Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax – Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)

Recent reports of Plasmodium vivax infections, the most widely distributed species of human malaria, show that this parasite is evolving and adapting, becoming not only more aggressive but also more frequent in countries where it was not present in the past, becoming, therefore, a major source of concern. Thus, it is extremely important to perform new studies of its distribution in West and Central Africa, where there are few reports of its presence, due to the high prevalence of Duffy-negative individuals. The aim of this study was to investigate the presence of P. vivax in Angola and in Equatorial Guinea, using blood samples and mosquitoes. The results showed that P. vivax seems to be able to invade erythrocytes using receptors other than Duffy, and this new capacity is not exclusive to one strain of P. vivax, since we have found samples infected with two different strains: VK247 and classic. Additionally we demonstrated that the parasite has a greater distribution than previously thought, calling for a reevaluation of its worldwide distribution

The International Limits and Population at Risk of Plasmodium vivax Transmission in 2009

Growing evidence shows that Plasmodium vivax malaria is clinically less benign than has been commonly believed. In addition, it is the most widely distributed species of human malaria and is likely to cause more illness in certain regions than the more extensively studied P. falciparum malaria. Understanding where P. vivax transmission exists and measuring the number of people who live at risk of infection is a fundamental first step to estimating the global disease toll. The aim of this paper is to generate a reliable map of the worldwide distribution of this parasite and to provide an estimate of how many people are exposed to probable infection. A geographical information system was used to map data on the presence of P. vivax infection and spatial information on climatic conditions that impede transmission (low ambient temperature and extremely arid environments) in order to delineate areas where transmission was unlikely to take place. This map was combined with population distribution data to estimate how many people live in these areas and are, therefore, exposed to risk of infection by P. vivax malaria. The results show that 2.85 billion people were exposed to some level of risk of transmission in 2009

Intestinal strongyloidiasis and hyperinfection syndrome

In spite of recent advances with experiments on animal models, strongyloidiasis, an infection caused by the nematode parasite Strongyloides stercoralis, has still been an elusive disease. Though endemic in some developing countries, strongyloidiasis still poses a threat to the developed world. Due to the peculiar but characteristic features of autoinfection, hyperinfection syndrome involving only pulmonary and gastrointestinal systems, and disseminated infection with involvement of other organs, strongyloidiasis needs special attention by the physician, especially one serving patients in areas endemic for strongyloidiasis. Strongyloidiasis can occur without any symptoms, or as a potentially fatal hyperinfection or disseminated infection. Th(2 )cell-mediated immunity, humoral immunity and mucosal immunity have been shown to have protective effects against this parasitic infection especially in animal models. Any factors that suppress these mechanisms (such as intercurrent immune suppression or glucocorticoid therapy) could potentially trigger hyperinfection or disseminated infection which could be fatal. Even with the recent advances in laboratory tests, strongyloidiasis is still difficult to diagnose. But once diagnosed, the disease can be treated effectively with antihelminthic drugs like Ivermectin. This review article summarizes a case of strongyloidiasis and various aspects of strongyloidiasis, with emphasis on epidemiology, life cycle of Strongyloides stercoralis, clinical manifestations of the disease, corticosteroids and strongyloidiasis, diagnostic aspects of the disease, various host defense pathways against strongyloidiasis, and available treatment options

Description de

Dans les frottis sanguins colorés au Giemsa d’un singe Cercocebus albigena capturé en République Centrafricaine, trois espèces d’hématozoaires ont été identifiées : Plasmodium gonderi Rodhain et Van Den Berghe, 1936 (nouvel hôte et nouvelle localisation géographique), Plasmodium petersi n. sp. et Plasmodium georgesi n. sp.. P. petersi se caractérise par la présence fréquente chez les jeunes trophozoites de deux ou trois vacuoles coiffées d’un gros noyau ovalaire, par la morphologie des schizontes presque mûrs contenant de 12 à 18 noyaux arrondis, homogènes et assez gros, et possédant un cytoplasme bleu clair formant souvent une auréole très pâle autour de certains noyaux, par la formation d’un pigment en aiguilles noires et par l’apparition tardive de granulations globulaires très fines, grisâtres, de même taille et relativement peu nombreuses, dans une hématie augmentée de volume, à bords nets et de teinte normale. P. georgesi n. sp. se caractérise par l’allongement en arc de cercle du noyau de ses trophozoïtes, par la grande taille et l’aspect polygonal des noyaux des jeunes schizontes immatures (contenant de 2 à 8 noyaux), par le nombre de noyaux des schizontes presque mûrs (22 à 26), par l’augmentation de volume importante des hématies parasitées qui prennent souvent une forme polygonale, par l’apparition relativement tardive de nombreuses granulations globulaires de tailles irrégulières, devenant de plus en plus violettes et intenses au fur et à mesure que le parasite mûrit, et par la formation tardive d’un pigment punctiforme jaunâtre

Infestation humaine par

Les auteurs décrivent un cas d’infestation par Trichostrongylus vitrinus chez une marocaine âgée de 53 ans

Les formes atypiques de

Les auteurs décrivent une forme atypique de Plasmodium vivax originaire du Gabon, caractérisée par la présence de nombreux globules rouges parasités par plusieurs trophozoïdes amoeboïdes (jusqu’à 6). Ils attirent l’attention sur les nombreuses atypies morphologiques que peuvent présenter les stades intraérythrocytaires de P. vivax : infections multiples fréquentes, formes « évoquant » P. ovale, schizontes « de crise » contenant un nombre réduit de mérozoïtes... Ils discutent la répartition géographique de P. vivax en Afrique Centrale, en étudiant les facteurs pouvant permettre l’observation de cas sporadiques d’importation de ce parasite en provenance de cette région

Relapsing

A case of atypical Plasmodium vivax malaria is presented. The clinical follow-up has allowed to characterize three consecutive malaria clinical episodes within one year. At the first attack, 39 % of the infected red blood cells were parasitized by gametocytes. Furthermore, rare crisis forms, exceptional « pseudo-parthenogenesis » forms, a few equatorial trophozoites, malaria pigment-containing leucocytes and phagocytized parasites were also found in the thin blood smears. At the second malaria episode, morphological aspects were quite similar, but the gametocyte percentage decreased and that of the equatorial trophozoite forms increased. Only at the third attack, was the morphology typical of P. vivax. The Plasmodium species and the absence of mixed infection were unequivocally confirmed using polymerase chain reaction. Atypical strains of P. vivax are relatively frequent. Nevertheless, to our knowledge, neither so high a gametocyte percentage, nor extensive P. vivax peripheral phagocytosis were previously reported