Essential role of platelet-activating factor in control of Leishmania (Leishmania) amazonensis infection

In the present study we investigated the role of platelet-activating factor (PAF) and prostaglandins in experimental Leishmania (Leishmania) amazonensis infection and the relationship between these mediators and nitric oxide (NO) production. Mouse peritoneal macrophages elicited with thioglicolate were infected with leishmania amastigotes, and the infection index determined 48 h later. The course of infection was monitored for 5 weeks in mice infected in the footpad with promastigotes by measuring the footpad swelling and parasite load in regional lymph nodes and spleen. The addition of PAF to C57BL/6 mouse macrophages significantly inhibited parasite growth and induced NO production. Treatment of macrophages with a selective PAF antagonist, WEB2086, increased the infection, indicating that endogenously produced PAF regulates macrophage ability to control leishmania infection. This effect of PAF was abolished by addition of the inhibitor of NO synthesis, L-NAME, to the cultures. The addition of prostaglandin E(2) significantly increased the infection and NO production. Treatment with cyclo-oxygenase inhibitor, indomethacin, reduced the infection and PAF-induced release of NO. Thus, the increased NO production induced by PAF seems to be mediated by prostaglandins. The more-selective inhibitors of cyclo-oxygenase 2, nimesulide and NS-398, had no significant effect. Thus, antileishmanial activity correlates better with the presence of PAF or absence of prostaglandins than with NO production. In vivo treatment with PAF antagonists significantly increased leishmania lesions, as well as the parasite load, in regional lymph nodes and spleens. These findings indicate that PAF is essential for the control of leishmania infection.

Cytologic diagnosis of leishmaniasis in HIV infection. A report of eight cases

BACKGROUND

Leishmania organisms are among the intracellular microorganisms with a tendency to develop in patients with the acquired immunodeficiency syndrome (AIDS). With increasing travel to endemic areas by patients with human immunodeficiency virus (HIV) infection, it is becoming a more-frequent diagnosis in nonendemic areas.

CASES

Ten cytologic specimens from eight patients with leishmaniasis and AIDS were reviewed. Eight samples were obtained from lymph nodes through fine needle aspiration (FNA). Another sample was obtained after scraping a tongue ulcer. The last one was an ascitic fluid specimen. Smears showed numerous parasitized histiocytes with abundant intracellular Leishmania organisms (amastigotes). Extracellular microorganisms were also abundant. Diff-Quik-stained smears allowed the clear recognition of the characteristic morphologic appearance with a deep-staining area (nuclei) and paranuclear zone (kinetoplast). Intracellular organisms were round, while single, extracellular forms were a more elongated.

CONCLUSION

The polymorphous clinical manifestations usually seen in patients suffering from leishmaniasis and AIDS constitute a diagnostic challenge that can be facilitated by cytopathologic examination. Cytology permits easy and rapid identification of Leishmania amastigotes, allowing a specific diagnosis and treatment.

Leishmania major infections in Phlebotomus duboscqi fed on murine models immunized with L. major subcellular antigens and sandfly gut antigens

The ability of antibodies in bloodmeals of mice and hamsters immunized with Leishmania major subcellular fractions and sandfly (Phlebotomus duboscqi) gut antigens to inhibit development of L. major in its vector P. duboscqi was examined. Antibodies from animals immunized with either L. major subcellular fractions alone or sandfly gut antigen alone were not very effective in inhibiting development of L. major in the sandfly. When P. duboscqi were fed on blood from animals immunized with both parasite flagella and sandfly gut antigen, development of L. major was significantly inhibited (P<0,05). Control sandflies fed on naive animals displayed a normal pattern of parasite development to the metacyclic stage. Electron microscopy studies showed that one of the mechanisms through which antisandfly gut antibody can cause inhibition of parasite development is by lysing sandfly gut epithelium. This study has demonstrated that it is possible to reduce transmission of leishmaniosis through immunization against both the parasite and its sandfly vector.

Leishmaniasis in the United States military

Leishmaniasis is a recurrent health problem for the U.S. and other militaries. Health care workers may be unfamiliar with the risk factors, transmission, clinical features, diagnosis, and treatment of this disease. A team of highly trained specialists is required to properly manage service members with leishmaniasis. Such care is available only in a few medical centers. Although there are no prophylactic drugs to prevent this disease, control of insect populations and use of personal protection measures can minimize arthropod-related casualties. The impact of leishmaniasis on military operations and research initiatives to better prevent, diagnose, and treat infection are discussed.

