Transmission of leprosy within households.

As part of the leprosy control program, population follow-up studies were carried out during 1962 to 1970 in Gudiyatham Taluk, an administrative unit in South India (population: 400,000). More than 97% of the 23,285 contacts from 5,088 families having a leprosy patient were clinically examined using accepted methodology and confirmed as having or not having leprosy. New cases developing among household contacts of leprosy (secondary attack rates) were determined and studied in relation to characteristics of the index case and that of contacts. The secondary attack rate is defined as the number of new cases discovered in the contacts of leprosy patients per 1,000 person-years, which is equivalent to observing 1,000 persons per year. Nearly two-thirds of all new cases were of the tuberculoid type of leprosy and another one-sixth of indeterminate type. Lepromatous and borderline cases each constituted about ten percent of the total new cases. The total secondary attack rate was 6.8 per 1,000 person-years. Compared to an annual incidence rate of 0.8 per 1,000 in the total population, this incidence rate among the contacts is nearly ten times higher. Such enhanced risks are observed clearly and consistently when studied by the number of patients within a family for both sexes and in various age-groups. The rate for females (6.3 per 1,000 person-year) though less, was not significantly different from that of males (7.1 per 1,000 person-year). The differences observed between males and females for each type of leprosy were also not statistically significant. The risks for children (less than 15 years) are significantly higher than those for adults. Among boys, the maximum risk was observed in the age-group 5-14 years, whereas for females the risk is highest in the age-group 5-9 years, dropping down significantly after that. Furthermore, it was observed that significant differences existed between children and adults only in males but not in females. The secondary attack rates almost doubled when there were multiple index cases in the family. Regardless of the number of index cases, the male-female differences were not statistically significant. Attack rates were significantly enhanced when there was a bacilliferous type of leprosy (lepromatous or borderline) in the family. This was true for the specific attack rates of each type of leprosy too. However, a significantly higher proportion of lepromatous and borderline types is also seen when there is a bacilliferous type of leprosy present. The study reiterates the differences in susceptibility to leprosy among males and females, especially during younger ages. Further immunological studies are necessary to determine the differences in host responses in males and females that produce such a characteristic sex-ratio in prevalence of leprosy. There is still a great need to obtain more data on incidence rates both in general population and among contacts on the basis of prospective observation using acceptable statistical technics in design and analysis.     

Infectivity of secondary dapsone-resistant cases

The incidence rate of leprosy among 517 household contacts of 113 cases of secondary dapsone resistance with 5074 person years at risk were studied. The incidence rate of leprosy was 4.3 per 1000 person years at risk, which is very similar to the incidence rate (4.8) among household contacts of lepromatous cases. Two, possibly three, cases of primary dapsone resistance were detected among the 27 contacts who developed multibacillary leprosy. There was no evidence of dapsone resistance among 48 paucibacillary leprosy cases assessed when treated with dapsone monotherapy. The possibility that secondary dapsone-resistant cases will infect and will result in an increase in the number of primary dapsone-resistant cases needs to be investigated further.     

Patient contact is the major determinant in incident leprosy: implications for future control.

Notwithstanding the elimination efforts, leprosy control programs face the problem of many leprosy patients remaining undetected. Leprosy control focuses on early diagnosis through screening of household contacts, although this high-risk group generates only a small proportion of all incident cases. For the remaining incident cases, leprosy control programs have to rely on self-reporting of patients. We explored the extent to which other contact groups contribute to incident leprosy. We examined retrospectively incident leprosy over 25 years in a high-endemic village of 2283 inhabitants in Sulawesi, Indonesia, by systematically reviewing data obtained from the local program and actively gathering data through interviews and a house-to-house survey. We investigated the contact status in the past of every incident case. In addition to household contact, we distinguished neighbor and social contacts. Of the 101 incident cases over a 25-year period, 79 (78%) could be associated to contact with another leprosy patient. Twenty-eight (28%) of these 101 cases were identified as household contacts, 36 (36%) as neighbors, and the remaining 15 (15%) as social contacts. Three patients had not had a traceable previous contact with another leprosy patient, and no information could be gathered from 19 patients. The median span of time from the registration of the primary case to that of the secondary case was 3 years; 95% of the secondary cases were detected within 6 years after the primary case. The estimated risk for leprosy was about nine times higher in households of patients and four times higher in direct neighboring houses of patients compared to households that had had no such contact with patients. The highest risk of leprosy was associated with households of multibacillary patients. The risk of leprosy for households of paucibacillary patients was similar to the risk of leprosy for direct neighboring houses of multibacillary patients, indicating that both the type of leprosy of the primary case and the distance to the primary case are important contributing factors for the risk of leprosy. Contact with a leprosy patient is the major determinant in incident leprosy; the type of contact is not limited to household relationships but also includes neighbor and social relationships. This finding can be translated into a valuable and sustainable tool for leprosy control programs and elimination campaigns by focusing case detection and health promotion activities not only on household contacts but also on at least the neighbors of leprosy cases.     

