Joint chemotherapy trials in lepromatous leprosy conducted in Thailand, the Philippines, and Korea.

Chemotherapy trials in lepromatous leprosy using various combinations of existing antileprosy drugs were conducted jointly by Korea, The Philippines, and Thailand. The general objective of these trials was to determine the most effective and practicable regimen or regimens for field application. Lepromatous patients were divided into two groups: Group I was comprised of new, untreated patients infected with dapsone-sensitive Mycobacterium leprae and Group II consisted of relapsed patients with dapsone-resistant disease. Four different regimens were administered to each group for 5 years. Comparison among the regimens was based on antileprotic efficacy, drug safety, acceptability, field practicability, and economic feasibility. No significant differences were noted among the various regimens as judged by the reduction in the bacterial index (BI), clinical response, and change in biopsy index. Toxicity was seen only in the regimens containing prothionamide and rifampin. The regimens were acceptable to the patients and all were found practical for field use. Clofazimine, even in low doses, was found to suppress the frequency and severity of erythema nodosum leprosum. A multidrug regimen effective against both new and relapsed cases of lepromatous leprosy, whether dapsone sensitive or dapsone resistant, is recommended for field use. Given priority, the cost of the regimens is affordable in the three countries.

Immunoepidemiological studies on subclinical infection among leprosy household contacts in Thailand.

Three-thousand-fourteen leprosy house-hold contacts in Thailand were surveyed by their personal history, physical examination, and immunological tests. The results were compared with those obtained from villagers in leprosy-endemic and nonendemic areas. The percentages of young people, students, children and grandchildren of the patient, the contacts of multibacillary leprosy cases, long duration of contact, BCG vaccination, FLA-ABS and Dharmendra's lepromin-positive responders were significantly higher in the household contacts than those in the villagers. The percentages of neural and dermal symptoms were not significantly different between the household contacts and the villagers in the endemic area, but the percentages were higher than those of the villagers in the nonendemic area. A PPD skin test was more frequently negative in the former two groups than in the latter. Both FLA-ABS and lepromin tests showed a significant correlation with the age of the contacts, their occupations, blood relation to the patient, the duration of contact, BCG vaccination, dermal signs such as an ill-defined plaque or macule with or without sensory loss, but did not correlate with sex, type of leprosy in the patient, or other skin diseases. The FLA-ABS test in the house-hold contacts and the villagers in an endemic area showed a significant correlation with the neural signs, such as enlargement of the peripheral nerve without sensory loss. These suspicious dermal and neural signs and symptoms were therefore considered signs of Mycobacterium leprae infection. The FLA-ABS test was sufficiently sensitive for detecting this infection and did not correlate with the lepromin or PPD skin tests. FLA-ABS-positive but lepromin-negative responders were found in 33.5% of the house-hold contacts. They were considered to be a high-risk group who may develop clinical leprosy. Nearly half of them were treated with dapsone or BCG according to the results of the PPD skin test. Follow up of these contacts, together with the remaining contacts without treatment, is in progress.

Immunoglobulins in leprosy.

Serum immunoglobulins were estimated by the single radial immunodiffusion technique and the results were compared among various groups of leprosy patients. Most of the serum immunoglobulin classes are increased in lepromatous leprosy patients. Controls from different regions in Thailand and even from two populations in the same region show different results. This can lead to different interpretations of results in leprosy patients and may explain apparent discrepancies in earlier studies of serum immunoglobulins in leprosy.