A household survey to assess the burden of influenza in rural Thailand.

Little is known about the disease burden of influenza in middle-income tropical countries like Thailand. The recent outbreak of avian influenza (H5N1) and studies on influenza from neighboring countries highlight the need for data on incidence, access to care, and health care cost. In May/ June 2003, we conducted a province-wide household survey using two-stage cluster sampling to determine the burden of influenza-like illness in Sa Kaeo Province. We used the total number of reported influenza that occurred in May 2003 and a prospective study of outpatient influenza in clinic patients to develop an estimate of the annualized incidence of influenza. Of 718 subjects, 16 (2.2%) suffered an episode of influenza-like illness in the preceding month; 14 sought care, of whom 7 went to a hospital facility. Fifty percent reported missing on average 3 days of work or school. The total individual cost per illness episode was 663 baht (15.78 US dollars). The proportion of outpatients with influenza-like illness caused by an influenza virus in May was 16% and the annualized influenza incidence was estimated to be 5,941/100,000 in Sa Kaeo Province. This survey adds to information indicating that in rural Thailand, the burden of influenza is substantial and costs associated with an illness episode are up to 20% of an average monthly income.

Hospitalization due to human parainfluenza virus-associated lower respiratory tract illness in rural Thailand.

BACKGROUND: Human parainfluenza viruses (HPIVs) are an important cause of acute respiratory illness in young children but little is known about their epidemiology in the tropics. METHODS: From 2003-2007, we conducted surveillance for hospitalized respiratory illness in rural Thailand. We performed reverse-transcriptase polymerase chain reaction on nasopharyngeal specimens and enzyme immunoassay on paired sera. RESULTS: Of 10,097 patients enrolled, 573 (5%) of all ages and 370 (9%) of children <5 years of age had evidence of HPIV infection (HPIV1=189, HPIV2=54, HPIV3=305, untyped=27). Average adjusted annual incidence of HPIV-associated hospitalized respiratory illness was greatest in children aged <1 year (485 per 100,000 person years). CONCLUSIONS: In Thailand, HPIV caused substantial illnesses requiring hospitalization in young children.

A comparison of population-based pneumonia surveillance and health-seeking behavior in two provinces in rural Thailand.

OBJECTIVES: Pneumonia is a leading cause of death worldwide, but there are limited population-based data on the burden of disease. We sought to determine the incidence of pneumonia in rural Thailand. METHODS: Active, population-based surveillance for hospitalized, radiologically-confirmed pneumonia was conducted in two rural Thai provinces. Incidence rates were calculated using census data. Residents of each province were surveyed regarding healthcare utilization for pneumonia. Survey results were used to adjust the incidence of hospitalized pneumonia for incomplete use of hospital care. RESULTS: In the province of Nakhon Phanom, active surveillance identified 1457 radiologically-confirmed, hospitalized pneumonia cases during the period September 2003-August 2004. The unadjusted incidence was 201/100,000/year; adjusted for incomplete radiography, the incidence was 485/100,000/year. Incidence was highest in persons aged <5 years (2783/100 000/year) and >or=65 years (1573/100,000/year). The community survey found that 58% of persons with probable pneumonia reported seeking healthcare at hospital facilities. Adjusted for healthcare access, pneumonia incidence in Nakhon Phanom was 831/100,000/year, compared with 495/100,000/year in the province of Sa Kaeo during 2002-2003. CONCLUSIONS: The incidence of pneumonia in rural Thailand is high. Ongoing surveillance can guide and evaluate prevention strategies. Community surveys complement pneumonia surveillance data by providing a more complete estimate of disease burden.