Tropica Infections Research Articles

Tape-disc-loop-mediated isothermal amplification (TD-LAMP) method as noninvasive approach for diagnosis of cutaneous leishmaniasis caused by L. tropica

Cutaneous leishmaniasis (CL) is a parasitic disease caused by the bite of infectious female sand flies with high socioeconomic burdens. There is currently no non-invasive, point-of-care, diagnostic method with high sensitivity and specificity available for CL. We herein report the development of a non-invasive tape disc (TD) sampling method combined with a loop-mediated isothermal amplification (LAMP) assay using primer sets targeting kinetoplast DNA (kDNA) of Leishmania tropica (L. tropica) with a colorimetric readout for species-specific diagnosis of CL. We tested our Tape-Disc (TD)-LAMP method on a panel of skin samples collected by TD from 35 confirmed L. tropica patients, 35 healthy individuals and 35 patients with non-L. tropica infections. The detection limit of the TD-LAMP assay was determined as 1 fg (fg), and the assay sensitivity and specificity of 97 % and 100 % for L. tropica infection, respectively. This non-invasive, sensitive and rapid diagnostic method warrants further exploration of its use for differential diagnosis of CL in disease endemic settings.

In vivo comparative study of the efficacy of β-sitosterol, ketoconazole 2% and mupirocin for the treatment cutaneous leishmaniosis.

Cutaneous leishmaniosis (CL) is an important parasitic disease characterized by specific skin lesion, includes the vector that cause the CL and treatment in general. The study aimed to identify the effect of three different drugs which are β-sitosterol, ketoconazole 2% and mupirocin in the treatment of cutaneous leishmaniosis. The study was conducted at Dermatological Unit of Al Hussein Teaching Hospital/Thi-Qar/Iraq from October to November 2021. The patients presented with a lesion will be involved in this study and its involved isolation of parasites from the lesion of patients and the parasite was replicated in (NNN) media then the inoculum was concentered. A total of 40 male of mice (Mus musculus) of BALB/c strain injected by parasite suspension, after the appearance of lesion, β-sitosterol, ketoconazole 2% and mupirocin was applied on a lesions daily for 2 weeks, the statistical analysis was done by SPSS program. In the current study, the β-sitosterol was most effective in the treatment of skin leishmanial lesion than the other drugs with mean is (11.9±1.449 mm) in compared with the other drugs under P-value < 0.046 with the complete recovery. β-sitosterol was highly effect on the L. tropica infections with complete recovery and no scar appearance than ketoconazole and mupirocin and can be used for treatment of the disease lesion.

Leishmania tropica: What we know from its experimental models.

Leishmania tropica causes different forms of leishmaniasis in many parts of the world. Animal models can help to clarify the issues of pathology and immune response in L. tropica infections and can be applied to the control, prevention and treatment of the disease. The aim of this article is to summarize published data related to experimental models of this parasite, presenting an overview of the subject. We also present in brief the epidemiology, transmission and human manifestation of L. tropica infection. Mice, rats and hamsters have been used for experimental models of L. tropica infection. Main findings of the published studies show that: (1) Hamsters are the best animal model for L. tropica infection, with the drawback of being outbred hence not suitable for many studies. (2) L. tropica infection causes a non-ulcerative and chronic pathology as cutaneous form in mice and usually visceral form in hamsters. (3) L. tropica infection in mice results in a weaker immune response in comparison to Leishmania major. (4) While the Th1 responses are evoked against L. tropica, Th2 responses do not explain the outcomes of this infection, and IL-10 and TGF-β are two main suppressive cytokines. (5) The host genotype affects the immune response and disease outcome of L. tropica infection and the dose, strain, routes of inoculation, and sex of the host are among the factors affecting disease outcome of this species.

Canine leishmaniosis caused by Leishmania major and Leishmania tropica: comparative findings and serology

