Abstract
An outbreak of influenza A (H1N1) in Li district, Lamphun Province in November
2007 led to investigation and control of the event and an epidemiologic study to determine the characteristics of the outbreak, to define the cause and factors associated with
the outbreak, and to implement effective prevention and control measures. Methods included
descriptive epidemiology, environmental survey and laboratory study. A total of
80 cases were identified in this outbreak; 58.8 percent were students and 35 percent were
children aged 5-9 years. The causative virus, influenza A (H1N1), was identified by PCR
technique in 61 out of 77 cases (79.2%). The highest incidence rate of 38.31 per 1,000
population was evident in Village 5 of Srivichai subdistrict. The propagated source epidemic
probably started after introduction of influenza virus A by a student who contracted
it from the local market and then spread it at his school. The health team implemented
comprehensive control measures, including health education on disease etiology
and prevention for local residents both in the school and the community, screening and
isolation of new cases, giving prompt treatment, providing masks and promoting hand
washing among school children and teachers, temporary closure of schools to cut the
transmission chain, and active surveillance and early treatment in the community. A
field hospital was set-up in a temple to accommodate and provide treatment to overloaded
cases from Li Hospital. As a result of all intervention measures implemented by
public health agencies, community leaders and villagers, the outbreak was curtailed
quickly, with no further outbreak in nearby areas.
