Analysis of Bordetella pertussis agglutinin titers during an outbreak of pertussis at a university in Japan.

In 2007, a large outbreak of pertussis occurred at a university in Japan. Initially, a student, suffering from nocturnal cough and post-tussive vomiting for 3 weeks was diagnosed with pertussis. During the subsequent outbreak, 361 university students and staff members presented with a primary complaint of a cough. In the present study, we analyzed bacterial agglutinin titers against two Bordetella pertussis strains, Yamaguchi (epidemic strain) and Tohama (vaccine strain), in 310 patients with a cough and evaluated its diagnostic accuracy for adolescent and adult pertussis. These serological analyses showed a significant difference (P<0.001) in the levels of Yamaguchi agglutinin titer, but not in those of Tohama agglutinin titer, between patient and healthy adult groups. Therefore, the bacterial agglutination assay against strain Yamaguchi may be a useful tool for diagnosis of adolescent and adult pertussis, especially in young adults, when an agglutinin titer cutoff value of >or=160x is used in combination with clinical symptoms and other clinical laboratory tests.