T-cell recognition of mycobacterial GroES peptides in Thai leprosy patients and contacts.

We report here the mapping of T-cell-stimulatory determinants of the GroES 10-kDa heat shock protein homologues from Mycobacterium leprae and Mycobacterium tuberculosis, which are known as major immunogens in mycobacterial infections. Peripheral blood mononuclear cells (PBMC) from treated tuberculoid leprosy or lepromatous leprosy patients and from healthy household or hospital staff contacts of the patients were cultured with 20 16-mer peptides covering the entire sequences of both M. leprae and M. tuberculosis GroES. The total number of recognized peptides was found to be the largest in family contacts, while responder frequencies to the individual tested peptides varied (5 to 80%) with specificity between the patient and contact groups. Proliferative responses to some peptides showed positive or negative associations of low statistical significance with DR and DQ alleles, though responses to most GroES peptides were genetically permissive. Notably, the sequence of the 25-40 peptide of M. leprae, but not that of M. tuberculosis, was more frequently stimulatory in tuberculoid leprosy patients than in either group of sensitized healthy contacts. This peptide bound to a number of HLA-DR molecules, of which HLA-DRB5*0101 had the strongest affinity. The epitope core binding to this allele was localized to the 29-to-37 sequence, and its key residue was localized to the M. leprae-specific glutamic acid at position 32. This epitope may be of interest for the development of a blood test- or skin test-based diagnostic reagent for tuberculoid leprosy, subject to further clinical evaluation in untreated patients.

Ofloxacin containing combined drug regimens in the treatment of multibacillary leprosy.

The results of ofloxacin containing combined drug regimens in the treatment of 60 multibacillary leprosy cases from January 1989 to June 1995 are reported. The objective of the trial is to compare the antileprotic property of ofloxacin and rifampicin in multibacillary leprosy patients and to study the killing rate of M. leprae by ofloxacin and rifampicin before mass treatment can be recommended. The complications and side-effects of ofloxacin and rifampicin were of a mild nature and both drugs were well tolerated. Moderate to marked clinical improvement was noticed in a short period with ofloxacin containing regimens in multibacillary leprosy patients. No persisters were detected in any of the 33 specimens (of mouse footpads) that had been obtained after treatment for 6 months. Ofloxacin if added to the currently used WHO recommended MB-MDT regimen may shorten the duration of treatment. Ofloxacin, therefore, may be considered as a suitable alternative in suspected/proven rifampicin resistant cases and where rifampicin is contraindicated. The results were evaluated on the basis of the clinical conditions, mycobactericidal effectiveness, signs of drug toxicity and side effects.

Combined chemotherapy trials with regimens containing ofloxacin and rifampicin for multibacillary leprosy patients.

The results of combined chemotherapy trials with regimens containing ofloxacin and rifampicin for the treatment of 60 multibacillary leprosy cases from January 1989 to September 1995 was reported. Clinical improvement was achieved by all regimens from the end of the first month. Most patients continued to improve for 3 years. Bacterial indices were gradually reduced during the treatment. Patients on regimens containing rifampicin were clear of M. leprae at the end of the 5th year. The complications and side-effects of ofloxacin and rifampicin were trivial and both drugs were well tolerated. Ofloxacin added to the current WHO recommended M.B.-MDT regimen may shorten the duration of treatment. Ofloxacin may be an alternative in suspected/proven rifampicin resistant cases or rifampicin contraindicated.

Detection of Mycobacterium leprae infection by PCR.

PCR amplification of the 531-bp fragment of the Mycobacterium leprae pra gene in fresh biopsy and slit skin smear samples was evaluated for its usefulness in the detection of leprosy bacilli in patients in Thailand. In multibacillary patients, 87.1% (27 of 31) of biopsy specimens and 41.9% (13 of 31) of slit skin smear specimens were positive by PCR, whereas in paucibacillary patients, 36.4% (8 of 22) of biopsy specimens and 18.2% (4 of 22) of slit skin smear specimens yielded detectable PCR amplification. Compared with other diagnostic procedures, PCR showed a clear advantage over both microscopic examination of slit skin smears and serologic detection of anti-phenolic glycolipid 1 antibody, especially in paucibacillary patients when bacterial indexes were 0 and seropositivity was only 6.25%. PCR was also evaluated for its potential to help monitor bacterial clearance in some of these patients during chemotherapeutic treatment. The PCR results on slit skin smear samples at 1, 3, and 6 months of chemotherapy showed that the number of PCR-positive cases of both multibacillary and paucibacillary types decreased sequentially. The results of this study are encouraging. However, investigation of a larger number of clinical specimens with an improvement in PCR methods, especially on slit skin smears, needs to be done before PCR can be established as a diagnostic procedure for leprosy patients and subclinical cases or as a tool for drug assessment.

Leprosy situation in Thailand.

The prevalence rate of leprosy in Thailand was approximately 5 per 1,000 in 1953. Specialized leprosy control programme was first launched in 1956 in Khon-Kaen Province and gradually expanded to cover the whole country in 1972. After successful control, it has been partially integrated in provincial health services in 1971 and fully integrated into primary health care system in 1976. Effective case finding in combination with chemotherapy using WHO multidrug therapy regimen and health education have brought about a decline in the prevalence of the disease to only 0.537 per 1,000 in 1987. However, the estimated prevalence rate by random survey is approximately twice the number of registered cases. Reduction in number of lepromatous leprosy patients, particularly the new cases, decrease in number of patients with deformities caused by leprosy and increased number of patients who voluntarily came to attend at the treatment centres imply the successful control at a certain level. It is then justified to aim at the goal of eradication of leprosy by combination of chemotherapy, immunotherapy and immunoprophylaxis with antileprosy vaccines in the future.