Re: WI: 2012 Whooping cough cases (SUMMARY)
SUMMARY OF CASES
From January 1, 2012 through October 14, 2012, 4,912 cases (3,593 confirmed and 1,319 probable) of pertussis with completed investigations have been reported among Wisconsin residents. Thus far, during the first 12 months of the current statewide outbreak (July 1, 2011 through June 30,2012), 4,781 confirmed and probable cases have been reported (incidence = 84.1 cases per 100,000). During the previous 12 months (July 1, 2010 through June 30, 2011) 659 cases were reported (incidence = 11.6 cases per100,000). Note: Additional cases may have occurred during recent weeks that have not been completely investigated or reported to DPH,
The recent reported pertussis activity is the most observed since the large pertussis outbreak during 2004-05. More than 5,600 reported cases occurred during 2004.
Among the 71 Wisconsin counties with cases that have been reported during 2012, the greatest numbers have occurred in Dane, Waukesha, and Milwaukee Counties. Reported incidence of pertussis was greatest in Forest, Oneida, and Columbia Counties.
Median age at cough onset was 12.4 years (range: <1 m onth to 91 years). Approximately half of all cases in each region occurred among children and adolescents aged 5 to 14 years. In the Southern and Northeastern regions, adults aged ≥20 years accounted for 28% and 23%, respectively, of all
reported cases in the region.
Hospitalization of 2% of case patients was reported. The median length of stay was 3 days (range: 1 to 15 days) and the median age of hospitalized case patients was 5 months (range: <1 month to 89 years).
74% of case patients aged 0 to 10 years were up to date for age with pertussis immunizations before cough onset.
79% of case patients aged 11 to 18 years had reportedly received Tdap before cough onset.
Vaccination against pertussis provided significant protection, but only during the years immediately following vaccination. Among Wisconsin children turning 5 years old in 2012, the rate of reported pertussis was approximately 5 times higher among those who had received 0 doses of DTaP compared to those who were fully vaccinated (had received 5 doses of DTaP). Among children who had received 5 doses of DTaP, the incidence of pertussis increased with increasing time since last dose of DTaP. Similarly, among Wisconsin children turning 11 or 12 years old in 2012, those who had not received Tdap were significantly more likely than those who had received Tdap to have a reported case of pertussis. (Source of population immunization information: Wisconsin Immunization Registry.)
262 cases of pertussis were reported among children aged <1 year; 64% were aged <6 months at cough onset, 1 (<1%) died, and 47 (18%) were hospitalized (for a median 3 days).
55% were up to date for age with pertussis immunizations, 19% were too young for immunization, 16% were under-immunized for age, and 10% were age-eligible for another dose but not delayed.
http://www.dhs.wisconsin.gov/immunization/pertussis.htm
