title: Diphtheria outbreak in Thailand, 2012; seroprevalence of diphtheria antibodies among Thai adults and its implications for immunization programs.
abstract: An age distribution shift in diphtheria cases during a 2012 outbreak in northeastern of Thailand suggests adults are increasingly at risk for infection in Thailand. Data regarding immunity against diphtheria among the adult Thai population is limited. We review a 2012 diphtheria outbreak in Thailand and conducted a nationwide seroepidemiological survey to determine the prevalence of diphtheria antibodies among Thai adults in order to inform immunization programs. A total of 41 confirmed cases, 6 probable cases and 101 carriers of diphtheria were reported from northeastern and upper southern Thailand. The diphtheria outbreak in northeastern Thailand occurred among adults aged > or =15 years; sporadic cases occurred among children from upper southern Thailand. We conducted a seroepidemiological survey of 890 Thai adults from 4 age groups (20-29, 30-39, 40-49 and 50-59 years) in 7 different geographical areas of Thailand (Chiang Mai, Ratchaburi, Chon Buri, Nakhon Si Thammarat, Phitsanulok, Khon Kaen and Songkhla). Diptheria toxin antibody levels were measured with a commercially available ELISA test. The seroprotection rate ranged from 83% to 99%, with the highest in eastern Thailand (Chon Buri, 99%) and the lowest in northern Thailand (Chiang Mai, 83%). Diphtheria antibodies declined with increasing age. We recommend one doseof diphtheria-tetanus toxoid (dT) vaccine once after 20 years of age in order to boost the antibody and revaccinations every 10 years to prevent future outbreaks.
authors.forename: Nasamon
authors.initials: N
authors.lastname: Wanlapakorn
authors.forename: Pornsak
authors.initials: P
authors.lastname: Yoocharoen
authors.forename: Piyanit
authors.initials: P
authors.lastname: Tharmaphornpilas
authors.forename: Apiradee
authors.initials: A
authors.lastname: Theamboonlers
authors.forename: Yong
authors.initials: Y
authors.lastname: Poovorawan
mesh_terms: D000328:Adult; D017677:Age Distribution; D004165:Diphtheria / Q000453:epidemiology* / Q000517:prevention & control; D004167:Diphtheria Toxin / Q000276:immunology; D022422:Diphtheria-Tetanus Vaccine / Q000008:administration & dosage; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D017589:Immunization Programs; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016036:Seroepidemiologic Studies; D013785:Thailand / Q000453:epidemiology
chemical_list: D004167:Diphtheria Toxin; D022422:Diphtheria-Tetanus Vaccine