The Identity ofLeishmania TropicaWright, 1903, andHerpetomonas PapatasiiAdler, 1925

The mechanism behind the antileishmanial effect of zinc sulphate. I. An in-vitro study

In an attempt to determine the possible mechanism(s) behind the antileishmanial activity of zinc sulphate, promastigotes, axenic amastigotes and intracellular amastigotes of both Leishmania major and L. tropica were incubated with different concentrations of the compound. For each of the two Leishmania species, all three forms were found to be inhibited by the zinc sulphate, in a dose-dependent manner, the promastigotes being the most resistant form, followed by the axenic amastigotes. These results indicate that zinc sulphate has a direct antileishmanial effect. Compared with macrophages from starch-treated mice, the macrophages recovered from mice that had been injected intraperitoneally with zinc sulphate (daily for the 4 days prior to the macrophage collection) or BCG (once, 4 days before the cell collection) showed increased phagocytosis and increased killing of L. major and L. tropica. As the effects of the zinc sulphate were not statistically different from those of the known immunomodulating agent BCG, zinc sulphate appears to have an immunomodulating effect, in addition to its direct antileishmanial effect.

Leishmania major and Leishmania tropica: I the in vitro effects of an immunomodulator, S2-Complex

This study was undertaken to try to determine the possible anti-leishmanial activity of S2-Complex, an organic complex of copper chloride, ascorbic acid, and nicotinamide. The promastigotes, axenic amastigotes, and intracellular amastigotes of both Leishmania major and Leishmania tropica were incubated with different concentrations of S2-Complex. The EC50 for each form was calculated. Results show that all forms of the parasites were dose dependently inhibited by S2-Complex. The promastigotes of both parasites were the most resistant with highest EC50 followed by axenic amastigotes. While intracellular amastigotes were the most sensitive with the lowest EC50. These results indicate that S2-Complex has a direct anti-leishmanial effect. When mice were treated with S2-Complex or BCG for four days before harvesting the macrophages, and the macrophages infected with both L. major and L. tropica, they showed increased phagocytosis and increased parasite killing. The results of S2-Complex were not statistically different from the immunomodulating agent BCG. These results indicate that S2-Complex has an immunomodulating effect in addition to the direct anti-leishmanial effect.

Cutaneous involvement in a rare case of adult visceral leishmaniasis acquired in Israel

Skin lesions are rare in visceral leishmaniasis, especially in Mediterranean countries. We describe an unusual case of visceral leishmaniasis in a 41-year-old man that began with a skin lesion. The parasites isolated from both the skin lesion and the bone marrow were typed as Leishmania donovani sensu stricto. This pathogen is not endemic in Israel or neighboring countries; its contribution to adult visceral leishmaniasis in Israel is summarized.

Cell biology of Leishmania

Leishmania are digenetic protozoa which inhabit two highly specific hosts, the sandfly, where they grow as motile flagellated promastigotes in the gut, and the mammalian macrophage, where they survive and grow intracellularly as non-flagellated amastigotes in the phagolysosome. Leishmaniasis is the outcome of an evolutionary 'arms race' between the host's immune system and the parasite's evasion mechanisms, which ensure survival and transmission in the population. The diverse spectrum of patterns and severity of disease reflect the varying contributions of parasite virulence factors and host responses, some of which act in a host protective manner while others exacerbate disease. This chapter describes the interaction of the Leishmania with their hosts, with emphasis on the molecules and mechanisms evolved by the parasites to avoid, subvert or exploit the environments in the sandfly and the macrophage, and to move from one to the other.

Zinc sulphate in the treatment of cutaneous leishmaniasis: an in vitro and animal study

This study was designed to evaluate the effectiveness of zinc sulphate both in vitro and in an animal model against both strains of old world cutaneous leishmaniasis. The in vitro sensitivities of promastigotes and axenic amastigotes of both Leishmania major and L. tropica to zinc sulphate was determined, the LD50 calculated and compared to the standard treatment for cutaneous leishmaniasis pentavalent antimony compounds. The results show that the two forms of both strains were sensitive to zinc sulphate and their respective LD50 were lower compared to the pentavalent antimony compound. Furthermore the sensitivities of the forms of both strains were tested using a simple slide method and compared to results of the standard method. To confirm this result, zinc sulphate was administered orally to mice infected with cutaneous leishmaniasis both therapeutically and prophylactically. Results showed that oral zinc sulphate was effective in both treatment and prophylaxis for cutaneous leishmaniasis. These results encourage the use of oral zinc sulphate in the treatment of cutaneous leishmaniasis clinically.

