Travelers with cutaneous leishmaniasis cured without systemic therapy.

BACKGROUND: Cutaneous leishmaniasis (CL) is a disfiguring but not life-threatening disease. Because antileishmanial drugs are potentially toxic, the World Health Organization (WHO) recommends simple wound care or local therapy as first-line treatment, followed or replaced by systemic therapy if local therapy fails or cannot be performed. METHODS: To determine the feasibility and impact of the recommended approach, we analyzed the results of a centralized referral treatment program in 135 patients with parasitologically proven CL. RESULTS: Infections involved 10 Leishmania species and were contracted in 29 different countries. Eighty-four of 135 patients (62%) were initially treated without systemic therapy. Of 109 patients with evaluable charts, 23 of 25 (92%) treated with simple wound care and 37 of 47 (79%) treated with local antileishmanial therapy were cured by days 42-60. In 37 patients with large or complex lesions, or preexisting morbidities, or who had not been cured with local therapy, the cure rate with systemic antileishmanial agents was 60%. Systemic adverse events were observed in 15 patients, all receiving systemic therapy. CONCLUSIONS: In this population of CL patients displaying variable degrees of complexity and severity, almost two-thirds of patients could be initially managed without systemic therapy. Of these, 60 were cured before day 60. The WHO-recommended stepwise approach favoring initial local therapy therefore resulted in at least 44% of all patients being cured without exposure to the risk of systemic adverse events. Efforts are needed to further simplify local therapy of CL and to improve the management of patients with complex lesions and/or preexisting comorbidities.

Phase 2 trial of WR6026, an orally administered 8-aminoquinoline, in the treatment of visceral leishmaniasis caused by Leishmania chagasi.

There are no recognized orally administered treatments for any of the leishmaniases. The 8-aminoquinoline WR6026 is an orally administered analog of primaquine that cured 50% of patients with kala-azar in Kenya at a dose of 1 mg/kg/day for 28 days. A further phase 2, open-label, dose-escalating safety and efficacy study was performed for kala-azar in Brazil. Cure rates for Brazilian patients treated for 28 days were as follows: 1 mg/kg/day: 0 of 4 (0%); 1.5 mg/kg/day: 1 of 6 (17%); 2.0 mg/kg/day: 4 of 6 (67%); 2.5 mg/kg/day: 1 of 5 (20%); and 3.25 mg/kg/day: 0 of 1 (0%). Nephrotoxicity that was not anticipated from preclinical animal studies or from phase 1 studies was seen at 2.5 mg/kg/day in 2 patients and in the single patient administered 3.25 mg/kg/day. WR6026 demonstrated the unusual clinical features of lack of increased efficacy against Brazilian kala-azar with increased dosing above 2 mg/kg/day and toxicity that was not present in previous investigations.

Malaria in Brazilian military personnel deployed to Angola.

BACKGROUND: Malaria represents one of the most important infectious disease threats to deployed military forces; most personnel from developed countries are nonimmune personnel and are at high risk of infection and clinical malaria. This is especially true for forces deployed to highly-endemic areas in Africa and Southeast Asia where drug-resistant malaria is common. METHODS: We conducted an outbreak investigation of malaria cases in Angola where a total of 439 nonimmune Brazilian troops were deployed for a 6-month period in 1995-1996. A post-travel medical evaluation was also performed on 338 (77%) of the 439 soldiers upon return to Brazil. Questionnaire, medical record, thick/thin smear, and serum anti-Plasmodium falciparum antibody titer (by IFA) data were obtained. Peak serum mefloquine (M) and methylmefloquine (MM) metabolite levels were measured in a subsample of 66 soldiers (42 cases, 24 nonmalaria controls) who were taking weekly mefloquine prophylaxis (250 mg). RESULTS: Seventy-eight cases of malaria occurred among the 439 personnel initially interviewed in Angola (attack rate = 18%). Four soldiers were hospitalized, and 3 subsequently died of cerebral malaria. Upon return to Brazil, 63 (19%) of 338 soldiers evaluated were documented to have had clinical symptoms and a diagnosis of malaria while in Angola. In addition, 37 (11%) asymptomatically infected individuals were detected upon return (< 1% parasitemia). Elevated, post-travel anti-P. falciparum IFA titers (> or = 1:64) were seen in 101 (35%) of 292 soldiers tested, and was associated with a prior history of malaria in-country (OR = 3.67, 95% CI 1.98-6.82, p <.001). Noncompliance with weekly mefloquine prophylaxis (250 mg) was associated with a malaria diagnosis in Angola (OR = 3.75, 95% CI 0.97-17.41, p =.03) but not with recent P. falciparum infection (by IFA titer). Mean peak levels (and ratios) of serum M and MM were also found to be lower in those who gave a history of malaria while in Angola. CONCLUSIONS: Malaria was a significant cause of morbidity among Brazilian Army military personnel deployed to Angola. Mefloquine prophylaxis appeared to protect soldiers from clinical, but not subclinical, P. falciparum infections. Mefloquine noncompliance and an erratic chemoprophylaxis prevention policy contributed to this large outbreak in nonimmune personnel. This report highlights the pressing need for development of newer, more efficacious and practical, prophylactic drug regimens that will reduce the malaria threat to military forces and travelers.

