Whooping cough (also known as pertussis) is a highly contagious bacterial diseas
ID: 3172801 • Letter: W
Question
Whooping cough (also known as pertussis) is a highly contagious bacterial disease that can be spread by coughing. People with pertussis have severe coughing attacks that can last for months. Infants too young for vaccination are at greatest risk for life-threatening cases of pertussis. By December 2014, 1856 cases of pertussis had been reported in the San Diego County. An additional 216 cases were reported late. There are 503, 096 students in San Diego County. Compute the attack rate of this outbreak: Of the 43, 827 kindergarteners in San Diego County in 2015, there are 97 students currently exempting the pertussis vaccination with PME (permanent medical exemption), and 1518 students with PBE (personal belief exemption). If San Diego County experiences a 2015 pertussis outbreak among 343 kindergarteners, and 287 of the cases are found to have exempted the vaccination: Calculate the attack rate amongst vaccinated kindergarteners: ____ Calculate the attack rate amongst unvaccinated kindergarteners: ____Explanation / Answer
2. (a) Number of students in the San Diego County = 503,096
Number of case reported in december, 2014 = 1856
and new case reported = 216
so for year 2015 whopping cough outbreak
attack rate = number of new cases of disease in population at risk/ number of persons in population at risk
Attack Rate = (216)/ ( 503096 - 1856) = 4.30 * 10-4
b. Attack rate amongst vaccinated kindergarterners
= No. of vaccinated kindergarterners affected / No. of vaccinated kindergarterners
= (343 -287)/ (43827 - 97 -1518) = 56/41925 = 0.00133
c. Attack rate amongst non -vaccinated kindergarterners
= No. of non-vaccinated kindergarterners affected / No. of non-vaccinated kindergarterners
= (287)/ (97 +1518) = 287/1615 = 0.1777
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