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Q&A on whooping cough: Are illegal immigrants fueling the outbreak? State officials say no

September 16, 2010 | 11:57 am

A number of readers have contacted The Times wanting to know more about the whooping cough outbreak and who has been affected by the severe bacterial disease. State officials said this week that the epidemic is now the worst in the state for pertussis in 55 years, killing nine people, all infants younger than 3 months of age.

As The Times continues to cover the outbreak, readers are encouraged to send their questions to ron.lin@latimes.com.

Question: What role have illegal immigrants played in spreading whooping cough in California?

Answer: Ken August, a spokesman for the California Department of Public Health, said state officials do not believe there is any connection between immigration and the whooping cough outbreak.

"We absolutely do not think either legal or illegal immigration has anything to do with the California pertussis epidemic," August said.

Public health officials, he said, have a number of reasons for reaching this conclusion. His response, edited for clarity, continues below:

  • Pertussis did not need to be imported into California. It's always been here.
  • Mexico does a great job vaccinating for pertussis. Until just a few years ago, Mexico was using the whole-cell vaccine,  which is probably more effective than the acellular vaccine that has been used in the U.S. since the 1990s.
  •  There is no pertussis outbreak/epidemic in Mexico.
  •  Immunization rates in Hispanic children are high.
  • All adults, whether they are from the U.S. or Mexico, are likely to be susceptible to pertussis.  A 2008 survey found that about 6% of U.S. adults stated they had received Tdap, a whooping cough inoculation for adolescents and adults that was approved by the U.S. Food and Drug Administration in 2005.  The number is actually likely to be lower since the responses were not verified.
  • Hispanic infants are overrepresented among pertussis cases, but this discrepancy disappears after six months of age when most infants have received three doses of Dtap -- the vaccine for infants -- and are much less vulnerable to pertussis. 
  • Overall rates of pertussis disease are highest in whites.  We think Hispanic infants are overrepresented among young infants because they are more likely to live in larger households, per census data, and have more contacts. More contacts means more opportunities to be exposed to someone with pertussis.

-- Rong-Gong Lin II

Previous Q & A: How many of the eight infants who died were immunized for whooping cough

Demographics: California weekly update for Sept. 14