Background & objective: Of the two reservoirs of infection of kala-azar i.e., patients of kala-azar and post kala-azar dermal leishmaniasis (PKDL), PKDL provides easy access for the sandfly to pick up the parasites. In the last epidemic of 1977 in India, the importance of PKDL as a potential cause of increase in number of kala-azar cases was ignored. During recent years, we found an increase in the cases of kalaazar whereas cases of PKDL were decreasing in Bihar. We undertook this study to find out reasons for this phenomenon.
Methods: These three different settings were selected to study the trends of the disease. (i) Cases of PKDL registered in the Dermatology Department of Patna Medical College Hospital (PMCH), one of the largest and oldest teaching hospital in Bihar, between 1970 and 2005; (ii) Rajendra Memorial Research Institute of Medical Sciences, Patna (RMRIMS), a research institute exclusively devoted to kala-azar (2000 and 2005); and (iii) interviews with two leading dermatologists of Patna selected by lottery on the incidence of PKDL and possible causes of its decrease, if any. The number of cases of kala-azar (visceral leishmaniasis, VL) from Bihar was studied from Malaria Departments of the Government of Bihar and Government of India, the two nodal departments dealing with the kala-azar.
Results: Analysis of data from Dermatology Department of PMCH showed increase in number of cases of PKDL from two in 1970 to 12 in 1976, a year before the first epidemic of kala-azar in 1977 with 100,000 cases. Kala-azar cases decreased to 11,120 in 1982 due to control measures taken between 1977- 1979 but cases of PKDL reached 28 and kept on increasing. During 1950 to 1977, low dose and short duration regimen of sodium antimony gluconate (SAG) was mainly used in the treatment of kala-azar. Between 1977-1991 increasing incidence of unresponsiveness to SAG, led to the usage of longer duration and higher dose regimen of SAG, more use of amphotericin B (AMB) for SAG resistant cases and also as a first line drug for kala-azar and PKDL. The number of kala-azar cases started decreasing after control measures taken during 1992-1994 but cases of PKDL continued decreasing. The effect of control measures on the incidence of kala-azar was visible upto 2002, but decrease in number of PKDL cases continued. In 2005 the number of PKDL cases was 14 but number of kala-azar cases reached 21,177 in Bihar. In the interview, the two dermatologists also opined that PKDL was decreasing due to increased use of amphotericin B in the treatment of kala-azar. Trend analysis done on the data of PMCH and RMRIMS showed that PKDL will decrease in coming years and kala-azar will increase.
Interpretation & conclusion: Incidence of PKDL decreased in PMCH and RMRIMS and also suggested by two dermatologists that extensive use of amphotericin B in the treatment of kala-azar might be responsible for decrease in number of cases of PKDL.