Visceral leishmaniasis

About: Visceral leishmaniasis is a research topic. Over the lifetime, 7486 publications have been published within this topic receiving 184865 citations. The topic is also known as: Kala-Azar & viscus leishmaniasis.

Endemic kala-azar in eastern Sudan: a longitudinal study on the incidence of clinical and subclinical infection and post-kala-azar dermal leishmaniasis.

Abstract: Between April 1991 and April 1993, a longitudinal study was performed in the village of Um-Salala (1,430 inhabitants) in the endemic area of kala-azar (visceral leishmaniasis) in eastern Sudan. During the two years, a total of 92 kala-azar cases were diagnosed (male:female ratio = 1.8:1, mean age 6.6 years). The annual incidence rates were 38.4/1,000 and 38.5/1,000 person-years, respectively. The ratio of clinical to subclinical cases was 1.6:1 in the first year and 2.4:1 in the second year. Post-kala-azar dermal leishmaniasis occurred in 48 (56%) of 85 kala-azar cases that were followed-up for at least six months. Kala-azar occurred only in previously leishmanin-negative individuals. The majority of the population had a positive leishmanin skin test result, probably due to previous exposure to Leishmania major causing cutaneous leishmaniasis in their homeland in western Sudan from which they had migrated in the 1980s. It was thus postulated that previous cutaneous leishmaniasis might protect against kala-azar but this could not be proved.

The immunopathology of experimental visceral leishmaniasis

Abstract: Experimental murine infection with the parasites that cause human visceral leishmaniasis (VL) results in the establishment of infection in the liver, spleen, and bone marrow. In most strains of mice, parasites are eventually cleared from the liver, and hepatic resistance to infection results from a coordinated host response involving a broad range of effector and regulatory pathways targeted within defined tissue structures called granulomas. In contrast, parasites persist in the spleen and bone marrow by mechanisms that are less well understood. Parasite persistence is accompanied by the failure of granuloma formation and by a variety of pathologic changes, including splenomegaly, disruption of lymphoid tissue microarchitecture, and enhanced hematopoietic activity. Here, we review the salient features of these distinct tissue responses and highlight the varied roles that cytokines of the tumor necrosis factor family play in immunity to this infection. In addition, we also discuss recent studies aimed at understanding how splenomegaly affects the survival and function of memory cells specific for heterologous antigens, an issue of considerable importance for our understanding of the disease-associated increase in secondary infections characteristic of human VL.

Cytokine profile and pathology in human leishmaniasis

Abstract: The clinical spectrum of leishmaniasis and control of the infection are influenced by the parasite-host relationship. The role of cellular immune responses of the Th1 type in the protection against disease in experimental and human leishmaniasis is well established. In humans, production of IFN-gamma is associated with the control of infection in children infected by Leishmania chagasi. In visceral leishmaniasis, an impairment in IFN-gamma production and high IL-4 and IL-10 levels (Th2 cytokines) are observed in antigen-stimulated peripheral blood mononuclear cells (PBMC). Moreover, IL-12 restores IFN-gamma production and enhances the cytotoxic response. IL-10 is the cytokine involved in down-regulation of IFN-gamma production, since anti-IL-10 monoclonal antibody (mAb) restores in vitro IFN-gamma production and lymphoproliferative responses, and IL-10 abrogates the effect of IL-12. In cutaneous and mucosal leishmaniasis, high levels of IFN-gamma are found in L. amazonensis-stimulated PBMC. However, low or absent IFN-gamma levels were observed in antigen-stimulated PBMC from 50% of subjects with less than 60 days of disease (24 +/- 26 pg/ml). This response was restored by IL-12 (308 +/- 342 pg/ml) and anti-IL-10 mAb (380 +/- 245 pg/ml) (P < 0.05). Later during the disease, high levels of IFN-gamma and TNF-alpha are produced both in cutaneous and mucosal leishmaniasis. After treatment there is a decrease in TNF-alpha levels (366 +/- 224 pg/ml before treatment vs 142 +/- 107 pg/ml after treatment, P = 0.02). Although production of IFN-gamma and TNF-alpha might be involved in the control of parasite multiplication in the early phases of Leishmania infection, these cytokines might also be involved in the tissue damage seen in tegumentary leishmaniasis.