data indicating a 31% efficacy in northwest Colombia. 6

Transcription

1 Am. J. Trop. Med. Hyg., 64(3, 4), 2001, pp Copyright 2001 by The American Society of Tropical Medicine and Hygiene TREATMENT FAILURE IN CHILDREN IN A RANDOMIZED CLINICAL TRIAL WITH 10 AND 20 DAYS OF MEGLUMINE ANTIMONATE FOR CUTANEOUS LEISHMANIASIS DUE TO LEISHMANIA VIANNIA SPECIES RICARDO PALACIOS, LYDA ELENA OSORIO, LUIS FERNANDO GRAJALES, AND MARÍA TERESA OCHOA Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia Abstract. Clinical response to supervised treatment of Colombian patients with cutaneous leishmaniasis was evaluated in a randomized controlled trial comparing 10 days versus 20 days of treatment with meglumine antimonate (20 mg Sb/kg/day). Masked examiners evaluated clinical response defined as 100% re-epithelialization of all lesions at 13 weeks and no relapses during 52 weeks of follow-up. The efficacy of meglumine antimonate for 10 days treatment was 61% (28 of 46) compared to 67% (24 of 36) for 20 days. There was a significantly lower clinical response for children 5 years in both 10-day (11%) and 20-day (25%) groups compared to patients aged 5 14 years (67% and 75%, respectively) and 15 years or more (81% and 83%, respectively). Overall efficacy of treatment schedules was comparable, but lower than expected, mainly because of low efficacy in children. Pathogenicity of infection and pharmacokinetics may affect the treatment response in children. New therapeutic alternatives should be evaluated in trials that include children and women. INTRODUCTION 187 In the New World, more than thirty-nine million people are at risk for cutaneous leishmaniasis and the estimated annual number of cases of this vector-borne disease is approximately 60, Most of these cases are due to species of the Leishmania Viannia subgenus. Systemic treatment is recommended for cutaneous leishmaniasis caused by Leishmania of this subgenus because of the risk of metastasis and mucosal involvement. Pentavalent antimonial compounds, pentamidine isethionate, and amphotericin B, are the currently available drugs with proven efficacy. Pentavalent antimonials have been the first-line therapy for cutaneous leishmaniasis since 1947, 2 in part because of the risk of more serious or irreversible toxicity with amphotericin B and pentamidine. Nevertheless, frequent adverse effects, parenteral route of administration (IV or IM), and the expense of the drug contribute to a high frequency of non-adherence to the current recommended treatment of 20 mg Sb/kg/d for 20 days. Daily doses less than 20 mg Sb/kg/d for days have shown a lower efficacy in previous clinical trials. 3 The logistic and economic impossibility of universal availability of the recommended dose for all patients in disease endemic countries and evidence of differing sensitivities of Leishmania species have motivated the evaluation of alternative regimens. 4 Reduction in the daily dose with a longer period of administration has been evaluated with success in Brazil. 5 However, a reduction in the duration of treatment, rather than in the daily dose, could decrease adverse effects, as well as the number of contacts with medical personnel, thereby improving adherence and lowering costs. In this regard, Arana and others reported 90% efficacy using ten days of antimonial therapy in Guatemala for lesions caused by Leishmania (Viannia) braziliensis in young male soldiers. 4 In addition, in a pilot study conducted by our group in the Colombian Pacific coast area, a 100% cure rate was achieved in 10 adult patients infected in areas where Leishmania (Viannia) panamensis predominates (Ochoa MT, unpublished data). However, Soto and others cited a report of historical data indicating a 31% efficacy in northwest Colombia. 