The kinetoplast in the diagnosis of visceral leishmaniasis.

In visceral leishmaniasis (as in all leishmanial infections), microscopic diagnosis is made by observing the intracellular amastigote form, complete with a kinetoplast, in aspirate smears or biopsied tissue. In the 2 clinically-ill patients described here, intracellular inclusions were demonstrated in a bone marrow aspirate or a colon tissue biopsy. Kinetoplasts associated with the inclusions were not identified in the marrow aspirate smear (although the patient was treated for visceral leishmaniasis), but were identified retrospectively in the colonic tissue (although the patient was treated for histoplasmosis). Both cases illustrate the importance to clinical consultants of microscopically observing (or not) an associated kinetoplast when faced with a tissue aspirate or biopsy specimen showing intracellular inclusions.

Fly bites and skin lesion in an asymptomatic traveler returned from Tanzania: Next steps?

A returned traveler had three features suggesting a risk for developing East African human trypanosomiasis - geographical exposure (Tanzania), likely tsetse fly bites and a trypanosomal chancre-like skin lesion. However, the traveler was asymptomatic at the time of presentation, raising the issue of how to proceed clinically.

Targeting IL-27 and/or IL-10 in Experimental Murine Visceral Leishmaniasis.

Interleukin-10 (IL-10) and interleukin-27 (IL-27) both exert counterregulatory immunodeactivation in visceral Leishmania donovani infection. We studied experimental L. donovani infection in the livers of IL-10-/- and IL-27Rα-/- mice and observed that in IL-27Rα-/-, but not IL-10-/- mice, interferon-gamma (IFN-γ) and tumor necrosis factor (TNF) were required for heightened granulomatous inflammation and accelerated control of intracellular parasite replication. This difference in mechanism, along with residual IL-10 activity in IL-27Rα-/- mice, suggested targeting IL-27 in addition to IL-10 in a macrophage-activating, anti-counterregulatory cytokine treatment strategy. In C57BL/6 wild-type mice with established liver infection, a single injection of anti-IL-27 p28 or anti-IL-10R monoclonal antibody enhanced granuloma assembly, enabled macrophage activation, and induced comparable parasite killing (49-56%). However, anti-IL-27 p28 plus anti-IL-10R combination treatment did not increase leishmanicidal effects. These results suggest that IL-27 and IL-10 may operate in a linked deactivating mechanism and that in this intracellular infection, either IL-27 or IL-10 is a suitable immunotherapeutic target.

Case Report: Mucosal Leishmaniasis in New York City.

The six previously reported civilian cases of mucosal leishmaniasis (ML) diagnosed in the United States have all represented imported New World ML. We describe two new patients with ML diagnosed in New York City-a Syrian immigrant with a nasal mass (Leishmania tropica), the first report of Old World ML in the United States, and an American ecologist who worked in Bolivia and had been treated for cutaneous infection 23 years before developing lesions (L. (Viannia) braziliensis) initially of the uvula, soft palate, and posterior pharynx and subsequently the larynx.

The Pretravel Consultation: Recent Updates.

Estimates suggest that 43%-79% of international travelers may develop travel-related illnesses. Most such illnesses are considered mild and self-limited; however, some are life-threatening. The pretravel consultation is aimed at assessing risks for a range of illnesses, communicating these risks, and then providing individualized recommendations and interventions to minimize or manage such risks. The effective consultation is predicated on a well-prepared clinician and motivated traveler, understanding the traveler's perception of, and tolerance for, risk, and providing education applicable to the actual itinerary. Integral to the clinician's preparation is regular review of up-to-date trip-specific recommendations; country-specific information and recommendations are readily available and can now be efficiently accessed. From the infectious diseases perspective, immunizations, malaria chemoprophylaxis, insect repellent use, and travelers' diarrhea and its self-management are cornerstones of the consultation. This review focuses primarily on updating these 4 topics with recently published information relevant to adult travelers.

