cmdtla.org - Saúde Tropical

Clinical Studies Group is based on the activities of two main R&D units, both based at IHMT: Clinic of Tropical Disease's Unit [Head: Jorge Atougia] and Tropical Pathology Unit [Head: Luís Távora Tavira]. These two medical-based units also run an outpatient clinic for tropical diseases and the central clinical laboratory at IHMT.Group Report

Jorge Atouguia	Luís Távora Tavira	Jorge Seixas	Rosa Teodósio	Nuno Rolão
Sónia Lima	Marcelo Silva	João Rodrigues	Luís Varandas	Fernando Ventura
Jaime Nina	Kamal Mansinho

Trypanosoma brucei experimental rodent model

The mouse has been the most widely used animal model for experimental trypanosomiasis. The CNS-trypanosomiasis mouse model used in our laboratory was developed by Jennings and collaborators in the Glasgow University Veterinary School and has proven to be an excellent model system.

We developed a study to have a better knowledge about travel medicine in the Lisbon area, with the following objectives: 1) To characterize the traveller to the Portuguese-speaking African Countries; 2) To determine general practitioners, travel agents and pharmacists' training, experience, and interest in travel medicine and to assess the technical quality of the information given; 3) To establish consensual quality standards and to assess structure, process and outcome quality in travel clinics.

Transmittable diseases of migrants and asylum seekers in Portugal [L. Távora Tavira / L. Atouguia] Transmittable diseases of migrants and asylum seekers in Portugal are now in the process of extension to migrant communities around Lisbon metropolitan area, targeting field projects related to migrants health.

This research line is part of the activity of EpiMigra - Nucleus for epidemiological studies on migrant's health, a research group established at the Clinical Unit of the Institute of Tropical Medicine. Of the more than 800 individuals enrolled on the study, data is already available from 490 migrants, coming mainly from sub-Saharan Africa.

Thirty two percent of the individuals had at least one transmittable infection, with frequent combination of two or more infections in the same person. Globally, at the time of first consultation, 20% of the study subjects had at least one sexually transmitted infection (STI) and 10% at least one intestinal parasite present. The prevalence of HIV infection was 4.7% (4.5% in men and 5.6% in women) in the studied population. In this line of work, a 6th EU Framework proposal was subscribed by a Consortium led by the University of Ghent, for the creation of a European network of reproductive health of refugees.

Collaborations within this research line: International Centre for Reproductive Health - Ghent University; Portuguese Centre for Refugees; Calouste Gulbenkian Foundation; Portuguese National Institute of Health; AJPAS (NGO) Associação de Jovens para uma Amadora Saudável; AGIR XXI (NGO); Hospital Egas Moniz - Ministry of Health

Animal parasites impact in human populations

The bio climate characteristics of Guinea-Bissau associated to large river valleys and wetlands or permanent accumulated water zones allow and favour the presence of several freshwater snail populations. These molluscs can act as intermediate hosts of certain species of parasites (Trematoda, Platyhelminthes), with special relevance for two genus Schistosoma and Fasciola.

The first one includes several species responsible for Schistosomiasis/bilharziasis in human and animals and it is considered the second worldwide human disease with impact on socio-economic and public health. The second with only one species in Guinea-Bissau is the causative agent of animal fascioliasis and human infection is unknown.

In Guinea-Bissau these water-related diseases have been mainly viewed within the clinical diagnostic and rapid therapeutic intervention context, especially concerning medical activities at human level. There is a lack of compared and collaborative studies relating biological, environmental, parasitological and medical issues, which emphasise the real extension of these diseases on men and animals in this country. Therefore, this project’s main goal is to establish the ecological limits of the interaction among the parasites water-related and the intermediate and vertebrate hosts in the freshwater ecosystems, highlighting the impact of parasitic transmission on animal and human populations in the drainage basin of the Geba River in Guinea-Bissau (Attachment 1), using a multidisciplinary approach (geographical, climatologic, epidemiological, medical and veterinary, molecular biology) and applying modern technologies (DNA, RNA research, immunoanalysis, RS and GIS). This study will be done based mainly, on field and laboratory work data and remote sensing (RS) information, integrated into a geographical information system (GIS) to support comparisons between results. A spatio-temporal epidemiological model to predict periods and areas of infection risk for vertebrate hosts (human and animals) using multivariate analysis will be created.

