title: Low incidence of primary infection with toxoplasma among women in Sheffield: a seroconversion study.
abstract: OBJECTIVE
  To determine the incidence of primary toxoplasma infection in women of childbearing age.
  
  
  METHODS
  A retrospective study of seroconversion on stored pairs of sera taken for routine antenatal testing.
  
  
  METHODS
  The antenatal clinics and general practices of Sheffield between July 1989 and October 1992.
  
  
  METHODS
  One thousand six hundred and twenty-one women on whom pairs of sera, separated by more than 500 days, had been received.
  
  
  METHODS
  Rate of primary infection determined by seroconversion as measured by the presence of antibody in the second serum and its absence in the first.
  
  
  RESULTS
  Of 1621 women, 160 (9.9%) were initially seropositive. One seroconversion was detected in 2966 woman years of observation for susceptibles. The projected rate for primary infections was 0.23 (95% CI 0.0059-1.3) per 1000 pregnancies.
  
  
  CONCLUSIONS
  The rate is much lower than for earlier estimates of incidence in the UK but agrees with a more recent estimate from Sheffield and suggests a falling incidence.
authors.affiliation: Sheffield Regional Public Health Laboratory, UK.
authors.forename: P M
authors.initials: PM
authors.lastname: Zadik
authors.forename: G
authors.initials: G
authors.lastname: Kudesia
authors.forename: A D
authors.initials: AD
authors.lastname: Siddons
mesh_terms: D004198:Disease Susceptibility; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000453:epidemiology*; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D014123:Toxoplasmosis / Q000453:epidemiology*