6,631 cases of whooping cough have been reported up to 9th November 2010 in California, breaking the previous record of 6,613 in 1950 for the whole year. With another seven weeks until this year ends, it is doubtful that the 1947 figure of 9,394 will be surpassed. The current whooping cough rate across the state is 16.9 per 100,000 people. Of the 200 new reported cases over the last seven days, 63% are confirmed, 19% probable and 19% suspect.
Experts say that the incidence of whooping cough has been steadily rising over the last 25 years, mainly because of a falling number of people, children and babies getting their routine vaccinations. Unfortunately, ten people have died from whooping cough so far this year, all of them babies.
9 of the ten fatalities had not been vaccinated at all, and the other one was a 28-week premature baby who received his first DTaP dose at the age of two months, just 15 days before developing symptoms - too early for immunization to properly kick in. Nine of the babies who died were Hispanic. 90% of the fatalities were aged 2 months or less when disease symptoms started.
Health authorities in California say that most infections among babies have affected those aged 3 months or less.
Among those for which hospitalization data is available, 11% had to be admitted to hospital, 58% of all hospitalized patients were aged 3 months or less, 75% were aged no more than six months. A significant proportion of them were Hispanic.
The immunization branch of the California Department of Public Health (CDPH) also issued the following updated information:
1.7% of all infected infants aged 3 months or less died
Whooping cough incidence among babies aged 6 months or less stands at 335.9 per 100,000
Incidence among children aged 6 months to 6 years is 40.9 per 100,000
For children aged 7 to 9 years incidence is 49.8 per 100,000
For children and teenagers aged 10 to 18 years 36.7 per 100,000, most of whom were not older than 11
The Hispanic rate (all ages) was 17.5 per 100,000, Caucasians 14.5 per 100,000
The Hispanic rate for babies aged 6 months or less was 414.9 per 100,000
Infants who are not immunized, or whose immunizations are incomplete are especially vulnerable to infections and complications, such as pneumonia and seizures.
In the 1920s and 1930s, before vaccinations against whooping cough existed, there were approximately 250,000 cases in the USA each year, and about 9,000 deaths. In the 1940s the DTP (pertussis, diphtheria and tetanus) vaccine was introduced. By 1976 whooping cough incidence had dropped by more than 99%.
This downward trend in whooping cough rates in the USA turned in the 1980s, and epidemics have started coming back over the last three decades. According to the CDC, 25,616 cases were reported in 2005. A pertussis epidemic was declared in California earlier this year.
Source: California Department of Public Health
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