Practical guide for the treatment of leishmaniasis

This article summarises the clinical features of visceral, cutaneous and mucocutaneous leishmaniasis, and leishmaniasis in HIV-coinfected patients. The characteristics and clinical use of pentavalent antimonials and the traditional drugs used in all forms of leishmaniasis are described. There have been important developments in therapy, such as aminosidine (paromomycin) conventional amphotericin B and lipid-associated amphotericin B. In most cases of leishmaniasis there is a range of treatment options which is determined by the geographical and clinical features. This review is intended to assist the clinician in choosing treatment and in using unfamiliar drugs with safety and efficacy.

The effect of intravenous or subcutaneous administration of meglumine antimonate (Glucantime) in dogs with leishmaniasis. A randomized clinical trial

The efficacy of i.v. versus s.c. administration of Glucantime (100 mg/kg of body weight/day) was studied in 41 dogs with leishmaniasis without serious renal insufficiency. Remission was obtained in 35 dogs (85.4%) after 3 to 6 weeks of treatment but there was a relapse within 1 year in 26 dogs (74.3%). The median period of remission was 6 months. Cross-over therapy resulted in remission in 17 of 20 dogs. The percentage of remission after initial and cross-over therapy, the median relapse free period, and survival did not differ significantly between the two groups. There were very few complications and most were of minor clinical importance. Thrombophlebitis developed in one dog after i.v. injection. In dogs with leishmaniasis without serious renal insufficiency, there is a 75% probability of survival for more than 4 years following treatment with Glucantime for 3 to 6 weeks, with additional treatment when relapses occur.

Up-regulation of T helper 2 and down-regulation of T helper 1 cytokines during murine retrovirus-induced immunodeficiency syndrome enhances susceptibility of a resistant mouse strain to Leishmania amazonensis

Resistance to and recovery from leishmania infection is dependent on cell-mediated immunity. C57BL/6 mice are resistant to Leishmania amazonensis (La) infection but susceptible to LP-BM5 murine leukemia virus (MuLV) infection. MuLV infection leads to a state of immunodeficiency characterized by severe compromise of cell-mediated immunity. When infected with La alone, C57BL/6 mice developed a small transient lesion that evolved to spontaneous healing or a lesion with extremely slow growth. Lesions were predominantly comprised of a lympho-macrophagic infiltrate with few parasitized macrophages. When infected with La and, 4 weeks later, with MuLV (La-MuLV), the mice developed a large uncontrolled nonhealing lesion containing vacuolated and heavily parasitized macrophages. In contrast, mice infected with MuLV first and La 4 weeks later (MuLV-La) developed a small but persistent lesion, characterized histologically by a small number of heavily parasitized macrophages and few lymphocytes. Eight weeks after MuLV infection, both had similar immunological profiles with decreased lymphocyte proliferation, diminished production of interferon-gamma, and high production of interleukins 4 and 10. At the time of L. amazonensis infection, La-MuLV animals have a normal T cell function whereas in MuLV-La mice this function is already impaired; this may influence the recruitment of macrophages to the site of leishmania injection.

Dermatologic manifestations of infectious diseases in cardiac transplant patients

Infection remains a significant cause of morbidity and mortality in cardiac transplant patients. Skin infections are not uncommon in these patients. Although usually caused by secondary dissemination after initial infection of another organ system, some skin infections may be primary infections, such as bacterial infections caused by the use of intravenous catheters or fungal infections in severely immunosuppressed patients. Nevertheless, the presence of skin lesions in a transplant patient may indicate infection in a primary site or another deep-seated focus of infection.

Recognition of the major cell surface glycoconjugates of Leishmania parasites by the human serum mannan-binding protein

Activation of complement on the surface of parasitic protozoa of the genus Leishmania appears to be important for parasite infectivity in the mammalian host, as it allows these parasites to attach to and invade macrophages via their surface complement receptors. Serum mannan-binding protein (MBP) is a known activator of complement. Therefore, in the present study, we have investigated whether serum MBP binds to live Leishmania parasites, and to mannose-containing saccharides derived from the parasite cell surface. We have observed by fluorescence microscopy that biotinylated MBP binds to the surface of L. major and L. mexicana promastigotes. At this developmental stage the parasites are coated by a mannose-containing lipophosphoglycan (LPG). We have observed that radioiodinated MBP binds in a mannose-inhibitable manner to purified LPG which has been immobilized in plastic microwells, as well as to purified mannose-terminating di-, tri- and tetrasaccharide fragments ('cap' structures) which have been released by mild acid hydrolysis from the outer chains of the LPG, converted into neoglycolipids and resolved by thin-layer chromatography. 125I-MBP also binds in the chromatogram-binding assay to the mannose-containing glycoinositol-phospholipids that are expressed in high copy number on both the promastigote and the intracellular amastigote stages of most Leishmania species. These data suggest that MBP has the potential to opsonize the major developmental stages of Leishmania parasites, and provide a possible mechanism for the antibody-independent activation of complement on their surface.

