Summary
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 supplementary
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.