© 1995 by Oxford University Press
research-article |
Prevention and Early Detection of Leprosy in Children
*Department of Paediatrics, S.N. Medical College Agra-282002, India
**Central JALMA Institute for Leprosy Agra, India
Address for correspondence: Dr Rajeshwar Dayal, Opposite Kidwai Park, Rajamandi, Agra-282 002, India
India with its 4 million cases of leprosy, accounts for one-third of the world's population of leprosy patients. One-fourth of them are below 15 years of age.
We report a 5-year follow-up study of healthy children who were close contacts of leprosy patients, in order to:
- detect subclinical infection and observe the development of overt disease by using the Fluorescent Leprosy Antibody Absorption Technique (FLA-ABS) and the lepromm test which assess the humoral and cell-mediated immunity (CM1), respectively;
- evaluate the efficacy of dapsone as a chemoprophylactic agent in the ‘at risk’ contacts.
Four-hundred-and-fifty-five healthy contacts were studied. Majority of the contacts of multibaciHary patients (303) were FLA-ABS positive (75 per cent) and lepromin negative (55 per cent) showing that although most of them had been infected, the Ieproniin status was negative (P < 0.01). On the other hand, the majority of the contacts of paucibacillary patients (152) were lepromin positive (57 per cent) (P<0.05). Furthermore, only 61 per cent of contacts of paucibacillary patients were FLA-ABS positive as compared to 75 per cent of contacts of multibacillary patients demonstrating that the former had been exposed to a lesser quantum of infection (P<0.05).
On the basis of results of FLA-ABS and lepromin tests, these 455 contacts were classified into four groups, viz. Group I comprising children who were FLA-ABS positive and lepromin positive; Group II, who were FLA-ASS positive and tepromm negative; Group HI, who were FLA-ABS negative and lepromm positive; and Group IV who were FLA-ABS negative and lepromin negative. During the follow- up period of 5 years, only two out of 155 children in Group I developed the disease showing that their good CMI had been able to contain the disease. Out of 166 contacts in Group II, 18 developed the disease mainly of the tuberculoid type. Most of these children were contacts of multibacillary patients. None of the children in Groups III and IV developed the disease. These findings were statistically significant (P <0.01).
Out of the 166 children in Group II (the ‘at risk’ group), 70 were treated as controls while 96 were put on prophylaxis with dapsone which was continued for 3 years after the contact with the source patient had ceased, or for 3 years after the source patient became non-infective. The incidence of disease was significantly lower among children who received chemoprophylaxis (P<0.05). Among controls the incidence rate of the disease was higher in (i) contacts below 5 years of age, (ii) males, and (iii) contacts of bacteriologically positive patients (P < 0.05). These contacts were labelled as the ‘high risk’ group.
The efficacy rate of Dapsone prophylaxis was significantly better in:
- contacts below 5 years of age as compared to older contacts (P <0.01) mainly because the latter were in late stages of incubation and also because there exists a tag period after which dapsone becomes effective as a prophylactic agent;
- males as compared to females, possibly because of better drug compliance by the former (P <0.05);
- contacts of bacteriologically positive patients (P < 0.05) indicating that contacts of bacteriologically negative patients had been infected earlier when their source patients were bacteriologically positive and were, therefore now in an advanced stage of incubation where prophylaxis was less effective;
- contacts whose source patients were under treatment as compared to those contacts whose source patients were not receiving treatment, stressing the need for simultaneous treatment of active source patients.
Our study demonstrates the value of the FLA-ABS and lepromin tests in detecting sub-clinical infection and for identifying the ‘at risk’ contacts of leprosy patients. It clearly establishes the chemoprophylactic value of Dapsone for the ‘at risk’ contacts, particularly for those in the ‘high risk’ category. In pursuance of our Government's policies under the National Leprosy Eradication programme, this study suggests the need to carry out surveillance surveys in the endemic population to identify, follow, and offer cbemoprophylaxis to those at risk.