Establishment and application of risk assessment model for avian influenza A (H5N1) virus infection in poultry workers

Objective To establish a risk assessment model for avian influenza A (H5N1) virus infection in poultry workers and to provide a basis for developing risk management strategies for avian influenza.Methods The lists of risk factors for human avian influenza A (H5N1) virus infection were made by literature retrieval;then the factors in the list were scored by 20 experts.Analytical hierarchy process method was used to establish risk assessment model and weights.The risk scores were calculated on the basis of products of weights and actual occurrences resulted from history data or field investigation among poultry workers in Jinhua city of Zhejiang province.Results Through three rounds of risk identification,the consistency of experts' scores was best in the third round consultation.There were a rule and an index layer in the model.The rule layer included highly pathogenic avian influenza H5N1 epidemic situation and other 8 elements (b1 to b9).The index layer included highly pathogenic avian influenza H5N1 epidemic in the local area and other 29 elements (c1 to c30).Each risk matrix had high consistency and satisfaction with the consistency index (CI) and consistency ratio (CR) less than 0.10 in the model.Five kinds of high risk factors were identified for poultry workers by combined weights,including highly pathogenic avian influenza H5N1 epidemic in the local area (c1),cross species barriers(poultry to human)transmission capacity (c26),rate of exposure to sick or dead birds in last week (c20),pathogenicity (c27),and percentage of special exposure subgroup (c29),with the weights of 0.1513,0.1387,0.1193,0.0925,and 0.0672,respectively.The risk scores of human avian influenza A (H5N1) for poultry workers in Jinhua city from 2011 to 2014 were 0.46,0.47,0.35,and 0.31,respectively.The major risk scores found were exposure (b6),protection (b7),characteristics of the new emerging avian influenza virus strain A (H5N1)(b8),characteristics of poultry workers (b9),poultry trade (b3)and poultry farming (b2).Conclusion The risk assessment model established is reliable and applicable.There is a certain risk of avian influenza A(H5N1)infection among poultry workers in Jinhua city and the management for this risk is necessary.