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Probability of vertical transmission of Chlamydia trachomatis estimated from national registry data
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Vertical Tabs

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  • Published on:
    This study did not measure vertical transmission of Chlamydia trachomatis

    The authors estimated vertical transmission of Chlamydia trachomatis by a retrospective analysis using national registry data and clinical records and concluded that transmission was much lower (<2%) than the rate commonly quoted (50-70%). Their suggested explanation is that the modern use of highly sensitive NAATs detects nonviable chlamydiae so that mothers testing positive could actually be noninfectious whereas older studies based on use of culture only identified infectious pregnant women. That is not a likely explanation for such a big difference. When NAAT performance with cervical swabs was evaluated about 2/3 of NAAT positive specimens were culture positive.
    A more likely explanation comes from examining their case definition. It is not chlamydial infection, but rather laboratory confirmed cases of chlamydial conjunctivitis or pneumonia. And that is very different. When prospective studies were being done in San Francisco 175 infants born to chlamydia infected mothers were followed: 31 (18%) developed pneumonia; 29 (17%) conjunctivitis; 64 (37%) were culture positive and 105 (60%) had serologic evidence of infection. Thus there were many more infections than cases of conjunctivitis and pneumonia. But the difference between cases of disease and infection in the Finnish material is probably greater. In the prospective study there were cases of very mild disease that would likely not have been diagnosed in ordinary circumstances (seeing the whole clinical s...

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    Conflict of Interest:
    None declared.