Usefulness of seroconversion rates for comparing infection pressures between countries.
Salmonella is a frequent cause of foodborne illness. However, since most symptomatic cases are not diagnosed, the true infection pressure is unknown. Furthermore, national surveillance systems have different sensitivities that limit inter-country comparisons. We have used recently developed methods for translating measurements of Salmonella antibodies into estimates of seroincidence: the frequency of infections including asymptomatic cases. This methodology was applied to cross-sectional collections of serum samples obtained from the general healthy population in three European countries. Denmark and The Netherlands had the lowest seroincidence (84,169 infections/1000 person-years), whereas Poland had the highest seroincidence (547/1000 person-years). A Bayesian method for obtaining incidence rate ratios was developed; this showed a 6·3 (95% credibility interval 3·3-12·5) higher incidence in Poland than in Denmark which demonstrates that this methodology has a wider applicability for studies of surveillance systems and evaluation of control programmes.
Simonsen
J
J
Division of Epidemiology, Statens Serum Institut, Copenhagen, Denmark. cob@ssi.dk
Teunis
P
P
van Pelt
W
W
van Duynhoven
Y
Y
Krogfelt
K A
KA
Sadkowska-Todys
M
M
Mølbak
K
K
D000907:Antibodies, Bacterial / Q000097:blood*; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D004812:Epidemiologic Methods; D005517:Foodborne Diseases / Q000175:diagnosis* / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D015994:Incidence; D009426:Netherlands / Q000453:epidemiology; D011044:Poland / Q000453:epidemiology; D012480:Salmonella Infections / Q000175:diagnosis* / Q000453:epidemiology*; D016036:Seroepidemiologic Studies
D000907:Antibodies, Bacterial