Successful topical treatment of murine cutaneous leishmaniasis with a combination of paromomycin (Aminosidine) and gentamicin.

Cutaneous leishmaniasis is presently treated with 20 days of parenteral therapy with a frequently toxic drug (antimony). Topical formulations of paromomycin (15%) plus methylbenzethonium chloride (MBCL, 12%) or plus urea (10%) in soft white paraffin have been tested for Old and New World disease in humans. We compared the efficacy of a new topical formulation, WR 279,396 (paromomycin [15%] plus gentamicin [0.5%]) to the clinical formulations in the treatment of cutaneous disease in BALB/c mice. Sixty-day-old lesions were treated twice a day for 10 days, and the response to therapy was determined over a further 70 days. For ulcers due to Leishmania major or to Leishmania mexicana, 100% of lesions in the WR 279,396 group healed by day 20 after therapy and did not relapse by day 70; 83% of lesions healed without relapse in the paromomycin-MBCL group. In the paromomycin-urea group, 100% of L. major lesions healed by day 30 but 30% relapsed. For ulcers due to Leishmania panamensis or Leishmania amazonensis, all lesions treated with WR 279,396 healed and did not relapse; < 50% of lesions treated with paromomycin-MBCL healed by day 30, and all lesions relapsed by day 70. In addition to being active, WR 279,396 was not toxic in this model and appears to have a cosmetic effect (promoting hair growth, healing, and limiting the size of the scar).

Humoral immune responses among mucosal and cutaneous leishmaniasis patients caused by Leishmania braziliensis.

Mucosal leishmaniasis is arguably the most morbid sequelae of cutaneous leishmaniasis. The importance of early diagnosis for effective therapy, coupled with the difficulty of diagnosing the disease parasitologically, prompted this investigation of humoral immune markers of mucosal disease. Promastigote soluble antigens of Leishmania braziliensis, isolated from cutaneous and mucosal lesions, were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis; antigens were identified by immunoblotting with parasite-specific IgG antibody-positive sera of patients with mucosal disease (n = 18) and cutaneous disease (n = 23). For antigens of the cutaneous parasite WR 2095, mucosal sera generally reacted intensely to antigens of 75, 66, and 45 kDa and weakly to 48-50-kDa antigens, whereas cutaneous sera generally detected weakly the first 3 antigens and intensely the latter doublet. The data suggest that the transition from the cutaneous antigenic profile to a mucosal antigenic profile could be used to predict mucosal disease in approximately half of mucosal patients. An additional finding was that antibodies present in the sera of patients with mucosal disease labeled a 66-kDa peptide of normal human lip mucosa more intensely than did cutaneous sera. Autoimmune processes stimulated by the reaction of IgG, originally directed against the 66-kDa of L. braziliensis, to the 66-kDa antigen of mucosal tissue may contribute to the clinical presentation of mucosal leishmaniasis.

Safety and efficacy of intravenous sodium stibogluconate in the treatment of leishmaniasis: recent U.S. military experience.

The efficacy and toxicity of sodium stibogluconate (SSG) at a dosage of 20 mg/(kg.d) for either 20 days (for cutaneous disease) or 28 days (for visceral, mucosal, or viscerotropic disease) in the treatment of leishmaniasis is reported. Ninety-six U.S. Department of Defense health care beneficiaries with parasitologically confirmed leishmaniasis were prospectively followed for 1 year. One patient was infected with human immunodeficiency virus; otherwise, comorbidity was absent. Clinical cure occurred in 91% of 83 cases of cutaneous disease and 93% of 13 cases of visceral/viscerotropic disease. Adverse effects were common and necessitated interruption of treatment in 28% of cases, but they were generally reversible. These included arthralgias and myalgias (58%), pancreatitis (97%), transaminitis (67%), headache (22%), hematologic suppression (44%), and rash (9%). No subsequent mucosal leishmaniasis was identified, and there were no deaths attributable to SSG or leishmaniasis.

An axenic amastigote system for drug screening.