Gamma Interferon-Regulated Chemokines in Leishmania donovani Infection in the Liver.

In the livers of C57BL/6 mice, gamma interferon (IFN-γ) controls intracellular Leishmania donovani infection and the efficacy of antimony (Sb) chemotherapy. Since both responses usually correlate with granulomatous inflammation, we tested six prominently expressed, IFN-γ-regulated chemokines-CXCL9, CXCL10, CXCL13, CXCL16, CCL2, and CCL5-for their roles in (i) mononuclear cell recruitment and granuloma assembly and maturation, (ii) initial control of infection and self-cure, and (iii) responsiveness to Sb treatment. Together, the results for the L. donovani-infected livers of chemokine-deficient mice (CXCR6-/- mice were used as CXCL16-deficient surrogates) indicated that individual IFN-γ-induced chemokines have diverse affects and (i) may be entirely dispensable (CXCL13, CXCL16), (ii) may promote (CXCL10, CCL2, CCL5) or downregulate (CXCL9) initial granuloma assembly, (iii) may enhance (CCL2, CCL5) or hinder (CXCL10) early parasite control, (iv) may promote granuloma maturation (CCL2, CCL5), (v) may exert a granuloma-independent action that enables self-cure (CCL5), and (vi) may have no role in responsiveness to chemotherapy. Despite the near absence of tissue inflammation in early-stage infection, parasite replication could be controlled (in CXCL10-/- mice) and Sb was fully active (in CXCL10-/-, CCL2-/-, and CCL5-/- mice). These results characterize chemokine action in the response to L. donovani and also reemphasize that (i) recruited mononuclear cells and granulomas are not required to control infection or respond to Sb chemotherapy, (ii) granuloma assembly, control of infection, and Sb's efficacy are not invariably linked expressions of the same T cell-dependent, cytokine-mediated antileishmanial mechanism, and (iii) granulomas are not necessarily hallmarks of protective antileishmanial immunity.

IFN-γ-induced macrophage antileishmanial mechanisms in mice: A role for immunity-related GTPases, Irgm1 and Irgm3, in Leishmania donovani infection in the liver.

In C57BL/6 mice, Leishmania donovani infection in the liver provoked IFN-γ-induced expression of the immunity-related GTPases (IRG), Irgm1 and Irgm3. To gauge the antileishmanial effects of these macrophage factors in the liver, intracellular infection was analyzed in IRG-deficient mice. In early- (but not late-) stage infection, Irgm3(-/-) mice failed to properly control parasite replication, generated little tissue inflammation and were hyporesponsive to pentavalent antimony (Sb) chemotherapy. Observations limited to early-stage infection in Irgm1(-/-) mice demonstrated increased susceptibility and virtually no inflammatory cell recruitment to heavily-parasitized parenchymal foci but an intact response to chemotherapy. In L. donovani infection in the liver, the absence of either Irgm1 or Irgm3 impairs early inflammation and initial resistance; the absence of Irgm3, but not Irgm1, also appears to impair the intracellular efficacy of Sb chemotherapy.

Cutaneous Leishmaniasis: Current Treatment Practices in the USA for Returning Travelers.

Leishmaniasis, a protozoal infection transmitted by sandfly bite, produces a clinical spectrum of disease ranging from asymptomatic infection to ulcerative skin and mucosal lesions to visceral involvement. Leishmaniasis is endemic in regions of Africa, the Middle East, south Asia, southern Europe, northern South America, and Central America. There has been an increase in imported leishmaniasis into developed, non-endemic countries due to increasing global travel. While pentavalent antimonials have been the mainstay of antileishmanial treatment for decades, newer therapeutic options have become available for all forms of infection, including liposomal amphotericin B, miltefosine, fluconazole, and ketoconazole. For the returning traveler with cutaneous leishmaniasis in the USA, treatment approaches are determined based on infecting species, initial presentation, extent and progression of disease, the advantages and drawbacks of available parenteral and oral drugs, and clinician-consultant experience.

