the use of human reagents for immune electron microscopy. Clearly the human antiserum used in their study, although considered by them to contain antibody to Norwalk virus, also contained antibody to astrovirus. This adds to the problems of misidentification, as the technique results in antibody coating of virus partiWilliam G. Green, MD, CM cles, which can mask characteris17 Hawthorne Cres. tic morphologic markers.2 Townsend, Ont. Finally, the detection of SRSV (Norwalk/Norwalk-like) 6 [CMAJ's P is to discourage Ws days after the onset of symptoms from using any abbs. except Sabbs. is unusual for this group of viruses. From our experience in Britain in their As. - Ed.] excretion for more than 2 days from the onset of symptoms is rare; in contrast, astroviruses are excreted for longer periods. Foodbornie It is important that the pregastroenteritis cise etiologic agent in foodborne due to Norwalk virus gastroenteritis be accurately docuin a Winnipeg hotel mented. We recommend that small, round viruses be critically W re are concerned with examined initially without the adx the micrographs sup- dition of antibody to establish posedly demonstrating morphologic characteristics and prototype Norwalk viruses in the thus allow precise identification. article by Dr. Laila Sekla and colleagues (Can Med Assoc J E. Owen Caul, PhD Ashley, FIMLS 1989; 140: 1461-1464). We sug- C.R. Regional Virus Laboratory gest that the illustrations actually Public Health Laboratory show classic astrovirus particles. Bristol, England Such particles have a smooth en- Alan Curry, PhD Laboratory tire edge, a surface star and a Virus Public Health Laboratory particle diameter of 27 nm, which Manchester, England is easily measured because of the smooth entire edge.' By contrast, References the Norwalk group of viruses, which in Britain are specifically 1. Madeley CR: Comparison of the featermed small, round, structured tures of astroviruses and calciviruses seen in samples of feces by electron viruses (SRSV), have a ragged microscopy. J Infect Dis 1979; 139: edge and an amorphous surface 5 12-523 structure, which accounts for the 2. Caul EO, Appleton H: The electron variable diameter estimation of microscopical and physical characteristics of small round human fecal viruses: 32 to 37 nm in the literature. an interim scheme for classification. J Similar problems of identification Med Virol 1982; 9: 257-265 in Britain have led to an interim classification scheme for small, [Dr. Sekla responds.] round viruses in fecal samples.2 This scheme has been used to The diagnosis of Norwalk virus great effect in Britain and avoids infection was made by Dr. Roger misidentification. Glass, of the US Centers for DisA second problem highlighted ease Control (CDC), Atlanta, and by Sekla and colleagues' article is Dr. David Cubitt, of Central Midshould change the P for Ws so that those of us who suffer from IAD, EAD or SAS will not have to S through the pp. of Js to discover what the Ws are talking about. This might increase the C to the Js, but it would surely stave off an RADA (reductio ad absurdum) such as this.

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dlesex Hospital, London, who was visiting CDC at the time. The diagnosis was based on the presence of SRSV in feces examined by electron microscopy and on a change in titre from 1:20 to 1:320 in immune electron microscopy with the use of acute and convalescent serum from a Norwalk volunteer and our fecal material as antigen. In addition, a new biotin avidin assay developed by Cubitt detected Norwalk antigen in both fecal samples. Glass and Cubitt concluded that these results indicated that the outbreak was definitely due to Norwalk virus. Laila Sekla, MB, BCh, DTM&H, DM, PhD Associate director Cadham Provincial Laboratory Winnipeg, Man.

GST on cosmetic procedures will drive patients away, surgeons say Icorrectioni his article (Can Med Assoc J 1990; 142: 55-56), by Patrick Sullivan, stated incorrectly that Dr. Lefter Mantse, of Ottawa, is a plastic surgeon. In fact he is a general surgeon (cosmetic surgery). We apologize for the error. - Ed.

Hypolipemic drug therapy Icorrectioni T n he fifth paragraph of this article (Can Med Assoc J 1989; 141: 1250), by Dr. Meng-Hee Tan, should have begun as follows: "Lovastatin causes myopathy (muscle weakness or myalgia or both, with a markedly elevated creatine kinase level) in 0.5% of patients taking the drug". In addition, Dr. Tan's name should have been hyphenated as shown here. -Ed.

Foodborne gastroenteritis due to Norwalk virus in a Winnipeg hotel.

the use of human reagents for immune electron microscopy. Clearly the human antiserum used in their study, although considered by them to contain anti...
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