508 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 11, No. 3, March 2005 person-years) is substantially higher than the findings of Nennig and others (10) among an urban population in San Francisco (176 cases per 100,000 person-years). This finding may be due to the difference in immunization practices between Israel and the United States (5 doses of DTP vaccine in the United States with...