Granzyme-mediated regulation of host defense in the liver in experimental Leishmania donovani infection.

In the livers of susceptible C57BL/6 (B6) mice infected with Leishmania donovani, CD8(+) T cell mechanisms are required for granuloma assembly, macrophage activation, intracellular parasite killing, and self-cure. Since gene expression of perforin and granzymes A and B (GzmA and GzmB), cytolytic proteins linked to CD8(+) cell effector function, was enhanced in infected liver tissue, B6 mice deficient in these granular proteins were used to gauge host defense roles. Neither perforin nor GzmA was required; however, mice deficient in GzmB (GzmB(-/-), GzmB cluster(-/-), and GzmA×B cluster double knockout [DKO] mice) showed both delayed granuloma assembly and initially impaired control of parasite replication. Since these two defects in B6 mice were limited to early-stage infection, innately resistant 129/Sv mice were also tested. In this genetic setting, expression of both innate and subsequent T (Th1) cell-dependent acquired resistance, including the self-cure phenotype, was entirely derailed in GzmA×B cluster DKO mice. These results, in susceptible B6 mice for GzmB and in resistant 129/Sv mice for GzmA and/or the GzmB cluster, point to granzyme-mediated host defense regulation in the liver in experimental visceral leishmaniasis.

Cutaneous leishmaniasis in North Dakota.

In the United States, autochthonous cutaneous leishmaniasis caused by infection with Leishmania mexicana has been reported from Texas and Oklahoma. Here, we describe a child with 2 new features: cutaneous infection acquired outside of the south-central United States (in North Dakota) and infection caused by Leishmania donovani species complex.

Regulatory actions of Toll-like receptor 2 (TLR2) and TLR4 in Leishmania donovani infection in the liver.

In livers of susceptible but self-curing C57BL/6 mice, intracellular Leishmania donovani infection enhanced Toll-like receptor 4 (TLR4) and TLR2 gene expression. In the liver, infected TLR4(-/-) mice showed reduced gamma interferon (IFN-γ), tumor necrosis factor (TNF), and inducible nitric oxide synthase (iNOS) mRNA expression, higher-level and slowly resolving infection, delayed granuloma formation, and little response to low-dose chemotherapy; in serum, the ratio of IFN-γ to interleukin 10 (IL-10) activity was decreased by 50%. In contrast, in TLR2(-/-) mice, control of liver infection, parasite killing, and granuloma assembly were accelerated and chemotherapy's efficacy enhanced. In livers of infected TLR2(-/-) mice, mRNA expression was not increased for inflammatory cytokines or iNOS or decreased for IL-10; however, the serum IFN-γ/IL-10 ratio was increased 6.5-fold and minimal responses to IL-10 receptor blockade suggested downregulated IL-10. In established infection in wild-type mice, blockading TLR2 induced parasite killing and triggering TLR4 strengthened resistance and promoted chemotherapy's effect. Thus, in experimental L. donovani infection in the liver, TLR4 signaling upregulates and TLR2 signaling downregulates macrophage antileishmanial activity, making both receptors potential therapeutic targets in visceral leishmaniasis for engagement (TLR4) or blockade (TLR2).

Leishmaniasis in the United States: treatment in 2012.

Although civilian physicians in the United States seldom encounter patients with leishmaniasis, therapeutic advances in endemic regions have opened the door to approaches that can be applied in this country. Advances revolve around the use of oral miltefosine in all forms of leishmaniasis and the use of short-course intravenous liposomal amphotericin B in visceral and possibly cutaneous infection. Lengthy, traditional intravenous treatment with pentavalent antimony (sodium stibogluconate) still has a role in the United States; however, although expensive, miltefosine and liposomal amphotericin B are considerably more appealing selections for initial therapy.

