Calif. Reports Largest Whooping Cough Outbreak in 70 Years

Nearly 10,000 cases of pertussis, or whooping cough, have been reported in California this year -- the largest outbreak in the state in about 70 years, according to a CDC report, MedPage Today's "The Gupta Guide" reports.

The data were reported in the Dec. 5 issue of CDC's Morbidity and Mortality Weekly Report.

Details of Outbreak

As of Nov. 26, 9,935 cases of whooping cough had been reported in California, or about 26 cases per 100,000 individuals (Smith, "The Gupta Guide," MedPage Today, 12/4).

The data show that the rate was highest among infants (Plevin, "KPCC News," KPCC, 12/4).

Specifically, the incidence among infants younger than one year old was 174.6 cases per 100,000. Rates were highest among Hispanic infants, at 207 cases per 100,000 ("The Gupta Guide," MedPage Today, 12/4).

The report noted that the high incidence among infants likely occurred because they are too young to receive the pertussis vaccination (HealthDay/U.S. News & World Report, 12/4). Despite an Advisory Committee on Immunization Practices recommendation that pregnant women receive the pertussis booster shot in their third trimester, the report found that just 17% of mothers of infants who later were infected had received it ("The Gupta Guide," MedPage Today, 12/4).

Infants also were more susceptible to complications and more likely to be hospitalized as the result of whooping cough, according to HealthDay/U.S. News & World Report. For example, of the 347 hospitalizations across California related to whooping cough, 275 of the cases involved an infant under one year old (HealthDay/U.S. News & World Report, 12/4).

Meanwhile, the report found a spike in the rate of infection among teenagers, with more than 2,000 cases reported among adolescents ages 14 to 16 (Morbidity and Mortality Weekly Report, 12/5).

The report noted that the majority of infected adolescents had been vaccinated, which suggests "that their illness was the result of waning immunity" ("The Gupta Guide," MedPage Today, 12/4). The researchers noted that the adolescent population might require booster shots with a more effective version of the vaccine (HealthDay/U.S. News & World Report, 12/4).

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