Largest measles epidemic in North America in a decade--Quebec, Canada, 2011: contribution of susceptibility, serendipity, and superspreading events.

BACKGROUND: The largest measles epidemic in North America in the last decade, occurred in 2011 in Quebec, Canada, where rates of 1- and 2-dose vaccine coverage among children 3 years of age were 95%-97% and 90%, respectively, with 3%-5% unvaccinated. METHODS: Case patients identified through passive surveillance and outbreak investigation were contacted to determine clinical course, vaccination status, and possible source of infection. RESULTS: There were 21 measles importations and 725 cases. A superspreading event triggered by 1 importation resulted in sustained transmission and 678 cases. The overall incidence was 9.1 per 100,000; the highest incidence was in adolescents 12-17 years old (75.6 per 100,000), who comprised 56% of case patients. Among adolescents, 22% had received 2 vaccine doses. Outbreak investigation showed this proportion to have been an underestimate; active case finding identified 130% more cases among 2-dose recipients. Two-dose recipients had milder illness and a significantly lower risk of hospitalization than those who were unvaccinated or single-dose recipients. CONCLUSIONS: A chance superspreading event revealed an overall level of immunity barely above the elimination threshold when unexpected vulnerability in 2-dose recipients was taken into account. Unvaccinated individuals remain the immunization priority, but a better understanding of susceptibility in 2-dose recipients is needed to define effective interventions if elimination is to be achieved.

Management of patients with primary central nervous system lymphoma treated with high-dose methotrexate.

Primary central nervous system lymphoma (PCNSL) is a rare, extranodal form of non-Hodgkin lymphoma that most commonly presents with neurologic changes. Comprehensive workup to diagnose PCNSL and rule out nodal non-Hodgkin lymphoma is critical to the development of an appropriate plan for therapy. Past PCNSL treatments have included whole-brain radiation or steroids, but high-dose methotrexate (MTX) has emerged as initial therapy. Although high-dose MTX is well tolerated, special considerations must be taken to administer the drug safely. Specific interventions include aggressive IV hydration with sodium bicarbonate fluids, monitoring blood chemistries, and the administration of leucovorin rescue. Nurses should evaluate and monitor patients closely during treatment to ensure safety and decrease drug toxicity.