Human metapneumovirus (hMPV), a newly discovered paramyxovirus, has been associated with acute respiratory tract infections (ARIs) ranging from upper ARIs to severe bronchiolitis and pneumonia. Important questions remain on the contribution of hMPV to ARIs and its impact on public health. During the 2001-2002 season, we conducted a collaborative study with four provincial public health laboratories to study the prevalence of this new virus in the Canadian population. A total of 445 specimens were collected from patients of all age groups with ARIs and were tested for the presence of hMPV by reverse transcription-PCR. Of these, 66 (14.8%) tested positive for hMPV. Positive specimens were found in all age groups and in all four provinces studied. Virus activity peaked in February and March. The age range of the patients with hMPV infection was 2 months to 93 years (median age, 25 years), with similar numbers of females (35%) and males (41%). Thirty-three percent (n ‫؍‬ 22) of hMPV-infected patients were hospitalized; of these, 27% (n ‫؍‬ 6) had rhinitis and pneumonia, 23% (n ‫؍‬ 5) had bronchiolitis, and 9% (n ‫؍‬ 2) had bronchitis. The hospitalization rates were significantly higher among patients <5 years of age (P ‫؍‬ 0.0005) and those >50 years of age (P ‫؍‬ 0.0044) than among those 6 to 50 years of age. Phylogenetic analysis of the F gene showed that two hMPV genetic clusters were cocirculating in the 2001-2002 season, and comparison with earlier studies suggests a temporal evolutionary pattern of hMPV isolates. These results provide further evidence of the importance of hMPV in ARIs, particularly in young children and elderly individuals.

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An outbreak of gastroenteritis affected 19 of 34 geriatric patients and four of 23 staff assigned to the ward in a period of 3 1/2 weeks in January 1980. Fourteen of the 19 patients with gastroenteritis (17 were tested properly) and four of the ten asymptomatic patients (five asymptomatic patients were not tested) showed evidence of rotavirus infection by virus positivity and/or a significant antibody response to rotavirus. One of the four staff members with gastroenteritis showed serologic evidence (three were tested) of rotavirus infection. Nine of the 18 asymptomatic staff members (two remaining staff members were not tested) showed a fourfold rise in antibody to rotavirus but four had antibody titers of 1:32 or more. The patients had diarrhea for a mean of 2.6 days. Most of them had five or fewer diarrheal stools in one day. Six patients had a severe illness and two died. Thirteen of 15 symptomatic patients who had serum samples, collected during the acute and convalescent phases, tested manifested high titers (greater than or equal to 1:32) of complement-fixing antibody to rotavirus antigen.

The relatedness of enteroviral isolates associated with two recent outbreaks in Canada was assessed using direct sequencing of amplicons derived from a large portion of the 5' nontranslated region (NTR) of the viral genome. The amplicons of 60 echovirus 30 isolates originating from seven different provinces in 1991 were found to share 99% or greater sequence identity. Recent coxsackievirus B1 isolates characterised in the same manner were identical to each other. When the 5' NTR sequence of these isolates was compared to prototype strains a difference of 11-15% in nucleotide composition was observed. These results indicate that the variability of nucleotide sequence found in 5' NTRs can be utilized to identify rapidly enteroviral strains associated with particular outbreaks and distinguish them from other strains and serotypes.

We describe two children who had central nervous system complications, encephalitis and meningoencephalitis, temporally associated with Mycoplasma pneumoniae. M pneumoniae was identified as the cause of the illnesses on the basis of at least a fourfold increase in complement fixation antibody titers. Despite extensive viral and bacterial investigation, no evidence of any other pathogen was found. Two strategies were used to determine whether M pneumoniae was directly invasive: (1) by examining cerebrospinal fluid using a M pneumoniae-specific DNA probe and (2) by determining whether complement-fixating antibody to M pneumoniae was produced locally through comparison of the cerebrospinal fluid/serum ratio of M pneumoniae antibody to the cerebrospinal fluid/serum ratio of immunoglobulin M. Both assessments were negative. M pneumoniae did not appear to directly invade the central nervous system in these two patients. We conclude that the direct invasion of the cerebrospinal fluid is not necessary in the pathogenesis of M pneumoniae-induced neurologic disease.

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Renal allograft rejection episodes are frequent in children and often lead to allograft failure. Frequent association of fever with rejection in our transplant program provoked a prospective evaluation of concurrent infection during rejection episodes. Because cytomegalovirus has an established role in rejection and allograft survival, evaluation of cytomegalovirus and other herpes viruses (human simplex virus type 1, varicella, Epstein-Barr virus, and human herpes virus type 6 [HHV-6]) was undertaken in addition to standard bacterial investigation. A total of 37 patients were followed over a 30-month period. Six of eight rejection episodes were associated with herpes viruses (HHV-6, n = 6, and Epstein-Barr virus, n = 1). Three of the herpes-group-associated rejection episodes were treated with antiviral therapy in addition to pulse steroid treatment, with full recovery. The three patients with HHV-6-associated rejection episodes who were treated with pulse steroids, but no antiviral therapy, developed chronic allograft rejection. The recipient's response to allograft antigens may be influenced by concomitant herpes infection, and specific antiviral therapy appears to be indicated when infection is confirmed in association with rejection. An antiviral treatment program coupled with modulation of standard antirejection immunotherapy has the potential to improve morbidity and mortality in the pediatric renal transplant population.