title: The correlation between infectivity and incubation period of measles, estimated from households with two cases.
abstract: The generation time of an infectious disease is the time between infection of a primary case and infection of a secondary case by the primary case. Its distribution plays a key role in understanding the dynamics of infectious diseases in populations, e.g. in estimating the basic reproduction number. Moreover, the generation time and incubation period distributions together characterize the effectiveness of control by isolation and quarantine. In modelling studies, a relation between the two is often not made specific, but a correlation is biologically plausible. However, it is difficult to establish such correlation, because of the unobservable nature of infection events. We have quantified a joint distribution of generation time and incubation period by a novel estimation method for household data with two susceptible individuals, consisting of time intervals between disease onsets of two measles cases. We used two such datasets, and a separate incubation period dataset. Results indicate that the mean incubation period and the generation time of measles are positively correlated, and that both lie in the range of 11-12 days, suggesting that infectiousness of measles cases increases significantly around the time of symptom onset. The correlation between times from infection to secondary transmission and to symptom onset could critically affect the predicted effectiveness of isolation and quarantine.
authors.affiliation: Theoretical Epidemiology, Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, Utrecht, The Netherlands. d.klinkenberg@uu.nl
authors.forename: Don
authors.initials: D
authors.lastname: Klinkenberg
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
mesh_terms: D050936:Basic Reproduction Number; D005192:Family Health; D006801:Humans; D008457:Measles / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D008954:Models, Biological; D011790:Quarantine; D013997:Time Factors