Cytokine patterns in the pathogenesis of human leishmaniasis

The host response to infection appears to be regulated by specific patterns of local cytokine production. In the mouse, resistance to many pathogens including Leishmania is associated with a TH1 cytokine profile, IL-2 and IFN-gamma; whereas susceptibility to infection is associated with production of TH2 cytokines, IL-4, IL-5, and IL-10. To determine the cytokine patterns of the local immune response to Leishmania infection in humans, we used the polymerase chain reaction to compare cytokine mRNAs in biopsy specimens of American cutaneous leishmaniasis. In localized cutaneous leishmaniasis and the Montenegro delayed-type hypersensitivity reaction, type 1 cytokine mRNAs such as IL-2, IFN-gamma, and lymphotoxin were relatively predominant. In the chronic and destructive mucocutaneous form of leishmaniasis, there was a mixture of type 1 and type 2 cytokines, with a striking abundance of IL-4 mRNA in lesions. These results suggest that clinical course of infection with Leishmania braziliensis in man is associated with specific local patterns of cytokine production.

Laboratory-acquired malaria, leishmaniasis, trypanosomiasis, and toxoplasmosis

Because of renewed interest in parasitic diseases, increasing numbers of persons in clinical and research laboratories have the potential for exposure to parasites and therefore are at risk for acquiring parasitic infections. In this review of laboratory-acquired parasitic infections, we concentrate on protozoan diseases that frequently have been reported to be laboratory acquired: malaria, leishmaniasis, trypanosomiasis (American and African), and toxoplasmosis. These diseases can be severe, even fatal, and may be difficult to diagnose. Many laboratorians who have acquired these diseases did not recall having had an accident. Of those with recognized accidents, needlestick injuries were the most common. Laboratories should have established protocols for handling specimens that may contain viable organisms and for responding to laboratory accidents.

Analysis of enhancing effect of sand fly saliva on Leishmania infection in mice

Salivary gland lysates of the sand fly Lutzomyia longipalpis markedly enhance the course of infection with Leishmania major in mice. Here we examine various parameters of this phenomenon. The exacerbative effect of L. longipalpis salivary gland lysates occurred in five different mouse strains; however, the character of the effect varied from one strain to another. Consistent exacerbation of infection was achieved with as little as 1/10 of a gland. The exacerbative effect applied to more than one Leishmania species and to more than one species of sand fly, since salivary gland lysates of L. longipalpis enhanced infection with L. mexicana amazonensis and salivary gland lysates of Phlebotomus papatasi enhanced infection with L. major. A synthetic rat calcitonin gene-related peptide was also found to exacerbate infection with L. major but was found to be approximately 100-fold less potent than saliva in mediating this effect. In addition, lesions induced at skin sites at which L. longipalpis had probed for a blood meal exhibited an exacerbated course of infection similar to that seen when parasites were injected with sand fly salivary gland lysates.

[Popular conceptions regarding cutaneous leishmaniasis in Colombia and their applicability in control programs]

A study was carried out to obtain information on prevailing popular ideas and attitudes about cutaneous leishmaniasis and its treatment in an isolated endemic area on the Colombian Pacific Coast. Interviews were conducted with a representative sample of individuals from the community and with health agents. The formal survey covered 736 households, 332 of them in a rural area (where leishmaniasis is endemic) and 404 in the city of Buenaventura (where there is no transmission of the disease.) The results showed that cutaneous leishmaniasis is well known in the rural area. The people have names for it (ya-te-vi or bejuco), have an understanding of its etiology (although their interpretation differs from that accepted by the scientific community), and have developed methods for preventing and treating it. The popular understanding of the disease results in behavior directed toward its prophylaxis and treatment that shares many characteristics with Western medicinal practices. The traditional treatments should be taken into account in the application of measures to control the disease in that area.

Leishmania donovani chagasi: new clinical variant of cutaneous leishmaniasis in Honduras

During surveillance for endemic visceral leishmaniasis on an island off the Pacific coast of Honduras, an unusual form of cutaneous leishmaniasis was encountered. By clinical and laboratory criteria, 17 cases were identified over 5 months; children aged 4 to 15 years were primarily affected. Lesions were generally few in number, small, always papular, and non-ulcerative, even when present for several years. Patients with skin lesions seemed otherwise healthy and were well nourished. Montenegro skin tests with Leishmania mexicana and L major antigens were positive in 10 of 17 patients tested, and lesions from 9 patients were positive by culture. Since the summer of 1988, cases of atypical cutaneous leishmaniasis continue to occur on the island (8) as well as on the mainland of southern Honduras (23). A total of 9 parasite isolates from skin lesions, 4 from bone marrow of patients with kala-azar, and 2 from sandflies were identified as L donovani chagasi and were indistinguishable from one another by isoenzyme analysis.

