Environmental factors contributing to the spread of H5N1 avian influenza in mainland China

• Published in: PloS one Vol. 3; no. 5; p. e2268
• Main Authors: Fang, Li-Qun, de Vlas, Sake J, Liang, Song, Looman, Caspar W N, Gong, Peng, Xu, Bing, Yan, Lei, Yang, Hong, Richardus, Jan Hendrik, Cao, Wu-Chun
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 28-05-2008; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Annual precipitation; Anxiety; Avian flu; Avian influenza; Avian influenza viruses; Bird migration; Birds; Case-Control Studies; Chickens; China - epidemiology; Disease Outbreaks; Disease transmission; Ecological risk assessment; Environmental effects; Environmental engineering; Environmental factors; Epidemics; Epidemiology; Farms; Geographic information systems; Handbooks; Health risks; Infection; Infections; Infectious diseases; Influenza; Influenza A Virus, H5N1 Subtype - isolation & purification; Influenza in Birds - epidemiology; Influenza in Birds - virology; Laboratories; Migratory birds; Outbreaks; Pandemics; Pathogens; Physiology; Poultry; Precipitation; Public health; Public Health and Epidemiology; Public Health and Epidemiology/Environmental Health; Public Health and Epidemiology/Epidemiology; Public Health and Epidemiology/Global Health; Public Health and Epidemiology/Infectious Diseases; Public Health and Epidemiology/Preventive Medicine; Regression analysis; Risk; Sanitation; Satellite navigation systems; Science; Viruses; Wetlands; Zoonoses; China; Beijing China; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0002268

Since late 2003, highly pathogenic avian influenza (HPAI) outbreaks caused by infection with H5N1 virus has led to the deaths of millions of poultry and more than 10 thousands of wild birds, and as of 18-March 2008, at least 373 laboratory-confirmed human infections with 236 fatalities, have occurred. The unrestrained worldwide spread of this disease has caused great anxiety about the potential of another global pandemic. However, the effect of environmental factors influencing the spread of HPAI H5N1 virus is unclear.
A database including incident dates and locations was developed for 128 confirmed HPAI H5N1 outbreaks in poultry and wild birds, as well as 21 human cases in mainland China during 2004-2006. These data, together with information on wild bird migration, poultry densities, and environmental variables (water bodies, wetlands, transportation routes, main cities, precipitation and elevation), were integrated into a Geographical Information System (GIS). A case-control design was used to identify the environmental factors associated with the incidence of the disease. Multivariate logistic regression analysis indicated that minimal distance to the nearest national highway, annual precipitation and the interaction between minimal distance to the nearest lake and wetland, were important predictive environmental variables for the risk of HPAI. A risk map was constructed based on these factors.
Our study indicates that environmental factors contribute to the spread of the disease. The risk map can be used to target countermeasures to stop further spread of the HPAI H5N1 at its source.