Leishmanin skin test in clinical and subclinical kala-azar cases

Leishmanin skin test was done on 25 active kala-azar (KA) patients, 41 healthy persons residing with KA patients and 14 treated cases of KA. All active cases of KA were Leishmanin test negative. Nine out of 41 (21.9 per cent) healthy household members gave positive reaction to Leishmanin antigen. These persons were previously exposed to Leishmania donovani infection which was overcome by developing cell mediated immunity. The infection in these persons remained subclinical or asymptomatic. This shows that all L. donovani infections do not progress to clinical stage.