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Estimating the incidence of subclinical infections with Legionella Pneumonia using data augmentation: analysis of an outbreak in The Netherlands
Author(s) -
Nagelkerke Nico J. D.,
Boshuizen Hendriek C.,
de Melker Hester E.,
Schellekens Joop F. P.,
Peeters Marcel F.,
Spaendonck Marina Conynvan
Publication year - 2003
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.1670
Subject(s) - subclinical infection , outbreak , legionella , incidence (geometry) , epidemiology , pneumonia , cluster (spacecraft) , legionnaires' disease , medicine , population , immunology , biology , virology , environmental health , legionella pneumophila , bacteria , genetics , physics , computer science , optics , programming language
Infections with Legionella bacteria can cause a potentially lethal form of pneumonia known as legionnaires' disease. In 1999 a major outbreak, causing 31 deaths, occurred among visitors and exhibitors of a consumer fair in The Netherlands. The epidemiology of subclinical infections is largely unknown, as there is no reliable method to diagnose such infections. To explore the incidence of subclinical infections, IgG and IgM antibody levels among exhibitors were compared to those among a representative sample of the Dutch population. As exhibitors were assumed to comprise both infected and uninfected individuals, their antibody levels were modelled as a mixture distribution. As infected individuals are expected to cluster around a point source, the spatial aspect of the spread of infections was taken into account. To estimate the distribution of antibody levels among infected individuals and to impute infection status among exhibitors, data augmentation was used. Subclinical infection appeared to be very common and its frequency declined with the distance from the putative source of the outbreak. Copyright © 2003 John Wiley & Sons, Ltd.