Design of the leprosy component of the Brazilian BCG revaccination trial for assessing BCG effectiveness against leprosy in school children

BACKGROUND: BCG vaccination confers protection against leprosy, and vaccination among household contacts has been recommended in Brazil. Nevertheless, vaccination of the entire community against leprosy is not advocated as leprosy has low incidence in most populations. Despite that, in Brazil, BCG vaccination is recommended among school children to prevent tuberculosis and this large scale vaccination may also affect the occurrence of leprosy, which led to investigations of its impact on leprosy in endemic areas of Brazil. OBJECTIVES: To estimate the effectiveness against leprosy of a dose of BCG vaccine given to school children in a population with a high coverage of neonatal BCG. Long term objectives are to compare the impact of vaccination among schoolchildren with the existing recommendation to vaccinate household contacts of leprosy. STUDY DESIGN: Cluster randomized controlled field trial with no placebo. STUDY POPULATION: Children aged 7 to 14 years attending state schools with high coverage of neonatal BCG. METHODS: 286 state schools in the city of Manaus, Brazil, were randomized to receive BCG or not. Identifying information was collected for 152,438 school children, of whom 72,980 are in intervention schools. BCG vaccination was given intradermically to children in schools allocated to vaccination. Follow-up relies on ascertainement of cases diagnosed at the health services and notified to the reference center for leprosy.     

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.     

Acedapsone in the prevention of leprosy: field trial in three high prevalence villages in Micronesia.

The 1,659 non-leprous people in a Micronesian population experiencing an annual leprosy incidence rate of about 7/1,000 were offered 15 acedapsone (DADDS) injections during 1967--1970 for leprosy prevention purposes. Subsequent annual surveillance showed an initial cessation of new cases during the 3-year DADDS campaign, followed by a resumption of cases thereafter at a yearly level of about 2/1,000 with a longer pause and slower rise among those who received the full regimen. A secondary wave of cases that has occurred since 1973 among children born after 1968 shows that post-campaign transmission occurred, probably principally from relapsing multibacillary cases with onset before the campaign. Recommendations are made for a balanced, long-term control program with DADDS preventive treatment limited to contacts of multibacillary cases.     

Chemoprophylaxis is effective in the prevention of leprosy in endemic countries: a systematic review and meta-analysis. MILEP2 Study Group. Mucosal Immunology of Leprosy

OBJECTIVE: To quantify the efficacy of chemoprophylaxis against leprosy. METHOD: Literature searching of Medline and Embase databases, hand-searching of references and correspondence with investigators. Study selection: published papers relating to the prevention of leprosy and the use of chemotherapy in leprosy were identified for critical appraisal. Trials were selected and grouped into three categories according to study design and control groups. Data analysis: the relative risks (RR) with 95% confidence intervals were calculated from the original data using a random effects model. To assess the cost-effectiveness of chemoprophylaxis, a further analysis of the rates of disease in the trial and control groups was done based on the numbers needed to be treated (NNT) to prevent one new case of leprosy. RESULTS: A total of 14 trials were identified from 127 published papers on chemoprophylaxis of leprosy. The trials were categorized into randomized controlled trials, non-randomized controlled trials, and uncontrolled trials. The overall results of the meta-analysis shows that chemoprophylaxis gives around 60% protection against leprosy. The NNT are low in trials of household contacts. CONCLUSIONS: The evidence shows that chemoprophylaxis against leprosy is an effective way to reduce the incidence of leprosy, particularly in household contacts. The role of chemoprophylaxis needs to be re-examined using newer drugs given the continuing case detection rates globally.     

