Seasonal trends in acute toxoplasmosis in pregnancy in Upper Austria
Abstract number: P1877
Sagel U., Mikolajczyk R.
Objectives: Acute toxoplasmosis in pregnant women bears a risk of infection for the unborn that might result in moderate to severe ocular and neurological disorders. Secondary prevention using general screening during pregnancy and antimicrobial treatment is cumbersome, still disputed and carried out only in few European countries like Austria. Pregnant women should be advised to avoid risk factors for infection, especially eating of undercooked meat. The role of other important risk factors is less well understood. We seek to verify a recent observation from Slovenia suggesting a significant increase in the incidence of acute toxoplasmosis in pregnant women in winter.
Methods: We investigated retrospectively records for the largest statutory health insurance company in Upper Austria (OÖGKK) about toxoplasmosis screening of pregnant women participating in the mother-child-pass preventive programme. We used a general additive model with locally weighted regression to visualise the trend in weekly incidence of toxoplasmosis over time and for the estimation of the seasonal trend during a year. Since the overall number of investigations did not change over the studied period, we used Poisson distribution to model the incidence of toxoplasmosis cases. Acute toxoplasmosis has been regarded as certain in case of significant titre rise in indirect immunofluorescence test and positive IgM, and uncertain if diagnosis has been solely made by positive IgM and low IgG-avidity.
Results: From 01.01.2000 to 31.01.2005 there were 191 uncertain and 51 certain acute infections. There was a clear variability across time in uncertain infections, with a higher incidence during the winter months (Figure 1a). This was confirmed in the seasonal trend analysis, with a more than 2 times higher incidence during the winter months (Figure 1b). The results were similar when the analysis was restricted only to certain cases. In seroconversions during pregnancy (n = 45), the mean duration between the last seronegative and first seropositive examination was 102 days (range: 30181 days).
Conclusion: We confirmed the trend observed in Slovenia using an independent sample from Upper Austria. Given the long times between examinations it can be expected that the observed peak in positive diagnoses in winter may actually reflect an increased incidence of infection in autumn. Further research should focus on risk factors that may explain the observed seasonal trends.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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