25- To 30-Nm Virus Particle Associated With a Hospital Outbreak of Acute Gastroenteritis With Evidence for Airborne Transmission

Abstract

Between November 1 and 22, 1985, an outbreak of acute, nonbacterial gastroenteritis occurred in a 600-bed hospital in Toronto, Ontario, Canada. Illness in 635 of 2,379 (27%) staff was characterized by fatigue, nausea, diarrhea, and vomiting and had a median duration of 24-48 hours. The finding of virus-like particles measuring 25-30 nm in six stool specimens and low rates of seroresponse to Norwalk virus (3/39) and Snow Mountain agent (1/6) suggest that a Norwalk-like virus was responsible for the outbreak. The outbreak was of abrupt onset and high incidence, affecting 79 people in a single day. No common food or water exposure could be identified. The attack rate was greatest (69%) for staff who had worked in the Emergency Room. Of 100 patients and their companions who visited the Emergency Room on November 11-12 for unrelated problems, 33 (33%) developed gastroenteritis 24-48 hours after their visit, versus 0 of 18 who visited the Emergency Room on November 8 (p less than 0.001). An analysis of housekeepers who worked at least once during the period from November 9-13, which included those who became ill during the period of November 9-14, showed that the risk of becoming ill was four times greater for those who visited or walked through the Emergency Room than for those who did not (p = 0.028). These data are consistent with the possibility of the airborne spread of a virus.

Outbreaks of food-borne and waterborne viral gastroenteritis

“…Transmission by aerosol has been demonstrated in outbreaks on cruise ships and in schools and was the likely cause of a common-source outbreak in a hospital (9,59,101).…”

“…However, the occurrence of illness in persons who handle or serve both food and ice may make it difficult to distinguish between the possible roles of contaminated raw food items, food handler contamination, or contaminated water sources as etiologic factors. Complicating these assessments is the additional potential for transmission of viral gastroenteritis from an infected serving person or party member by the respiratory or airborne route (96,101).…”

Norovirus gastroenteritis causes severe and lethal complications after chemotherapy and hematopoietic stem cell transplantation

“…8,9 Attack rates exceeding 50% have been reported during NV-GE outbreaks, resulting in ward closures and major disruption of hospital services. 10,11 Symptoms of NV-GE typically appear with abrupt onset and are mostly limited to 1-2 days in healthy patients, but surveillance data indicate that the duration of symptoms is prolonged in hospitalized patients. 6,12 In addition, a growing number of reports suggest that NV-GE could result in severe and, occasionally, life-threatening complications in immunocompromised patients associated with prolonged viral shedding.…”

Evidence for airborne transmission of Norwalk-like virus (NLV) in a hotel restaurant

“…Index patients who had vomited in their cabins were more likely to have had cabin mates who subsequently became ill than were index patients who had not vomited. An outbreak of acute gastroenteritis in a hospital in Toronto associated with NLVs has been reported with evidence for airborne transmission [11]. However, studies so far have not excluded hand/mouth transmission from environmental contamination [12].…”