Today's presentation was by Jennie Lavine from the Center for Infectious Disease Dynamics. It was a fantastically comprehensive talk about the infection dynamics of whooping cough, a disease caused by the bacteria Bordetella pertussis. You can find a summary of her work at the link to her name above, or by looking up these papers:
Lavine, J., Broutin, H., Harvill, E. and Bjornstad, O. In press. Imperfect vaccine-induced immunity and whooping cough transmission to infants. Vaccine.
Roy, S., Lavine, J., Chiaromonte, F., Terwee J., VandeWoude, S., Bjornstad, O. and Poss, M. 2009. Multivariate Statistical Analyses Demonstrate Unique Host Immune Responses to Single and Dual Lentiviral Infection. PLoS One 4(10): e7359 doi:10.1371/journal.pone.0007359.
Lavine, J. S., Poss, M., and Grenfell, B. T. 2008. Directly transmitted viral diseases: modeling the dynamics of transmission. Trends in Microbiology 16:165-172.The messages I took home from her talk were:
1. There have been changes in the distribution of which age groups are significantly infected with whooping cough after the introduction of vaccines - changing from mostly young children (0-5yrs) to teenagers.
2. Although still MUCH LOWER than pre-vaccination levels, there has been a steady increase in the incidence of whooping cough since 1979, likely due, ironically, to lack of continued exposure to the infection.
3. The most infected individuals are still babies 0-6 months and, surprisingly, teenagers, beginning at ~12yrs. Curiously, their infection dynamics are different, with the yearly infection rate peaking for babies during the summer, and for teenagers during the winter - indicating that there is likely little teenage-to-baby transmission. The peak for teenagers is likely due to higher contact during the winter months. The infection of infants is likely to to asymptomatic adults (adults who are infected, but with no outwardly visible symptoms). Note that although the bacteria is still more fatal in infants than teens, the disease can take 4-6months to run its course, making things very unpleasant for the teenagers.
4. The models of infection, even with vaccination still predict sections of outbreak, so the recommendations for boosters are to give booster vaccinations to both teenagers and to adults who will be in contact with children less than six months (parents, caregivers, daycare workers, etc) to cocoon the infants.I've already gotten my booster shot for this, but we need to make sure Scott gets it soon.