Tam John S
Department of Microbiology, Faculty of Medicine, Chinese University of Hong Kong, NT, Hong Kong Special Administrative Region of China, Shatin, PR China.
Vaccine. 2002 May 15;20 Suppl 2:S77-81. doi: 10.1016/s0264-410x(02)00137-8.
Worldwide pandemics of human influenza virus caused extensive morbidity and mortality around the world had been documented in the 20th century. However, the mechanisms involved in the emergence of novel influenza virus and the epidemiological factors leading to pandemics are unpredictable. Southern China is postulated as the epicentre of influenza epidemics due to its agricultural-based communities and high population density. Pandemic influenza viruses are through to arise from avian viruses through genetic reassortment among influenza viruses. An influenza virus (H5N1) known to infect only birds previously was found to infect human causing disease and death in Hong Knog in 1997 and the outbreak involved 18 patients with six deaths. Prior to the human outbreak, the H5N1 virus was found to cause extensive death in chickens in three farms in Hong Kong. The significance of this outbreak raised worldwide concern on the possibilities that such an influenza virus may become the next influenza pandemic strain. Investigations were initiated to find the source of the virus. In addition the extend of spread in individuals in contact with the index case and infected poultry was studied by H5-specific serology. Results demonstrated that individuals in close contact with the index case or with exposure to poultry were at risk of being infected. Out of the 18 cases of human infection, eleven had severe infection with symptoms of pneumonia and multi-organ failure. All severe cases presented with lower respiratory infection and lymphopenia and six eventually died. Case-fatality ratio was high among patients over 12 years of age (five out of nine). Control measures aimed at reducing exposure of human to potential H5-positive poultry were instituted which included culling of all poultry in Hong Kong, the segregation of water fowls and chicken, and the introduction of import control measures for chickens. Such measures had successfully controlled the outbreak and continuous surveillance of the poultry in Hong Kong of H5N1 infection is maintained to minimize future human exposure.
20世纪已记录到全球范围内人类流感病毒大流行在世界各地造成了广泛的发病和死亡。然而，新型流感病毒出现所涉及的机制以及导致大流行的流行病学因素是不可预测的。由于中国南方以农业为主的社区和高人口密度，它被假定为流感流行的中心。大流行性流感病毒被认为是通过流感病毒之间的基因重配从禽病毒中产生的。一种以前只感染鸟类的流感病毒（H5N1）于1997年在香港被发现感染人类并导致疾病和死亡，此次疫情涉及18名患者，6人死亡。在人类疫情爆发之前，H5N1病毒在香港的三个农场导致鸡大量死亡。这次疫情的重要性引起了全球对这种流感病毒可能成为下一个流感大流行毒株的可能性的关注。于是展开调查以寻找病毒来源。此外，通过H5特异性血清学研究了与首例病例和受感染家禽接触的个体中的传播范围。结果表明，与首例病例密切接触或接触家禽的个体有被感染的风险。在18例人类感染病例中，11例感染严重，出现肺炎和多器官功能衰竭症状。所有重症病例均表现为下呼吸道感染和淋巴细胞减少，6例最终死亡。12岁以上患者的病死率较高（9例中有5例）。采取了旨在减少人类接触潜在H5阳性家禽的控制措施，包括扑杀香港所有家禽、隔离水禽和鸡，以及实施鸡的进口控制措施。这些措施成功控制了疫情，并对香港家禽的H5N1感染持续进行监测，以尽量减少未来人类接触。
