Glossary

  • Chloroplast DNA

    constitutes the chloroplast genome: transmitted only by mothers, very little variation over time, makes it possible to track maternal lineages

  • Mitochondrial DNA

    constitutes the mitochondrial genome: transmitted only by mothers, very little variation over time, makes it possible to track maternal lineages

  • Apoptosis

    ability to induce programmed cell death

  • Blood-brain barrier Barrier (BBB)

    barrier between the peripheral blood and central nervous system

  • Endothelial cell

    specialized cell that is part of the composition of blood vessels

  • NK cells

    class of immune cells with a cytotoxic function

  • Chloroplasts

    cellular compartments in plants responsible for photosynthesis. Transmitted only by mothers.

  • Cytoadherence

    ability to adhere to cells, particularly endothelial cells

  • Epitope

    immunogenic protein fragment

  • Phylogenetic Study

    Development study of the genetic evolution of a living being (micro-organism, plant, animal)

  • Hepatocyte

    specialized liver cells

  • Hepatoma

    malignant liver tissue cell

  • Isolate

    a parasite strain isolated from the field

  • Deep microvascular beds

    small blood vessels in the deep tissues, in particular the brain

  • Mitochondria

    cellular structures in animals, responsible for energy synthesis. Transmitted only by mothers.

  • Pathogenicity

    ability to induce disease

  • PBMC

    peripheral blood mononuclear cells

  • Phenotypic

    related to the structure

  • Phylogeography

    analysis that also takes into account the geographical distribution of the lines studied

  • Primatology

    study of the species of the order of primates

  • Primatologist

    someone who specializes in the science of primates.

  • CTL response

    cytotoxic immune response

  • Reservoir

    animal species that hosts a pathogen over a long period

  • Trypanosomiasis

    sleeping sickness

Medical Parasitology Unit

The Medical Parasitology Unit pursues two major research themes: malaria and Loa loa filariasis, also known as loiasis. However, in 2006 a research program on toxoplasmosis was also initiated.

 

OBJECTIVES


- Study parasitic diseases of regional interest.

- Understand the mechanisms that lead to the amicrofilaremic state  (people infected but with no microfilaria in the blood) to develop new control and/or treatment methods

- Evaluate the anti-parasitic activities of Gabonese medicinal plants

- Develop new diagnostic methods

TEAM

 

Unit Director : Frédéric ARIEY

Authorization to supervise research, University of Paris VI, 2010

Doctor of Science, Specialty Logic of Life (University of Paris VI, France, 2001),

MD, Specialty Medical Biology, Paris XII, France 1998.

Head of the Medical Parasitology Unit  since 2010

On secondment from the Pasteur Institute in Paris.

 

MALARIA

Head: Dr. Fousseyni S Toure Ndouo

- Pathophysiology Team: Dr. Fousseyni S Toure Ndouo

o Endothelial Cell Interactions / P. falciparum

Estelle Sonya Zang Edou (2nd year Science Thesis)

Hervé Ekomi (Medical resident)

Faustin Lekoulou (Technician)

 

o Anaemia and Parasite Genetic Polymorphism

Dr. Jean-Bernard Lekana Douki

Sylvatrie Danne Dinzouna Boutamba (Master 2 Research)

 

- Drug Team: Dr. Jean-Bernard Lekana Douki

o Epidemiological Surveillance: anti-malarial drug resistance in Plasmodium falciparum isolates

Dr Jean Bernard LEKANA-DOUKI

Rafika Zatra (Research Engineer, VI)

Hervé Ekomi (Medical Resident)

Faustin Lekoulou (Technician)

o Antiplasmodial activity of Gabonese  medicinal plants and Synthetic Molecules

Dr Jean Bernard LEKANA-DOUKI

Gabin MWANDE MAGUENE (2nd year of Science Thesis)

 

FILARIASIS
Head : Dr Jean Paul AKUE
- Immunoparasitology and Drug Team: Dr. Jean Paul Akue

o Sero Molecular Epidemiology of loiasis and toxoplasmosis

Roger Mbou (Technician)

Hubert Moukana (Technician)

o Anti-filariasis Activity of Gabonese Medicinal Plants

Dr Jean Paul AKUE

SERVICE ACTIVITIES


 

MALARIA

We are currently developing three research projects on P. falciparum malaria:

 

1) The study of the pathogenicity of plasmodium isolates circulating in the region

We are trying to understand why some plasmodium isolates give severe forms (anaemia, cerebral malaria, respiratory distress, etc.) that are fatal, while others give only basic forms. The objective is to identify molecules associated with this severity that can be targets for therapy and / or vaccines.

