Abstract Introduction
In 2018 in France, reports of (N=14) aggregated cases in 3 different areas of isolated transverse limb reduction defects, a rare congenital anomaly (1.7 for 10,000 total births) generated a large mediatic interest with environmental factors overtly pointed out. Resemblance with the Corby cluster was suggested. Our aim is to describe the investigations carried out and to share the challenges we met. Methods: Investigations included case ascertainment, epidemiological analyses, and search for a common exposure. Standardized Incidence Ratios were computed.. Parents filled a questionnaire addressing environmental and occupational exposures. Environmental databases were consulted as well as animal health surveillance data.
Results
The excess of cases was ascertained in two aggregates in two towns in the western part of France, comprising respectively 3 children born in 2007-2008 (SIR: 87.8 CI95%:[17-256]) and 4 children born in 2011-2013 (79.8 [21.5-204.2]). The third signal included 7 cases born between 2009 and 2014 residing in 7 towns located above the Alps and did not yield a significant excess when related to expected cases in the administrative subdivision (0.94 [0.38-1.95]). A concurrent analysis by the local registry found a significant excess, generating a lengthy debate. None of the investigations identified a common cause or notable exposure. Delayed feedback and negative conclusions led to incomprehension among families.
Conclusions
Informing stakeholders timely is crucial.Communicating effectively about methods used and negative results can be challenging. Cluster investigations involve a scientific and a societal component that must be considered when organizing the public health response. External funding details