Identifying Sources and Transmission Routes of Norovirus Outbreaks : Molecular epidemiological methods as the basis for targeted prevention strategies

Abstract

Norwalk virus, the prototype norovirus was first recognized as a cause of gastroenteritis in 1972 by means of electron microscopy (EM) on stool samples. Norwalk virus was identified by visualization of small round virus particles in stool samples from infected students and contacts during an outbreak in Norwalk, Ohio, in 1968. Originally norovirus was characterized based on the shape and structure by electron microscopic analysis. Later, immunological methods were applied however, these methods had serious limitations in accuracy and reproducibility and never provided a reliable scheme for antigenic classification of virus strains. In 1990, the first norovirus genome was sequenced , after which, researchers from the CDC Atlanta provided a systematic overview of the diversity of noroviruses (then named Norwalk-like virus [NLV]) based on sequencing and genetic characterization. The norovirus were classified as a genus of the family Caliciviridae and the official name of norovirus was decided by the International Committee on Taxonomy of Viruses. Norovirus was originally known as the etiological agent of winter vomiting disease, and is now considered to be the most common cause of acute gastroenteritis in both developed and developing countries worldwide.