Australia Battling Whooping Cough Epidemic, Entering a New and Disturbing Phase

Ernie Shannon's picture
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A four-year long whooping cough epidemic in Australia is entering a new and disturbing phase as one strain of the disease evades the vaccine most used to combat it. Researchers warn the new strain has been detected in other countries suggesting it has the potential to spark epidemics elsewhere.

Recent studies at the University of New South Wales show a new strain called the Bordetella pertussis bacterium is proving resistant to the acellular vaccine commonly employed to protect people. The research is highlighted in the current issue of The Journal of Infectious Diseases.

Whooping cough is a respiratory illness that can be fatal if not treated properly. In Australia, the death of infants under six months of age from whooping cough is one in 200 according to health experts in the country. Often, they say, young children acquire the disease from adolescents and adults who pass it to them.

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“The prolonged whooping cough epidemic in Australia that began in 2008 has been predominantly caused by the new genotype of B. pertussis,” said one of the study authors, Professor Ruiting Lan of the School of Biotechnology and Biomolecular Sciences. “The genotype was responsible for 31 percent of cases in the 10 years before the epidemic and that’s now jumped to 84 percent – a nearly three-fold increase, indicating it has gained a selected advantage under the current vaccination regime.”

Routinely, Australian health authorities vaccinate infants at two, four, and six months with additional boosters given at age four and during high school years. However, with the vaccine showing signs of ineffectiveness, Dr. Lan believes more aggressive action is needed.

“The vaccine is still the best way to reduce transmission of the disease and reduce cases, but it appears to be less effective against the new strain and immunity wanes more rapidly. We need to look at changes to the vaccine itself or increase the number of boosters,” he said.
In the United States, the Center for Disease Control released statistics last year showing a marked increase in Bordetella pertussis in 2010 after a big drop off beginning in 2005.

Interestingly, prior to the use of the acellular vaccine, physicians depended on a whole-cell vaccine. Then, in 1997, because of the side-effects, the old vaccine was cast aside and the new vaccine was introduced. However, the whole-cell treatment provided broad protection against many strains of Bordetella pertussis. The acellular vaccine contains only three to five antigens.

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