Vaccination against leprosy at Ben San Leprosy Centre, Ho Chi Minh City, Vietnam.

Three vaccines, BCG alone, BCG + 10(7) killed Mycobacterium vaccae and 10(8) killed M. vaccae alone, were studied in children living in close contact with leprosy. In the year before vaccination, 14/446 (3.1%) children had developed leprosy. Among those who were not vaccinated, 9/74 (12.2%) developed the disease in the first 4 years of the study and 5/65 (7.7%) developed the disease in the second 4 years. In comparison with this, among those vaccinated, 20/343 (5.8%) developed leprosy in the first 4 years and 5/323 (1.5%) developed leprosy in the second 4 years. This represents 52.5% protection in the first 4 years and 80.5% in the second 4 years. There were no significant differences in protection afforded by each of the three vaccines but the success of the killed preparation of M. vaccae is an important finding.

Skin test studies on close contacts of leprosy patients in India.

Skin-test studies with a series of tuberculins have been carried out in close contacts of multibacillary (MB) leprosy patients around three leprosy centers in India, and casual contacts of the disease around two centers. The results show that the rate of acquisition of leprosin A positivity is associated with age and the closeness of contact with MB leprosy. At the age of 15 years, the differences between the two types of contact were highly significant (p less than 0.00001). Many responses to leprosin A are directed toward the group iv species-specific, antigens of the leprosy bacillus, and the significance of positivity is discussed in relation to protective immunity from leprosy. The differences from Iran show that positivity to leprosin A is not solely the effect of the degree of contact with the disease, but must also have a genetic or environmental element, the latter being favored. The results from Miraj show that the high levels of tuberculin, scrofulin, and vaccin positivity seen in Fathimanagar, and to a lesser extent in Karigiri, are not a consequence of contact with leprosy. BCG vaccination made little difference to the leprosin A positivity of close contacts of leprosy patients, although it significantly enhanced positivity among casual contacts around Miraj (p less than 0.002). BCG vaccination significantly increased tuberculin positivity in Miraj and Karigri, and in those under 11 years of age in Fathimanagar. It made no difference to the already high level of positivity found in older persons around Fathimanagar.(ABSTRACT TRUNCATED AT 250 WORDS)

Vaccination and skin test studies on the children of leprosy patients.

In an attempt to achieve maximal skin-test positivity to leprosin A in children of leprosy patients living in Baba Baghi Leprosy Sanatorium in Iranian Azerbaijan, two new vaccines have been employed. Children without scars of previous BCG and without response to leprosin A were given a vaccine containing 10(8) viable units of BCG Glaxo plus 10(7) killed Mycobacterium vaccae per dose (vaccine B). Children with BCG Pasteur (Teheran) scars but without response to leprosin A were given a vaccine containing 10(8) killed M. vaccae alone (vaccine D). Eight years later skin testing was repeated, and both new vaccines were found to have significantly increased the numbers of children responding to leprosin A above the level that would have been expected had they received BCG Pasteur alone. This increase was due in large part to increases in the proportions of individuals responding to group i (common mycobacterial) antigens, and known as category 1 responders. The use of suspensions of killed M. vaccae in conjunction with BCG may represent a considerable advance in inducing protection from multibacillary leprosy in close contacts of leprosy patients if leprosin A positivity is truly a correlate of protective immunity. A comparison, using the same criteria, with the other proposed vaccines for leprosy would be very interesting.

Vaccination and skin test studies on children living in villages with differing endemicity for leprosy and tuberculosis.

The purpose of this study carried out in Iranian Azerbaijan was to determine the pattern of skin-test positivity to mycobacterial antigens in children living in the valley, and to assess the effect on this of a series of vaccines against mycobacterial disease. Set up in 1978, 1707 tuberculin-negative children without scars of previous BCG vaccination were vaccinated with BCG Glaxo alone (vaccine A) or with the addition of a suspension of killed Mycobacterium vaccae (vaccine B). One hundred children were vaccinated with BCG Glaxo plus a suspension of M. leprae (vaccine C). Eight to 10 years later about half of the children were found for follow up. At this time further children were skin tested, and the results obtained were related to whether or not they had scars of vaccination with BCG Pasteur (Teheran) given by the local health authorities. Between setting up the study and the first follow up, cases of leprosy or tuberculosis had occurred in some of the villages, although not among those we had vaccinated. Differences between the effects of the vaccines were only found in villages with cases of leprosy. In these villages positivity to leprosin A was significantly greater after vaccine B (49%) than after vaccine A (36%; p less than 0.04). The results for scrofulin and vaccine were the same after both vaccines, and significantly lower than in the villages without cases of leprosy. The general reduction in skin-test positivity in the villages with leprosy cases was mainly due to a loss of category 1 responders to group i, common mycobacterial, antigens. It was concluded that where casual contact with cases of leprosy occurs the combination of BCG with killed M. vaccae is likely to be a better vaccine for leprosy than is BCG alone. Although few children received the combination with M. leprae, the results obtained were not particularly promising.