Vaccination programs against whooping cough may not be fully effective because the bacteria that cause the disease have evolved new strains, a University of New South Wales study has found.
A team of Australian scientists has shown for the first time that two of the most common strains of the Bordetella pertussis bacteria in Australia have undergone significant genetic changes since 1997, according to a report of the study published in the journal Emerging Infectious Diseases.
Those mutations coincided with changes to the type of vaccine used in Australia and with apparent increases in the number of cases of Australians contracting the highly contagious respiratory disease.
Before 1997, a "whole cell" vaccine was used. That was phased out over two years – due to concerns about side-effects – and since 1999 a new "acellular" vaccine has been used.