Infectious Diseases News Brief - December 24, 2009

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HIV-Infected Infants Respond Poorly To Childhood Vaccination

It is known that HIV-infected children who do not receive appropriate antiretroviral drugs experience immune depression, and may become susceptible to infectious diseases that would otherwise be prevented by childhood immunization. It is therefore important to find out to what extent HIV-infected children are able to generate adequate levels of antibodies following routine childhood immunizations. A new article describes the results of a cross-sectional study carried out amongst 18-36 month-old children born to HIV-infected mothers and living in Central Africa. The study suggested that immuno-suppressed HIV-infected children have a low persistence of antibodies to the vaccines of the Expanded Program on Immunization. The study was conducted in Cameroon and the Central African Republic by pediatricians, epidemiologists, bacteriologists and virologists, and coordinated by the Institut Pasteur. The researchers found that antibody levels to measles vaccine was particularly low amongst children who were HIV infected, and that antibody levels to vaccine amongst HIV-uninfected children born to HIV-infected mothers were lower than expected. This latter finding raises the possibility that HIV exposure during pregnancy might influence the response to EPI vaccines in the first weeks of life. These results suggest that children living with HIV may need an adapted EPI vaccine schedule.

Source: Science Daily December 7, 2009
http://www.sciencedaily.com/releases/2007/12/071205095404.htm

Improved Virological Outcomes in British Columbia Concomitant with Decreasing Incidence of HIV Type 1 Drug Resistance Detection

Background. There have been limited studies evaluating temporal changes in the incidence of detection of drug resistance among human immunodeficiency virus type 1 (HIV-1) isolates and concomitant changes in plasma HIV load for treated individuals in a population-wide setting.

Methods. Longitudinal plasma viral load and genotypic resistance data were obtained from patients receiving antiretroviral therapy from the British Columbia Drug Treatment Program from July 1996 through December 2008. A total of 24,652 resistance tests were available from 5422 individuals. The incidence of successful plasma viral load suppression and of resistance to each of 3 antiretroviral categories (nucleoside/nucleotide reverse-transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors) was calculated for the population receiving therapy.

Results. There has been a drastic decrease in the incidence of new cases of HIV-1 drug resistance in individuals followed during 1996–2008. In 1997, the incidence rate of any newly detected resistance was 1.73 cases per 100 person-months of therapy, and by 2008, the incidence rate had decreased >12-fold, to 0.13 cases per 100 person-months of therapy. This decrease in the incidence of resistance has occurred at an exponential rate, with half-times on the order of 2–3 years. Concomitantly, the proportion of individuals with plasma viral load suppression has increased linearly over time (from 64.7% with HIV RNA levels <50 copies/mL in 2000 to 87.0% in 2008.

Conclusions. The researchers results suggest an increasing effectiveness of highly active antiretroviral therapy at the populational level. The vast majority of treated patients in British Columbia now have either suppressed plasma viral load or drug-susceptible HIV-1, according to their most recent test results.

Source: Clinical Infectious Diseases 1 December 2009
http://www.journals.uchicago.edu/doi/abs/10.1086/648729

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