Oral miltefosine for Indian visceral leishmaniasis

BACKGROUND

There are 500,000 cases per year of visceral leishmaniasis, which occurs primarily in the Indian subcontinent. Almost all untreated patients die, and all the effective agents have been parenteral. Miltefosine is an oral agent that has been shown in small numbers of patients to have a favorable therapeutic index for Indian visceral leishmaniasis. We performed a clinical trial in India comparing miltefosine with the most effective standard treatment, amphotericin B.

METHODS

The study was a randomized, open-label comparison, in which 299 patients 12 years of age or older received orally administered miltefosine (50 or 100 mg [approximately 2.5 mg per kilogram of body weight] daily for 28 days) and 99 patients received intravenously administered amphotericin B (1 mg per kilogram every other day for a total of 15 injections).

RESULTS

The groups were well matched in terms of age, weight, proportion with previous failure of treatment for leishmaniasis, parasitologic grade of splenic aspirate, and splenomegaly. At the end of treatment, splenic aspirates were obtained from 293 patients in the miltefosine group and 98 patients in the amphotericin B group. No parasites were identified, for an initial cure rate of 100 percent. By six months after the completion of treatment, 282 of the 299 patients in the miltefosine group (94 percent [95 percent confidence interval, 91 to 97]) and 96 of the 99 patients in the amphotericin B group (97 percent) had not had a relapse; these patients were classified as cured. Vomiting and diarrhea, generally lasting one to two days, occurred in 38 percent and 20 percent of the patients in the miltefosine group, respectively.

CONCLUSIONS

Oral miltefosine is an effective and safe treatment for Indian visceral leishmaniasis. Miltefosine may be particularly advantageous because it can be administered orally. It may also be helpful in regions where parasites are resistant to current agents.

Visceral leishmaniasis: current status of control, diagnosis, and treatment, and a proposed research and development agenda

Visceral leishmaniasis is common in less developed countries, with an estimated 500000 new cases each year. Because of the diversity of epidemiological situations, no single diagnosis, treatment, or control will be suitable for all. Control measures through case finding, treatment, and vector control are seldom used, even where they could be useful. There is a place for a vaccine, and new imaginative approaches are needed. HIV co-infection is changing the epidemiology and presents problems for diagnosis and case management. Field diagnosis is difficult; simpler, less invasive tests are needed. Current treatments require long courses and parenteral administration, and most are expensive. Resistance is making the mainstay of treatment, agents based on pentavalent antimony, useless in northeastern India, where disease incidence is highest. Second-line drugs (pentamidine and amphotericin B) are limited by toxicity and availability, and newer formulations of amphotericin B are not affordable. The first effective oral drug, miltefosine, has been licensed in India, but the development of other drugs in clinical phases (paromomycin and sitamaquine) is slow. No novel compound is in the pipeline. Drug combinations must be developed to prevent drug resistance. Despite these urgent needs, research and development has been neglected, because a disease that mainly affects the poor ranks as a low priority in the private sector, and the public sector currently struggles to undertake the development of drugs and diagnostics in the absence of adequate funds and infrastructure. This article reviews the current situation and perspectives for diagnosis, treatment, and control of visceral leishmaniasis, and lists some priorities for research and development.

A policy for leishmaniasis with respect to the prevention and control of drug resistance

At the moment no country has a policy designed to control or prevent drug resistance in leishmaniasis. The risk of resistance is high in areas of anthroponotic visceral leishmaniasis, for example North Bihar, India, where the rate in some areas is 60%. Post-epidemic Sudan is also at risk. Zoonotic areas in which HIV co-infection is common could also be at risk as sandflies can become infected from co-infected individuals. Many factors determine the choice of drug for the treatment of visceral leishmaniasis, and drug resistance may not be the over-riding priority. In anthroponotic areas reduction in transmission through public health measures will be important, but the use of two drugs in combination should be seriously considered. Pharmacokinetic and other features of the drugs available, relevant to their use in combination are discussed and tentative suggestions made concerning trials of possible combinations. These include miltefosine plus paromomycin and allopurinol plus an azole. Lessons may be learnt from the experiences of similar problems in malaria, leprosy and tuberculosis. Guidelines are offered for the introduction of policies to use drugs in combination, which differ between anthroponotic and zoonotic areas of transmission.

Efficacy and Tolerability of Miltefosine for Childhood Visceral Leishmaniasis in India

Miltefosine has previously been shown to cure 97% of cases of visceral leishmaniasis (VL) in Indian adults. Because approximately one-half of cases of VL occur in children, we evaluated use of the adult dosage of miltefosin (2.5 mg/kg per day for 28 days) in 80 Indian children (age, 2-11 years) with parasitologically confirmed infection in an open-label clinical trial. Clinical and parasitological parameters were reassessed at the end of treatment and 6 months later. One patient died of intercurrent pneumonia on day 6. The other 79 patients demonstrated no parasites after treatment, had marked clinical improvement, and were deemed initially cured. Three patients had relapse, and 1 patient was lost to follow-up. The final cure rate was 94% for all enrolled patients and 95% for evaluable patients. Side effects included mild-to-moderate vomiting or diarrhea (each in approximately 25% of patients) and mild-to-moderate, transient elevations in the aspartate aminotransferase level during the early treatment phase (in 55%). This trial indicates that miltefosine is as effective and well tolerated in Indian children with VL as in adults and that it can be recommended as the first choice for treatment of childhood VL in India.

