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358pertussis using the LAMP method is still unprece-dented, and this is the first report. The serum antibody titer was investigated in a previous report on whooping cough outbreak3), however, we surveyed the outbreak using LAMP. There are several types of Nucleic acid Amplifica-tion Test (NATs) available. The sensitivity of the LAMP method is comparable to that of the real-time PCR method, and the time to judgment of the test result is shorter than that of PCR. The analyt-ical sensitivity of LAMP was 83% and was equal to that of the IS481 real-time PCR4).Although clinical specimen of LAMP was incu-bated for 60 minutes, PCR results can be available in 2-24 hours4, 5). Since the ptxp region of the Borde︲tella pertussis gene is amplified, specificity is also higher than that of the PCR method, which tests the insertion sequence IS481. Positivity of LAMP for pertussis was persistent in one subject in the present study, but infectivity was unclear and preferable to be investigated. While LAMP is useful in diagnosing the presence of Bordetella pertussis, it also detects dead bacteria. Thus, it is difficult to distinguish whether a positive case is an active infection. Long-term detection of Bordetella pertussis has been reported using the NATs tests6). It was difficult to judge whether the detected Bordetella pertussis was infectious.Macrolide antibiotics were re-administered to the subjects who were LAMP-positive on the 3rd screening test. For treatment against Bordetella pertussis, generally, re-administration is not performed because the bacterium cannot be detected on culture test after administration of a proper antimicrobial agent for 5 days. However, relapse of whooping cough after proper macrolide antibiotic administration has been reported7), and persistent culture positivity due to failure of eradi-cation of the bacteria has also been reported depending on the type of macrolide antibiotics8). Prevention of nosocomial infection spread by active preventive macrolide administration to Bordetella pertussis-exposed persons with no disease develop-ment has also been reported9). A significant booster effect was acquired by administration of 0.2 mL of DTap vaccine to young adults10) and additional administration of DTap vaccine to adults was included in the indication in 2017.There are few opportunities to directly contact patients in hospital clerical departments, but pertussis infection may then be spread through health care workers, to which attention should be paid. The pertussis infection may spread before it is noted in the working place. It is difficult to diag-nose whooping cough based on the cough symptom alone. Tdap vaccine is administered to prevent the outbreak of whooping cough in adults in western countries. In Japan, periodic administration of DTap vaccine instead of Tdap vaccine is desired. Niizuma T wrote the first draft of the article with contribution from Obinata K and Shimizu T. Kinoshita K negotiated with the ethical commit-tees. All authors edited and approval the final version of the article. The authors declare no conflicts of interest asso-ciated with this manuscript.This study won the highest award in the 61st Annual conference of the Japanese Association for Infectious Diseases, Eastern regional conference.We thank Hiromi Ikari and Ikumi Uragami for nasal sampling from affected individuals. 1） Deville JG, Cherry JD, Christenson PD et al: Frequency of unrecognized Bordetella pertussis infections in adults. Clin Infect Dis, 1995; 21: 639-642. 2） Miyashita N, Kawai Y, Yamaguchi T, Ouchi K, Kurose K, Oka M: Outbreak of pertussis in a university labo-ratory. Intern Med, 2011; 50: 879-885. 3） Kamano H, Mori T, Maeta H et al: Analysis of Borde︲tella pertussis agglutinin titers during an outbreak of Pertussis at a university in Japan. Jpn J Infect Dis, 2010; 63: 108-112. 4） Kamachi K, Toyoizumi-Ajisaka H, Toda K et al: Devel-opment and evaluation of a loop-mediated isothermal amplification method for rapid diagnosis of Bordetella pertussis infection. J Clin Microbiol. 2006; 44: 1899-1902. 5） Wendelboe AM and Van Rie A: Diagnosis of pertussis: a historical review and recent developments. Expert Rev Mol Diag, 2006: 6: 857-64. 6） Bidet P, Liguori S, De Lauzanne A et al: Real-time PCR measurement of persistence of Bordetella pertussis DNA in nasopharyngeal secretions during antibiotic treatment of young children with pertussis. J Clin Microbiol, 2008; 46: 3636-3638. 7） Steinberg JM, Srugo I: Reoccurrence of culture-posi-tive pertussis in an infant initially treated with azithro-mycin and steroids. Arch Pediatr Adolesc Med, 2002; ContributionConflict of interestAcknowledgementsReference