Abstract
Background: On 23rd May 2014, Lamlukka Hospital was notified by the Bureau of Epidemiology (BOE) that a pertussis
patient was hospitalized in a pediatric ward of a tertiary hospital during 4th-15th May 2014. A joint investigation teams
of Pathumthani Provincial Health Office, BOE and Office of Disease Prevention and Control including the tertiary
hospital conducted an investigation to confirm a diagnosis, to describe the magnitude of outbreak by searching for
new cases and asymptomatic infections, and to control the outbreak from 26th May to 6thJune 2014.
Methods: Descriptive epidemiologic study was done by reviews of treatment records, nasopharyngeal swab for
pertussis PCR and environmental survey. A suspected case was defined as a person who developed prolong cough at
least one week in duration and met one of following symptoms 1) severe cough, 2) high pitch inspiratory whooping
cough or 3) vomiting after cough between May 26th and June 6th, 2014. A laboratory-confirmed cased was identified
by nasopharyngeal swab that revealed positive PCR for pertussis. Asymptomatic infection was a person who didn’t
have any respiratory tract symptom and NP swab revealed positive PCR for B. pertussis.
Results: An index case with lab confirmation was Thai boy aged 1 month and 20 days who lived with parents,
grandparents and an aunt in Kukot Subdistrict, Lamlukka District, Pathumthani Province. Since 20th April 2014, the boy
had developed symptoms of paroxysmal cough, vomiting with no fever for 2 weeks. His mother took him to see
doctor at a private clinic and he was diagnosed with common cold. His clinical got worse and was taken to a tertiary
hospital where he had been admitted following a diagnosis of pneumonia during 4th - 15th May 2014. His illness was
recovered and discharged from hospital and was found normal at the follow up visit on 20th May 2014. His lab result
of nasopharyngeal swab was yield positive Bordetella pertussis by PCR on 23rd May 2014. From interview, the mother
had common cold about 1 week prior to the illness onset of the child and her nasopharyngeal swab was also positive
for B. pertussis. The investigation identified 5 people who were asymptomatic infections including 1/10 physicians,
4/24 n urses a nd n one o f c ontacts o f p ositive h ealthcare w orkers. T he p ositive c ases w ere t reated b y oral
Azithromycin antibiotics.
Conclusion: The outbreak investigation determined 2 lab-confirmed cases (a son and mother) of pertussis in a family.
Additionally, 5 symptomatic infections among attending medical staff who might be infected by the boy were
identified. We educated the guardians about the importance of child immunization and transmission prevention as
well as advised them to take the child to hospital for vaccination as scheduled in the expanded program on
immunization. Surveillance for pertussis and nosocomial infection control was strengthened in the hospital.
Keywords: Pertussis, outbreak, nosocomial infection