Clinical features and diagnosis of 42 travellers with cutaneous leishmaniasis

BACKGROUND

Leishmania species that occur within different geographical areas may cause different clinical manifestations, virulence and drug sensitivity. Patients/Methods. All patients with a clinical diagnosis of cutaneous leishmaniasis seen at the Hospital for Tropical Diseases from 1997 to 2000 were identified and clinical details recorded onto a database, with emphasis on clinical presentation, risk factors, travel history and laboratory diagnosis.

RESULTS

Forty-two patients were identified, 23 of whom had travelled to New World and 19 to Old World countries. Clinical presentation typically consisted of a single nodule with ulceration. In 50% infection was caused by L. (Viannia) braziliensis. PCR was performed in specimens from 34 patients and species identification was possible in 32 cases (sensitivity 94%), the two PCR negative patients had amastigotes demonstrated by histology and culture. Patients were treated with established therapies. Seventy one percent were cured by treatment, 12% had a spontaneous cure, 7% were lost to follow-up and the remaining 10% required a second-line therapy. No relapses were reported during a mean follow-up period of 27 months.

CONCLUSIONS

Our study highlights the need for comprehensive investigations and the advantages of PCR in the diagnosis of patients with suspected leishmaniasis in non-endemic regions of the world.

Aminosidine and its combination with sodium stibogluconate in the treatment of diffuse cutaneous leishmaniasis caused by Leishmania aethiopica

Treatment of diffuse cutaneous leishmaniasis (DCL) caused by Leishmania aethiopica remains unsatisfactory as the parasite is relatively insensitive to antimonial compounds. Reports of the clinical effectiveness of aminosidine sulphate, especially in combination with sodium stibogluconate, in visceral leishmaniasis and the finding that this antibiotic is potent against L. aethiopica in vitro, prompted us to evaluate its usefulness in DCL. Two patients with long-standing, active DCL were treated for 60 d with aminosidine sulphate, 14 mg/kg/d parenterally. The skin lesions resolved completely in both patients although they relapsed subsequently. Synergism between aminosidine and stibogluconate was demonstrated in vitro against parasites isolated from the patients. This led us to administer combined therapy, aminosidine sulphate 14 mg/kg/d and sodium stibogluconate 10 mg/kg/d, to the 2 patients in relapse and to another, third patient. Treatment was continued for 2 months beyond parasitological cure. Side effects were minimal. Following treatment, a return of specific cell-mediated immunity occurred, as expressed by a moderate infiltration of lymphocytes into the lesions and by lymphocyte proliferation in vitro in the presence of live Leishmania antigen, with synthesis of interleukin-2 and interferon gamma with one patient and interleukin 4 with the other. During follow-up periods of 2 to 21 months after treatment, no sign of relapse was seen.

Miltefosine: issues to be addressed in the future

Future issues that need to be addressed for miltefosine are efficacy against non-Indian visceral leishmaniasis, efficacy in HIV-coinfected patients, efficacy against the many forms of cutaneous and mucosal disease, effectiveness under clinical practice conditions, generation of drug resistance and the need to provide a second antileishmanial agent to protect against this disastrous event, and the ability to maintain reproductive contraceptive practices under routine clinical conditions.

New World cutaneous leishmaniasis imported into Australia

A case of cutaneous leishmaniasis in a traveller from Belize, Central America is reported. Leishmaniasis presents rarely in Australia and delays in diagnosis and treatment often occur. A high index of suspicion in a patient who has returned from an endemic region is required. Subsequent confirmation of a diagnosis of cutaneous leishmaniasis is best achieved by demonstration of the organism on skin biopsy, aspiration or smear. The histology is variable and depends on geographic, parasite species and host factors. Speciation of New World disease as either Leishmania braziliensis or Leishmania mexicana is important to determine the risk of later development of mucosal disease, which normally only occurs with L. braziliensis infection, and for optimal treatment. Several different modes of treatment have been suggested, but antimonials, such as sodium stibogluconate, remain the treatment of choice in New World cutaneous leishmaniasis.

Leishmania infecting man and wild animals in Saudi Arabia. 8. The influence of prior infection with Leishmania arabica on challenge with L. major in man

A clinical trial is described of an attempt to protect against Leishmania major by prior vaccination with live L. arabica. After a single, previously leishmanin-negative, adult male volunteer was bitten by 8 Phlebotomus papatasi infected with L. arabica, no infected lesions were observed. He remained leishmanin-negative and his lymphocytes reacted weakly to antigens of L. arabica or L. major. Subsequently he and 3 other leishmanin-negative adult male volunteers were vaccinated with cultures containing 4 x 10(6) promastigotes of L. arabica. All remained leishmanin-negative but their lymphocytes showed some response to both L. arabica and L. major antigens. 96 d after vaccination these 4, and another, non-vaccinated, volunteer were challenged with 2 x 10(6) promastigotes of L. major. Active cutaneous, ulcerated lesions developed in all 5 volunteers. The lesions in 3 vaccinated volunteers were associated with marked lymphadenitis and beading, but the lesions started to heal spontaneously within 120-250 d after challenge. The lesion in the fourth vaccinated volunteer was less severe and lymphadenitis was not observed. The lesion in the unvaccinated subject developed more slowly and was smaller, but more chronic, than those in the vaccinated individuals. Marked cross-reactivity in terms of lymphocyte proliferation and interferon-gamma production was observed between L. major and L. arabica in both directions in subjects exposed first to one or the other organism. Although the procedure followed in this trial failed to give protection against L. major, further studies in volunteers should be considered.