Abstract
In November 2011, a cluster of initially five cases of hepatitis A infection with closely related strains was identified in the Netherlands. England reported possibly related cases. Strains with identical sequences had been involved in previous outbreaks linked to semi-dried tomatoes. Investigation of the Dutch cluster suggested a link with ready-to-eat salads including those containing semi-dried tomatoes. Despite trace-back, a source was not identified. Vigilance is needed, and rapid sharing of data may help source-tracing.
Highlights
In November 2011, a cluster of initially five cases of hepatitis A infection with closely related strains was identified in the Netherlands
Viral RNA is extracted from IgM positive sera, and the 460 nt VP1/2A region is sequenced and compared to sequences recorded in the Dutch [8] and an international hepatitis A virus (HAV) sequence database of the Food-Borne Viruses in Europe (FBVE) network [9]
Confirmed cases were defined as laboratory-confirmed HAV cases who had no travel history to endemic countries, no male-to-male sexual contacts and was considered as exposed to an unknown source in the Netherlands, who had a date of symptom onset from July to November 2011 and who was infected with the specific genotype IB strain identical to strains that caused previous outbreaks in Europe and Australia in 2009–10 [1,2,3,4,5], i.e. Hu/Netherlands/RIVM-006/2010, closely related to Genbank accession number FJ687511, or Hu/Netherlands/RIVM-077/2010, closely related to strain FR-2010-LOUR
Summary
Another possible food-borne outbreak of hepatitis A in the Netherlands indicated by two closely related molecular sequences, July to October 2011. Citation style for this article: Fournet N, Baas D, van Pelt W, Swaan C, Ober HJ, Isken L, Cremer J, Friesema I, Vennema H, Boxman I, Koopmans M, Verhoef L In November 2011, a cluster of five cases of hepatitis A was identified through voluntary molecular surveillance in the Netherlands It involved two highly similar strains of hepatitis A virus (HAV) genotype IB that were closely related to strains found in travellers from a specific region in the Middle East. We aim to alert other countries to be aware that this hepatitis strain and the contaminated product may be circulating, and to initiate source tracing if they detect the strain
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