Estimating the sensitivity of passive surveillance for HPAI H5N1 in Bayelsa state, Nigeria

Geographical and Historical Patterns in the Emergences of Novel Highly Pathogenic Avian Influenza (HPAI) H5 and H7 Viruses in Poultry

Over the years, the emergence of novel H5 and H7 highly pathogenic avian influenza viruses (HPAI) has been taking place through two main mechanisms: first, the conversion of a low pathogenic into a highly pathogenic virus, and second, the reassortment between different genetic segments of low and highly pathogenic viruses already in circulation. We investigated and summarized the literature on emerging HPAI H5 and H7 viruses with the aim of building a spatio-temporal database of all these recorded conversions and reassortments events. We subsequently mapped the spatio-temporal distribution of known emergence events, as well as the species and production systems that they were associated with, the aim being to establish their main characteristics. From 1959 onwards, we identified a total of 39 independent H7 and H5 LPAI to HPAI conversion events. All but two of these events were reported in commercial poultry production systems, and a majority of these events took place in high-income countries. In contrast, a total of 127 reassortments have been reported from 1983 to 2015, which predominantly took place in countries with poultry production systems transitioning from backyard to intensive production systems. Those systems are characterized by several co-circulating viruses, multiple host species, regular contact points in live bird markets, limited biosecurity within value chains, and frequent vaccination campaigns that impose selection pressures for emergence of novel reassortants. We conclude that novel HPAI emergences by these two mechanisms occur in different ecological niches, with different viral, environmental and host associated factors, which has implications in early detection and management and mitigation of the risk of emergence of novel HPAI viruses.

Chinese farmers' willingness to accept compensation to practice safe disposal of HPAI infected chicken

Highly Pathogenic Avian Influenza (HPAI) is a high morbidity and mortality zoonotic disease, which threatens poultry and human health. An outbreak of disease in China requires strict slaughter and disposal of all chickens within a three-kilometer radius, incurring large private costs for farmers and encouraging black market transactions. A stated preference survey of 331 farmers across six provinces in China was conducted in 2015, in order to measure the responsiveness of farmers to accept various compensation prices for safely disposing of HPAI infected chicken. Findings suggest that about 25% and 40% of farmers in South and North China respectively would not adopt safe disposal at the current compensation price (10 yuan/bird) offered by the government. However, 80% of farmers would adopt safe disposal if the compensation price increased to 14.1 yuan in South China and 18.9 yuan in North China. The adoption of safe disposal by farmers was positively and significantly influenced by compensation price (p=0.000) and regular contact with epidemic prevention staff (p=0.094). However, adoption was negatively and significantly influenced by net farm income (p=0.100) and chicken production income percentage (p=0.014). Although half of (51%) of farmers were willing to receive zero compensation, a reasonable compensation scheme along with strengthened supervision, may be considered the most effective strategy to encourage safe disposal of HPAI infected chicken and reduce the risks associated with black market transactions.