Haemogregarina bigemina (Protozoa : Apicomplexa : Adeleorina) – Past, present and future

This paper reviews past, current and likely future research on the fish haemogregarine, Haemogregarina bigemina Laveran et Mesnil, 1901. Recorded from 96 species of fishes, across 70 genera and 34 families, this broad distribution for H. bigemina is questioned. In its type hosts and other fishes, the parasite undergoes intraerythrocytic binary fission, finally forming mature paired gamonts. An intraleukocytic phase is also reported, but not from the type hosts. This paper asks whether stages from the white cell series are truly H. bigemina. A future aim should be to compare the molecular constitution of so-called H. bigemina from a number of locations to determine whether all represent the same species. The transmission of H. bigemina between fishes is also considered. Past studies show that young fish acquire the haemogregarine when close to metamorphosis, but vertical and faecal-oral transmission seem unlikely. Some fish haemogregarines are leech-transmitted, but where fish populations with H. bigemina have been studied, these annelids are largely absent. However, haematophagous larval gnathiid isopods occur on such fishes and may be readily eaten by them. Sequential squashes of gnathiids from fishes with H. bigemina have demonstrated development of the haemogregarine in these isopods. Examination of histological sections through gnathiids is now underway to determine the precise development sites of the haemogregarine, particularly whether merozoites finally invade the salivary glands. To assist in this procedure and to clarify the internal anatomy of gnathiids, 3D visualisation of stacked, serial histological sections is being undertaken. Biological transmission experiments should follow these processes

Le problème de la composition politique chez Spinoza : hypothèses ontologiques et perspectives pratiques

Dans cet article, il s’agit de s’interroger sur le sens de l’étonnante invitation de Spinoza à « se convenir tous en tout, en sorte que les Esprits et les Corps de tous composent pour ainsi dire un seul Esprit et un seul Corps » (Éthique, IV, 18, scolie) à partir de l’articulation entre physique et éthique, dans laquelle la question politique semble jouer un rôle capital

La extensión como espacio curricular en las carreras de grado

La investigación acción es una alternativa de los métodos de investigación cualitativa, y proviene de Kurt Lewin (1946), una forma de investigación que podía ligar el enfoque experimental de la ciencia social con programas de acción social que respondieran a los problemas principales de entonces, argumentando que se podía lograr de manera simultánea avances teóricos y cambios sociales. La investigación – acción es un proceso que sigue una evolución sistemática, y cambia tanto al investigador como las situaciones en las que éste actúa. Sobre todo en entornos académicos con una fuerte vinculación de la teoría con la práctica, donde el proceso de aprendizaje- conocimiento- acción, permite vincular el análisis de los problemas en un contexto determinado con programas de acción social, que producen un conjunto de espirales cíclicas de planeamiento, acción, observación y reflexión. En el contexto educacional contemporáneo, reviste importancia y aplicabilidad  en distintas áreas de desarrollo social, y procesos formativos enriqueciendo e incorporando  a académicos  en el trabajo con esta metodología de estrategias educativas en el proceso de enseñanza-aprendizaje. González Maura, argumenta que es apropiada para el ámbito de la educación, cuando elimina la dicotomía teoría-práctica y sujeto-objeto de investigación, característicos de la investigación tradicional en al campo de la educación. La inclusión curricular de la extensión desde un enfoque metodológico de  investigación- acción, para lograr  simultáneamente conocimientos y cambios sociales y los resultados de sus acciones para aprender de ellas desde una relación dialógica en construcción con la sociedad, responde adicionalmente a la integración extensión-docencia-investigación. Esta es una propuesta de creación de asignaturas de extensión en carreras de grado, empleando el método de investigación-acción, con un enfoque proyectual que busca la formación de ciudadanos críticos, con capacidad innovadora. La futura articulación en Red de estos espacios curriculares, con espacios curriculares similares de otras universidades, es una posibilidad real y tiene el objetivo de fortalecer el vínculo entre la Universidad y la sociedad, logrando un impacto multiplicador en el medio regional. La conjunción de extensión con investigación acción resulta en una acción estratégica en respuesta al contexto,  uno de los retos de la Universidad de hoy

Geographical distribution and epidemiological features of Old World Leishmania infantum and Leishmania donovani foci, based on the isoenzyme analysis of 2277 strains