Active surveillance of leprosy contacts in country with low prevalence rate

For advanced control of leprosy in Pakistan where the World Health Organization leprosy elimination goal was achieved in 1996, we conducted surveillance of Mycobacterium leprae-seropositive patients and their contacts and drug resistant strains of M. leprae.We measured anti-PGL-I antibody level in sera from leprosy patients and their contacts for early detection of M. leprae infection. Out of 34 leprosy patients undergoing treatment, 4 lepromatous leprosy patients were antibody positive, and 6.8 to 23.7 percent of occupational or household contacts were seropositive. Furthermore, three cases (1.2%) had a high antibody titer. For surveillance of drug resistant strains of M. leprae, dapsone and rifampin were targeted. Four out of 18 polymerase chain reaction (PCR) positive samples had mutation in folP gene, and among 10 PCR positive samples, one had a mutation in the rpoB gene.These results indicate that serological analysis of patient contacts might be useful to find out high risk individuals, and there are M. leprae strains resistant to chemotherapeutic agents in Pakistan.     

Passive versus active tuberculosis case finding and isoniazid preventive therapy among household contacts in a rural district of Malawi.

SETTING: Thyolo district, rural Malawi. OBJECTIVES: To compare passive with active case finding among household contacts of smear-positive pulmonary tuberculosis (TB) patients for 1) TB case detection and 2) the proportion of child contacts aged under 6 years who are placed on isoniazid (INH) preventive therapy. DESIGN: Cross-sectional study. METHODS: Passive and active case finding was conducted among household contacts, and the uptake of INH preventive therapy in children was assessed. RESULTS: There were 189 index TB cases and 985 household contacts. Human immunodeficiency virus (HIV) prevalence among index cases was 69%. Prevalence of TB by passive case finding among 524 household contacts was 0.19% (191/100000), which was significantly lower than with active finding among 461 contacts (1.74%, 1735/100000, P = 0.01). Of 126 children in the passive cohort, 22 (17%) received INH, while in the active cohort 25 (22%) of 113 children received the drug. Transport costs associated with chest X-ray (CXR) screening were the major reason for low INH uptake. CONCLUSIONS: Where the majority of TB patients are HIV-positive, active case finding among household contacts yields nine times more TB cases and is an opportunity for reducing TB morbidity and mortality. The need for a CXR is an obstacle to the uptake of INH prophylaxis.     

Antibodies to a synthetic analog of phenolic glycolipid-I of Mycobacterium leprae in healthy household contacts of patients with leprosy

Fifty-four household contacts of lepromatous patients, 39 household contacts of tuberculoid patients, and 99 control persons were examined with an enzyme-linked immunosorbent assay for their antibody responses to phenolic glycolipid-I (PGL-I) of Mycobacterium leprae using a synthetic analog (PGL-ISA) with the same terminal sugar epitope, namely, O-(3, 6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(alpha-L-rhamnopyranosyl )-(1----9)-oxynonanoyl-BSA. This study was conducted in the Gurage area of Ethiopia in 15 households with a leprosy patient and 15 matched control households. Household contacts with more than 1 year of exposure to a lepromatous patient had antibodies to PGL-ISA significantly more often (19 of 34 persons) than did household contacts with less than 1 year of exposure to a lepromatous patient (4 of 20 persons), household contacts of tuberculoid patients (8 of 39 persons), and persons without exposure to leprosy in the household (33 of 99 persons). No significant association was found between the prevalence of antibodies to PGL-ISA in the household contacts and disease activity in the lepromatous index patients at the time of examination; nor was there a significant association between antibody responses and age or sex of the contacts. The increased prevalence of antibodies to M. leprae antigen in healthy persons with more than 1 year of contact with a lepromatous patient provides further evidence that subclinical infection in leprosy is common, and is related to the type of leprosy in the index patient. The fact that antibodies to PGL-ISA were detected in one third of the persons without household exposure to leprosy emphasizes the necessity to always include comparable controls from the same endemic area in studies of leprosy contacts.     

