The disease has been endemic in India for a long time and the earliest outbreaks occurred in the early nineteenth century.  Kala-azar used to occur in cyclical epidemics at the intervals of 10-15  years.  With  the  launching  of  insecticidal  spraying  under  National  Malaria  Control Programme/ National Malaria Eradication Programme in 1953 and 1958 respectively, the disease declined  to  negligible  proportions  as  a  result  of  the  reduction  of  densities  of  the  vector, Phlebotomus argentipes.  Withdrawal of insecticidal spraying from erstwhile malaria endemic areas following successful malaria control resulted in a gradual build up of vector populations and renewed transmission of the disease.  A resurgence of Kala-azar during 1970ís, initially in four
district of Bihar followed and eventually engulfed the entire north Bihar, parts of south Bihar and several districts of West Bengal. The Kala-azar also began to be reported from erstwhile endemic districts of eastern Uttar Pradesh.