Investigating the endemic presence and persistence of HPAI H5N1 virus on
Java, Indonesia
Abstract
HPAI is endemic across parts of Indonesia, but the mechanisms of viral
persistence in the poultry production system have not been well
investigated. This mixed methods research conducted in Purbalingga
District, Java characterised poultry populations and trade and contact
networks and performed risk-based sampling for the active detection of
HPAI virus in live bird markets, collector yards, backyard poultry,
nomadic ducks and commercial farms. Approximately 60% of households
kept birds, about half of which contributed towards household income.
Traders tended to use multiple collector yards and live bird markets,
and poultry might be presented at multiple markets before sale. Only the
commercial farm sector implemented biosecurity practices and
vaccination. Samples were screened for avian influenza virus (AIV) and
positive samples were tested for the H5 and H9 sub-types. H5 virus was
detected in all enterprise types, although there were few positive
results in commercial farms, the backyard sector and nomadic duck
flocks. The highest numbers of AIV, H5 and H9 viruses were found in the
live bird markets and collector yards. The odds of detection of H5 in
live bird markets and collector yards were similar; however, these were
3½ to 4 times higher than in backyard birds and nomadic ducks and 25 to
30 times higher than in commercial poultry. This suggests that
transmission of infection in backyard poultry and duck production was
likely to be driven more strongly by the value chain than by direct or
indirect contacts at source. We could not determine whether the value
chain concentrates or amplifies virus along its length, or whether AIV
persists and actively circulates in live bird markets and collector
yards. H5 and H9 viruses were detected year-round and were
co-circulating in the different enterprise types, although no inference
can be drawn regarding interactions between these HPAI and LPAI viruses.