Currently available primary screens for selection of candidate antileishmanial compounds are not ideal. The choices include screens that are designed to closely reflect the situation in vivo but are labor-intensive and expensive (intracellular amastigotes and animal models) and screens that are designed to facilitate rapid testing of a large number of drugs but do not use the clinically relevant parasite stage (promastigote model). The advent of successful in vitro culture of axenic amastigotes permits the development of a primary screen which is quick and easy like the promastigote screen but still representative of the situation in vivo, since it uses the relevant parasite stage. We have established an axenic amastigote drug screening system using a Leishmania mexicana strain (strain M379). A comparison of the 50% inhibitory concentration (IC50) drug sensitivity profiles of M379 promastigotes, intracellular amastigotes, and axenic amastigotes for six clinically relevant antileishmanial drugs (sodium stibogluconate, meglumine antimoniate, pentamidine, paromomycin, amphotericin B, WR6026) showed that M379 axenic amastigotes are a good model for a primary drug screen. Promastigote and intracellular amastigote IC50s differed for four of the six drugs tested by threefold or more; axenic amastigote and intracellular amastigote IC50s differed by twofold for only one drug. This shows that the axenic amastigote susceptibility to clinically used reference drugs is comparable to the susceptibility of amastigotes in macrophages. These data also suggest that for the compounds tested, susceptibility is intrinsic to the parasite stage. This contradicts previous hypotheses that suggested that the activities of antimonial agents against intracellular amastigotes were solely a function of the macrophage.

Inefficacy of allopurinol as monotherapy for Colombian cutaneous leishmaniasis. A randomized, controlled trial.

BACKGROUND: Hundreds of thousands of cases of cutaneous leishmaniasis occur each year worldwide. Available therapies are parenteral, moderately toxic, and costly. OBJECTIVE: To determine the efficacy of and tolerance for oral allopurinol as monotherapy for cutaneous leishmaniasis. DESIGN: Randomized, controlled trial. SETTING: Outpatient clinics in 11 regions of Colombia in which cutaneous leishmaniasis is endemic. PATIENTS: 187 otherwise healthy adults with cutaneous leishmaniasis. Eighty-four percent of patients were infected with or were from regions with Leishmania panamensis; 16% were infected or were from regions with L. braziliensis. INTERVENTION: Patients were randomly assigned to one of three treatment groups. The first group received allopurinol, three 100-mg tablets four times daily (20 mg/kg of body weight per day) for 28 days. The second group received three placebo tablets four times daily for 28 days. The third group received Glucantime, 20 mg of intramuscular antimony/kg per day for 20 days. MEASUREMENT: Complete cure was defined as complete clinical reepithelialization of all lesions at 3 months and no relapse during 12 months of follow-up. RESULTS: Of 182 patients whose data could be analyzed, 157 (86%) were evaluated. In the allopurinol group, 18 of 55 (33% [95% CI, 21% to 47%]) patients were cured; in the placebo group, 17 of 46 patients (37% [CI, 23% to 52%]) were cured (difference, 4% [CI, -14% to 22%]; P = 0.68); and in the Glucantime group, 52 of 56 patients (93% [CI, 83% to 98%]) were cured (P < 0.001 compared with the allopurinol and placebo groups combined). In most cases, therapy was considered to have failed because the lesion did not reepithelialize by 1.5 months after the end of therapy. Three cases of relapse (two in the allopurinol group and one in the placebo group) at the nasal mucosa (mucosal leishmaniasis) had occurred by the end of 12 months of follow-up. CONCLUSIONS: Allopurinol monotherapy has no effect on Colombian cutaneous disease primarily caused by L. panamensis and therefore is unlikely to be effective against cutaneous leishmaniasis in other endemic regions.

Leishmania spp: temperature sensitivity of promastigotes in vitro as a model for tropism in vivo.

Since in humans, skin temperature is lower than internal temperature, the temperature sensitivity of Leishmania may influence the tropism of Leishmania in the human host; temperature-sensitive parasites may remain in the skin, temperature-resistant parasites may go to the viscera. In order to pursue the genetic factors controlling Leishmania tropism, we have developed an in vitro promastigote temperature model. Promastigote growth is measured at 30, 32, and 34 degrees C and compared with growth at the control temperature (25 degrees C). The results from tests of the promastigote temperature sensitivity of eight species (33 different strains) show that visceral species (L. donovani and L. chagasi) are more temperature resistant than cutaneous species (L. major, L. tropica, L. mexicana, L. braziliensis, L. panamensis, and L. amazonensis), that Old World species are more temperature-resistant than New World species, and that within the New World cutaneous species there are three distinct temperature sensitivity groupings (L. mexicana > L. braziliensis and L. panamensis > L. amazonensis). Interestingly, viscerotropic L. tropica from Operation Desert Storm and L. donovani complex strains isolated from cutaneous lesions are more and less temperature-sensitive, respectively, than strains of the same species with the expected tropism in vivo.

