Status of tuberculosis control in Thailand.

The national tuberculosis control program (NTP) was implemented in Thailand as integrated with the provincial general health services since 1967, with BCG vaccination successfully introduced from the beginning, but progress in expansion of case-finding and chemotherapy had only been achieved following the establishment of hospitals at the district level since the late seventies. At present, case-detection and treatment have operated in more than 95% of the 600 district hospitals and 87 hospitals at provincial and regional levels, with patient follow-up by health centers, logistically supported and technically supervised by 12 zonal TB centers. The trend of the disease has shown noticeable decline as indicated by the three national surveys in 1962, 1977 and 1991, that is, morbidity rate as suspected by x-ray of 2.1%, 1.4% and 1.01%; infectious case rate of 0.5%, 0.31% and 0.24% respectively, a reduction of about 2-3% per year. The infection rate of children 0-14 years of age was found to be 15.2% in 1977; 8.9% in 1983; and 5.18% in 1987, giving the annual risk of infection (ARI) of 4.9%, 2.3% and 2.0% respectively. Currently the program detects and treats about 31,000 smear-positive TB cases plus an equal number of smear-negative cases per year. Short-course chemotherapy was introduced since 1985 and expanded to cover all the former by 1991, resulting in improvement of the treatment success rate from less than 50% when using the old standard 18-24 months regimen to 70-80%. As the coverage of case detection and treatment is still only about 60% of the incidence or 30% of the prevalence, trials of primary health care approach have yielded substantially increased case detection coverage as well as improved cure rates. BCG vaccination as part of the Expanded Program on Immunization has reached 90-100% coverage of infants.

Nontuberculous mycobacterial infection of the lung in a chest hospital in Thailand.

In a continuing study on the occurrence of nontuberculous mycobacterial lung disease by screening sputum cultures and from clinical judgement, from 1979 to 1987, a second series of 42 patients were suspected of having pulmonary infection caused by nontuberculous mycobacteria. As identified by the WHO Collaborating Center for Mycobacteria in Prague, Mycobacterium avium complex was isolated from the greatest number of patients (21 or 50%); M. scrofulaceum from seven; M. kansasii from six, and M. gorgonae from four. The remaining four patients yielded one strain each of M. fortuitum, M. asiaticum, M. szulgai, and one with suspected M. simiae. However, clinical significance was confirmed in only 30 patients, 20 of whom had M. avium complex; three had M. scrofulaceum; three had M. kansasii, and one each had M. gordonae, M. asiaticum, M. szulgai, and suspected M. simiae. Retrospective analysis revealed that 24 of the 30 patients had pre-existing disease, including 20 who had tuberculosis. Blood examinations of 10 patients recalled so far proved negative for HIV infection. Diseases caused by nontuberculous mycobacteria is still rare in Thailand.

Pulmonary infection caused by atypical mycobacteria: a report of 24 cases in Thailand.

From 1969 to 1978, 24 patients were suspected of having pulmonary disease caused by atypical mycobacteria. Seven were infected with Mycobacterium avium-intracellulare, six with Mycobacterium avium, six with Mycobacterium scrofulaceum, two with Mycobacterium fortuitum, and one with Mycobacterium gordonae. One patient had a strain of scotochromogens antigenically related to Mycobacterium simiae. Mycobacterium kansasii was found in only one patient. Retrospective analysis revealed that 20 of the patients had preexisting pulmonary diseases, including 16 who had tuberculosis. Disease caused by atypical mycobacteria is rare in Thailand, and possible reasons for the rarity are discussed.