Chlamydia pneumoniae as a new source of infectious outbreaks in nursing homes.

OBJECTIVE: To determine the extent and severity of illness and mode of transmission of Chlamydia pneumoniae infection in 3 nursing home outbreaks. DESIGN AND SETTING: Retrospective cohort study in 3 nursing homes in Ontario from September to November 1994. SUBJECTS: A total of 549 residents and 65 staff members. MAIN OUTCOME MEASURES: Morbidity and mortality were determined by a review of disease surveillance forms, residents' charts, and a self-administered questionnaire to staff. Single and paired serum samples for C pneumoniae serological testing and nasopharyngeal swabs for C pneumoniae culture were collected, and direct fluorescent antibody assays were performed to confirm C pneumoniae infection. RESULTS: The attack rates for confirmed and suspected cases combined were 68%, 46%, and 44% among residents in nursing homes A, B, and C, respectively, and 34% among nursing home C staff. A total of 16 cases of pneumonia confirmed by chest x-ray and 6 deaths were identified. The spectrum of illness among nursing home C residents included a new cough in 58 (100%), fever in 37 (64%), sore throat in 14 (24%), and hoarseness in 8 (14%). Staff members at nursing home C were more likely to report hoarseness (P<.001) and sore throat (P<.001). Residents who smoked had onset of illness earlier than nonsmokers (P=.007), which perhaps is related to airborne transmission in a designated smoking room. CONCLUSIONS: Chlamydia pneumoniae caused serious morbidity and mortality among residents and morbidity among staff; C pneumoniae is an important cause of respiratory disease outbreaks in nursing homes, and diagnostic tests must be readily available for early recognition of C pneumoniae infections.

Vibrio cholerae O139 Bengal infections among tourists to Southeast Asia: an intercontinental foodborne outbreak.

To determine the source and extent of an outbreak of Vibrio cholerae O139 Bengal infections among 630 cruise ship passengers to Southeast Asia, a retrospective cohort study was done. Questionnaires were sent to all passengers from the United States, Canada, and the United Kingdom, and serum samples were requested from all passengers reporting diarrhea. A case was defined as diarrheal illness with onset between 8 and 28 February 1994 and a cholera antitoxic antibody titer > or = 800. Six passengers, including 1 with bacteremia, met the case definition. Illness was associated with eating yellow rice at a buffet restaurant in Bangkok on 10 February (relative risk undefined, P = .005). This international outbreak demonstrates foodborne transmission of Vibrio cholerae O139 Bengal, an emerging cause of epidemic cholera in Asia, to tourists from Western countries. Physicians should suspect infection with either V. cholerae O1 or O139 in any patient with severe watery diarrhea after travel to the developing world.

The changing epidemiology of invasive meningococcal disease in Canada, 1985 through 1992. Emergence of a virulent clone of Neisseria meningitidis.

OBJECTIVE: To describe the occurrence of invasive meningococcal disease (IMD) in Canada with respect to demographic variables and characteristics of the isolated strains of Neisseria meningitidis. DESIGN: National surveillance case series. SETTING: Canada, 1985 through 1992. OUTCOME MEASURES: Morbidity and mortality. MAIN RESULTS: The incidence of IMD averaged 1.38 per 100,000 person-years, with considerable regional variation. In 1988, serogroup C organisms became more common, with one strain of the electrophoretic type 37 (ET-37) complex of N meningitidis, termed ET-15, the predominant group C strain identified. With the increase in group C disease, a greater proportion of cases were older than 5 years. By 1991, ET-15 was the most common strain identified in most parts of the country. Electrophoretic type 15 had a case fatality of 17.8% vs 8.1% for all other IMD (P < .001). Among cases 20 years and older the case fatality for ET-15 was 22.4%. CONCLUSIONS: The group C, ET-15 strain of N meningitidis, first identified in Canada, was more virulent than other prevalent strains during this period. Active surveillance, rapid identification, and typing of N meningitidis will assist public health decision making in the control of emerging strains.

An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid.