6 The present investigation sought to determine whether 10 days of treatment with 20 mg Sb/kg/d had an efficacy comparable to that of 20 days with the same dosage (i.e., no greater than 25% reduction in efficacy) for the supervised treatment of patients infected in endemic areas for cutaneous leishmaniasis where L. (V.) panamensis is the predominant species. In order to address this question taking into consideration the patient profile of endemic areas, women and children were included in the trial and supervised treatment was achieved with the participation and training of health volunteers recruited from the affected communities. MATERIALS AND METHODS Patients. Patients consulting the clinical facilities of the Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM) in Cali and Tumaco from April 1996 to March 1997 and who had a parasitological diagnosis of cutaneous leishmaniasis were invited to participate in the study. Tumaco is an endemic area on the Colombian Pacific Coast where most of recruited patients live in rural areas. Cali is the largest city in the southwestern region, and patients residing in non-endemic areas are often referred to Cali for diagnostic tests and medical attention. Patients who had been treated previously with antimonials, ketoconazole, or another imidazole, amphotericin B or pentamidine, as well as those with mucosal leishmaniasis, severe cardiovascular, renal, hepatic, or pancreatic disease, and pregnant or nursing women were excluded from the trial. After explaining the purpose, potential risks and benefits and voluntary nature of participation, signed consent was obtained from each patient or from the guardian in the case of children less than 18 years of age. All protocols were reviewed and approved by the Institutional Review Board of CIDEIM in accordance with the guidelines of the United States Federal Policy for Protection of Human Subjects (Title 45, Code of Federal Regulations, Part 46) and the Colombian Ministry of Health.

2 188 PALACIOS AND OTHERS Direct smear, culture of aspirates, and a skin biopsy of the skin lesions, histopathology, and hamster inoculation were used for parasitological diagnosis and parasite isolation as described elsewhere. 7 The area of each lesion was calculated by multiplying its longest horizontal and perpendicular axes. 8 Parasites were identified by species using monoclonal antibodies 9 and/or isoenzyme analysis. 10 After medical examination, patients who were eligible and agreed to participate in the study were randomized to 10 or 20 days of treatment. The assignment process was performed using permuted block randomization. 11 Meglumine antimonate was prescribed according to the current recommendations of the Pan-American Health Organization/World Health Organization (PAHO/WHO), and the Ministry of Health of Colombia at a dosage of 20 mg Sb/Kg/day with no upper limit on the daily dose. 12 Treatment was applied intramuscularly, once a day during 10 or 20 days depending on the study group. The Ministry of Health of Colombia provided the meglumine antimonate (Glucantime, Rhone Poulenc-Rorer, France) and only two lots of drugs (312-2 and 312-3) were utilized. Due to the ethical considerations of applying a placebo by intramuscular injection over 10 days, the administration of treatment was not masked. Before the trial began, the research team trained health volunteers from the community of Tumaco in the administration of intramuscular injection. Thereafter, these volunteers applied the treatment to patients in their communities. Supervision of treatment was achieved by regular periodic visits by research personnel and a record of the daily dose administered to each patient signed by the corresponding volunteer. Each registry was reviewed at the end of the treatment and compared with the number of ampoules (empty or full) that were returned. In Cali, the treatment was administered by the physician in charge of the clinic and supervised by the use of a signed registry as in Tumaco. In order to define clinical response, all patients were clinically evaluated at 13, 26, and 52 weeks after initiation of treatment by a physician other than the one prescribing treatment and who was masked with respect to which study group the patient belonged. The response was classified at 13 weeks after the beginning of therapy as initial clinical response if the patient had complete re-epithelialization and absence of inflammatory signs of all lesions. Those patients with initial clinical response and no relapses of lesions between 13 and 52 weeks of follow-up were classified as having a final clinical response. Otherwise, the response was considered as a clinical failure. The adverse effects of antimonials were monitored over the treatment period using a structured questionnaire. Study personnel or health volunteers questioned patients about the presence of malaise, headache, myalgias, arthralgias, and anorexia. No laboratory tests were performed