A series of 2277 Leishmania strains from Old World visceral leishmaniasis foci, isolated between 1973 and 2008, were studied by isoenzyme analysis. The strains were obtained from humans, domestic and wild carnivores, rodents and phlebotomine sandflies, and came from 36 countries. In all, 60 different zymodemes were identified and clustered by a phenetic analysis into 3 different groups corresponding to the typically visceralizing species L. donovani (20 zymodemes, 169 strains), L. archibaldi (3 zymodemes, 46 strains) and L. infantum (37 zymodemes, 2,062 strains). The taxonomic position of these isoenzymatic groups is discussed in view of contradictory results obtained from recent molecular studie

Reader technique as a source of variability in determining malaria parasite density by microscopy

BACKGROUND: Accurate identification and quantification of malaria parasites are critical for measuring clinical trial outcomes. Positive and negative diagnosis is usually sufficient for the assessment of therapeutic outcome, but vaccine or prophylactic drug trials require measuring density of infection as a primary endpoint. Microscopy is the most established and widely-used technique for quantifying parasite densities in the blood. METHODS: Results obtained by 24–27 expert malaria microscopists, who had independently read 895 slides from 35 donors, were analysed to understand how reader technique contributes to discrepancy in measurements of parasite density over a wide range of densities. RESULTS: Among these 35 donations, standard deviations ranged from 30% to 250% of the mean parasite density and the percent discrepancy was inversely correlated with the mean parasite density. The number of white blood cells indexed and whether parasites were counted in the thick film or thin film were shown to significantly contribute to discrepancy amongst microscopists. CONCLUSION: Errors in microscopy measurements are not widely appreciated or addressed but have serious consequences for efficacy trials, including possibly abandoning promising vaccine candidates

Monophyly of the species of Hepatozoon

Haemogregarines (Apicomplexa: Adeleiorina) are a diverse group of haemoparasites reported from almost all vertebrate classes. The most commonly recorded haemogregarines to parasitize anurans are species of Hepatozoon Miller, 1908. To date 16 Hepatozoon species have been described from anurans in Africa, with only a single species, Hepatozoon hyperolli (Hoare, 1932), infecting a member of the Hyperoliidae. Furthermore, only two Hepatozoon species are known from South African anurans, namely Hepatozoon theileri (Laveran, 1905) and Hepatozoon ixoxo Netherlands, Cook and Smit, 2014, from Amietia delalandii (syn. Amietia quecketti) and three Sclerophrys species, respectively. Blood samples were collected from a total of 225 individuals representing nine hyperoliid species from several localities throughout northern KwaZulu-Natal, South Africa. Twenty frogs from three species were found positive for haemogregarines, namely Afrixalus fornasinii (6/14), Hyperolius argus (2/39), and Hyperolius marmoratus (12/74). Based on morphological characteristics, morphometrics and molecular findings three new haemogregarine species, Hepatozoon involucrum Netherlands, Cook and Smit n. sp., Hepatozoon tenuis Netherlands, Cook and Smit n. sp. and Hepatozoon thori Netherlands, Cook and Smit n. sp., are described from hyperoliid hosts. Furthermore, molecular analyses show anuran Hepatozoon species to be a separate monophyletic group, with species isolated from African hosts forming a monophyletic clade within this cluster.Peer reviewe

A rapid and robust tri-color flow cytometry assay for monitoring malaria parasite development

Microscopic examination of Giemsa-stained thin blood smears remains the gold standard method used to quantify and stage malaria parasites. However, this technique is tedious, and requires trained microscopists. We have developed a fast and simple flow cytometry method to quantify and stage, various malaria parasites in red blood cells in whole blood or in vitro cultured Plasmodium falciparum. The parasites were stained with dihydroethidium and Hoechst 33342 or SYBR Green I and leukocytes were identified with an antibody against CD45. Depending on the DNA stains used, samples were analyzed using different models of flow cytometers. This protocol, which does not require any washing steps, allows infected red blood cells to be distinguished from leukocytes, as well as allowing non-infected reticulocytes and normocytes to be identified. It also allows assessing the proportion of parasites at different developmental stages. Lastly, we demonstrate how this technique can be applied to antimalarial drug testing