The following activities will contribute to fulfil the lack of knowledge in these issues:

- Identification of ecological factors that allow the presence of parasites and intermediate host populations and guarantee the transmission processes using: geographical and climatic framework, water physical and chemical characteristics, aquatic flora composition, presence/absence of animal and human populations and water pattern contact;

- Characterization of the parasites water-related (Schistosoma haematobium, S. mansoni, S. bovis e Fasciola gigantica) at morphological, biological, immunological and molecular level in the infected intermediate (Lymnaea sp., Biomphalaria sp., Bulinus spp.) and vertebrate hosts;

- Evaluation of parasitic water-based diseases impact on the vertebrate hosts, based on local communities in the neighbourhood of the sampling sites will be performed through:

- clinic diagnosis and treatment of human population, according to WHO methodologies, and epidemiological inquiry targeting childhood and adults,

- assessment of the nutritional status of children, as recognized by WHO protocols,

- characterization of the animal production system based on inquiries focussed on animal owners,

- prevalence of infection in men, domestic and, if possible, wild animals co-inhabitants of the same ecosystem, based on parasitological exams.

- Application of different multivariate analysis approaches (Geographical Weighted Regression and multivariate geostatistic) to estimate spatial data connected with parasitic water-related disease distribution to produce risk maps to be used on risk assessment.

This multidisciplinary approach contributes for the accomplishment of the following Millennium Development Goals: 1st, Eradicate extreme poverty and hunger; 3rd, Reduce child mortality; 5th, Improve maternal health; 6th, Combat HIV/AIDS, malaria and other diseases; 7th, Ensure environmental sustainability.

PTDC/SAU-ESA/72146/2006 Ciências da Saúde - Epidemiologia, Saúde Pública e Ambiente approved July 2008

Dinâmica das doenças parasitárias emergentes de ecossistemas dulçaquícolas na bacia do Rio Geba (Guiné-Bissau) e suas repercussões em Saúde Pública

Dynamic of parasitic water-related diseases in freshwater ecosystems at the Geba River basin (Guinea-Bissau) and their repercussions in Public

Team

Fernanda Henriques de Jesus Rosa (Inv. Responsável); Telmo Renato Landeiro Raposo Pina Nunes, António Jorge Gonçalves de Sousa; Luís Alfredo Pires de Távora Tavira; Ana Maria de Oliveira Morgado; Fernando Eduardo Lagos Costa; Mónica Catarina do Vale Oliveira Botelho; Yolanda Maria Vaz Investigador; Vítor Manuel Rosado Marques; Maria do Carmo Sequeira Nunes; José Manuel Alves Correia da Costa; Jorge Luis Marques da Silva Atouguia

The impact of giardiasis on public health, together with the few studies conducted on Portugal that address the molecular characterization of Giardia parasites have been conducted justify the interest of understanding the epidemiology and transmission of G. intestinalis both in an endemic area (Alentejo), as well as in the migrating population that attends the Travel and Tropical Medicine Units at IHMT. This project is developed in collaboration with Manuela Vilhena from the Evora University.

Team: Jorge Atouguia, Luís Távora Tavira, Filipa Santana Ferreira, Sónia Centeno-Lima

Complement system activation and erythrocyte complement-regulatory receptors inpatients infected with Plasmodium falciparum.

Many works suggest that erythrocyte complement-regulatory proteins, in particular complement receptor 1 (CR1), are important in the pathogenesis of severe malaria. The objective of this study will be to investigate regulatory-complement molecules expression and complement system activation on surface erythrocytes isolated from patient infected with Plasmodium falciparum parasite. Five distinct possible invasion profiles will be studied, such as CR1, DAF, CD59, GPA and GPC receptors.

Additionally, erythrocyte asymmetry membrane and soluble complement molecules and pro-inflammatory mediators present in serum, such as nitric oxide, cytokines, C3a and C5a anaphylatoxins, will be analysed.

This investigation may be contributed for molecular basis of invasion pathways in natural Plasmodium falciparum infections. Submitted grant project PIC/IC/82931/2007 to Fundação para a Ciência e a Tecnologia.

Coordinator: Prof. Dr. Luis Távora Tavira Principal investigator: Dr. Marcelo Sousa Silva

Sousa K, Silva MS and Tavira LT. Variation of nitric oxide levels in imported  Pasmodium falciparum malária episodes. African Journal of Biotecnology, 2008.

Possible contribute of complement system and metalloproteinases in the pathogenesis of Trypanosoma brucei infection.
 

