A Note on the Concept of the Incubation Period in HIV Infection
本文讨论了HIV感染中潜伏期概念的特殊性，指出其比水痘等常见疾病更模糊，并建议根据具体情境灵活定义潜伏期终点。
Classically in epidemiological thinking a 'susceptible' individual acquires infection after interaction with an 'infected'. There may be a latent period between infection and the development of infectivity. The development of overt symptoms marks the end of the incubation period, after which the fact that a person is infected is obvious. Because of this, and perhaps because these symptoms may represent the body's effective immune response to the invading organism, there may be justification in equating the end of the infectious period with the end of the incubation period; for many common diseases, infectivity is greatest before symptoms develop. Certainly the transmission of the disease from infected to susceptible can be altered by quarantine easily after the incubation period but with more difficulty during the incubation period. Infection with HIV is characterised by some features which make the concept of 'incubation period' rather more nebulous than for other diseases such as chickenpox. Some weeks or months following infection there is a flu-like illness characterised by a transient rash, fever and myalgia (Cooper et al., 1985). These symptoms may last several weeks. During or after this period antibodies to HIV proteins appear in the blood, i.e. seroconversion occurs. Over a period of years some aspects of immune function deteriorate; an association between AIDS and tuberculosis has been reported in Florida (Centers for Disease Control, 1986a); infection with the related organism, mycobacterium avium intracellulare becomes common (Whyte, personal communication) as does active infection with cytomegalovirus. These diseases do occur in the HIV-free population although not so commonly as in those compromised by HIV infection. After a period of years, much less common diseases such as pneumocystis or Kaposi's sarcoma occur. These are so uncommon as to lead the physician to seek some underlying predisposing disease and AIDS is diagnosed. In such a continuum, where should the end of the 'incubation period' be defined? The answer is that we should define it in whatever way is convenient, but that if each of several definitions is convenient under different circumstances then we should not confuse them.