Infectious Diseases News Brief - January 22, 2010

[Current Issue -Table of contents]

Profile of serogroup Y meningococcal infections in Canada: Implications for vaccine selection

Canada is a leader in establishing routine infant immunization programs against meningococcal C disease. Currently, all provinces have routine programs to provide meningococcal C conjugate vaccines to infants and children. The result of the existing programs has been a decrease in serogroup C incidence. The second most common vaccinepreventable serogroup in Canada is serogroup Y, the incidence of which has been stable. The availability of a quadrivalent conjugate vaccine against serogroups A, C, Y and W135 focuses attention on serogroup Y disease as it becomes relatively more prominent as a cause of vaccine-preventable invasive meningococcal disease. This vaccine was licensed in November 2006 but is not routinely used except in Nunavut, New Brunswick and Prince Edward Island. To allow a better understanding of the 'value added' by a serogroup Y-containing vaccine, it is necessary to have a contemporary profile of Y disease in Canada. In the present paper, recent surveillance data on invasive meningococcal disease across Canada are summarized.

Source: The Canadian Journal of Infectious Diseases and Medical Microbiology
Winter 2009, volume 20 Issue 4:  130-134
http://www.pulsus.com/journals/abstract.jsp?sCurrPg=abstract&jnlKy=3&atlKy=9226&isuKy=891&isArt=t&fromfold=Current%20Issue

Laboratory diagnosis of mumps in a partially immunized population: The Nova Scotia experience

Background: In 2007, Atlantic Canada experienced a large outbreak of mumps predominately in university students who had received a single dose of measles, mumps and rubella vaccine. The present study describes the performance characteristics of reverse transcriptase polymerase chain reaction (RT-PCR) on buccal and urine specimens and immunoglobulin M (IgM) serology in this partially immune population.

Methods: Patients presenting with symptoms suspicious for mumps had a serum, urine and a buccal swab collected for diagnostic testing. Persons were classified as a 'confirmed' case according to the Public Health Agency of Canada's definition. Sera were tested using an enzyme-linked immunoassay. Detection of mumps virus in buccal swabs and urine samples was performed by RT-PCR.

Results: A subset of 155 cases and 376 non-cases that had all three specimens submitted was used for calculating the performance characteristics. The sensitivity of RT-PCR on buccal swabs, urine specimens and IgM serology were 79%, 43% and 25%, respectively. The specificity of RT-PCR on buccal swabs, urine specimens and IgM serology was 99.5%, 100% and 99.7%, respectively. Only 12 of 134 (9%) patients had positive urine specimens in the presence of negative oral swabs.

Conclusion: RT-PCR on buccal swabs is the ideal specimen for diagnosis. Testing an additional urine sample in an outbreak setting did not increase the diagnostic yield significantly, but doubled testing volume and cost. In addition, the data suggest that, in this partially immune group, IgM serology has little value in the diagnosis of acute infection.

Source: The Canadian Journal of Infectious Diseases and Medical Microbiology
Winter 2009, volume 20 Issue 4: 157-162
http://www.pulsus.com/journals/abstract.jsp?sCurrPg=abstract&jnlKy=3&atlKy=9221&isuKy=891&isArt=t&fromfold=Current%20Issue

Epidemiology of Hepatitis B Virus Infection in a US Cohort of HIV-Infected Individuals during the Past 20 Years

Background. The epidemiologic trends of hepatitis B virus (HBV) infection in human immunodeficiency virus (HIV)–infected patients over the past 20 years are largely unknown.

Methods. Prevalence and risk factors for HBV infection overall, at the time of HIV infection, and after HIV infection were examined in an ongoing observational HIV cohort study. Risk factors for HBV infection at the time of diagnosis of HIV infection were evaluated using logistic regression, and risk of incident HBV infection after diagnosis of HIV infection was evaluated using Cox proportional hazards models.

Results. Of the 2769 evaluable participants, 1078 (39%) had HBV infection, of whom 117 (11%) had chronic HBV infection. The yearly cross-sectional prevalence of HBV infection decreased from a peak of 49% in 1995 to 36% in 2008. The prevalence of HBV infection at the time of diagnosis of HIV infection decreased during 1989–2008 from 34% to 9% . The incidence of HBV infection after diagnosis of HIV infection decreased from 4.0 cases per 100 person-years during the pre–highly active antiretroviral therapy (HAART) era to 1.1 cases per 100 person-years during the HAART era; however, this incidence remained unchanged during 2000–2008, with >20% of HBV infections occurring after HIV infection being chronic. Decreased risk of HBV infection after diagnosis of HIV infection was associated with higher CD4 cell count and the use of HBV-active HAART. Receipt of 1 dose of HBV vaccine was not associated with reduced risk of HBV infection after diagnosis of HIV infection.

Conclusions. Although the burden of HBV infection overall is slowly decreasing among HIV-infected individuals, the persistent rate of HBV infection after diagnosis of HIV infection raises concern that more-effective prevention strategies may be needed to significantly reduce the prevalence of HBV infection in this patient population.

Source: Clinical Infectious Diseases 2010;50:426-436
http://www.journals.uchicago.edu/doi/abs/10.1086/649885