The new research investigations focus on the biochemical characterization of the metalloptroteinases (MPs) that we found to be present in bloodstream forms of Trypanosoma brucei brucei parasite (manuscript in preparation). To this end, we will continue our current line of research by testing different substrates and inhibitors of these enzymes.

We will also averiguate the possible interaction between MPs and complement system in the pathogenesis of Trypanosoma brucei infection in different in vivo and in vitro models. This study may be important if we consider the highly complex immune evasion mechanisms that this protozoon display, as well as the role of MPs and complement system in the homeostasis and inflammatory processes.

Coordinator: Prof. Dr. Jorge Atouguia; Principal Investigator: Dr. Marcelo Sousa Silva

Sousa KP, Atouguia J and Silva MS. The bloodstream forms of Trypanosoma brucei brucei contain metalloproteinase that is by tetracycline and derivates, in preparation.

DNA vaccine approach for African trypanosomiasis

DNA Vaccine or genetic vaccination have been extensively studied because they are able to induce different mediators and immune response mechanisms with involvement of T helper CD4+ and CD8+ cells and different antibodies subclass production. Recently we have cloned two antigenic candidate genes from Trypanosoma brucei in pVax1 plasmid.

These plasmid DNA vectors, called ISGpVAx1 and TSApVAX1, carried respectively the Invariant Surface Glycoprotein gene (ISG) and Trans-sialidase gene (TSA) from bloodstream forms of Trypanosoma brucei parasites. When injected in Balb/c and CD1 mice they have induced antibodies that bind to a purified protein extract from T. brucei brucei.

The proposed work aims to a better understanding of how the immune system is activated after stimulation of ISG and TSA expressing plasmid vectors and testing if this activation will be sufficient to protect murine animals. This work has complementary objectives to the ongoing projects: Development of DNA vaccine prototypes for veterinary trypanosomiasis (POCI/CVT/61090/2004) and Use of the vaccine adjuvant for immunomodulation of the infection caused by Trypanosoma brucei: an approach to vaccine design (PTDC/CVT/72624/2006), both supported by Fundação para a Ciência e a Tecnologia (FCT).

Coordinator: Prof. Dr. Jorge Atouguia; Principal Investigator: Dr. Marcelo Sousa Silva

• Silva MS, Lança A, Prazeres DMF, Atouguia J, and Monteiro GA. Trans-sialidase from Trypanosoma brucei as a potential target in DNA vaccine development against African Trypanosomiasis. Vet. Immunol. Immunopathol. 2008 - submmited.
• Silva MS, Monteiro GA, Atouguia J, Liberato P, and Prazeres DMF. Humoral immune response induced in outbred CD1 mice by DNA vaccine against African Trypanosomiasis. Medimond International Proceedings, 88:597-602, 2006.
• Silva MS. DNA vaccine: the experimental immunization model against African Trypanosomiasis. PhD thesis. Universidade Técnica de Lisboa, 2006.

tsetse2

Our group has recently developed a new approach to detect trypanosome DNA in Glossina that uses the entire fly body for DNA extraction and analysis, avoiding the laborious and time-consuming on-site fly dissection.

Our group has recently developed a new approach to detect trypanosome DNA in Glossina that uses the entire fly body for DNA extraction and analysis, avoiding the laborious and time-consuming on-site fly dissection.

The results of this new approach, tested in well preserved tsetse from Equatorial Guinea were presented as an oral communication in an International Congress, and accepted for publication at the Journal of Infection in Developing Countries.  Present work is developing on the analysis of poor preserved flies collected in two HAT focus in Northern Angola, at the endemic provinces of Zaire and Uige.

Human African trypanosomiasis (HAT) is a neglected disease and a severe public health problem in Angola. The limited available funds are mainly used for disease control activities, which include systematic patient detection and treatment and vector control. Knowledge on the genotypes of Trypanosoma brucei ssp. circulating in transmission foci in Angola, clarification of the role played by peridomestic animals as reservoirs and the determination of the trypanosomes infecting the tsetse flies will contribute for more effective disease control activities.

Our objectives are the characterization of the molecular epidemiology of sleeping sickness in Angola, the development of new tools for genotyping the parasites infecting patients, tsetse and peridomestic animals as well as determining the relationship between human disease characteristics and the observed parasite genotypes. This project was approved by the National Angolan Ethics Committee.

This work is developed in collaboration with the ICCT, Institute of Trypanosomiasis Control Programme, Angola.

Team: Jorge Atouguia, Jorge Seixas, Luís Távora Tavira, Filipa Santana Ferreira, Joana Gomes, Sónia Centeno-Lima