Patient-related factors predicting the effectiveness of rifampicin chemoprophylaxis in contacts: 6 year follow up of the COLEP cohort in Bangladesh.

OBJECTIVES: The COLEP trial in Bangladesh showed a 57% reduction in leprosy incidence among contacts of newly diagnosed patients in the first 2 years after chemoprophylaxis with single dose rifampicin (SDR). We assessed the impact of this intervention after 6 years and identified characteristics of the leprosy index patients predicting the effectiveness of this intervention. DESIGN: The cohort of 1037 patients and their 28 092 contacts that participated in the randomised placebo controlled field trial with single dose rifampicin was followed for 6 years. The leprosy status of contacts was established at 2, 4 and 6 years after the intervention. We assessed the association between characteristics of the index leprosy patients and the development of clinical leprosy among their contacts using logistic regression. RESULTS: The protective effect of SDR was seen only in the first 2 years, with no additional effect after 4 and 6 years. However, the total impact of the intervention was still statistically significant (P = 0.025) after 6 years and no excess cases were observed in the SDR arm at a later stage. The intervention prevented leprosy in contacts that actually received SDR, but did not offer protection to members of the same contact group who did not take chemoprophylaxis. The intervention was most effective in contact groups of female index patients, an enhanced effect was also observed in contact groups of patients belonging to a cluster of two or more leprosy patients at intake as well. CONCLUSION: These easy to recognise patient characteristics indicate a possible enhanced risk of transmission of Mycobacterium leprae to contacts in the vicinity of patients and are useful for deciding about preventive measures, such as early detection or chemoprophylaxis.

Effectiveness of single dose rifampicin in preventing leprosy in close contacts of patients with newly diagnosed leprosy: cluster randomised controlled trial.

OBJECTIVE: To determine the effectiveness of chemoprophylaxis using a single dose of rifampicin to prevent leprosy in close contacts. DESIGN: Single centre, double blind, cluster randomised, placebo controlled trial. SETTING: Leprosy control programme in two districts of northwest Bangladesh with a population of more than four million. PARTICIPANTS: 28,092 close contacts of 1037 patients with newly diagnosed leprosy. 21,711 contacts fulfilled the study requirements. INTERVENTIONS: A single dose of rifampicin or placebo given to close contacts in the second month of starting the index patient's treatment, with follow-up for four years. MAIN OUTCOME MEASURE: Development of clinical leprosy. RESULTS: 18,869 of the 21,711 contacts (86.9%) were followed-up at four years. Ninety one of 9452 contacts in the placebo group and 59 of 9417 in the rifampicin group had developed leprosy. The overall reduction in incidence of leprosy using a single dose of rifampicin in the first two years was 57% (95% confidence interval 33% to 72%). The groups did not differ between two and four years. The overall number needed to treat (NNT) to prevent a single case of leprosy among contacts was 297 (95% confidence interval 176 to 537). Differences were found between subgroups at two years, both in reduction of incidence and in NNT. CONCLUSION: A single dose of rifampicin given to contacts of patients with newly diagnosed leprosy is effective at preventing the development of clinical leprosy at two years. The effect was maintained, but no difference was seen between the placebo and rifampicin groups beyond two years. TRIAL REGISTRATION: Current Controlled Trials ISRCTN61223447 [controlled-trials.com].

Physical distance, genetic relationship, age, and leprosy classification are independent risk factors for leprosy in contacts of patients with leprosy.

BACKGROUND: Close contacts of patients with leprosy have a higher risk of developing leprosy. Several risk factors have been identified, including genetic relationship and physical distance. Their independent contributions to the risk of developing leprosy, however, have never been sufficiently quantified. METHODS: Logistic-regression analysis was performed on intake data from a prospective cohort study of 1037 patients newly diagnosed as having leprosy and their 21,870 contacts. RESULTS: Higher age showed an increased risk, with a bimodal distribution. Contacts of patients with paucibacillary (PB) leprosy with 2-5 lesions (PB2-5) and those with multibacillary (MB) leprosy had a higher risk than did contacts of patients with single-lesion PB leprosy. The core household group had a higher risk than other contacts living under the same roof and next-door neighbors, who again had a higher risk than neighbors of neighbors. A close genetic relationship indicated an increased risk when blood-related children, parents, and siblings were pooled together. CONCLUSIONS: Age of the contact, the disease classification of the index patient, and physical and genetic distance were independently associated with the risk of a contact acquiring leprosy. Contact surveys in leprosy should be not only focused on household contacts but also extended to neighbors and consanguineous relatives, especially when the patient has PB2-5 or MB leprosy.

Association between anti-pGL-I IgM and clinical and demographic parameters in leprosy.

OBJECTIVE: To determine the risk factors and clinical significance of anti-PGL-I seropositivity. DESIGN: A large-scale sero-epidemiological study (COLEP) was carried out in northwest Bangladesh. Blood on filter paper from 1025 newly diagnosed patients was collected before treatment was started and tested with an anti-PGL-I ELISA; the relation between patient determinants and seropositivity was calculated using logistic regression. RESULTS: The median age was 30 years and the male:female ratio 1.9. Overall, 342 patients (33.4%) were seropositive. The following determinants showed a significant correlation with seropositivity (P < 0-05) in multivariate analysis: sex, age, disability grade, bacterial index and classification according to the World Health Organization (WHO) system. The number and extent of clinical signs correlated with seropositivity, except for the presence of satellite lesions. People with or without a BCG vaccination scar had a similar risk to be seropositive. CONCLUSION: Serology is a marker for a higher systemic bacterial load and may identify potential infectious sources among patients with few clinical signs. The size of skin lesions was positively correlated with seropositivity. We did not find different levels of seropositivity among patients with one or two skin lesions, neither did we find different levels among patients with or without satellite