A new intralesional therapy of cutaneous leishmaniasis with hypertonic sodium chloride solution

One hundred and fifty-eight lesions of acute cutaneous leishmaniasis in 70 patients were treated with hypertonic sodium chloride solution "HSCS" (88 lesions) or sodium stibogluconate (50 lesions); 20 lesions were left untreated as controls. The injections were given at 7-10 day intervals, and patients were followed-up for 42 days. "HSCS" was shown to be a very effective local therapy (96.05% cure rate) and was as effective as local sodium stibogluconate (96.42% cure rate). With both types of therapy, most lesions needed only one injection. Mild improvement was noticed 7-10 days after the first injection, and the cure was complete within 2-6 weeks (mean 4 weeks) of follow-up. None of the control lesions showed a cure within the six weeks follow-up. The mechanisms of action of both "HSCS" and sodium stibogluconate probably involve interference with the osmotic pressure of the cell cytoplasm of the parasites and lesional tissues. Scarring was either absent or minimal following healing of the treated lesions with both types of treatment. Post-inflammatory hyperpigmentation was observed in all patients. We strongly recommend intralesional "HSCS" as a cheap, safe, and effective local method for treating cutaneous leishmaniasis.

Axenic cultivation of amastigotes of Leishmania donovani and Leishmania major and their infectivity

Two clones of promastigotes, one of Leishmania donovani and one of L. major, and an uncloned stock of L. major were axenically transformed to heat-shock amastigotes, at 35 and 37 degrees C, respectively. Of the four different culture media tested, a relatively cheap, liquid medium, RBLM, was found to be the best, both for the transformation of the promastigotes and the serial, axenic cultivation of the amastigotes. In an experiment of 30 days duration, serial cultivation, in an atmosphere with 5% CO2, was possible by subculturing every three days. There were significant differences in virulence in BALB/c mice between axenically-cultured amastigotes and promastigotes, both in terms of the weights, lengths and parasite burdens of the spleens of mice infected intraperitoneally (ip) with L. donovani or L. major and of the appearance, type and size of the cutaneous lesions which developed in mice given L. major by intradermal inoculation.

Comparative diagnostic study of kala azar

Sera from 58 children with hepatosplenomegaly were tested for kala azar by gel diffusion immunoelectrophoresis, countercurrent immunoelectrophoresis and micro-ELISA. The results are compared with those from bone marrow cultures: 40 cases were diagnosed as kala azar by the four immunological techniques and Leishmania parasites were grown in 37 of 40 bone marrow cultures. The techniques used are discussed in terms of sensitivity, specificity and simplicity. The micro-ELISA technique was the most sensitive and convenient to carry out and is strongly recommended for use in routine diagnosis and epidermiological surveys.

The Noguchi-Adler phenomenon: an ultrastructural study of the effects of homologous antiserum on the growth of promastigotes of Leishmania braziliensis braziliensis and Leishmania hertigi hertigi

A light and electron microscope study was made of the agglutinated bodies formed on growing promastigotes of a Leishmania b braziliensis and a L. h. hertigi strain in their homologous antisera to determine the role of leishmanial excreted factor (EF) in the Noguchi-Adler phenomenon, since the L. b. braziliensis strain produced a demonstrable EF, whereas the L. h. hertigi strain did not. Promastigotes of L. b. braziliensis, when grown in high concentrations of homologous antiserum, formed Noguchi-Adler (N-A) bodies, in which the cells were embedded in an extensive amorphous matrix. The cells of L. b. braziliensis in the embedding matrix often appeared unhealthy or dead, with swollen flagellar pockets and distorted flagella, with which small visicles were associated. Even though promastigotes of L. h. hertigi do not produce an EF that precipitates with homologous antibody, N-A bodies containing agglutinated cells separated by a thin structured layer of precipitate were formed during growth in homologous antiserum. In high concentrations of antiserum, some of the agglutinated cells of L. h. hertigi were enlarged and showed syncytial characters that included up to five nuclei, two dividing nuclei and five basal bodies associated with a single kinetoplast. Small vesicles and membranous folds were also observed between cells. The complexity of the Noguchi-Adler phenomenon and significance of the morphological changes seen are discussed.

The primary isolation of Leishmania donovani from Iraq on different culture media

Leishmania donovani was isolated by culturing bone marrow aspirates from kala-azar patients, on three types of culture media. The isolation was successful in 88% of the cases. The effects of pH, D-glucose, L-proline and antibiotic concentration in the isolation were investigated. The semi-solid medium used (pH 7.4) with L-proline, was better than the modified NNN media for the primary isolation.