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The term super-spreader refers to a host that infects disproportionally more secondary contacts than others also infected with the same virus or bacteria. Some cases of super-spreading conform to the 20/80 rule,〔Alison P. Galvani, Robert M. May. "Epidemiology: Dimensions of superspreading." ''Nature'' Super-spreading events are shaped by multiple factors including a decline in herd immunity, nosocomial infections, virulence, viral load, misdiagnosis, airflow dynamics, immune suppression, and co-infection with another pathogen.〔Richard A. Stein. Superspreaders in Infectious Disease. ''International Journal of Infectious Diseases'' ==Defining a super-spreading event== Although loose definitions of super-spreading exist, some effort has been made at defining what qualifies as a super-spreading event (SSE) more explicit. Lloyd-Smith et al. (2005) define a protocol to identify a super-spreading event as follows:〔 # estimate the effective reproductive number, ''R'', for the disease and population in question; # construct a Poisson distribution with mean ''R'', representing the expected range of ''Z'' due to stochasticity without individual variation; # define an SSE as any infected person who infects more than ''Z(n) others'', where ''Z(n)'' is the nth percentile of the Poisson(''R'') distribution. This protocol defines a 99th-percentile SSE as a case which causes more infections than would occur in 99% of infectious histories in a homogeneous population.〔 During the 2003 SARS outbreak in Beijing, China, epidemiologists defined a super-spreader as an individual with transmission of SARS to at least eight contacts.〔Z. Shen, F. Ning, W. Zhou, L.He, C. Lin, D. Chin, Z. Zhus, A. Schuchat. Superspreading events, Beijing, 2003. Emerging Infectious Diseases. Vol. 10, No. 2. Feb. 2004.〕 Super-spreaders may or may not show any symptoms of the disease. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Super-spreader」の詳細全文を読む スポンサード リンク
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