Idiopathic thrombocytopenic purpura due to vivax malaria in the Brazilian Amazon.

We describe a rare case of idiopathic thrombocytopenic purpura (ITP) triggered by Plasmodium vivax infection. The patient developed thrombocytopenia and bleeding associated with three episodes of malaria, and became dependent on corticosteroid therapy. The mechanisms by which this parasite evokes thrombocytopenia remain obscure.

The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part II.

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined by the WHO. Furthermore, malaria (caused by various Plasmodium species) can be considered a neglected disease in certain countries and with regard to availability and affordability of the antimalarials. Living organisms, especially plants, provide an innumerable number of molecules with potential for the treatment of many serious diseases. The current review attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs. In part I, a general description of the diseases, the current state of therapy and need for new therapeuticals, assay methods and strategies applied in the search for new plant derived natural products against these diseases and an overview on natural products of terpenoid origin with antiprotozoal potential were given. The present part II compiles the current knowledge on natural products with antiprotozoal activity that are derived from the shikimate pathway (lignans, coumarins, caffeic acid derivatives), quinones of various structural classes, compounds formed via the polyketide pathways (flavonoids and related compounds, chromenes and related benzopyrans and benzofurans, xanthones, acetogenins from Annonaceae and polyacetylenes) as well as the diverse classes of alkaloids. In total, both parts compile the literature on almost 900 different plant-derived natural products and their activity data, taken from over 800 references. These data, as the result of enormous efforts of numerous research groups world-wide, illustrate that plant secondary metabolites represent an immensely rich source of chemical diversity with an extremely high potential to yield a wealth of lead structures towards new therapies for NTDs. Only a small percentage, however, of the roughly 200,000 plant species on earth have been studied chemically and only a small percentage of these plants or their constituents has been investigated for antiprotozoal activity. The repository of plant-derived natural products hence deserves to be investigated even more intensely than it has been up to present.

The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part I.

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined as such by WHO due to the neglect of financial investment into research and development of new drugs by a large part of pharmaceutical industry and neglect of public awareness in high income countries. Another major tropical protozoan disease is malaria (caused by various Plasmodium species), which -although not mentioned currently by the WHO as a neglected disease- still represents a major problem, especially to people living under poor circumstances in tropical countries. Malaria causes by far the highest number of deaths of all protozoan infections and is often (as in this review) included in the NTDs. The mentioned diseases threaten many millions of lives world-wide and they are mostly associated with poor socioeconomic and hygienic environment. Existing therapies suffer from various shortcomings, namely, a high degree of toxicity and unwanted effects, lack of availability and/or problematic application under the life conditions of affected populations. Development of new, safe and affordable drugs is therefore an urgent need. Nature has provided an innumerable number of drugs for the treatment of many serious diseases. Among the natural sources for new bioactive chemicals, plants are still predominant. Their secondary metabolism yields an immeasurable wealth of chemical structures which has been and will continue to be a source of new drugs, directly in their native form and after optimization by synthetic medicinal chemistry. The current review, published in two parts, attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs.

Thrombocytopenia in patients with dengue virus infection in the Brazilian Amazon.

Thrombocytopenia may be occasionally observed in dengue fever (DF) but is a constant feature and one of the diagnostic criteria of dengue hemorrhagic fever (DHF). Its clinical presentation and relevance is still poorly described in the literature. Patients with fever and bleeding were referred to a tertiary care center in Manaus, in the Western Brazilian Amazon during the outbreak of dengue in 2001. They were hospitalized for clinical observation and supportive care. Platelet counts were performed on admission and throughout the hospitalization. Only patients with a serological confirmation or viral isolation of the dengue virus were included. One hundred and seventy eight patients were enrolled in the study (118 with DF and 60 with DHF). There was no association between the presence of active bleeding and the degree of thrombocytopenia on admission (P = 0.302). A positive tourniquet test, hematemesis and ecchymoses were more frequent in DHF patients (P < 0.05). Patients with DHF had lower platelet counts than patients with DF (P < 0.001). There was a positive correlation between platelet counts and plasma albumin levels (r = 0.217; P = 0.016) and a negative correlation with ALT values (r = -0.3; P = 0.001). Clinical manifestations of thrombocytopenia are not related only to the number of peripheral platelets in dengue infection, but its recovery is associated with clinical improvement. The level of platelets correlates with the vascular leakage of proteins and liver damage.