to evaluate toxicity of the treatments. Patients in either group who were classified as a clinical failure received a new treatment with meglumine antimonate at the same dose for 20 days. Two cultures of aspirates from the scars (initial clinical response) or active lesions (clinical failure) were performed at week 13 of follow-up for the evaluation of parasitological response. The sample size to detect a 25% or greater difference in efficacy between the 10- and 20-day treatment groups with a 95% confidence level and a beta error of 20% was 42 patients per group. A 25% difference was considered clinically significant, taking into account the potential benefits of a 10-day treatment as opposed to 20 days, the high efficacy of pentavalent antimonials reported in the literature for the treatment of New World cutaneous leishmaniasis (88 100%) 5,8,13 16 and the 100% cure we obtained in a previous pilot study involving 10 adult patients treated with meglumine antimonate for 10 days (Ochoa MT, unpublished data). The number of participants in the total study population was increased to 136 to compensate for the expected loss to follow-up. If the amount of drug that a patient received was 10% above or 10% below the target dosage of 20 mg Sb/kg/d, the dose was considered inadequate. Patients who received doses in a period longer than 12 days in the 10-dose group or 25 days in the 20-dose group, were considered non-adherent to treatment. Patients who received an inadequate dose or who were non-adherent to treatment as described above, or who missed the 13 th week follow-up (analysis of initial response), and/or the 52-week follow-up (final response) were excluded from the efficacy analysis. A cutaneous lesion was considered new if located in a site different from the initial lesion and distant from its lymphatic drainage. 17 Patients presenting a new parasitologically-confirmed cutaneous leishmaniasis lesion during the follow-up were also excluded. Non-adherent patients and those who missed follow-up examinations were, however, included as clinical failures in our analysis of minimal effectiveness. Data analysis was performed using SPSS 7.5 for Windows 1996 (SPSS Inc., Chicago, IL). The proportion of therapeutic response and its 95% confidence intervals were compared between groups. A chi-square test and a Fisher exact test were used for the comparison of categorical data. Comparison of two groups by no normally distributed continuous data was performed using non-parametric test (Mann-Whitney U test). For all the tests, P values less than 0.05 were considered statistically significant. RESULTS One hundred and thirty-six patients of 191 eligible individuals were enrolled in the study. Nine patients were recruited in Cali (7%) and 127 in Tumaco (93%). Reasons for ineligibility and the process of enrollment and follow-up of patients are shown in Figure 1. Sixty-eight patients were randomized to each study group. The two groups were comparable in sociodemographic and principal clinical characteristics, although patients randomized to receive 20 days of treatment bore lesions with median areas that were significantly larger and had less frequent regional adenopathies than patients who received 10 days of treatment. The 136 patients had a total of 321 cutaneous lesions (Table 1). Of the 136 patients randomized initially, 56 (41%) were not included in the efficacy analysis: six received an inadequate dose, 32 were non-adherent to treatment, 13 did not return for the 13-week follow-up examination, and three did not return for the 52-week evaluation (Figure 1). A total of 46 patients in the 10-day group and 36 in the 20-day group were analyzed for final response. Patients not included in the

