Molecular epidemiology of human enteric caliciviruses in The Netherlands.

In The Netherlands, illness due to Norwalk-like viruses (NLVs) of the family Caliciviridae is quite common. NLVs cause >80% of the outbreaks of gastroenteritis reported to municipal public health centers and at least 5% of the cases of gastroenteritis for which a general practitioner is consulted. In addition, up to 18% of community cases of gastroenteritis in the 1998/1999 winter season have been attributed to NLVs. Patterns of disease activity differ remarkably, with "normal years, when outbreaks occur that are caused by different types of NLV, and "epidemic years, when outbreaks appear to be caused by a single strain. This observation suggests selection of antigenic variants with increased virulence or altered modes of transmission. In addition, since caliciviruses related to the NLVs from humans have been detected in stool specimens from calves at 45% of the dairy farms in The Netherlands, the possibility of spillover of epidemic strains from an animal reservoir to humans should be considered.

A Generic Disjunctive/Conjunctive Decomposition Model for n-ary Relations.

This paper discusses a generic decomposition model that represents an arbitrary n-ary relation as a disjunctive or conjunctive combination of a number of n-ary component relations of a prespecified type. An important subclass of order-preserving decompositions is defined and its properties are derived. The generic model is shown to subsume various known models as special cases, including the models of Boolean factor analysis, hierarchical classes analysis, and disjunctive/conjunctive nonmetric factor analysis. Moreover, it also subsumes a broad range of new models as exemplified with a novel model for multidimensional parallelogram analysis and novel three-way extensions of nonmetric factor analysis. Copyright 1999 Academic Press.