Qualitative Risk Analysis of the Transmission of Highly Pathogenic Avian Influenza (HPAI) H5N1 through Manure Trade in Côte d'Ivoire

Abstract

The contamination with Highly Pathogenic Avian Influenza (HPAI) H5N1 viruses occurs via the digestive tract following the ingestion of water or food contaminated with droppings of asymptomatic carriers or sick birds. Regarding the local practice of the use of poultry manure as an agricultural fertilizer, this study focuses on the risk of spread of the HPAI through the manure trade pathway in Côte d'Ivoire. For this purpose, epidemiological data and 96 poultry droppings samples were collected from 18 farms. The droppings samples were tested using the real time polymerase chain reaction (RT-PCR). The qualitative risk assessment (QRA) took into account event patterns by integrating all the pathways involved in the spread of HPAI. From the diagnostic test, all the 96 samples tested negative. Further investigations revealed that 74% of the Agnibilékrou farms experienced HPAI outbreaks in the past two years. The main risk factors identified were the movement of people, animals and fomites from one infected area to another. Additionally, the duration of storage of droppings and the distance between stockpiles and farms were potential risk factors. The QRA identified two levels of risk: moderate to high (60%) and low to negligible (40%). The estimated high risk occurs when the dropping is fresh and is low after an optimal period of storage. It is therefore necessary to make storage systematic and mandatory as a measure of treatment before the adoption of other complex measures such as composting and industrial processing.