Non-oral treatment with ivermectin for disseminated strongyloidiasis.

Critically ill patients with disseminated strongyloidiasis may not be candidates for oral treatment. We report four patients with disseminated strongyloidiasis, believed to be unable to absorb oral therapy, who were treated with ivermectin by rectal and/or subcutaneous administration. Obtaining subcutaneous ivermectin and dosing it appropriately is a challenge. These cases underscore the need for improved access to subcutaneous ivermectin and more pharmacological data to guide use of this treatment approach.

Single-dose liposomal amphotericin B for visceral leishmaniasis in India.

BACKGROUND: Some 50% of patients with visceral leishmaniasis (kala-azar) worldwide live in the Indian state of Bihar. Liposomal amphotericin B is an effective treatment when administered in short courses. We wanted to determine whether the efficacy of a single infusion of liposomal amphotericin B was inferior to conventional parenteral therapy, consisting of 15 alternate-day infusions of amphotericin B deoxycholate. METHODS: In this open-label study, we randomly assigned 412 patients in a 3:1 ratio to receive either liposomal amphotericin B (liposomal-therapy group) or amphotericin B deoxycholate (conventional-therapy group). Liposomal amphotericin B (at a dose of 10 mg per kilogram of body weight) was given once, and patients were discharged home 24 hours later. Amphotericin B deoxycholate, which was administered in 15 infusions of 1 mg per kilogram, was given every other day during a 29-day hospitalization. We determined the cure rate 6 months after treatment. RESULTS: A total of 410 patients--304 of 304 patients (100%) in the liposomal-therapy group and 106 of 108 patients (98%) in the conventional-therapy group--had apparent cure responses at day 30. Cure rates at 6 months were similar in the two groups: 95.7% (95% confidence interval [CI], 93.4 to 97.9) in the liposomal-therapy group and 96.3% (95% CI, 92.6 to 99.9) in the conventional-therapy group. Adverse events in the liposomal-therapy group were infusion-related fever or rigors (in 40%) and increased anemia or thrombocytopenia (in 2%); such events in the conventional-therapy group were fever or rigors (in 64%), increased anemia (in 19%), and hypokalemia (in 2%). Nephrotoxicity or hepatotoxicity developed in no more than 1% of patients in each group. CONCLUSIONS: A single infusion of liposomal amphotericin B was not inferior to and was less expensive than conventional therapy with amphotericin B deoxycholate. (ClinicalTrials.gov number, NCT00628719.)

New treatment approach in Indian visceral leishmaniasis: single-dose liposomal amphotericin B followed by short-course oral miltefosine.

BACKGROUND: In Bihar, India, home to nearly one-half of the world's burden of visceral leishmaniasis, drug resistance has ended the usefulness of pentavalent antimony, which is the traditional first-line treatment. Although monotherapy with other agents is available, the use of 2 drugs with different modes of action might increase efficacy, shorten treatment duration, enhance compliance, and/or reduce the risk of parasite resistance. To test the feasibility of a new approach to combination therapy in visceral leishmaniasis (also known a kala-azar), we treated Indian patients with a single infusion of liposomal amphotericin B (L-AmB), followed 1 day later by short-course oral miltefosine. METHODS: We used a randomized, noncomparative, group-sequential, triangular design and assigned 181 subjects to treatment with 5 mg/kg of L-AmB alone (group A; 45 subjects), 5 mg/kg of L-AmB followed by miltefosine for 10 days (group B; 46 subjects) or 14 days (group C; 45 subjects), or 3.75 mg/kg of L-AmB followed by miltefosine for 14 days (group D; 45 subjects). When it became apparent that all regimens were effective, 45 additional, nonrandomized patients were assigned to receive 5 mg/kg of L-AmB followed by miltefosine for 7 days (group E). RESULTS: Each regimen was satisfactorily tolerated, and all 226 subjects showed initial apparent cure responses. Nine months after treatment, final cure rates were similar: group A, 91% (95% confidence interval [CI], 78%-97%]; group B, 98% (95% CI, 87%-100%); group C, 96% (95% CI, 84%-99%]; group D, 96% (95% CI, 84%-99%); and group E, 98% (95% CI, 87%-100%). CONCLUSIONS: These results suggest that treatment with single-dose L-AmB followed by 7-14 days of miltefosine is active against Indian kala-azar. This short-course, sequential regimen warrants additional testing in India and in those regions of endemicity where visceral leishmaniasis may be more difficult to treat. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00370825 .