BackgroundInfection and clinical disease associated with Leishmania major and Leishmania tropica, two common agents of human cutaneous leishmaniosis, have rarely been reported in dogs. This study describes dogs infected with these Leishmania spp. prevalent in the Middle East and North Africa, and compares the serological response of dogs infected with Leishmania infantum, L. major or L. tropica to whole promastigote antigen enzyme-linked immunosorbent assay (ELISA) of each species and to rK39 dipstick.ResultsLeishmania major infection in a 5-month-old male dog was associated with alopecic and ulcerative periocular and limb skin lesions which responded to allopurinol treatment. Infection was detected by skin and blood polymerase chain reaction (PCR) and confirmed by DNA sequencing but the dog was seronegative. Leishmania tropica infection was detected in a 3-month-old female dog co-infected with Babesia vogeli and Anaplasma platys and with no skin lesions. PCR and DNA sequencing of the blood and parasite culture were positive for L. tropica. Sera from 11 dogs infected with L. infantum, L. major or L. tropica were reactive with all three Leishmania spp. antigens except for sera from a dog with L. major infection. No significant differences were found between reactivity of dog sera to the antigen of the infecting species, or to the other Leishmania spp. antigens. Sera from dogs infected with L. infantum and L. tropica were positive with the rK39 antigen kit, while dogs with L. major infection were seronegative.ConclusionsSkin lesions in L. major infected dogs from this study and previous reports (n = 2) were ulcerative and located on the muzzle, feet and foot pads and not associated with generalized lymphadenomegaly and splenomegaly. In previous L. tropica infections, skin lesions were proliferative mucocutaneous in young dogs (n = 2), or associated with widespread dermatitis, lymphadenomegaly and splenomegaly in older dogs with similarity to L. infantum infection (n = 2). This study suggests that ELISA serology with whole promastigote antigen is not distinctive between L. infantum, L. major and L. tropica canine infections and that some L. major infections are not seropositive. PCR with DNA sequencing should be used to discriminate between canine infections with these three species.

Detection of Leishmania major and Leishmania tropica in domestic cats in the Ege Region of Turkey

Leishmaniosis is a group of diseases caused by different species of Leishmania parasites in mammalian species. The aim of the present study was to investigate the presence of Leishmania spp. DNA in cats using real time polymerase chain reaction (RT-PCR) assays targeting internal transcribed spacer (ITS1) and heat-shock protein 70 gene (Hsp70) regions with Leishmania species-specific primers and probes.Blood samples were collected from 147 cats (73 female; 74 male) in the endemic regions for zoonotic visceral leishmaniasis in the western provinces of Turkey and analyzed using two RT-PCR assays. Additionally, Hsp70 RT-PCR products were sequenced. ELISA assays for feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) were also carried out for 145 of the 147 samples.Overall, 13/147 (8.84%) cats were positive for Leishmania by RT-PCR (4 L. major and 9 L. tropica). FIV and FeLV antibody and/or antigen was detected in 4 and 5 cats among Leishmania DNA positives, respectively.To the best of our knowledge, this study is the first to investigate and report the presence of L. major and L. tropica infections in a large group of domestic cats in Turkey. The results obtained indicate that species identification of Leishmania is essential for epidemiological understanding and that clinical signs alone are not indicative for leishmaniosis in cats, as it is in dogs. This study suggests that extensive research should be carried out in cat populations in order to fully understand the role of cats in the epidemiology of the disease.

Detection of high levels of anti-α-galactosyl antibodies in sera of patients with Old World cutaneous leishmaniasis: a possible tool for diagnosis and biomarker for cure in an elimination setting.

In the Kingdom of Saudi Arabia (KSA), Old World cutaneous leishmaniasis (CL) is mainly caused by Leishmania major and Leishmania tropica parasites. Diagnosis of CL is predominately made by clinicians, who at times fail to detect the disease and are unable to identify parasite species. Here, we report the development of a chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) to measure the levels of anti-α-galactosyl antibodies in human sera. Using this assay, we have found that individuals infected with either Leishmania spp. had significantly elevated levels (up to 9-fold higher) of anti-α-Gal IgG compared to healthy control individuals. The assay sensitivity was 96% for L. major (95% CI; 94-98%) and 91% for L. tropica (95% CI; 86-98%) infections and therefore equivalent to restriction fragment length polymorphism-polymerase chain reaction analysis of parasite ITS1 gene. In addition, the assay had higher sensitivity than microscopy analysis, which only detected 68 and 45% of the L. major and L. tropica infections, respectively. Interestingly, up to 2 years following confirmed CL cure individuals had 28-fold higher levels of anti-α-Gal IgG compared to healthy volunteers. Monitoring levels of anti-α-Gal antibodies can be exploited as both a diagnostic tool and as a biomarker of cure of Old World CL in disease elimination settings.

