Epidemiology and Infection



A prolonged outbreak of Norwalk-like calicivirus (NLV) gastroenteritis in a rehabilitation centre due to environmental contamination


M.  KUUSI  a1 c1, J. P.  NUORTI  a1, L.  MAUNULA  a2, N. N.  TRAN MINH  a1, M.  RATIA  a1, J.  KARLSSON  a3 and C.-H.  VON BONSDORFF  a2 a4
a1 Department of Infectious Disease Epidemiology, National Public Health Institute, Helsinki, Finland
a2 Department of Virology, HUCS Diagnostics, Helsinki, Finland
a3 Environmental Health Unit, Siuntio, Finland
a4 Department of Virology, Haartman Institute, Helsinki University, Finland

Abstract

An outbreak of Norwalk-like calicivirus (NLV) gastroenteritis occurred in a rehabilitation centre in southern Finland between December 1999 and February 2000. An epidemiological investigation was conducted to determine the source and extent of the outbreak. More than 300 guests and staff members became ill during the outbreak. No food or activity in the centre could be linked epidemiologically to illness. NLV genogroup II was detected by RT–PCR in stool samples of symptomatic guests and employees. All strains reacted similarly with the microplate hybridization probe panel and showed the same nucleotide sequence, indicating that they represented the same NLV strain. Food and water samples were negative for NLV, whereas NLV was detected in three environmental specimens. The strains from patients and environment were identical based on microplate hybridization probes, suggesting that environmental contamination may have been important for the spread of calicivirus and the protracted course of the outbreak.

(Accepted March 17 2002)


Correspondence:
c1 Author for correspondence: Dr Markku Kuusi, Department of Infectious Disease Epidemiology, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki, Finland.


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