Seroconversion and seroreversion rate of Helicobacter pylori infection in women attended at hospital for delivery

BACKGROUND AND OBJECTIVE: Helicobacter pylori infections are acquired primarily during childhood. Nevertheless, infections also develop in the adult population and it is not clear how the cumulative effect of these infections occurs throughout life. With the aim to contribute to the current data on the evolution of H. pylori infection in the adult population of Spain, the incidence and prevalence rates in a population of women who went to the hospital for delivery were studied. SUBJECTS AND METHOD: The study considered the sero-conversion and sero-reversion of H. pylori antibodies in 1441 women from Gipuzkoa (Basque Country, Spain), between 15 and 41 years-old (mean 28.5 [3.4]). These women delivered after September 1989 and had a second childbirth 2 to 8 years later. A serum sample was obtained at the time of each childbirth. Results were determined by enzymoimmunoanalysis (Pyloriset(R) EIA-G New, Finland). RESULTS: H pylori antibodies were detected in the first serum specimen of 648 women (45.0% prevalence). Twenty-four out of the 793 women who were initially seronegative underwent a seroconversion in successive years, and an annual infection rate of 0.77% (95% CI 0.49-1.14) was estimated. Twenty-six women, who were initially seropositive, yielded negative result in the second serum specimen, which led to an annual sero-reversion rate of 1.03% (95% CI 0.671.50). CONCLUSIONS: These results suggest that in our environment, infections by H. pylori occur with a, moderate frequency in adults. The fact that the sero-reversion rate is similar to or higher than the sero-conversion one suggests that the prevalence of H. pylori infection in the adult population is currently decreasing.