Participants will have an initial visit with a full physical evaluation, and blood and urine tests (including leukapheresis to provide sufficient numbers of blood cells for testing). Within 1 month of the first visit, participants will have a single infusion of either reslizumab or a placebo. The infusion visit is estimated to last approximately 5 hours. Three to 7 days after the infusion, participants will begin a 21-day course of DEC (taken by mouth) to treat the infection. Participants will stay overnight at the Clinical Center during the first 3 days of treatment with DEC to be monitored for side effects, and will continue to take the DEC at home after the inpatient treatment. A study coordinator will call participants each day to ask about any symptoms or side effects. Participants will be seen for an additional eight outpatient follow-up visits (at days 7, 14, and 28, and months 3, 6, 12, 18, and 24) for evaluation of signs and symptoms of infection.