Drug unresponsiveness & combination therapy for kala-azar.

Area of Science:

• Medical Parasitology
• Infectious Diseases
• Drug Discovery

Background:

• Pentavalent antimonials (SbV) have been the mainstay for kala-azar treatment for decades.
• Increasing unresponsiveness (60%) to WHO regimens and resistance to pentamidine and miltefosine necessitate new therapeutic strategies.
• Leishmania donovani infection impairs cell-mediated immunity, shifting the balance towards Th2-suppressive cytokines.

Purpose of the Study:

• To address treatment failures and reduce therapy length for kala-azar.
• To explore combination therapy as a viable option for managing resistant and complex cases.
• To evaluate novel therapeutic approaches for visceral leishmaniasis.

Main Methods:

• Review of existing treatment protocols and drug resistance patterns for kala-azar.
• Analysis of combination therapy efficacy, including sodium stibogluconate (SSG) with other agents.
• Exploration of immunotherapy and vaccine-based strategies in conjunction with chemotherapy.

Main Results:

• Conventional dosages of SbV show significant unresponsiveness in Bihar, India.
• Resistance has emerged to pentamidine and is a concern for miltefosine due to its long half-life.
• Previous combinations like SSG with paromomycin or IFN-gamma yielded discouraging results.

Conclusions:

• Combination therapy with potent, host-immune-independent drugs like amphotericin B and miltefosine may shorten treatment and overcome unresponsiveness.
• Combination therapy is particularly recommended for kala-azar co-infected with HIV/AIDS.
• Future options include immunotherapy with Th1-stimulating cytokines or antileishmanial vaccines combined with chemotherapy.