In Canada in late 1987 there was an outbreak of an acute illness characterized by gastrointestinal symptoms and unusual neurologic abnormalities among persons who had eaten cultivated mussels. Health departments in Canada solicited reports of this newly recognized illness. A case was defined as the occurrence of gastrointestinal symptoms within 24 hours or of neurologic symptoms within 48 hours of the ingestion of mussels. From the more than 250 reports received, 107 patients met the case definition. The most common symptoms were vomiting (in 76 percent of the patients), abdominal cramps (50 percent), diarrhea (42 percent), headache, often described as incapacitating (43 percent), and loss of short-term memory (25 percent). Nineteen patients were hospitalized, of whom 12 required intensive care because of seizures, coma, profuse respiratory secretions, or unstable blood pressure. Male sex and increasing age were associated independently with the risks of hospitalization and memory loss. Three patients died. Mussels associated with this illness were traced to cultivation beds in three river estuaries on the eastern coast of Prince Edward Island. Domoic acid, which can act as an excitatory neurotransmitter, was identified in mussels left uneaten by the patients and in mussels sampled from these estuaries. The source of the domoic acid appears to have been a form of marine vegetation, Nitzschia pungens, also identified in these waters in late 1987. The contaminated mussels from Prince Edward Island were removed from the market, and no new cases have occurred since December 1987. We conclude that the cause of this outbreak of a novel and severe intoxication was the ingestion of mussels contaminated by domoic acid, a potent excitatory neurotransmitter.

An International Outbreak of Salmonella Nima from Imported Chocolate.

Twenty-nine confirmed cases of Salmonella nima enterocolitis in Canada and four cases in the United States were traced to gold-foil wrapped chocolate coins from Belgium. Illness in Canadian cases occurred between September 1985 and October 1986 where the primary case in each of 24 affected families was a child ≤ 14 years of age. A product recall was issued on October 3, 1986 in Canada. Quantitative analysis of four composite samples of suspect chocolate by the most probable number (MPN) technique showed levels of 4.3 to 24.0 S. nima per 100 g product. These levels of contamination and consumption of approximately 25 g of chocolate by primary cases suggest that small numbers of S. nima precipitated clinical symptoms.

Immunity to rubella in prepubertal girls in Prince Edward Island.

A survey of rubella immunity was conducted among prepubertal girls in Prince Edward Island. Of the 431 girls enrolled in grade 4 in a random sample of schools 83% had a school record of having been vaccinated after their first birthday. A screening test of finger-prick samples revealed that 95% of the girls with a written history of vaccination after their first birthday were immune, 79% of those vaccinated before their first birthday or for whom the date of vaccination was uncertain were immune, and 40% of unvaccinated girls were immune. Of the 49 susceptible girls 43 were vaccinated; all but 2 were found to be immune on retesting. The findings support the recommendation of the National Advisory Committee on Immunization to vaccinate all prepubertal girls without a written history of rubella vaccination after their first birthday.

A severe outbreak of Escherichia coli O157:H7--associated hemorrhagic colitis in a nursing home.

In September 1985, an outbreak of Escherichia coli O157:H7 enteritis affected 55 of 169 residents and 18 of 137 staff members at a nursing home. The outbreak was characterized by two phases: a primary wave whose source was probably a contaminated sandwich meal and a secondary wave compatible with person-to-person transmission of infection. Among the elderly residents, the incubation period was 4 to 9 days (mean, 5.7 +/- 1.2). Older age and previous gastrectomy increased the risk of acquiring the infection (P = 0.01 and 0.03, respectively). Antibiotic therapy during exposure was associated with acquiring a secondary infection (P = 0.001). Hemolytic uremic syndrome developed in 12 affected residents (22 percent), 11 of whom died. Overall, 19 (35 percent) of the affected residents died, 17 (31 percent) from causes attributable to their infection. Antibiotic therapy after the onset of symptoms was associated with a higher case fatality rate in the more severe cases, possibly because patients with more severe disease tended to be treated with antibiotics. There were no complications or deaths among the affected members of the staff. Evidence of infection by verotoxin-producing E. coli O157:H7 was detected in 30 of 70 cases on the basis of isolation of this organism or demonstration of free verotoxin in stools. All isolates belonged to the same phage type. The high morbidity and mortality associated with this condition emphasize the need for proper food hygiene, rapid identification of outbreaks of disease, and prompt institution of infection-control techniques among the institutionalized elderly.

Trends in ectopic pregnancy in Canada.

The incidence in Canada of one complication of sexually transmitted disease, ectopic pregnancy, was examined by age group for the years 1971 through 1980 by means of hospital statistics provided by Statistics Canada. The denominator was "reported pregnancies"--the total of live births, stillbirths, legal abortions and ectopic pregnancies in a given year. In 1980, 4123 ectopic pregnancies (9.3/1000 reported pregnancies) were reported, a 63% increase from 1970. The incidence had increased in each age stratum. This trend may be related to increasing rates of gonococcal infection and of hospitalization for pelvic inflammatory disease and lends confirmation to data from other countries that relate the increase in the rate of ectopic pregnancy to rising rates of sexually transmitted disease.