A large increase of Salmonella infections in 2003 in the Netherlands: hot summer or side effect of the avian influenza outbreak?

Van Pelt W, Mevius DJ, Stoelhorst H, Kovats S, Van De Giessen AW, Wannet W, Duynhoven Y.

Centrum voor Infectieziekten Epidemiologie (CIE, Centre for Infectious Diseases Epidemiology), RIVM, The Nertherlands.

In June 2003, the Dutch national Salmonella centre reported a significant excess isolation rate of Salmonella Enteritidis when compared with earlier years in most regional public health laboratories. By the end of 2003, this amounted to an extra 540 laboratory confirmed cases for the whole of the Netherlands, which implies an estimated 7500 extra cases of gastroenteritis caused by S. Enteritidis in the general population, an increase of 50% on previous years. The hot summer could not explain the findings. Strong evidence has been found to suggest that the increase in importation of salmonella contaminated eggs, as a side effect of a concurrent avian influenza outbreak, was the most probable reason for this excess.