Cutaneous Leishmaniasis Caused byLeishmania killicki,Algeria

Cutaneous Leishmaniasis Caused by<i>Leishmania killicki,</i>Algeria

The Route of Leishmania tropica Infection Determines Disease Outcome and Protection against Leishmania major in BALB/c Mice

Leishmania tropica is one of the causative agents of leishmaniasis in humans. Routes of infection have been reported to be an important variable for some species of Leishmania parasites. The role of this variable is not clear for L. tropica infection. The aim of this study was to explore the effects of route of L. tropica infection on the disease outcome and immunologic parameters in BALB/c mice. Two routes were used; subcutaneous in the footpad and intradermal in the ear. Mice were challenged by Leishmani major, after establishment of the L. tropica infection, to evaluate the level of protective immunity. Immune responses were assayed at week 1 and week 4 after challenge. The subcutaneous route in the footpad in comparison to the intradermal route in the ear induced significantly more protective immunity against L. major challenge, including higher delayed-type hypersensitivity responses, more rapid lesion resolution, lower parasite loads, and lower levels of IL-10. Our data showed that the route of infection in BALB/c model of L. tropica infection is an important variable and should be considered in developing an appropriate experimental model for L. tropica infections.

The fitness of antimony-resistant Leishmania parasites: lessons from the field

Because antimony compounds are the primary antileishmanial drugs in most developing countries, an understanding of the fitness cost associated with the acquisition of drug resistance is important for the management of leishmaniasis. The clinical manifestations of the disease range from self-healing cutaneous and mucocutaneous skin ulcers to a fatal visceral form, called visceral leishmaniasis or kala-azar. In the absence of effective vaccines, the only way to treat and control leishmaniasis is through the use of affordable medications.

Liposomal amphotericin B treatment of cutaneous leishmaniasis due to Leishmania tropica

Cutaneous leishmaniasis (CL) is endemic in Israel, and in the past, has been attributed almost exclusively to Leishmania major. Over the last decade or so, an increase in Leishmania tropica (L. tropica) infections has occurred in several regions of Israel. Topical treatment of Old World CL is usually the rule, however, in some cases systemic treatment is indicated. Liposomal amphotericin B (L-AmB) is efficacious and safe for treating visceral leishmaniasis but its role in treating various forms of CL is yet to be defined. In this study, we summarize the efficacy and safety of L-AmB treatment in a series of Israeli patients with L. tropica infection. Cases of PCR-proven CL caused by L. tropica were treated in an outpatient setting. Treatment schedule consisted of five consecutive days of 3 mg/kg L-AmB, followed by a sixth dose on day 10. Thirteen consecutive patients (11 men, two women), received L-AmB. Mean age was 15.3 years; of the 13 patients, 85% had facial lesions. Six had previously failed intralesional sodium stibogluconate treatment and four had failed topical paromomycin treatment. Eleven of 13 patients (84%) achieved complete clinical cure within 2 months. Mean follow-up of 11 months revealed no relapses. Side effects were mild and none terminated treatment prematurely. A non-randomized study, with a small number of patients. Liposomal amphotericin B treatment for L. tropica is effective, well tolerated and cost beneficial in countries where cost of hospital-care is significant.

Epidemiologic and Clinical Features of Cutaneous Leishmaniasis in Southeastern Tunisia

Species-specific diagnosis was performed in 66 patients with cutaneous leishmaniasis (CL) living in Tataouine focus in southeastern Tunisia. Leishmania DNA was extracted directly from dermal scrapings (n = 66) and from parasites obtained in culture (n = 12). Species were identified by using polymerase chain reaction-restriction fragment length polymorphism analysis for internal transcribed spacer region 1 and isoenzyme analysis. Leishmania tropica and L. major were identified in 31 (47%) and 35 (53%) cases respectively. Leishmania tropica CL cases were geographically scattered, and L. major CL cases were clustered. Lesions caused by L. tropica were mostly single (83.8%) and face-localized (55.8%), and lesions caused by L. major were multiple (57.1%; P < 0.001) and situated on limbs (83.7%; P < 0.001). For both species, most lesion onsets were reported during June-January. However, lesions that emerged during February-May were mainly caused by L. tropica (83.3%; P < 0.01). Moreover, the delay before seeking medical advice was higher for L. tropica infections than for L. major infections (P < 0.05).

Leishmania killickiImported from Tunisian Desert

<i>Leishmania killicki</i>Imported from Tunisian Desert

Cell contact-mediated macrophage activation for antileishmanial defense. II. Identification of effector cell phenotype and genetic restriction.

