Decreased survival of HTLV-I carriers in leprosy patients from the Democratic Republic of the Congo: a historical prospective study.

In this historical prospective study using sera stored for 22 years, we investigated the effect of HTLV-I infection on survival in a population of leprosy patients in the Democratic Republic of the Congo (formerly Zaire). We also determined the distribution of HTLV-I by subpopulation, age, and gender. Stored sera taken from a population of leprosy patients and controls in 1969 were tested for HTLV-I. Follow-up survival data on these patients were obtained in 1991. The sera collected in 1969 from 520 individuals was used to determine the prevalence of HTLV-I. Included in this number were 328 patients resident in the sanatorium. Survival and other data were available for 327 of these. A multivariate survival analysis using a logistic regression model was performed to evaluate the influence of HTLV-I status, age, type of leprosy, gender, duration of hospitalization, and ethnic group on survival. The overall prevalence of HTLV-I among the 520 individuals in the prevalence study was 34%, with 37.4% in the leprosy group and 25.2% in the control group (p < 0.01). Multivariate analysis using logistic regression showed that females of the Mongo and Ngombe ethnic group taken together were significantly more likely to be infected than the other groups (OR = 3.67, 95% CI: 2.14 to 6.30). A comparison of the death rates directly standardized for age and sex showed that the rate was significantly higher for HTLV-I positive (5.5/100 person-years of observation) compared with HTLV-I negative (3.6/100 person-years of observation). A survival analysis using the Cox model showed a risk ratio of 1.4 (CI: 1.04 to 1.89) for those infected with HTLV-I. An increase in the death rate was associated with HTLV-I infection in leprosy inpatients. The decreased survival associated with HTLV-I infection may result from an increased susceptibility to a variety of diseases.

PIP: Preservation of stored sera collected in 1969 from leprosy patients at a sanatorium in the Democratic Republic of the Congo's Equator Province enabled an analysis of the survival of carriers of human T-cell lymphotropic virus type 1 (HTLV-1). The HTLV-1 prevalence in the sera collected from 377 leprosy patients and 143 controls in 1969 was 34% (37.4% and 25.2%, respectively). Multivariate survival analysis was performed to evaluate the impact of HTLV-1 status, age, type of leprosy, gender, duration of hospitalization, and ethnic group on the survival of leprosy patients. Members of the Mongo ethnic group were more likely than those of the Ngombe ethnic group to be infected. After adjustment for age and sex, mortality was significantly higher among HTLV-1-positive cases (5.5 per 100 person-years of observation) than HTLV-1-negative persons (3.6 per 100 person-years of observation). A survival analysis using the Cox model revealed a mortality risk ratio of 1.4 (95% confidence interval, 1.04-1.89) for HTLV-1-positive individuals. The reduced survival observed in HTLV-1-infected leprosy patients presumably resulted from concomitant increased susceptibility to other diseases.

Eliminating leprosy as a public health problem--is the optimism justified?

Systematic use of multidrug therapy has proved to be so effective that leprosy can be eliminated as a public health problem by the end of the century. However, because of the long incubation period of this disease, together with the time-lag in case detection, the factors involved in achieving and sustaining its elimination have to be very carefully defined.

Selection of MDT strategies through epidemiometric modeling.

The epidemiometric model of leprosy, built on Polambakkam, India, data, is used to compare the impact on incidence of dapsone and different multidrug therapy (MDT) strategies. The simulations show that generalization of MDT could have a dramatic impact on transmission of the disease. Relapses after MDT, although important from an individual point of view, have a negligible influence on the incidence. Introduction of MDT requires investments that, during the first few years of the program, are much greater than for dapsone monotherapy. These are, however, rapidly absorbed due to the rapidly declining number of new cases, particularly when MDT is not limited to multibacillary cases but is administered to all patients.

Leprosy in Portugal 1946-80: epidemiologic patterns observed during declining incidence rates.

Compulsory notification of leprosy in Portugal formed the basis for the establishment of a national patient registry used in an epidemiological study. Highest incidence rates were observed in the coastal counties in the middle of Portugal and particularly in the municipalities with a high annual rainfall. Peak incidence rates in males was observed at the age of 25-29 years against 50-59 in females. A continuous and increasing decline in incidence rates was observed throughout the observation period, 1946-80. Towards the end of the period the slopes of the incidence curves seemed to be identical with those observed in other countries where leprosy has previously been eradicated. This is consistent with the notion that towards the end of an endemic situation no new transmission of the disease occurs, and the incidence curve takes the shape of the right part of the distribution of incubation periods which apparently is uniform in leprosy, irrespective of time and place. The pattern observed in other areas during declining incidence rates, of an increase in age at onset by year of onset together with a lack of increase in age at onset by year of birth was confirmed by the Portuguese data, also consistent with a break in the transmission of the disease a long time before the final termination of the endemic situation.