The Epidemiology of Highly Pathogenic Avian Influenza H5N1 in Poultry From West Timor, Indonesia

Abstract

Highly pathogenic avian influenza (HPAI), caused by subtype H5N1, is a serious viral disease of birds with significant public health concerns due to its zoonotic and pandemic potential. In West Timor (WT), Indonesia the disease resulted in the deaths or slaughter of hundreds of chickens between 2004 and 2006. The study described in this thesis was designed to provide evidence to support the current HPAI (H5N1) disease freedom status of WT. Data were analyzed to describe the historical spatio-temporal distribution of H5N1 in WT, questionnaire surveys conducted to determine husbandry and biosecurity measures adopted by poultry producers and the market network for poultry and poultry products, and a risk analysis performed to identify the risk of entry of HPAI H5N1 into WT so that suitable preventive programs could be developed. The retrospective study found that HPAI H5N1 was present at a high prevalence in sampled birds (50.8%, 95%CI: 45.1, 56.5) in 2004 which subsequently reduced in the following years. The highest prevalence was detected in the Kupang City District. Although seropositive chickens were detected in 2012 and 2013 these originated from farms that vaccinated birds against H5N1 and were likely false positive results. Pharyngeal-cloacal swabs were collected from 300 poultry (292 chickens and 8 Muscovy ducks) from 10 villages and 5 markets between August and October 2013. No positive results were obtained using the Anigen® Rapid H5 AIV antigen test (0%; 95%CI: 0.0-0.8%). A questionnaire was administered to 150 owners of chickens sampled. The results highlighted the adoption of management and husbandry practices, including a lack of biosecurity measures, which had the potential to increase the risk of poultry being exposed to H5N1. The risk analysis study found that the probabilities of importing infected chickens P(Inf1) and importing asymptomatically infected chickens P(Asym) had significant impacts on the likelihood of entry of HPAI H5N1, while the probability of infected chickens infecting local chickens P(Inf2) had the greatest impact on the probability of having an outbreak of HPAI in WT. The social network analysis conducted demonstrated that there were extensive poultry movements within Kota Kupang and from there to other districts, highlighting that Kota Kupang plays an important role as the potential entry-point for disease into WT. The current management, husbandry and biosecurity practices adopted by poultry farmers/households and the extensive movement of poultry means that there is a sizeable risk of disease spread if it were introduced to the region.

It is concluded that there is a need to: develop suitable educational material to: improve small-holder poultry owners‘ knowledge about avian influenza and the adoption of good husbandry and biosecurity measures; encourage disease reporting to the local Department of Agriculture; and to establish farmer groups to disseminate relevant information. 

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