Contact examination for tuberculosis in Hong Kong is useful.

SETTING: The tuberculosis programme of the Hong Kong Government Tuberculosis and Chest Service. OBJECTIVE: To determine the outcome of examination of household contacts in Hong Kong. DESIGN: A retrospective cohort study of all household contacts of 970 randomly selected index cases from a total of 5757 registered for treatment with the Chest Service. RESULTS: Of 2678 household contacts (three/index case) identified, 90% were examined; 41 active cases were found, at a rate of 1720/100000 (95%CI 1238-2329). The rate was highest among two extremes of age, 3604/100000 (95%CI 990-3615) in children < or = 5 years and 3347/100000 (95%CI 1456-6489) in those >60 years of age. Contacts of index cases whose sputum smear and culture were positive had the highest rate of disease, 2904/100000 (95%CI 1669-4673); but contacts with negative bacteriology also had a high rate of 1478/100000 (95%CI 678-2789). Active cases identified through contact tracing could be source cases rather than secondary cases. Eight per cent of children aged < or = 5 years had positive tuberculin reactions; as BCG vaccination is given to all newborns, with 99% coverage in Hong Kong in the past 30 years, it was difficult to estimate the rate of infection in these children. CONCLUSION: In Hong Kong, an area with an intermediate burden of tuberculosis, contact investigation is a very useful procedure for active case finding.     

Induction of lepromin positivity and immunoprophylaxis in household contacts of multibacillary leprosy patients: a pilot study with a candidate vaccine, Mycobacterium w

We screened 487 household contacts of multibacillary (MB) patients for evidence of disease and their lepromin status. From the 444 results available, 302 (68.02%) were lepromin positive and 142 (31.98%) were lepromin negative on initial testing. The initial lepromin status as assessed in the group of 54 contacts having disease at the outset showed 24 out of 46 (52.2%) to be lepromin positive and 22 of 46 (47.8%) to be lepromin negative. In the same group, among 24 lepromin positives, 22 (91.7%) had paucibacillary (PB) and 2 (8.3%) had multibacillary (MB) disease; among the lepromin negatives, 12 (54.5%) had PB and 10 (45.5%) had MB disease. Out of 72 initially lepromin-negative contacts administered Mycobacterium w vaccine and followed up, the cumulative percentages show that 53 (73.6%) converted to positivity after a single dose, 10 (87.5%) after a second dose and 67 (93.1%) after the third dose. The incidence of new cases with leprosy was 8 out of 231 (3.46%) among lepromin-positive contacts and 5 out of 93 (5.38%) among lepromin-negative contacts administered Mycobacterium w vaccine. Among 231 lepromin-positive contacts, the new cases occurred in those with a 1+ and 2+ lepromin response only, and no case occurred among 51 contacts with a 3+ lepromin response. The incidence among lepromin-positive contacts in this study (3.46%) was similar to the observations in two other studies: 3.2% by Dharmendra, et al. and 6.9% by Chaudhary, et al. However, the incidence among lepromin-negative contacts administered Mycobacterium w vaccine was significantly lower than that observed among lepromin-negative contacts not administered any vaccination in the other two studies (14.1% by Dharmendra, et al. and 29.0% by Chaudhary, et al.). To conclude, although a study of small sample size, the preliminary evaluation indicates that administration of Mycobacterium w vaccine seems to have the potential to reduce the incidence of leprosy among household contacts of leprosy patients. More explicit results about the vaccine will be available from the ongoing field trials in Kanpur Dehat in the near future.     

