RESEARCH ARTICLE J.L. Romalde ® I. Torrado ® C. Ribao ® J.L. Barja Global market: shellfish imports as a source of reemerging food-borne hepatitis A virus infections in Spain Received: 10 July 2001 /Accepted: 10 September 2001 / Published online: 27 November 2001 Ó Springer-Verlag and SEM 2001 Abstract A total of 16 mollusk imports from South America to Spain, including clam and scallop species, were analyzed for hepatitis A virus (HAV), due to the great concern about this type of food after an important hepatitis A outbreak in eastern Spain in September 1999. In addition, clams from the stock that had caused the outbreak were also tested. Of the 17 stocks, four were positive for the presence of HAV RNA as demonstrated by RT-PCR and Southern hybridization. Contradictory analyses confirmed the results of the primary tests in all cases. The findings obtained in this work strongly sup- port the role of mollusk imports from endemic areas of HAV as an important vehicle of hepatitis A, and dem- onstrate the imperative need for sanitary control mea- sures to prevent future outbreaks of this disease. Keywords Hepatitis A virus ® Shellfish ® Foodborne infection ® International commerce Introduction Outbreaks of viral enteric diseases, mainly hepatitis A and gastroenteritis, associated with shellfish consump- tion constitute a major health problem worldwide [9]. Current sanitary control methods are based on bacterial indicators [4, 10], however, these may fail to detect viral contamination [12]. Hepatitis A is one of the most serious viral infections linked to shellfish consumption, causing a serious de- bilitating disease and even death. Although hepatitis A is a common endemic infection in developing areas, its prevalence in developed countries has declined due to improved sanitary conditions [1, 6, 7]. A consequence of this decline is that adult human populations are more susceptible to potential food- or water-borne hepatitis A epidemics or to acquiring the infection when traveling to endemic areas [1, 9, 11]. The increase in international trade between endemic and non-endemic areas can also account for the reemergence of hepatitis A infections. In fact, in recent years, countries historically considered to be important seafood consumers, such as Spain and France, have become the main importers of mollusks from diverse developing countries, where these natural resources have become essential for their economies. In September 1999, an important outbreak of hepa- titis A, affecting 188 people, was detected in Valencia (eastern Spain), a non-endemic area for this disease. Further studies [3] demonstrated its association with the consumption of wedge clams (Donax sp.) imported from Peru. Although not required by the regulations con- trolling imports, the Spanish sanitary authorities have since adopted, as a preventive measure, the systematic analysis of imported shellfish samples for the presence of hepatitis A virus (HAV). This work presents further evidence that shellfish imported from countries where hepatitis A is endemic can be a significant source of reemerging infection in developed countries. Materials and methods Samples From November 1999 to May 2001, 16 samples from South American imports of different types of bivalve mollusks, which had been distributed in several cities in Spain, were analyzed for the presence of HAV. Frozen mollusks were shipped under appropriate isothermal conditions. In addition, clams retained from the stock associated with the HAV outbreak in Valencia were also analyzed. Therefore, the study included six stocks of wedge clam (Donax sp.), six of carpet clam (Tapes sp.), and five of scallop (Argopecten sp.), which, taken together, represented an import volume of approxi- mately 300 tons. The stocks were sampled following standard procedures [10]. Int Microbiol (2001) 4: 223–226 DOI 10.1007/s10123-001-0041-0 J.L. Romalde (&) ® I. Torrado ® C. Ribao ® J.L. Barja Departamento de Microbiologı´a y Parasitologı´a. Facultad de Biologı´a, Universidad de Santiago de Compostela. 15782 Santiago de Compostela, Spain E-mail: mpromald@usc.es Tel.: +34-981563100 ext. 13252 Fax: +34-981596904