Genetic diversity among Trichophyton mentagrophytes isolates using random amplified polymorphic DNA method.

Trichophyton mentagrophytes is a common cosmopolitan dermatophyte species composed of two varieties: T. mentagrophytes var. interdigitale (anthropophilic form) and T. mentagrophytes var. mentagrophytes (zoophilic form). We used a random amplified polymorphic DNA (RAPD) method to study the genetic diversity of 46 clinical isolates of the T. mentagrophytes complex collected from 38 patients with different geographical origins (Europe, Africa, South America). The T. mentagrophytes were isolated either from a unique lesion for 31 patients, including two patients living together, or from at least two sites for seven patients. Only one primer of 15 primers tested showed DNA polymorphism in the isolates, producing 23 distinct patterns belonging to three clusters. There was no specific cluster grouping isolates from the same geographical origin. The same pattern is shared by all the four T. mentagrophytes var. mentagrophytes and 13 of 42 T. mentagrophytes var. interdigitale. An identity of strains responsible for several lesions in seven individuals suggests an homogeneous T. mentagrophytes population in the case of multiple lesions. In contrast, the dissimilarity of two strains recovered from two patients living together argues against person-to-person transmission in that case. This study indicates that RAPD can be successfully applied to show genetic diversity among T. mentagrophytes isolates.

Pathogeny and immunological control of toxoplasmosis.

1. Toxoplasma gondii is a ubiquitous, obligate intracellular parasite of worldwide distribution. In humans, the parasite exists in two forms: the tachyzoite is the rapidly multiplying stage of the parasite which actively invades host cells and represents the principal pathogenic form at the acute phase of the disease; the bradyzoite is the form which multiplies slowly in host cells, resulting in the formation of cysts which persist in tissues. Several antigenic components have been identified, some of which are characteristic for each parasitic stage; particularly, in tachyzoites, the 30 kDa membrane protein represents up to 5% of the total protein content. 2. Toxoplasma infection in humans is usually asymptomatic because of effective immunity involving antibodies, T cells and cytokines. Activated macrophages, CD4 and CD8 lymphocytes and cytokines, such IFN gamma, play a major role in the control of acute infection and the maintenance of infection at the chronic stage. The alteration of immune functions, as observed in congenitally infected children and in HIV-infected patients, may induce the recrudescence of previously latent toxoplasmosis, in relation to disruption of the cyst form of the parasite. The resulting reactivation is responsible for life-threatening infections which are frequently manifested as toxoplasmic encephalitis. 3. In this review, the parasite and immunological factors participating in the pathogenesis of the lesions associated with acute, chronic and reactivated toxoplasmosis are presented.

Pathogeny and immunological control of toxoplasmosis

1. Toxoplasma gondii is a ubiquitous, obligate intracellular parasite of worldwide distribution. In humans, the parasite exists in two forms: the tachyzoite is the rapidly multiplying stage of the parasite which actively invades host cells and represents the principal pathogenic form at the acute phase of the disease; the bradyzoite is the form which multiplies slowly in host cells, resulting in the formation of cysts which persist in tissues. Several antigenic components have been identified, some of which are characteristic for each parasitic stage; particularly, in tachyzoites, the 30 kDa membrane protein represents up to 5% of the total protein content. 2. Toxoplasma infection in humans is usually asymptomatic because of effective immunity involving antibodies, T cells and cytokines. Activated macrophages, CD4 and CD8 lymphocytes and cytokines, such IFN gamma, play a major role in the control of acute infection and the maintenance of infection at the chronic stage. The alteration of immune functions, as observed in congenitally infected children and in HIV-infected patients, may induce the recrudescence of previously latent toxoplasmosis, in relation to disruption of the cyst form of the parasite. The resulting reactivation is responsible for life-threatening infections which are frequently manifested as toxoplasmic encephalitis. 3. In this review, the parasite and immunological factors participating in the pathogenesis of the lesions associated with acute, chronic and reactivated toxoplasmosis are presented

[Experimental Schistosomiases. I. Study of S. mansoni fecondity as regards to its adaptation to different Biomphalaria glabrata strains (author's transl)]. / Schistosomose expérimentale. I. Etude de la fécondité de Schistosoma mansoni en fonction de son adaptation a la souche de Biomphalaria glabrata

We compared the infestation of different strains of B. glabrata from Brasil (Recife). Guadeloupe, Martinique and Porto-Rico with 6 to 8 miracidia of S. mansoni (from Recife. We noted the four following points: 1. The planorbid snails from Martinique and Guadeloupe had a low resistance to infestation. 2. The guadeloupean snails showed the lesser rate of positivity and the lower medium amount of emitted cercaries but, in the four strains of snails, the level of the issued cercaries is quite the same. 3. many planorbid snails in the groups studied during more than 2 months, showed significant periodic variations in the emission of cercaries, We thought that those variations might be caused by the alternate maturations of sporocysts born from the same miracidium or from different miracidia. 4. Infestation by S. mansoni had a strong effect on fecondity of the snails but the laid eggs had a normal development.