a1 Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province, Papua New Guinea
Rates of acquisition and mean duration of nasal carriage of different serotypes of Streptococcus pneumoniae have been estimated by fitting a stochastic model to longitudinal carriage data in children from Papua New Guinea. Immunogenicity and two indices of relative invasiveness were determined for each serotype. Immunogenic serotypes were less frequently acquired and were carried for shorter periods, but no relationship between immunogenicity and invasiveness was apparent using either index of invasiveness. Frequent invasion was associated with a high acquisition rate and high frequency and prolonged duration of carriage. Carriage studies can provide a broad indication of which serotypes cause invasive disease but not the proportion of disease due to individual serotypes; some serotypes which cause invasive disease (e.g. serotype 46) are not found even in extensive carriage studies. The antibiotic resistance of carriage organisms, however, does approximate the resistance patterns of invasive organisms and thus may be used to monitor changing patterns of antimicrobial susceptibility in the community.
(Accepted December 08 1992)
c1 Corresponding author.
p1 Present address. Department of Public Health and Epidemiology, Swiss Tropical Institute, Socinstrasse 57, CH-4002 Basel, Switzerland.
p2 Present address. Mater Hospital, Stanley St, South Brisbane, Queensland 4101, Australia.
p3 Present address. Queensland Institute of Medical Research, Herston Road, Brisbane, Queensland 4029, Australia.
p4 Present address. Tropical Health Program, University of Queensland, Faculty of Medicine, Herston Road, Herston, Queensland 4006, Australia.