diseases.
They collected and analyzed serum samples, along with epidemiologic data, from 1,129 people from three Zhejiang cities in the province that had human H7N9 cases. The group also collected serum samples and nasal swabs from 396 people who had occupational exposure to poultry in districts where human cases had been found.
Among poultry workers, 6.3% had antibodies against the new H7N9 virus, based on hemagglutinin inhibition (HI) assay titers of 80 or greater. In contrast, the investigators found no evidence of antibodies in the general population.
No viral evidence was found in the workers’ nasal swab samples.