Study on the establishment of the early diagnosis of Pertussis and the efficacy of vaccination

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(1) Isolation of bacteria and establishment of the early diagnosis.As an early diagnostic method of pertussis isolation of the bacteria was performed. It has been reported that the positivity of the isolated was low. However, in our current study, the isolation rate was high as 51.8%. Furthermore, 34.2% of our isolated cases were cases who had been treated with antibiotics before the isolation. This shows that isolation of the bacteria is an useful method on the early diagnosis of pertussis. And it is necessary to attempt the isolation on cases suspective of pertussis disregard the medication of antibiotics or not. On the other hand, if case who had been failed in the isolation, evaluation on a method to detect the IgM antibodies serologically as an early diagnosis has been performed, and a system of detection of the PT (pertussis toxin) IgM antibody has been established.(2) Investigation on familial infection and adult pertussisFamilial investigation to isolated cases were performed. … More As a result, bacteria were also isolated from siblings and parents who had been vaccinated. All these cases showed no typical clinical manifestation of pertussis, but only showing long term chronic coughing without serious attacks. And some mothers even did not show any coughing. Laboratory data also showed no obvious leukocytosis or relative lymphocytosis (mean white blood cell count 7040, %lymphocyte 36%). Source of infection to infants was estimated to be siblings and parents. Therefore, investigation on the familial infective status is an effective way to evaluate the efficacy of DTP vaccine, as the number of pertussis cases are decreasing in the recent years. Although the number of subject is small, the efficacy of DTP vaccine was 82%.(3) Evaluation of the efficacy of vaccineThe persistence of antibody level is studied as a method on the evaluations of the efficacy of the vaccine. A comparative study between children vaccinated with the acellular pertussis vaccine (DTaP) improved in 1981 in Japan and children vaccinated with the whole cell pertussis vaccine (DTwP) was performed. As a result, children vaccinated with the DTaP showed higher levels of diphtheria, tetanus antibody and FHA (filmentous hemagglutinin) antibody than those vaccinated with DTwP.It might also be influenced by epidemics of pertussis in the past, the persistence of antibody was better in the DTaP vaccinees. Less