Part 1: Census and survey
Poultry husbandry and production is a ubiquitous and heterogeneous
activity in Purbalingga District. Small-scale poultry keeping is common
(approximately 60% of households kept small numbers of birds, nearly
half of which contributed towards supplementary household income).
Although 30% of households reported having had sick or dead poultry in
the previous 12-month period, these mortalities were not reported to any
surveillance system. The distribution of backyard poultry density
(highest in higher-populated areas), collector yards (correlated with
backyard poultry density), live bird markets (in urban centres and in
proximity to roads) and commercial farms (somewhat removed from human
population dense areas) was much as would be expected. Nomadic duck
flocks consisted of relatively large flocks which were grazed on rice
paddy fields post-harvest, often on contract basis (consistent with the
description of Henning et al., 2010). Approximately 20 flocks were found
to move from village to village per 2 week period, within Purbalingga
but also to and from neighbouring Districts. Although biosecurity was
not consistently practised, H5N1 vaccination was carried out. However,
the type of vaccination and vaccine schedules could not be ascertained.
Commercial production units mostly consisted of Sector 3 layer and
broiler chickens, with a smaller number of duck farms, and a small
number of Sector 2 and Sector 1 farms. AI vaccination was most commonly
performed in the layer sector, and to intents and purposes not at all in
the backyard sector. Nomadic duck farmers reported using vaccine, but
the type of vaccine and vaccination schedule could not be reliably
recorded.
It was common practice for live birds at collector yards to be taken to
other villages (by buyers) after sale. Traders at LBMs often did not
sell all of their birds (collected from different sources); surplus
birds were taken back to their homes. These traders reported attending
multiple markets to sell their birds. Although the commercial sector was
not entirely closed, there were less opportunities for transmission of
infection than between backyard poultry and ducks. Moreover,
transmission between these smallholder populations was likely to be
driven more strongly by the value chain and by the husbandry system than
by direct or indirect contacts in the source populations. As a
consequence, clinical outbreaks are more likely to manifest as ‘jumps’
between villages or locations than showing a pattern of local spread.