3 LOW RESPONSE TO MEGLUMINE ANTIMONATE IN CHILDREN 189 FIGURE 1. Trial profile efficacy analysis did not differ in sociodemographic and principal clinical characteristics from those analyzed. The efficacy of meglumine antimonate for the 10-day treatment regimen was 62% (29 of 47) at the 13 th week evaluation and 61% (28 of 46) at the 52 nd week of follow-up. The initial response was 71% for the 20-day treatment regimen (27 of 38) and the final response 67% (24 of 36). There was not a significant difference between groups in the efficacy analysis at the initial or final response. The 95% confidence interval of the difference between the final clinical response of the 10-day and 20-day groups includes zero ( to 0.134). As shown in Figure 2, confidence intervals of response to treatment in both groups were wide and overlapped. When we included those patients who were lost to followup or non-adherent with the medication, the calculated minimum effectiveness for 10 days of meglumine antimonate was classified as initial clinical response in 56% (38 of 68) of patients and as final clinical response in 46% (31 of 68). In the 20-day group the initial clinical response was observed in 65% (44 of 68) of patients, but decreased to 57% (39 of 68) in the evaluation of final response. In order to identify possible risk factors for treatment failure, comparisons between patients who failed and those who responded to treatment were performed in the 10-day and 20-day groups. A significant difference in final clinical response rates was observed between children under 5 years for both 10 days (11%, n 9) and 20 days (25%, n 8) of treatment as compared with children from 5 to 15 years TABLE 1 Demographic and clinical characteristic of the randomized patients 10-day course n 68 (%) 20-day course n 68 (%) P value (10 versus 20 days) Gender Male 40 (58.8) 36 (52.9) 0.49 Female 28 (41.2) 32 (47.1) Race Black Indigenous Mestizo White 42 (61.8) 17 (25.0) 9 (13.2) 0 45 (66.2) 15 (22.1) 6 (8.8) 2 (2.9) Weight (kg) Age (years) Median Median (22.2) 29 (42.6) 13 (19.1) 8 (11.8) 3 (4.4) (25.0) 25 (36.8) 16 (23.5) 5 (7.4) 4 (5.9) Residence in endemic area Age of lesion (months) Yes Median (91.2) 2 38 (56) 21 (31) 3 (4) 6 (9) 58 (85.3) 2 44 (65) 17 (25) 4 (6) 3 (4) Lesions Total Number per patient (median) Lesion characteristics Ulcer Plaque Nodule Papule Regional adenopathy Satellite lesion Area (median) 119 (71) 29 (17) 10 (6) 8 (5) 35 (29) 39 (23) mm (77) 21 (14) 9 (5) 5 (4) 27 (17) 45 (29) mm * * Meglumine antimonate prescribed dose Median (mg Sb/kg/day) * P 0.05

4 190 PALACIOS AND OTHERS FIGURE 2. Initial and final clinical response to treatment with meglumine antimonate in the ten- and twenty-day treatment groups. FIGURE 3. Clinical response to treatment with ten and twenty days of meglumine antimonate by age groups. (67%, n 21, P for 10 days and 75%, n 16, P for 20 days) and with patients older than 15 years (81%, n 16, P for 10 days and 83%, n 12, P for 20 days group) (Figure 3). This difference was also found using the minimum effectiveness calculated as described above in the 10-day group ( 5 years; 7% versus 5 to 14 years: 53%, P and versus 15 years or more 61%, P ) and the 20-day group ( 5 years: 24% versus 5 to 14 years: 68%, P and versus 15 years or more 69%, P 0.004). Statistically significant differences were not detected in the number of lesions (1 or 2 versus 3 or more), time of evolution (0 3 months and 3 months), localization, total area of lesions, lot of drug, or gender. Lesions of all the patients with treatment failure at the week 13 evaluation had substantially improved and healed after the second course of treatment schedule with 20 days of meglumine antimonate. Parasite isolates obtained from 88 cultures were identified. Most cases (84) were due to L. (V.) panamensis. Leishmania (V.) braziliensis was identified in 4 cases. Of 38 who were not completely healed at 13 weeks, 8 (21%) had a positive culture of the aspirate obtained at 13 weeks. One patient was culture-positive among 68 who were completely healed by 13 weeks and did not have a cutaneous or mucosal recurrence by 52 weeks of follow-up and who had their scars aspirated. The most frequent adverse reactions in both the 10-day and 20-day groups were anorexia (25%), headache (25%), myalgias (24%), and malaise (23%) without statistically significant differences between groups. In contrast, arthralgias were significantly more frequent (P 0.021) in patients who were treated for 20 days with meglumine antimonate (25%) than those who were treated for 10 days (9%). No patient stopped treatment because of adverse effects (Figure 4). DISCUSSION It is logistically challenging to conduct clinical trials in endemic areas for leishmaniasis that take into account the facilities available to the community and health system, as FIGURE 4. Rate of adverse effects with meglumine antimonate in patients with adherence to treatment for 10- and 20-dose groups. The lines represent the 95% confidence interval.