Host defense in cutaneous leishmaniasis, due to Leishmania tropica, is largely--if not exclusively--cell mediated. We observed in vitro that draining lymph node lymphocytes from L. tropica-infected C57BL/6 mice activate L. tropica-infected macrophages to kill the intracellular parasites (leishmanicidal effect). Because direct cell contact between lymphocytes and infected macrophages is required to achieve a maximum leishmanicidal effect, this effect cannot be attributed solely to lymphokines. Furthermore, because effector lymphocytes induced no detectable damage to infected macrophages, the effect also differs from conventional lymphocyte-mediated cytotoxicity. The present study identifies the phenotype of the effector lymphocyte and assesses the genetic restriction of the lymphocyte-macrophage interaction. Nylon wool column-enriched T lymphocytes from infected mice activate macrophages for antileishmanial effects; treatment of lymphocytes with anti-Thy-1.2 antibody plus complement abolishes this capacity. Furthermore, treatment with anti-Lyt-1 antibody plus complement (but not with anti-Lyt-2 plus complement) likewise abolishes the effector capacity of the lymphocytes. Parallel studies reveal that the percentage of Lyt-1+2- cells present in draining lymph nodes increases during the course of infection and reaches a peak with the onset of spontaneous resolution of the infection. Syngeneic, but not allogeneic, combinations of lymphocytes and infected macrophages result in macrophage activation. Furthermore, treatment of cells with appropriate anti-Ia monoclonal antibody abrogates the antileishmanial effects. These results indicate that Lyt-1+2- lymphocytes obtained from mice with spontaneously healing L. tropica infections can exert antileishmanial effects in vitro. This effect is genetically restricted--most likely to the I region of the MHC--and requires direct cell contact. The temporal relationship between the appearance of these effector lymphocytes in mice and the onset of disease resolution argues that they may also exert these antileishmanial effects in vivo.

Susceptibility of inbred mice to Leishmania tropica infection: genetic control of the development of cutaneous lesions in P/J mice.

Leishmania tropica infections of P/J mice are characterized by the development of progressive nonhealing cutaneous lesions, followed by visceral metastases to liver and spleen. To analyze the genetic control of this disease, we produced F1, backcross (BX), and F2 progeny by breeding susceptible P/J mice with L. tropica-resistant C3H/HeN mice. Infections in these hybrid animals suggested that genetic control of the cutaneous lesion was by a single, autosomal, dominant gene. Resistance was the dominant trait. Analysis of liver and spleen impression smears in these animals, however, indicated that development of the cutaneous lesion segregates independently of the second component of L. tropica infections, systemic disease.

Experimental Cutaneous Leishmaniasis: Disseminated Leishmaniasis in Genetically Susceptible and Resistant Mice *

Abstract Leishmania tropica infections in mice provide models for the study of non-healing leishmanial infections similar to diffuse cutaneous leishmaniasis (DCL) in man. BALB/c mice infected with L. tropica developed large non-healing primary lesions as well as multiple metastatic lesions on the feet, face and ears. This susceptibility was not dose- or route-dependent. In contrast, C57BL/6 mice, when inoculated intradermally (ID), developed cutaneous lesions which healed. However, when the normally resistant C57BL/6 mice were inoculated intravenously (IV), they developed multiple non-healing lesions which resembled the infection seen in susceptible BALB/c mice. Thus, non-healing leishmanial infections similar to those of human DCL can be produced in both a genetically susceptible (BALB/c) and resistant (C57BL/6) strain of mouse. Although the eventual outcome of the infection is similar in BALB/c and IV inoculated C57BL/6 mice, the immunological parameters of the infection in the two models differed significantly. L. tropica infection in BALB/c mice was associated with a non-specific immunodepression, as assessed by lymphocyte proliferative responses to concanavalin A, phytohemagglutinin and lipopolysaccharide. In contrast, no evidence of generalized immunodepression was observed in the IV-inoculated, non-healing C57BL/6 mice. These two models also differed in their ability to express a delayed skin response to leishmanial antigen during infection. BALB/c mice were capable of mounting a transient delayed skin response, while IV-inoculated C57BL/6 mice developed no detectable delayed hypersensitivity. Both non-healing and healing infections were accompanied by the development of specific indirect immunofluorescent antibody, although the titers were significantly higher in non-healing infections. Spleen cells from infected BALB/c and C57BL/6 (ID- or IV-inoculated) mice responded to leishmanial antigen in a lymphocyte transformation assay. In BALB/c mice the ability to respond to antigen could be demonstrated throughout the course of infection; however, non-healing C57BL/6 mice developed a suppressor cell late in the infection which suppressed leishmanial antigen responses.

Leishmania tropica and Leishmania mexicana: Cross-immunity in mice

The effect of a previous or concurrent Leishmania tropica major infection on a L. mexicana infection was studied. Mice which were recovering from or had recovered from a L. tropica infection were found to be totally resistant to L. mexicana. Infection of mice already carrying a L. mexicana infection with L. tropica resulted in subsequent ulceration and eventual healing of the lesions caused by both Leishmania species. Mice infected with L. mexicana were found normally to be no more susceptible to L. tropica than untreated mice: Only when L. tropica infections were located in the region of a draining lymph node already serving a L. mexicana infection did lesions of the former parasite persist.