Epidemiological, clinical & pharmacological study of antimony-resistant visceral leishmaniasis in Bihar, India

Sodium antimony gluconate (SAG) is reported to be losing its efficacy in Bihar as a first line drug for treatment of visceral leishmaniasis (VL). Concerned with the increasing incidence of antimony-resistant VL patients in Bihar, we undertook an epidemiological, clinical and pharmacological study to formulate a scientific basis for choosing a suitable first line drug for VL.

Consecutive, fresh and parasitologically confirmed patients of VL from different geographical areas of Bihar were considered for inclusion in the study. Parasites isolated from patients were tested in vitro to assess their response to sodium antimony gluconate (SAG) to 20 microg/ml, response to 20 mg/kg of SAG for 5 days in experimentally induced VL in BALB/c mice from those isolates, and response to SAG in patients treated with SAG for 28 days. Similarly response in culture (1 microg/ml) to amphotericin B (AMB) of all 282 isolates, (1 mg/kg body wt for 20 days) in patients and infected BALB/c mice (1 mg/kg body wt for 5 days) was determined. Antimony levels of plasma were determined at 2, 8 and 24 h after intramuscular injection of SAG. Patients unwilling for SAG treatment or relapsed after SAG treatment and withdrawn from SAG group because of toxicity were treated with AMB. Plasma antimony levels were estimated by atomic absorption spectrometer.

Though antimony sensitive and resistant patient were distributed in all 14 districts of Bihar studied, there was a significant variation from district to district. Of the 123 patients included in the SAG treatment group, 19 were withdrawn due to development of toxicity and 2 died; 178 patients were treated with AMB. No patient in AMB group developed any toxicity or died. Only 47 (46%) of 102 patients, 106 (37.6%) of 282 infected macrophages, 90 (52.9%) of 170 experimental infections were cured with SAG. Mc Nemar's test on paired comparisons showed statistical significance difference (P<0.01) between infected macrophage and experimental infection. AMB cured all patients, infected mice and cleared parasites from all isolates.

Antimony resistant strains of L. donovani were wide spread over different geographical areas in Bihar. SAG cured lesser percentage of VL cases clinically compared to AMB and should be replaced by AMB as a first line drug.