5 LOW RESPONSE TO MEGLUMINE ANTIMONATE IN CHILDREN 191 well as the gender and age composition of the patient population. Ambulatory treatment is the rule in endemic areas and non-adherence is a high risk both outside and within the framework of a clinical trial. The results of this study underscore the advantage of conducting clinical trials in the endemic communities with the affected population. The overall low efficacy of pentavalent antimonials in this population and the relationship of age with poor clinical response would not have been detected in the adult male populations usually recruited for efficacy studies. 5,8,13,15,16 This study was designed as a two-arm active-medicine clinical trial because the use of placebo was considered unethical in view of the risk of mucosal or cutaneous relapses reported previously in the area. 17 The results did not reveal significant differences in efficacy between 10 and 20 days of supervised treatment with 20 mg Sb/kg/d. However, this does not imply that both treatment schedules have the same effect because there is no test to establish that a statistically significant similarity exists. 11 Clinical response is considered to be the main indicator of the therapeutic response in New World cutaneous leishmaniasis because of the lack of concordance between the parasitological and clinical response to treatment in this trial and other studies in which viable parasites have been isolated from healed lesions. 14,15,18 The role of these parasites in the reactivation of lesions or metastasis 17 and as a source of infection in a putative anthroponotic cycle of the Leishmania Viannia 19 are issues that need to be elucidated through experiments to demonstrate the availability of the parasite in infected humans. Comparing our data with other trials conducted in patients with New World cutaneous leishmaniasis, the response rate observed in this study for ten days of treatment with meglumine antimonate was higher (i.e., 31%, noted by Soto and others in Urabá, in northwest Colombia n 26, 95% CI, 15 52%); however, the sociodemographic characteristics of the patients included in that study were not described. 6 On the other hand, the unexpectedly low response to the recommended dose and duration of therapy using pentavalent antimonials in our study merits special attention. Published efficacy trials of pentavalent antimonial drugs using a regimen of 20 mg Sb/kg/d for 20 days in Colombia and the Americas, have documented an efficacy of 88 to 100% for the treatment of cutaneous leishmaniasis caused by species of the Leishmania Viannia subgenus. 5,8,13 16,20 One group in the Colombian southwest and close to our study area, reported efficacy of meglumine antimonate with a 15-day regimen, to be 40%, 21,22 and close to the 36 37% efficacy of placebo reported by other investigators in other areas of Colombia. 8,20 All of these trials have involved young-adult populations primarily. Our study, in contrast, included a high proportion of children (39.7% aged 5 to 14 years, 23.5% 5 years). The age distribution of the study participants reflects the high incidence (28.7 cases/10,000 population 5 years versus 13.7 cases/10,000 general population in 1996, Palacios R, unpublished data) of clinically apparent infection in this age group during this period in the study site, the municipality of Tumaco. A previous study in this area showed that younger age is associated with higher pathogenicity. 23 Children younger than 5 years of age had a particularly poor treatment response (10 days: 11%, 20 days: 25%), while the adults responded within the low end of the range reported in other studies. The high proportion of children in this study clearly influenced the observed efficacy, and we believe that this finding merits further investigation. The factors that account for these results may be related to the drug, the parasite, and the host. In relation to the drug, all the patients received either of two lots of meglumine antimonate (Glucantime, Rhone Poulenc-Rorer, Paris, France, lots and 312-3). With respect to the parasites, all the patients contracted their infections in areas where L. panamensis predominates and L. braziliensis is locally transmitted. 10 The identification by species of parasites isolated from the participating patients substantiates the predominance of L. panamensis and comparable distribution of the two species among the age and treatment groups of participants. Therefore, neither differences in the drug received nor the infecting species of Leishmania explain the disparity in efficacy between adults and children or between the treatment groups. Worthy of note, the clinical-failure treatment was not absolute; healing was achieved by a second course of treatment with 20 mg Sb/kg/d for 20 days. However, we cannot rule out differences in the sensitivity to Sb of the Leishmania strains circulating in the study area. Widely divergent sensitivity of Leishmania to pentavalent antimonials has been reported, 24,25 and could have been a factor in the response to treatment. 