Summer vomiting disease?
MJA 1999; 171: 686
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To the Editor: "Winter vomiting disease" is a term frequently used to
describe the self-limited profuse vomiting and diarrhoea of 1 to 2
days' duration characteristically associated with infection by the
Norwalk-like group of viruses (NLV)1 (Figure 1).
In northern hemisphere countries such as the United Kingdom,2 the Netherlands3 and the United States,4 a peak for NLV-associated illness has often been found in the colder months of the year and a trough in the warmer months. Intriguingly, this seasonality has not been mirrored by a peak in the southern hemisphere winter/spring in temperate Victoria, Australia. The Victorian Infectious Diseases Reference Laboratory (VIDRL) is the public health virology laboratory for Victoria and the site of diagnosis of sporadic and outbreak-associated cases of NLV infection in the State by electron microscopy and polymerase chain reaction. Studies of all NLV incidents (defined as the occurrence of NLV, involving one or more individuals, for which a single source was thought responsible)5 received at VIDRL for 1997-1998 show peaks in December for both years (Figure 2). A modified chi-squared test showed that the number of incidents per quarter (for the combined years 1997-1998) was significantly (P <0.015) higher in the fourth quarter (Oct-Dec) than in the first three quarters (Jan-Sep). This agrees with the trend reported by Wright et al for 1995-1996;5 for 1980-1994, there were insufficient incidents to derive statistically significant results for individual quarters, but incidents were again concentrated in the latter part of the calendar year.5 The reason for this trend is unclear; the records provided do not mention recent overseas travel, so that this trend appears of local origin. It is not known whether the trend will persist over a longer period, but even so this disparate seasonality of NLV in the two hemispheres is worth further exploration. John A Marshall Lilly Yuen Michael G Catton Peter J Wright
©MJA 1999
Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company. Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au>". <URL: http://www.mja.com.au/> ª 1999 Medical Journal of Australia. We appreciate your comments. | |||
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Figure 1: Electron micrograph showing NLV particles. Bar represents 50 nm.
Figure 2: Monthly detection of NLV gastroenteritis incidents in Victoria for the years 1997-1998. | |||
