The management of smallholder duck flocks in Central Java, Indonesia, and potential hazards promoting the spread of Highly Pathogenic Avian Influenza virus

Ducks are considered to play an important role in the transmission and maintenance of the Highly Pathogenic Avian Influenza (HPAI) virus. However, there is limited information on duck management practices in countries where HPAI is endemic. A cross-sectional questionnaire survey was conducted on 96 'stationary' smallholder duck farms in Indonesia to describe the management of ducks and to identify practices that could potentially promote the risk of HPAI spread. The mean flock size was 29 ducks, ranging from 1 up to 150 birds. Both the sale and the consumption of eggs were the most important purposes of duck keeping, followed by the use of droppings for fertilizer and the production of meat ducks. About 77% of duck owners allowed their ducks to scavenge. Important hazards for interspecies HPAI virus transmission related to scavenging were identified: 1) intermingling between ducks and chickens on duck farms (48%); 2) frequent contact with neighbours' chickens (44%); 3) visits to the same paddies by duck flocks from other farms (88%); 4) in the paddies, contact between duck flock and other ducks, chickens, people and wild birds as reported by 88%, 30%, 80% and 77% of duck owners respectively; 5) the keeping of singing birds by 17% of farmers; 6) predators such as the small Asian mongoose (Herpestes javanicus) (25%) and feral cats (20%) visiting the duck farms (these species are susceptible to HPAI infection and might play a role in the spread of the HPAI virus). Many duck owners associated deaths of their birds with the use of pesticides in the rice paddies, and appeared to be more concerned about pesticide toxicity, problems that inhibit scavenging ability and external parasites than about HPAI, which in general was not considered to be of high importance. Hence HPAI vaccination or preventive culling of ducks during disease outbreaks was not conducted on the study farms.