Accelerated control of visceral Leishmania donovani infection in interleukin-6-deficient mice.

In patients with visceral leishmaniasis, increased levels of circulating interleukin-6 (IL-6) regularly accompany fully expressed, progressive infections (kala-azar). To experimentally test the role of IL-6, responses to an intracellular Leishmania donovani infection in the livers of IL-6(-/-) and wild-type mice were compared. IL-6(-/-) mice showed an enhanced control of the infection and earlier, rapid parasite killing along with additional evidence of a stimulated antileishmanial Th1-cell-type response: increased levels of circulating gamma interferon, accelerated granuloma assembly, and heightened responsiveness to chemotherapy. In this model of visceral leishmaniasis, IL-6 appears to act in a suppressive, macrophage-deactivating fashion, which identifies it as a potential target for therapeutic blockade.

Amphotericin B treatment for Indian visceral leishmaniasis: response to 15 daily versus alternate-day infusions.

BACKGROUND: For patients with Indian visceral leishmaniasis, amphotericin B deoxycholate is usually given as 15 alternate-day infusions of 1 mg/kg over 30 days (total dose, 15 mg/kg); daily treatment with 1 mg/kg for 20 days (total dose, 20 mg/kg) is also used. This study was done to address the unsettled therapeutic questions of administration schedule (alternate-day vs. daily administration) and dose (1 vs. 0.75 mg/kg) and to determine whether the duration of amphotericin B treatment in Bihar, India, can be shortened to 15 days. METHODS: To compare alternate-day versus daily administration and 1-mg/kg versus 0.75-mg/kg doses and to determine whether the duration of treatment could be abbreviated, Indian subjects randomly received 15 infusions of 1 mg/kg (group A; 245 patients) or 0.75 mg/kg (group B; 244 patients) on alternate days or 1 mg/kg (group C; 500 patients) or 0.75 mg/kg (group D; 496 patients) daily. Noninferiority testing compared 6-month cure rates using a 5% margin. RESULTS: Overall, 1439 of the 1485 subjects completed treatment and responded. Treatment interruptions (nephrotoxicity) but not infusion-associated reactions or study removals were more common with daily administration. Final cure rates at 6 months were similar: group A, 234 patients (96%; 95% confidence interval [CI], 92%-98%); group B, 225 patients (92%; 95% CI, 88%-95%); group C, 483 patients (97%; 95% CI, 95%-98%); and group D, 476 patients (96%; 95% CI, 94%-97%; P>.05). CONCLUSIONS: Provided that the serum creatinine level is repeated once, daily treatment with amphotericin B, 0.75 mg/kg for 15 days (total dose, 11.25 mg/kg), is efficient and effective for visceral leishmaniasis in India. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00310505.

Responses to Leishmania donovani in mice deficient in both phagocyte oxidase and inducible nitric oxide synthase.

Mice deficient in phagocyte oxidase (phox) and inducible nitric oxide synthase (iNOS), which are primary macrophage killing mechanisms, generated tissue granulomas but showed unrestrained Leishmania donovani visceral replication and suboptimal initial responsiveness to antimony treatment. Nevertheless, visceral infection was controlled post-treatment and did not recur. A phox/iNOS-independent macrophage mechanism, which was not triggered by L. donovani, emerges after chemotherapy.