Microtubule inhibitors: structure-activity analyses suggest rational models to identify potentially active compounds.

Trifluralin, a dinitroaniline microtubule inhibitor currently in use as an herbicide, has been shown to inhibit the proliferation of Plasmodium falciparum, Trypanosoma brucei, and several species of Leishmania, in vitro. As a topical formulation, trifluralin is also effective in vivo (in BALB/c mice) against Leishmania major and Leishmania mexicana. Although trifluralin and other dinitroaniline herbicides show significant activity as antiparasitic compounds, disputed indications of potential carcinogenicity will probably limit advanced development of these substances. However, researchers have suggested that the activity of trifluralin is due to an impurity or contaminant, not to trifluralin itself. We have pursued this lead and identified the structure of the active impurity. This compound, chloralin, is 100 times more active than trifluralin. On the basis of its structure, we developed a rational structure-activity model for chloralin. Using this model, we have successfully predicted and tested active analogs in a Leishmania promastigote assay; thus, we have identified the putative mechanism of action of this class of drugs in Leishmania species. Potentially, this will allow the design of noncarcinogenic, active drugs.

Efficacy of the herbicide trifluralin against four P-glycoprotein-expressing strains of Leishmania.

Drug resistance has emerged as a major obstacle to chemotherapy for many infectious diseases. Trifluralin, an antimicrotubule herbicide, is a new experimental drug for treatment of leishmaniasis. Here, we found that it was effective against two strains of Leishmania that express the multidrug-resistant genes ldmdr1 and lmpgpA and two strains that express proteins that are immunologically cross-reactive with mammalian P glycoproteins. These results suggest that trifluralin is not subject to counteractions of these multidrug resistance mechanisms of Leishmania species.

Evaluation of a direct immunofluorescent antibody (DIFMA) test using Leishmania genus-specific monoclonal antibody in the routine diagnosis of cutaneous leishmaniasis.

A direct immunofluorescent antibody (DIFMA) test using a Leishmania genus-specific monoclonal antibody was evaluated in the routine diagnosis of cutaneous leishmaniasis (CL) in Ecuador. This test was compared with the standard diagnostic techniques of scrapings, culture and histology. Diagnostic samples were taken from a total of 90 active dermal ulcers from patients from areas of Ecuador known to be endemic for cutaneous leishmaniasis. DIFMA was positive in all lesions. It was shown to be significantly superior to standard diagnostic methods either alone or in combination. The sensitivity of DIFMA did not diminish with chronicity of lesions. This test proved to be extremely useful in the routine diagnosis of CL because it is highly sensitive, is easy to use and produces rapid results.

Diagnosis of symptomatic visceral leishmaniasis by use of the polymerase chain reaction on patient blood.

To diagnose symptomatic visceral leishmaniasis (kala-azar) using peripheral blood rather than tissue aspirates, a polymerase chain reaction (PCR) technique was developed for which the detection limit is 1 Leishmania-infected macrophage in 8 mL of blood. For Indian, Kenyan, or Brazilian patients with parasitologically confirmed kala-azar, 57 of 63 cases before treatment had blood that was PCR-positive (90% sensitivity). None of 40 clinically healthy persons had PCR-positive blood (100% specificity). Twelve (92%) of 13 clinically cured Indian patients had negative PCR reactions 1-6 months after treatment. This PCR procedure can provide a parasitologic diagnosis for the vast majority of kala-azar cases before therapy, may identify patients who have been successfully treated by chemotherapy, and should substantially reduce the need for invasive tests.

Successful treatment of New World cutaneous leishmaniasis with a combination of topical paromomycin/methylbenzethonium chloride and injectable meglumine antimonate.

Colombian patients with New World cutaneous leishmaniasis were treated with a combination of a topical formulation (15% paromomycin sulfate/5% methylbenzethonium chloride, twice a day) and parenteral meglumine antimonate (20 mg of antimony [Sb]/kg.d]). Cohort 1 received topical therapy for 10 days and Sb for 7 days; 18 (90%) of the 20 patients were cured (follow-up, 12 months). Other clinical data suggested that neither the topical formulation alone nor the 7-day regimen of Sb alone would have cured many patients. In a subsequent cohort, which received topical therapy for 10 days and Sb for 3 days, the cure rate was 42% (eight of 19 patients). In Colombian cohorts (historical controls) treated with Sb alone for 10-15 days, the cure rate was 31%-36%. Side effects in cohort 1 patients consisted of local reactions to the topical formulation: burning and pruritus in 25% of patients and vesicle formation in 15% of patients. This is the first report that a regimen partially composed of topical antimicrobial agents can be highly effective for treatment of New World cutaneous leishmaniasis.

