OBJECTIVEBased on analyzing the characteristics of a case with human avian influenza and the effects of field epidemiological study.

METHODSAn emergency-response-system was started up to follow the probable human Highly Pathogenic Avian Influenza case initially detected by the "Undefined Pneumonia Surveillance System of Shenzhen". Public health professionals administered several epidemiologic investigations and giving all the contacts of the patient with a 7-day-long medical observation for temporally related influenza-like illness. Reverse transcriptase-polymerase chain reaction (RT-PCR) with primers for H5 and N1 was applied to test respiratory tract samples and/or throat swabs of the patient and all his contacts specific for the hemagglutinin gene of influenza A H5N1. Activities and strategies such as media response,notification in the public, communications with multiple related sectors, social participation and information exchange with Hong Kong were involved in field control and management.

RESULTSThe patient was a male, 31 years old,with an occupation as a truck driver in a factory,and had been residing in Shenzhen for 7 years. Started with an influenza-like syndrome, the patient received treatment on the 4th day of the onset, from a clinic and on the 6th day from a regular hospital. On the 8th day of the disease course, he was confirmed by Shenzhen Center for Disease Control and Prevention as human avian flu case and was then transferred to Intensive Care Unit (ICU). On the 83rd day of commence, the patients was healed and released from the hospital. The patient had no significant exposure to sick poultry or poultry that died from the illness before the onset of the disease. The patient and five family members lived together, but no family member was affected and no contact showed positive results for H5N1. A small food market with live poultry, which was under formal supervision and before illness the patient once visited, located near his apartment. Totally, 35 swabs from live birds and bird's coops in the market for H5 nucleic acid were tested and all were negative. The influenza H5N1 virus isolated for the case was named as A/Guangdong/02/2006 (H5N1) or GD/2/06. Phylogenetic relationships and molecular characterization analysis revealed that all the segments of the H5N1 virus named GD/2/06 still belonged to avian segments. Investigation process and control measures were released to the general public through the media. Soon after the laboratory confirmation, information was released to the society, as well as Hong Kong Center for Health Protection. Local Departments of Agriculture, Industries & Business, and Entry-Exit Inspection & Quarantine Bureau together with the Public Health Department put up combined actions. A computer-based telephone survey was initiated to investigate attitudes and knowledge of residents in town, revealing that positive atmosphere dominated and no panic existed.

CONCLUSIONRapid laboratory diagnosis of the virus was the key for successful treatment and survival result of the case. Still, the pathogen was from birds resources. No human-to-human transmission was observed, however, source of infection was unclear. Field epidemiological study could offer special methods for the responses of emergency public health problems.