Monday, April 30, 2012

Jonathan Reisman, Pneumococcal colonization in Alaska Native people

PGY-2 Med-peds resident at MGH

I received a Centers of Excellence travel grant to conduct a research project under the auspices of the CDC-Arctic Investigations Program (AIP) in Anchorage, AK. I studied the socioeconomic and demographic risk factors for nasopharyngeal colonization with Streptococcus pneumoniae in Alaska Native people of all ages. Historically, Alaska Native children have had some of the highest rates of several vaccine-preventable infections - including H. flu, pertussis, measles, and hepatitis B. Interestingly, in the early part of the 20th century, the Iditarod mushing race trail was used to get diphtheria anti-toxin to Nome because of an outbreak there among native children. The prevalence of many of these infections has been dramatically reduced by vaccination.

Currently, the AIP is conducting ongoing surveillance of Strep pneumoniae, as Alaska Native children have some of the highest rates in the world, and a vaccine was recently introduced. Each spring, the AIP visits eight villages in Western Alaska along the cachement basin of the Bering Sea. Interviews are conducted with families and nasopharyngeal swabs are taken. Swabs are cultured for pneumococcus, and serotypes and antibiotic sensitivities are determined. PCV-7 was introduced into this population in 2000, and surveillance studies showed that it reduced invasive disease rates. "Replacement disease" with non-vaccine serotypes was seen throughout the country, however, it was much more pronounced among Alaska Natives than in non-native populations. This suggests that colonization remains an important source of transmission of these infecting serotypes. In terms of colonization, prevalence of nasopharyngeal carriage did not change after PCV7, but rather non-vaccine serotypes simply replaced vaccine serotypes. PCV13 was introduced in 2008 and studies now are ongoing concerning infections and colonizations.

My project was to look at the last 4 years of colonization data, and to determine whether colonization is significantly impacted by risk factors such as age, gender, region of Alaska, access to in-home running water, household crowding, number of people in the house, recent antibiotic use, and recent infections. This data had not been analyzed in this way to date. I helped swab children in the Yup'ik villages of Koliganek and Manokotak.

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