1) 百日咳

Pertussis

百日咳は，年少児が罹患した場合は合併症や生命予後が特に憂慮される疾患であり，乳児早期からのDPTワクチン接種により予防を心がけることが何よりも大切である．また，近年は年長児や成人の患者増加が国内外で問題となっている．彼らの症状は軽症や非定型的な場合も多く，正確な診断がなされずに放置され，周囲への感染源となることもしばしばである．百日咳菌は家族内や接触者間での感染力が強く，社会や集団で菌が伝播すれば，最も被害を受けるのは年少児である．より多角的な観点からの，ワクチンを用いた百日咳制御策を本邦でも検討する必要がある．

Pertussis brings a lot of morbidity and mortality, especially to infants and neonates.　Vaccination at appropriate early months of age should be encouraged for prevention.　Recently, increase of pertussis patients among elder children and adults has also been reported through the world.　Their clinical manifestations are often mild or atypical, so that they are left without proper diagnosis of pertussis.　In those cases, they become the source of spread of infection.　Bordetella pertussis is easily transmitted among close contacts such as household members, which often leads to a big disease burden for younger children.　Diversified vaccination strategies have to be discussed in Japan.