IgM antibodies to native phenolic glycolipid-I in contacts of leprosy patients in Venezuela: epidemiological observations and a prospective study of the risk of leprosy

In a randomized, double-blind vaccine trial in Venezuela, about 29,000 contacts of leprosy patients have been vaccinated with either a mixture of heat-killed Mycobacterium leprae and BCG or BCG alone, and are being re-surveyed annually to detect new cases of leprosy. All contacts had a serum sample collected at the time of entry into the trial, and 13,020 of these sera have been analyzed for antibodies to phenolic glycolipid-I (PGL-I). Antibody levels have been related to various characteristics of the contacts and to their risk of developing leprosy in the following 4 years. A strong association was found between PGL-I antibody level and the risk of developing leprosy, in spite of possible modification of the incidence rate induced by vaccination. Antibody levels were higher in females than in males, and declined progressively with age. Household contacts had higher levels than did non-household contacts, and levels were higher in individuals from the state in Venezuela which has the highest incidence of the disease. No substantial differences were found in antibody levels between contacts of multibacillary and paucibacillary patients, which may in part reflect the influence of treatment, and there was no clear association with the presence of BCG or lepromin scars or with skin-test responses to PPD and leprosy soluble antigen. The assay of antibodies to PGL-I seems unlikely to provide a sensitive or specific test for infection with M. leprae, and measuring PGL-I antibody levels as a screening procedure to identify those at high risk of developing leprosy is unlikely to be particularly useful in most leprosy control programs. Such assays may be useful for the epidemiological monitoring of changes in the intensity of infection with M. leprae in a community and for the study of carefully defined groups of contacts during some phases of control programs.     

Human monkeypox: a study of 2,510 contacts of 214 patients

A study of 2,510 contacts of 214 patients with human monkeypox was conducted in Zaire from 1980 to 1984. Among the contacts of 130 primary cases of human monkeypox, a further 22 co-primary and 62 secondary cases were detected, and an additional fourteen people who had no evidence of clinical disease had positive serological results. A majority of the clinical and subclinical cases of monkeypox occurred in children less than 10 years of age. Immunity in vaccinated persons now appears to be waning because 16 overt cases occurred in contacts who had been vaccinated. The overall attack rate for contacts without a vaccination scar (7.2%) differed significantly from the attack rate for those who had been vaccinated in the past (0.9%). The attack rate for household contacts was significantly higher than that for other contacts, among both unvaccinated (four times higher) and vaccinated (seven times higher) household contacts. Many unvaccinated contacts living in the same household as the index case under conditions of maximum exposure, however, escaped not only the disease but also infection.     

The spatial distribution of leprosy in four villages in Bangladesh: An observational study

Background  

There is a higher case-detection rate for leprosy among spatially proximate contacts such as household members and neighbors. Spatial information regarding the clustering of leprosy can be used to improve intervention strategies. Identifying high-risk areas within villages around known cases can be helpful in finding new cases.     

Infection and disease among household contacts of patients with multidrug-resistant tuberculosis.

SETTING: Urban public teaching and referral hospital in Espirito Santo, Brazil. OBJECTIVE: To assess whether rates of infection and progression to active tuberculosis (TB) differed between household contacts of patients with multidrug-resistant (MDR) and drug susceptible (DS) pulmonary tuberculosis. DESIGN: Household contacts were assessed for evidence of TB infection and disease by purified protein derivative (PPD) skin testing, physical examination, chest X-ray, and sputum smear and culture. RESULTS: Among 133 close contacts of patients with MDR-TB, 44% were PPD-positive (> or =10 mm) compared to 37% of 231 contacts of the DS-TB cases (P = 0.18, chi2 test, OR 1.2, 95%CI 0.8-2). In a multivariate logistic regression analysis, after allowance for between-household variation in PPD responses, PPD positivity among household contacts of patients with MDR-TB remained comparable to PPD positivity in contacts of patients with DS-TB (OR 2.1, 95%CI 0.7-6.5). Respectively six (4%) and 11 (4%) contacts of the MDR- and DS-TB cases were found to have active TB at the time of initial evaluation or during follow-up (P = 0.78, chi2 test). Five of six contacts of MDR-TB cases and nine of nine contacts of DS-TB cases who developed TB, and for whom drug susceptibility test results were available, had the same bacterial susceptibility profiles as their index cases. DNA fingerprinting analysis of Mycobacterium tuberculosis isolates was identical between household contacts with active TB and the index MDR or DS-TB case for all 14 pairs compared. CONCLUSION: Our data suggest that the prevalence of tuberculous infection and progression to active TB among household contacts exposed to DS and MDR-TB cases is comparable, despite a longer duration of exposure of contacts to the index case in patients with MDR-TB.     

