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Foodborne infection most likely cause of HAV transmission in Netherlands

Foodborne transmission is one of the most probable sources for contracting hepatitis A virus in the Netherlands, according to recent study results.

Researchers combined routine surveillance with real-time strain sequencing in the Netherlands to determine food’s role as a source of hepatitis A virus (HAV) infection. All included cases were submitted to a municipal health service (MHS) agency between July 1, 2008 and June 30, 2010.

Of 421 cases reported (1.2 cases/100,000 population from 2008 to 2009; 1.3 cases/100,000 from 2009 to 2010), serum samples were obtained for 292 patients, and 253 tested positive for HAV using polymerase chain reaction. In the final analysis, 248 cases (59%) were included, and sequencing was limited to 402-458 nt for 21 strains.

Probable modes of transmission for 268 reported cases before typing was determined by MHS were travel-associated transmission (141), person-to-person (76), male-to-male sexual contact (33) and foodborne (18). Foodborne transmission was suspected in 4% of reported case patients. With typing, however, foodborne transmission increased to 16%.

From the clusters, multiple cases had probable foodborne outbreaks, according to study results. Researchers said four cases were linked to a restaurant, where a cook was infected and continued to work; and in two cases, patients had unique genotype IA strains not previously detected and then both had eaten mussels. Approximately 17 cases in another cluster (during two consecutive outbreaks) were related to semidried tomatoes.

“We advise revision of HAV surveillance so that it provides baseline information to support foodborne illness detection,” the researchers wrote. “Broad sampling, data sharing and centralized interpretation of data should be part of an enhanced surveillance system.”

Disclosure: The researchers report no relevant financial disclosures.