The pathogenesis of Leishmania aethiopica infection in BALB/c mice

A mouse model for L. aethiopica infection is described. BALB/c mice were unable to clear an infection with 1 x 10(7) promastigotes injected into the hind footpad. However, there was no ulceration of the lesion and no development of overt clinical symptoms after 203 days of infection. Spread of viable organisms was evident in the draining lymph node but not in the spleen or liver. The control of the infection was associated with the development of classical delayed hypersensitivity responses to phenolized promastigotes and appeared as a localized granulomtaous infiltration. The infiltration had features of classical tuberculoid granulomas, but superimposed on it was a strong eosinophilic infiltration. The relevance of such cells though unclear is discussed.

Efficacy of prolonged therapy with stibogluconate in post kala-azar dermal leishmaniasis

Fifty three (30 male and 23 female), previously untreated, patients with post kala-azar dermal leishmaniasis (PKDL) were treated with sodium stibogluconate, at the dose of 20 mg/kg/bw/d/im/(with a maximum of 8.5 ml) for 120 days (or more, if necessary). All the patients were followed up for 12 months. The patients were assessed after 40 days and thereafter at an interval of 20 days. The mean age of onset was 24 yr, maximum number of patients developed the disease within 3 yr of apparent cure of kala-azar. Maximum number of patients sought treatment within 5 yr of the onset of PKDL. The disease affected the face (98%), trunk (83%), upper limb (72%), lower limb (40%), genetalia (6%), and mucus membrane of the tongue 40%. The lesions observed were nodules (19%), papules (30%), and hypopigmented (45%) and reddish macules (7%). The parasites could be demonstrated in the nodules (100%), papules (69%) and macules (59%). The response to treatment started in 72 per cent of patients in the first 20 days and in 40 days in all patients. All the nodules and papules disappeared in 120 days, and the macules within 200 days. The side effects of treatment noted were changes in S T and T in electrocardiogram (7%), arthralgia (11%), allergic rash (7%), swelling at the site of injection (5%), neuralgia (4%) and metalic taste (6%). The S T and T changes reverted to normal when the drug was discontinued for 20 days. Arthralgia improved with indomethacin. The higher dosages and longer course of treatment were well tolerated and resulted in a cure in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[An outbreak of cutaneous leishmaniasis caused by Leishmania infantum in Geokchaĭ District, Azerbaijan SSR]

A more than 60-case outbreak of cutaneous leishmaniasis was documented in the Geokchaĭ District of Azerbaijan between 1987 and 1988. The disease was noted in the rural areas only. All age groups were involved. The clinical picture of the disease was significantly different from anthropogenic cutaneous leishmaniasis caused by L. tropica but similar to cutaneous patterns caused by L. infantum which was a prevalent pattern in the southern France. Isoenzyme assay of the strain isolated in the Geokchaĭ causative agent defined it as Leishmania donovani sensu lato. Though an undoubted similarity of its enzymatic profile to L. infantum was observed it was distinguished as a singular zymodeme. A total of 9 Phlebotominae species were isolated in the Geokchaĭ District. Among them 5 species (P. kandelakii, P. tobbi, P. transcaucasicus, P. brevis, P. alexandri) were reviewed in the literature with regard to L. infantum transmission. Thus cutaneous leishmaniasis caused by L. infantum species in the rural area of the USSR was identified for the first time.

Excreted factors and membrane-associated carbohydrates of Indian leishmaniae

Antigenic identity between the cell surface carbohydrate ligands and their excreted factor (EF) in all forms of Indian leishmaniasis were assessed by 11 carbohydrate-specific lectins. Our results demonstrated that 3 lectins, viz. PNA, SBA and WFA showed unique selectivity towards skin-dwelling parasites. The EFs of visceral leishmaniasis (VL), post-kala-azar dermal leishmaniasis (PKDL) and cutaneous leishmaniasis (CL) formed band against ConA at 1000, and 500 micrograms/ml concentration, respectively. RCA-120 at 3 mg/ml concentration was positive to both Leishmania tropica and L. major, whereas SBA was specific to L. tropica, L. major and PKDL strains at the same concentration. Antisera directed against the EFs (EF-As) induced agglutination to homologous promastigotes suspension. Cross-reactivity of agglutination was observed in different strains but highest was found among PKDL and CL strains. Although PKDL cases are normally found in patients with the history of visceral leishmaniasis (kala-azar), surprisingly in this study, the surface saccharides of PKDL strains had close affinity to CL type instead of VL.