Cysticercosis surveillance: locally acquired and travel-related infections and detection of intestinal tapeworm carriers in Los Angeles County.

A surveillance system for cysticercosis was initiated in January 1988 in Los Angeles County to measure the incidence of the disease, to more accurately assess the level of locally acquired and travel-related infection, and to evaluate household contacts for intestinal tapeworm infection. In three years of surveillance (1988-1990), 138 incident cases were reported for an average crude annual incidence rate of 0.6 per 100,000 population. The highest rates were among Hispanics (1.6/100,000), most of whom were Mexican immigrants. Eight (5.8%) cases were fatal. Nine (6.5%) probable travel-associated cases occurred among persons born in the United States who had traveled to Mexico. Ten (7.2%) autochthonous cases of cysticercosis were documented. Taenia eggs were recovered more commonly in specimens from contacts with cysticercosis cases (1.1%) than in specimens from noncontact patients (0.2%). At least one Taenia tapeworm carrier was found among contacts of five (6.9%) of 72 cysticercosis patients. Carriers were more likely to be found among contacts of patients born in the United States (22.2%) than among those of foreign-born (4.8%) patients (odds ratio = 5.4) Cysticercosis causes appreciable morbidity and mortality in Los Angeles County, principally among Hispanic immigrants. However, these results indicate that both travel-acquired and locally acquired cysticercosis may be more common than previously recognized. Public health followup of cysticercosis cases, including screening of household contacts, can identify tapeworm carriers, who can be treated and removed as potential sources of further infection.     

Additional risk of developing TB for household members with a TB case at home at intake: a 15-year study.

OBJECTIVE: To assess the additional risk to household contacts from an infectious case of tuberculosis (TB) at home in a rural community in south India. METHODS: In all, 3506 contacts of smear-positive (S+C+) and 2910 contacts of smear-negative TB cases (S-C+) and 246 845 persons with no TB case at home were followed for 15 years, with a repeat survey every 2.5 years consisting of radiographic and sputum examination, selective follow-up of high-risk individuals and passive surveillance. If a case developed during follow-up, all household members were subsequently considered as contacts. Cox's proportional hazards model (multivariate) was employed to compare incidences. RESULTS: The annual incidence of culture-positive TB was respectively 526 and 271 per 100000 population for contacts of smear-positive and smear-negative patients, and 198/100000 in non-contacts. The adjusted hazard rate was 3.4 for contacts of smear-positive patients (95% CI 3.0-3.9) and 1.7 for contacts of smear-negative patients (95% CI 1.4-2.0) as compared to non-contacts. Of 3942 incident cases, 337 (8.5%) came from households with a TB case. CONCLUSION: Although family contacts had a significantly higher incidence, their contribution to total new caseload was meagre. Contact chemoprophylaxis as a public health measure would therefore have limited impact on community TB incidence.     

Seroepidemiological studies of leprosy in northern Malawi based on an enzyme-linked immunosorbent assay using synthetic glycoconjugate antigen

A total of 6002 blood samples from total population samples in four separate areas within Karonga District, Northern Malawi, were tested for anti-Mycobacterium leprae antibody using an ELISA based on synthetic glycoconjugate antigen. Results are presented using different criteria for seropositivity. Regardless of the criterion used, the proportion of individuals classified as "positive" rose to a peak at 20-30 years of age and then fell, and it was higher at all ages in females than in males. There was no difference in seropositivity levels between individuals with or without BCG scars. Although leprosy cases, in particular those with positive smears, had higher antibody levels than nonleprosy cases, analysis of age-standardized data revealed only weak evidence for a correlation between the prevalence rates of clinical leprosy and of seropositivity within the four areas. There was no evidence for higher seropositivity levels in household contacts of leprosy cases compared to noncontacts. The implications of these results for the epidemiology of leprosy in this population are discussed.