California's Whooping Cough Epidemic Centered in Rich, White Counties

Pertussis is a disease of the wealthy, according to the data from the California Department of Public Health. Their latest report, with data on the whooping cough epidemic in California through Nov. 9, 2010, contains the case counts and case rates by county. When those data are combined with data from the Census Bureau on the Latino population of California counties and the Department of Agriculture on median county income, a picture begins to emerge about the real demographics of this illness outbreak.

Twenty California counties have reported 100 or more cases of pertussis in 2010. Those counties contain 85 percent of the state's population, and 88 percent of the state's Latino population. They have reported, in total, 5,900 cases of whooping cough out of the state total of 6,631 cases.

Latinos have been the subject of intense speculation because the California Department of Public Health is reporting that the epidemic appears to be affecting Hispanic infants more than other races. CDPH only has hospitalization information on 40 percent of the cases and draws their conclusions on the epidemic's effects from those limited data.

Internet comments have accused illegal immigrants of being the source of the epidemic. Even officials at the Centers for Disease Control have suggested that Hispanic families have unique living conditions that are contributing to the epidemic.

Of the 20 California counties reporting over 100 cases of pertussis, eight have a higher percentage of Latino residents than the state's rate of 32 percent. These counties have about 44 percent of the state's residents, and are 58 percent Latino. These counties have reported 2,686 cases, 41 percent of the state's total. The average median income for these counties, as of 2008, was 25 percent lower than the statewide median income.

The remaining 12 California counties have Latino populations lower than the state average. They hold 41 percent of the state's population but only have a 29 percent Latino population. They have reported 3,214 cases of whooping cough, 49 percent of the state's total. These same 12 counties have an average median income that is 14 percent higher than the state's.

The CDPH weekly report has been showing for several weeks that whites have the highest rate per 100,000 for whooping cough infection in all age groups over 6 months. Hispanics have the highest rate in infants.

Infants do not receive their first vaccination for pertussis until age 2 months. About 600 cases have been reported in infants too young to have been immunized. The second immunization at four months and the third at six months both demonstrate a drop in cases numbers after they have been received.

The California whooping cough epidemic seems to be heaviest in areas that have fewer Latinos than the statewide average, and that have a median income well above the statewide average. It appears that income and race do play a role in the California epidemic, with well-to-do white people being the center of the outbreak.