WEDNESDAY, Feb. 6 (HealthDay News) -- The bacteria responsible for whooping cough may be evolving into different strains, and the current vaccine can't offer complete protection against these new strains, researchers report.
In recent years, cases of whooping cough have risen dramatically. Tens of thousands have been sickened, and 18 deaths have been reported, mostly in infants, according to the U.S. Centers for Disease Control and Prevention.
Several recent studies have focused on the potential of waning immunity from the whooping cough vaccine over time. In a letter in the Feb. 7 issue of the New England Journal of Medicine, researchers pointed out that there may be another culprit: an evolution in the bug itself.
The vaccine contains a number of components that help give the body immunity against the whooping cough bacteria (Bordetella pertussis). One of these components is called pertactin.
Strains of the whooping cough bacteria that are pertactin-negative have been found in Japan, France, Finland and, now, the United States, the researchers reported in the letter. That means that at least one component of the current vaccine is ineffective against these newly found strains.
"There are several theories as to why we're seeing more pertussis," said Dr. Kenneth Bromberg, chairman of pediatrics and director of the Vaccine Research Center at the Brooklyn Hospital Center, in New York City. "One theory is better diagnosis. A second [theory] is that the vaccines are not as good in terms of longevity as the whole-cell vaccine was. The third theory is that there have been genetic changes in the strains of pertussis, such that it makes new strains immune or relatively immune to the current vaccines."
"The thought is that the bacteria have gotten smart and are eliminating the pertactin in themselves," said Bromberg, who was not involved in the cur
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