Epidemiology of pertussis and studies on culture positive pertussis cases in Japan

Abstract

The number of pertussis patients has decreased steadily in the late 1960s and was extremely small in early 1970s. During 1973-74 the first national survey on pertussis cases confirmed by culture was conducted, when whole cell pertussis vaccine was used. The study revealed that 33.3% of culture positive cases had 2-4 doses of DT combined with whole cell pertussis vaccine. Acellular pertussis vaccine was introduced in 1981 and for the last several years the number of pertussis patients became low for the second time. During 1988-92 exactly the same study was conducted as the previous one. Among 2501 pertussis cases diagnosed clinically 403 were culture positive. Most of the patients were below 1 year of age. Most of the patients were below 1 year of age. Clinical symptoms of those infants were more serious than those of older children. Only 7 out of 403 (1.8%) had a history of 2-4 doses of DT combined with acellular pertussis vaccine. This proved that the acellular pertussis vaccine is by far more effective than the whole cell pertussis vaccine. Serotypes of 377 Bordetella pertussis were identified and 370/377 (98.1%) were serotype 1-3 group.