An investigation on diphtheria outbreak in foreign children in construction camp A in Sai Noi District, Nonthaburi Province, Thailand, 22 July–9 August 2015

Abstract

Backgrounds: On 10 July 2015, Bureau of Epidemiology was notified about a first confirmed diphtheria case in Nonthaburi who is 1 year 9 months old, Laotian boy admitted in Samut Prakan Hospital. We conducted an investigation to identify source of the outbreak, magnitude of the problem of diphtheria related to this event, survey diphtheria vaccine coverage in community and recommend prevention and control measures.
Methods: We interview case’s parents for possible source of infection, active case finding among person who lived in construction camp A between 12 June–1 July 2015 and had at least 1 symptom of upper respiratory tract infection (URI) symptom or found white patch on the day of the investigation or every close contact with confirmed case or carrier within 14 days before or 2 days after onset date until recovered and person who contact with their family member or children age under 12 years old. Throat swab were collected for Corynebacterium diphtheriae in eligible person. We survey for vaccine coverage in the area near by the camp and in children and worker who lived in the construction camp.
Results: One confirmed cases and one carrier were found. The index case was confirmed by detected C. diphtheriae with toxigenicity and the second case who had mild symptom (only fever) was confirmed by detect C. diphtheriae without toxigenicity as “Symptomatic carrier”. No epidemiology linkage between these two cases. He and fifty-two close contacts and seventy suspected were treated with antibiotics. Diphtheria-tetanus-pertussis (DTP) vaccination coverage in children less than 5 year who live in area near by the camp was 100%, while vaccine coverage in adult age over 12 years was 38.89%. Diphtheria vaccine coverage among worker in construction camp A after 3-round mop-up vaccination was 84.74%. Poor hygiene, poor sanitation, and high population density, mix nationalities and dynamic of population were observed in this camp.
Conclusions: The source of outbreak was possibly imported from Laos PDR via Index case’s brother. The pattern of dynamic population which composes of mix nationality is a common problem in urban and sub- urban area elsewhere in Thailand that need systematic problem solving to prevent outbreak of vaccine preventable diseases. The government should consider for increasing number of public health personnel in area with high magnitude of migrant population for possibility in proactive prevention activity among this group.