Changing epidemiology of dengue hemorrhagic fever in Thailand.

Dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) are reportable diseases, the third most common causes for hospitalization of children in Thailand. Data collected from the Ministry of Public Health were analysed for trends. Rates of DHF increased in Thailand until 1987 when the largest epidemic ever, 325/100000 population, was recorded. Whereas the disease used to be confined to large cities, the rate is now higher in rural (102.2 per 100000) than urban areas (95.4 per 100000 in 1997). The age of highest incidence has increased, and the age group most severely affected is now those 5-9 years old (679/100000 in 1997). The case fatality rate has decreased with improved treatment and is now only 0.28%.

Saliva-based HIV-antibody testing in Thailand.

OBJECTIVE: To determine whether saliva could serve as an alternative to serum for HIV-antibody testing in an ongoing sentinel surveillance program in Thailand. METHODS: Serum and saliva specimens were collected from 1955 individuals in four of the 73 sentinel sites of the national surveillance program in Thailand. Intravenous drug users, female prostitutes, and men attending sexually transmitted disease clinics were included as participants. All specimens were collected and tested anonymously. Saliva was gathered with the Omni-Sal collection device and analyzed for the presence of HIV antibodies using the immunoglobulin G antibody-capture enzyme-linked immunosorbent assay (GACELISA) laboratory test, specially designed for low concentration body fluids. Our gold standard was serum, collected and analyzed independently from the saliva specimens, using an ELISA test for screening and Western blot for confirmation. Linkage between serum and saliva was blind to the laboratory. A set of HIV-positive and HIV-negative quality assurance samples for both serum and saliva were also analyzed blind. RESULTS: Findings are presented as observed in the field, and as quality assurance samples after the correction of various field and laboratory errors. The sensitivity of the GACELISA with saliva was 98.0% in the field (298 HIV-positive specimens), 100% after correction of errors (300 HIV-positive specimens), and 100% among the quality assurance samples (95 HIV-positive specimens). The specificity of the GACELISA was 99.4% in the field (1653 HIV-negative specimens), 99.6% after correction of errors (1654 HIV-negative specimens), and 100% among the quality assurance samples (96 HIV-negative specimens). CONCLUSION: Our findings support other published studies that also featured the GACELISA. We conclude that saliva is comparable to serum for assessing HIV antibodies in individuals for surveillance and screening purposes.

A Thai monk: an agent for smoking reduction in a rural population.

Monks in a rural community in northern Thailand were observed to conduct anti-smoking activities. To evaluate the effects of the monks' efforts on change of people's smoking behaviour and attitudes, we conducted a survey of adults > or = 15 years of age in this village (intervention village sample) and a randomly selected village (control village sample) in the same subdistrict. Between March and April 1991, we interviewed 372 individuals in the intervention village and 664 in the control village. The two villages were of similar socioeconomic status. The proportion of ever smokers who had tried to quit was greater in the intervention sample (79.6%) than in the control sample (72.0%) (P = 0.048). The proportion of former smokers who had stopped smoking for > or = 1 year was significantly greater in the intervention sample (25.5% of ever smokers) than in the control sample (16.6%) (P = 0.011). Of current smokers in the intervention village, 45.8% reported smoking less tobacco during the year preceding the survey than in the previous 1-year period compared with 35.2% in the control village (P = 0.034). Many former smokers (80.3%) in the intervention village cited the suggestion of a monk as one important reason for quitting compared with 25.6% in the control village (P = 0.000). The proportion of individuals who were well aware of the harmful effects of smoking on health was greater in the intervention village than in the control village. Religious leaders may be helpful in a community-based smoking prevention programme.

Epidemic of fever of unknown origin in rural Thailand, caused by influenza A (H1N1) and dengue fever.

In the late summer (rainy season) of 1987, a sharp outbreak of fever of unknown origin (FUO) in rural southern Thailand was investigated by a field epidemiology team. In a random survey of households, 40 percent of the children and 20 percent of adults were reported to have had febrile illnesses within the last month. There was at least one death, possibly from Reye's syndrome. Testing 34 pairs of acute and convalescent sera showed significant HI antibody titer rises to influenza A (Taiwan/(H1N1) (9 cases) and dengue virus (12 cases). Testing 79 single sera with the antibody capture ELISA test for dengue, revealed that 23 percent had high titers in the IgM serum fraction suggesting recent infection. There were also six antibody titer rises to coxsackie B viruses, three from well controls. Dengue has previously been observed as a cause of FUO in rural areas in the tropics, but finding a combined epidemic of dengue and influenza was unexpected. With cooperative villagers, adequate personnel and laboratory support, especially the antigen capture ELISA test for dengue infections, it is feasible to successfully investigate disease outbreaks with serologic methods in remote villages.