Progress in the treatment of a neglected infectious disease: visceral leishmaniasis

Visceral leishmaniasis (kala-azar) is a disseminated intracellular protozoal infection. Most cases (90%) occur in the rural regions of five countries: India, Sudan, Nepal, Bangladesh and Brazil. As with other infectious diseases embedded in high-level poverty, developing and/or delivering new treatments for visceral leishmaniasis had been painfully slow or nonexistent. However, despite persistent unresolved obstacles (e.g., drug affordability), renewed interest in visceral leishmaniasis and numerous successful treatment trials have combined to turn a therapeutic corner in the past 5 years, yielding new alternatives to conventional pentavalent antimony. Advances include the use of low-cost generic pentavalent antimony, rediscovery of amphotericin B, short-course regimens via lipid formulations of amphotericin B, retesting injectible paromyomycin and, of clear-cut importance, identifying miltefosine (Impavido, Zentaris) as the first effective oral therapy for this neglected disease.

Drug policy for visceral leishmaniasis: a cost-effectiveness analysis

OBJECTIVE

To facilitate the choice of the best visceral leishmaniasis (VL) treatment strategy for first-line health services in (VL)-endemic areas, we compared in a formal decision analysis the cost and the cost-effectiveness of the different available options.

METHODS

We selected four drug regimens for VL on the basis of frequency of use, feasibility and reported efficacy studies. The point estimates and the range of plausible values of effectiveness and cost were retrieved from a literature review. A decision tree was constructed and the strategy minimizing the cost per death averted was selected.

RESULTS

Treatment with amphotericin B deoxycholate was the most effective approach in the baseline analysis and averted 87.2% of all deaths attributable to VL. The least expensive and the most cost-effective treatment was the miltefosine regimen, and the most expensive and the least cost-effective was AmBisome treatment. The cost of drug and medical care are the main determinants of the cost-effectiveness ranking of the alternative schemes. Sensitivity analysis showed that antimonial was competitive with miltefosine in the low-resistance regions.

CONCLUSION

In areas with >94% response rates to antimonials, generic sodium stibogluconate remains the most cost-effective option for VL treatment, mainly due to low drug cost. In other regions, miltefosine is the most cost-effective option of treatment, but its use as a first-line drug is limited by its teratogenicity and rapid resistance development. AmBisome in mono- or combination therapy is too expensive to compete in cost-effectiveness with the other regimens.

Drug resistance in Indian visceral leishmaniasis

Throughout the world, pentavalent antimonial compounds (Sb(v)) have been the mainstay of antileishmanial therapy for more than 50 years. Sb(v) has been highly effective in the treatment of Indian visceral leishmaniasis (VL: kala-azar) at a low dose (10 mg/kg) for short durations (6-10 days). But in the early 1980s reports of its ineffectiveness emerged, and the dose of Sb(v) was eventually raised to 20 mg/kg for 30-40 days. This regimen cures most patients with VL except in India, where the proportion of patients unresponsive to Sb(v) has steadily increased. In hyperendemic districts of north Bihar, 50-65% patients fail treatment with Sb(v). Important reasons are rampant use of subtherapeutic doses, incomplete duration of treatment and substandard drugs. In vitro experiments have established emergence of Sb(v) resistant strains of Leishmania donovani, as isolates from unresponsive patients require 3-5 times more Sb(v) to reach similarly effectiveness against the parasite as in Sb(v) responders. Anthroponotic transmission in India has been an important factor in rapid increase in the Sb(v) refractoriness. Pentamidine was the first drug to be used and cured 99% of these refractory patients, but over time even with double the amount of initial doses, it cures only 69-78% patients now and its use has largely been abandoned in India. Despite several disadvantages, amphotericin B is the only drug available for use in these areas and should be used as first-line drug instead of Sb(v). The new oral antileishmanial drug miltefosine is likely to be the first-line drug in future. Unfortunately, development of newer antileishmanial drugs is rare; two promising drugs, aminosidine and sitamaquine, may be developed for use in the treatment of VL. Lipid associated amphotericin B has an excellent safety and efficacy profile, but remains out of reach for most patients because of its high cost.

Intralesional therapy of American cutaneous leishmaniasis with pentavalent antimony in Rio de Janeiro, Brazil--an area of Leishmania (V.) braziliensis transmission

BACKGROUND

The drug of choice for leishmaniasis is pentavalent antimony and different regimens are under continuous evaluation. The ideal therapy should be simple, effective, and with no or minor side-effects. In this paper we have studied the efficacy of intralesionally applied antimony in New World cutaneous leishmaniasis.

METHODS

Seventy-four patients from Rio de Janeiro state, Brazil, and presenting with single ulcerative cutaneous lesions mainly located on the trunk or extremities were enrolled in the study. The drug employed was N-methyl glucamine (425 mg of Sbv in each 5 ml ampoule). Each lesion was infiltrated with the drug at the four cardinal points in order to achieve complete blanching.

RESULTS

Of the 74 patients, 59 (80%) were healed after a 12-week interval. Extensive follow-up (up to 10 years) disclosed no relapses or the development of mucosal lesions.

CONCLUSIONS

The aim of therapy in New World cutaneous leishmaniasis is the healing of the cutaneous lesion and the prevention of late mucosal damage. Both conditions were achieved with the treatment employed with no side-effects and a considerable decrease in costs. In addition, the method is easy to apply in the field.

Recombinant human granulocyte-macrophage colony-stimulating factor reverses neutropenia and reduces secondary infections in visceral leishmaniasis

Twenty-four patients with acute visceral leishmaniasis and leukopenia (< 1500 neutrophils/mm3) due to Leishmania chagasi were studied, 4 in an open-label pilot study and 20 in a double-blind, placebo-controlled trial. Patients received granulocyte-macrophage colony-stimulating factor (GM-CSF), 5 micrograms/kg daily, or placebo for 10 days, plus 10-20 mg/kg pentavalent antimony daily for 20 days. In GM-CSF recipients, neutrophil counts increased threefold and fourfold over baseline at 5 and 10 days, respectively, and were significantly higher than those in placebo recipients (P < .02). Eosinophil and monocyte counts were significantly increase in GM-CSF recipients at 10 days (P < or = .03). Secondary infections occurred in 3 GM-CSF and in 8 placebo recipients (P = .04). All patients had complete resolution of their leishmaniasis at 3 months. Few adverse events were recorded. GM-CSF, 5 micrograms/kg daily for 10 days, was safe, rapidly reversed neutropenia, and reduced the number of secondary infections in patients with leishmaniasis.