26 The mechanisms of experimentallyselected resistance strains are currently being studied. 27 In relation to the host factors that affect the response to treatment, the immune response, either innate or acquired, may differ in adults and children, especially if adults with a long history of residence in the endemic area had previously experienced infection. Prior disease evidenced by a typical scar has been shown to be associated with a more marked delayed-type hypersensitivity response to leishmanin and a lower number of parasites in subsequent lesions. 28 In this study, most of the adults that participated had lived more than ten years in the endemic area. Another possibility is that the pharmacokinetics of pentavalent antimonial compounds differ in children and adults. Preliminary data show that the four children aged 7 years or less who were included in a pharmacokinetic study conducted by the US Centers for Disease Control and Prevention (CDC) and its collaborators had approximately a 3 5-fold higher volume of distribution (when normalized by body weight) for pentavalent antimony and approximately 2-fold higher clearance of antimony than adults (Herwaldt and others, unpublished data). Therefore, the serum levels achieved in children receiving the recommended dose were lower than those in adults. If this observation is confirmed, the distinct pharmacokinetic behavior of Sb in children could explain the low efficacy in this age group. Patients younger than 5 years of age with cutaneous leishmaniasis due to Leishmania Viannia have not previously been included in a controlled clinical trial of efficacy of pentavalent antimonials, despite the importance of this age group in the endemic areas Given the low response rate in children, the power to detect differences in adults between the 10- and 20-day treatment groups was limited because of the reduction of the sample size in the stratified analysis by age groups and the relatively high rate of non-adherence to the treatment. Nevertheless, our data do not provide compelling evidence for

6 192 PALACIOS AND OTHERS the superiority of 20 days of treatment compared with 10 days, especially given the increased rate of adverse effects, particularly arthralgias, and higher costs for the patients and the health system and the risk of non-adherence with the 20- day regimen. Therefore, we consider the use of a 10-day regimen in patients older than 5 years of age with uncomplicated cutaneous leishmaniasis along with an obligatory clinical evaluation 13 weeks after the treatment began to identify patients requiring re-treatment, to represent a practical and achievable therapeutic alternative in endemic areas of the Colombian Pacific coast. The overall efficacy of both treatment schedules was lower than expected, and this was particularly dramatic in young children. These findings underscore the need for alternatives to the currently available treatments for cutaneous leishmaniasis due to Leishmania Viannia. The trials evaluating these alternatives should include women and children groups with high prevalence and vulnerability to leishmaniasis in endemic areas. Acknowledgments: The authors wish to thank Thomas R. Navin for the assessment in the design and critical review of the manuscript, and Barbara L. Herwaldt and Nancy Gore Saravia for their valuable contributions to this manuscript. The participation in this trial of the health volunteers from the affected communities and the logistic support of the Hospital San Andrés and the Departamento de Control de Patologías Tropicales in Tumaco is much appreciated. The technical services of the personnel of the Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), particularly of José Rafael Tovar (statistical assistance); of Aura García, Andrés Dajome, and of Wilson Cortés (field assistance); and of Jaime Muñoz, Carmen Castillo, Marta Chica, Rubén Varela, and Hector Hernández (diagnosis and clinical evaluations), are gratefully acknowledged. Financial support: This work was supported by the Ministry of Health of Colombia and by a Young Investigator Studentship Grant from Colciencias to Ricardo Palacios. Authors addresses: Ricardo Palacios, Lyda Elena Osorio, Luis Fernando Grajales and María Teresa Ochoa, CIDEIM, Avenida 1 Norte Phone (57 2) Fax (57 2) Cali, Colombia. clinica@cideim.org.co Reprint requests: Ricardo Palacios, M.D. Clinical and Community Research Unit, CIDEIM, Avenida 1 Norte Phone: (57 2) Fax: (57 2) Cali, Colombia. clinica@cideim.org.co REFERENCES 1. 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