cmdtla.org - Saúde Tropical

Virgílio do Rosário	Ana Paula Arez	Henrique Silveira	João Pinto
Pedro Cravo	Gabriela S Gomes	Dinora Lopes	Fátima Nogueira
Patrícia Salgueiro	Catarina Alves	Olga Matos	Derek Charlwood

Keywords: Malaria, Leishmaniasis, Drug Resistance, Entomology

More information at Group Report

Attachments:

File	DESCRIPTION	File size
Internationalization.pdf		297 Kb
Introduction by Virgilio E. do Rosário.pdf		363 Kb
Leishmaniasis.pdf		2418 Kb
Malaria.pdf		3258 Kb
Molecular entomology.pdf		1275 Kb
PhD Thesis.pdf		45 Kb
Tick Transmitted diseases.pdf		760 Kb
Vectors innate immunity.pdf		810 Kb

PI - Ana Júlia Afonso: Antimalarial drug resistance – Rodent Model Plasmodium chabaudi.

Genetics of accelerated acquisition of drug resistance to multiple drugs (ARMD) in malaria parasites: dynamics and fitness studies. PTDC/BIA-MIC/65861/2006.  >> Malaria control is presently limited by the widespread occurrence of parasites resistant to antimalarial drugs, such as chloroquine and pyrimethamine/sulfadoxine combinations. Because the discovery and deployment of new antimalarial drugs moves slowly, the clinical efficacy of presently available drugs must be protected, for instance, by reducing the likelihood of resistance arising and/or of spreading.

PI: HENRIQUE SILVEIRA Our research is centred on Plasmodium sporogonic development, especially on the mosquito response to the infection and how this response can be modulated by outside factors. We have clearly established that cloroquine can alter mosquito immune response contributing to differences observed on the parasite development. Chloroquine acts not only at classical immune response pathways but also interferes with the expression of genes associated with apoptosis and cytoskeleton, which are major players for containment of parasite invasion. Our areas of activity are: a) mosquito hemolymph immune responses to Plasmodium infection; b) Anopheles gambiae immune-related genes variability in diferent geographic areas of Africa; c) alterations of immune-related genes transcription in mosquitoes infected with Plasmodum falciparum and/or Plasmodium vivax; and d) modulation of the mosquito innate immunity to Plasmodium using immunostimulatory molecules.

Visceral leishmaniosis caused by Leishmania infantum is an endemic zoonosis in southern European countries. Dogs are the main reservoirs of the parasite, which is transmitted by phlebotomine sand flies. Canine leishmaniosis represents an important veterinary medical and public health problem, i.e. information on the epidemiology of Leishmania infection in dogs is essential in order to define effective control measures for zoonotic leishmaniosis.

PI: Ana Paula Arez

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The extent of genetic diversity of Plasmodium natural populations is a key epidemiological issue of malaria. Although the sporadic interest in the subject, interspecific infections are frequent and studies with humans and rodents indicated that different species interact, affecting mortality, pathology (attenuation of falciparum disease severity) and infection dynamics. Also the extent of genetic variation of natural populations of the most lethal P. falciparum, is a crucial factor. Knowing the population structure of Plasmodium spp. has practical implications for control strategies, particularly when the origin and dissemination of drug resistance associated genes, or the evolution of vaccine-candidate surface antigens, are considered.

Our work has mainly focused the genetic diversity of Plasmodium populations (both between and within species) and the effect of mixed-infections in malaria transmission in the field. Our previous studies carried out in Guinea-Bissau and Mozambique revealed that Plasmodium transmission dynamics is very complex and is affected by interactions between different parasite populations. We intend now pursuing these studies applying new approaches in the use of experimental models [parallel analysis of mosquito infections with human plasmodia (P.falciparum/P.vivax) mimicked by a murine model (P.yoelii/P.chabaudi)], in order to overcome the inherent limitations of field studies.

On-going studies:

1. Cabo Verde - “Epidemiology of malaria in Santiago, Cabo Verde”

2. Angola - “The effect of the host and parasite factors in the susceptibility to malaria”

3. Equatorial Guinea – “Population diversity and transmission dynamics of Plasmodium sp. and Plasmodium falciparum in Equatorial Guinea”

Main collaborations: Univ. Agostinho Neto, Angola; Centro Investigação Saúde Manhiça (CISM), Mozambique (P. Alonso); Centro Hispano-Guineano Enfermedades Tropicales Spain/Equatorial Guinea (A. Benito, P. Bersoza); Malaria Vaccine Drug testing Centre (MVDC), Colombia  (S. Herrera)

PI: JOÃO PINTO Population genetics and Bio-ecology (PI: João Pinto) The origins and evolution of the malaria vector Anopheles gambiae are being studied in the islands of Bioko, Príncipe, São Tomé and Annobón, located in the Gulf of Guinea. A multi-gene approach comprising microsatellite genotyping and DNA sequencing (mtDNA and ITS-rDNA) is being used to establish the number of colonisation events of this mosquito into the islands. Genetic data is being combined with historical records of human population migration events in order to determine the importance of man-mediated mosquito dispersal.

PI: GABRIELA SANTOS-GOMES 

Leishmania/host interactions  

Zoonotic visceral leishmaniasis caused by the parasite Leishmania infantum is a major public health problem in the Mediterranean basin and South America, Middle East and China. Dogs constitute the main reservoir for L. infantum and play a crucial role in parasite transmission. Anti-leishmanial therapy used for human VL has proven to be ineffective in the treatment of canine leishmaniasis. Treated dogs enter temporary remission of clinical signs but there is no complete eradication of the parasite and they eventually regain infectivity and transmission risk. There are clinical and experimental evidences showing that disease resolution depends primarily on cell-mediated immune mechanisms.