early 2017, a 5th wave of H7N9 avian influenza (AI) virus infections in
man demonstrated the increasing spread of H7N9 virus among poultry in
China. In 1997, highly pathogenic H5N1 AI virus outbreaks were reported
in Hong Kong and soon became widely spread among poultry in China. It
eventually crossed the border into Vietnam and became enzootic among
Vietnam’s aquatic birds and poultry. There is growing concern that H7N9
will likewise become enzootic among poultry in Vietnam and cause
frequent severe infections in man. Surveillance for AI viruses in
Vietnam is very limited.
During the first three weeks of October 2017, Duke, Duke-NUS, and NIVR partnered in conducting a pilot study of aerosol and bird tracheal swab sampling in Hanoi’s largest live bird market (Havi). Ninety percent of 30 four-hour aerosol samples were positive for influenza A by qRT-PCR and these results correlated highly with pooled oral swab cultures
from nearby live birds which were 47% qRT-PCR positive. Egg cultures of aerosol and pooled oral swab cultures yielded 26 live viruses, five of which were H5. In this pilot, there was as yet no evidence of H7 viruses in this market.
Our NIVR collaborators believe this bird market to be at high risk of incursions with H7 viruses from China.
In this proposal, we will conduct a 12-month pilot study of active
surveillance for influenza A viruses at Hanoi’s largest bird market and
in six live bird markets sites near Vietnam’s northern border with
China. Our teams will travel to the live bird market in Hanoi weekly and
to six live bird markets in three remote provinces in Vietnam,
conducting 10 market visits per month. During these market visits, we
will employ novel bioaerosol AI surveillance techniques (less invasive,
larger sampling area, more sustainable), along with bird and cage
swabbing, as well as collect nasal washes and qualitative survey-based
interviews from a convenience sample of poultry workers. Molecular and
culture work will be performed at NIVR in Hanoi with close collaboration
(periodic visits) from Duke and Duke-NUS scientists. We estimate a
12-month total of 360 bioaerosol samples, 600 bird swab samples, 1200
environmental cage swab samples, and 600 poultry worker nasal wash
samples with questionnaires. The samples will be studied with molecular
assays, egg or virus culture, and when appropriate by sequencing studies
in our Duke One Health laboratory network to determine influenza A type.