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+-+-+-+-and cough was only noted in one subject. Cough was noted in 1 of the 4 negative subjects. The inde-terminate subject on the first test became LAMP-negative on the second test. A LAMP-neg-ative subject with no cough on the first test devel-oped cough and became LAMP-positive on the second test. The LAMP test-positive subject with cough and chest pain on the first LAMP test became negative.Third screening LAMP test for B. pertussis (n = 6)The third LAMP test was performed after 35 days in the 6 subjects who were positive on the second screening test. No cough was noted in these 6 subjects. Four subjects were positive for the third LAMP screening test and they received a second macrolide antibiotic administration.Fourth screening LAMP test for B. pertussis (n = 4)The fourth LAMP test was performed after 60 days in the 4 subjects who were positive on the third screening test. No cough was noted in any of these 4 subjects and only 1 subject was LAMP-positive.The presence or absence of cough as shown by the results of the pertussis LAMP test are presented in Figure 2. Cough was noted in 5 LAMP-positive and 6 LAMP-negative subjects in the first screening, but cough was noted in only one positive and one negative subjects in the second screening. Cough was not noted in any subject in the third or fourth 14121086420Figure 2　Symptomatic subjects with cough and asymptomatic subjects in each screening step are presented. The interval between the screenings is presented in braces.　+：LAMP positive,　-：LAMP negativescreening.Time to convert to LAMP-negative:Seven subjects were LAMP-positive. Negative conversion was confirmed in 6 of them after 20-115 days (mean: 76 days, median: 85 days). Positivity persisted for more than 115 days in only one case (Case 2) and negative conversion could not be confirmed. For measures taken during this episode, symptomatic subjects wore a mask and continued work. Suspension of work was not applied as a rule. No outbreak of whooping cough occurred in any of the other departments in the hospital throughout the course, showing that the infection did not spread throughout the hospital.The incidence of whooping cough in adults has increased and became problematic because it serves as a source of infection in children. When antibodies acquired in infancy attenuate, whooping cough can develop in adulthood. Outbreaks of whooping cough have been reported in wards as well as among hospital clerical employees and in university laboratories1, 2). Early diagnosis of atyp-ical whooping cough in adult patients is difficult, unlike the diagnosis of cases in wards, being a major problem spreading whooping cough to patients. The active surveillance report of the secondthird35 dayscough(+)cough(-)357first20 daysDiscussionfourth60 days