Whooping cough: the current scene.

Pertussis, a highly contagious disease caused by Bordetella pertussis, is making a comeback globally despite good immunization coverage. The developed countries have also shown a shift in the epidemiology of the disease to the adolescent and the adult age group, leading to a revision of their vaccination policies. The disease epidemiology in the South East Asian region seems poised for a similar change. Outbreaks have been reported among children and adults in countries such as Afghanistan, Israel, and Taipei. The anticipation and early recognition of this change in the epidemiology is important because the affected adolescents and adults act as reservoirs of the disease to the vulnerable population of infants, for whom the disease can be life threatening. The clinical presentation can be atypical in the adolescent age group, and the disease is often misdiagnosed. With the availability of polymerase chain reaction and serology, the disease can be diagnosed even later in the course of the disease when culture results are often negative. The whole-cell pertussis vaccine dramatically reduced the incidence of the disease but fell into disrepute due to the rare serious neurologic side effects that led to the introduction of the acellular pertussis vaccine, which led to fewer adverse reactions and also proved to be safe and effective in the adolescent age group when used as a booster. However, the cost of the acellular vaccine is may be prohibitive for widespread use in the developing nations of the South East Asian region.