Paromomycin resistance in Leishmania tropica: lack of correlation with mutation in the small subunit ribosomal RNA gene.

The aminoglycoside antibiotic paromomycin is a potentially useful anti-leishmanial chemotherapeutic agent. Resistance to this antibiotic was studied using Leishmania tropica. Promastigotes resistant to 210 micrograms/ml of paromomycin were selected by exposing them to gradual increments of this drug. Previous work in Escherichia coli, Tetrahymena, and yeast mitochondrial mutants has demonstrated mutations in the E. coli small subunit ribosomal RNA at the 1409:1491 basepair position, or equivalent positions in other organisms, resulting in basepair disruption. When the nucleotide sequence at both the DNA and RNA levels of the resistant L. tropica promastigotes cultured in the presence of paromomycin was compared with those of the drug-sensitive parent, there was no sequence change at the putative mutation site. Paromomycin resistance in L. tropica is apparently due to other mechanisms.

Limited efficacy of injectable aminosidine as single-agent therapy for Colombian cutaneous leishmaniasis.

Ninety military patients with cutaneous leishmaniasis in Colombia were randomly allocated to 3 treatment regimens of parenteral aminosidine sulphate: (i) 12 mg aminosidine base/kg/d for 7 d, (ii) 12 mg/kg/d for 14 d, and (iii) 18 mg/kg/d for 14 d. With the 89 evaluable patients, the cure rates 12 months after the end of treatment were 10%, 45%, and 50%, respectively. Fifty-eight of the 66 patients who were not cured had lesions that enlarged or were unchanged by 1.5 months after treatment follow up. The other 8 patients had lesions that relapsed between 3 and 12 months after therapy. Even in group (iii) the cure rate was inferior to that (> 90%) with antimony or pentamidine previously reported in this patient population. This study indicates that parenteral aminosidine alone is less likely to be successful in the treatment of cutaneous lesihmaniasis than visceral leishmaniasis, for which a 74% cure rate has been reported. Further trials might consider the combination of aminosidine with other antileishmanial drugs.

Evidence of sexual reproduction in the protozoan parasite Leishmania (Kinetoplastida: Trypanosomatidae).

Parasitic protozoa of the genus Leishmania (Kinetoplastida: Trypanosomatidae) are generally thought to multiply by binary fission; however, data from quantitative microspectrophotometry indicate that nuclear fusion or sexual reproduction takes place in the intracellular amastigote form. Among several different Leishmania species, the mean +/- SD nuclear DNA content of all promastigotes (extracellular form) and of some amastigotes (intracellular form) in macrophages was 0.098 +/- 0.032 relative units; in contrast, other amastigotes within the same macrophage had a mean +/- SD nuclear DNA content of 0.219 +/- 0.050. The latter population of amastigotes are apparently produced when the nuclei of a pair of 0.098 amastigotes fuse. These 0.219 amastigotes later go through what is probably the typical meiotic cycle to reform the 0.098 condition we observed among promastigotes. The demonstration of sexual reproduction in Leishmania has important implications for the future direction of research on this medically important parasite.

Pancreatitis induced by pentavalent antimonial agents during treatment of leishmaniasis.

Pentavalent antimony (Sbv), formulated as sodium stibogluconate or meglumine antimoniate, is the standard treatment for the leishmaniases. In 16 of 17 consecutive, prospectively observed patients in Washington D.C., serum levels of amylase and lipase rose to abnormal values after therapy with sodium stibogluconate was started; 12 of 17 had symptoms of pancreatitis. Sbv therapy was continued to completion in 7 of 17 patients and interrupted in 10 of 17. Pancreatitis improved in every patient after Sbv therapy was stopped. Sbv treatment was resumed after brief interruptions in 6 of 10 patients. All six of these patients had flares of pancreatitis, but each completed therapy. Subsequently, we measured amylase and lipase levels in stored sera from 32 patients treated in Peru with either sodium stibogluconate or meglumine antimoniate for mucosal leishmaniasis. In all 32 Peruvian patients, serum amylase and lipase rose to abnormal levels during Sbv therapy; 11 of 32 had symptoms of pancreatitis. Standard Sbv regimens induce pancreatitis in almost all patients, but continued therapy is often tolerated; pancreatitis subsides when therapy is stopped, and rechallenge may be tolerated after a brief halt in treatment.