 

2) Monitoring of ACTs (Artemisinin-based combination treatment)

For now, there is no resistance, but some signs have been identified in genes associated with resistance. The use of antimalarial drugs is resulting in the emergence of drug resistance. Therefore, it is essential to monitor the effectiveness of the molecules that make up the ACTs, which  are widely deployed in Gabon, based on the recommendations of Gabonese health authorities and the WHO.

 

 

3) Analysis of the antiparasitic and antiplasmodial activity of medicinal plants in Gabon: therapeutic prospects

Moreover, it is essential to find new molecules that may have inhibitory effects on the development of P. falciparum. This research can be done in two ways:

- By synthesizing new antimalarials based on current drugs whose effectiveness is diminished because of the development of resistance by P. falciparum.

- By searching for new active ingredients (medicinal plants).

 

Secondary Protocol: A Comparative analysis of the prevalence of malaria from July to November 2004 and 2008.

This work in the two hospitals in Franceville (HASG and CHRABF), allowed us to compare data obtained in 2004 and 2008 from July to November. During that time, we examined 481 children with fever. The prevalence of infection with P. falciparum (GE) was 68% (125/183) in 2004 compared to 18.12% (54/298) in 2008. Average parasitaemias were 101,458 (+/-139299) in 2004 compared to 13,295 (+/-45) in 2008. Here, we demonstrated a decrease in prevalence (p <10-8) of malaria and parasitaemia (p <0.0001) among children with malaria in 4 years in the hospitals of Franceville. Two cases of coma were observed in 2004 and no cases in 2008. These results show a significant decrease in the prevalence and severe forms of malaria and can certainly be attributed to the effectiveness of current control methods (use of insecticide treated bed nets, artemisinin-based combination treatment).

 

FILARIASIS

Loa loa filariasis.

Filariasis, in particular loiasis, is a parasitic disease highly endemic in Gabon and the study of Loa loa is thus naturally and historically one of the topics of the department.

Research activities focus on the immunological and molecular biology aspects.

Loa loa filariasis is widespread in the forest of equatorial Africa. It is the third leading cause of consultation in rural areas in some countries of this region of Africa. The loa loa nematode causes various problems, ranging from simple itching, Calabar swelling, ocular, renal, and cardiac inflammation to fatal encephalitis.

 

DEC (Notezine) and ivermectin (Mectizan) are effective only on the microfilariae, but not very active on the adult worms. Hence the need to seek alternative methods of treatment or control. The current diagnosis is based on the detection of microfilariae in the blood, while 70% of those infected have no microfilariae in the blood. Accordingly, there is a need to seek alternative diagnosis methods.

 

TOXOPLASMOSIS

Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii. This opportunistic disease is of particular interest because of the increasing prevalence of HIV. It can cause fatal encephalitis in the event of immunosuppression, and is responsible for embryopathy. Cats and other felines are the definitive hosts. Ongoing studies aim to:

- Analyze the current distribution of T. gondii in Gabon

- Analyze the molecular characteristics of the parasite types in circulation and their relationship with clinical manifestations of toxoplasmosis

 

RESEARCH ACTIVITIES IN 2009


 

- Sero-epidemiological study on parasites affecting the health of rural populations in Gabon

- Molecular epidemiology of T. gondii and coccidiosis in Gabon

- Natural Substances and Infectious Diseases (T. gondii, Loa loa, etc.)



RESOURCES


The Medical Parasitology Unit has a cell culture room (laminar flow hoods, ovens), a BSL-2 laboratory for molecular biology, and a Beta counter to test for drug resistance. Field strains and samples can be stored in liquid nitrogen.

The unit works with the field for the collection of strains. Since 1994 the CIRMF has had a field station 180 km from Franceville, in the village of Dienga, Ogouée Lolo. The station includes a dispensary and a laboratory for performing thick smears. The station is open at all times and is managed by an assistant nurse  employed by the CIRMF. A CIRMF doctor goes there to consult regularly. The station provides care for the entire population of the village, or around 2000 people.

This station offers the opportunity to work on cohorts of individuals (children / adults) with malaria and to perform different types of studies in malariology. Controlling consumption of antimalarials is an advantage for studying resistance and/or new molecules.

The inhabitants of Dienga have embraced the CIRMF and its activities, and remain favourable to the studies, since the free medical care and further examinations are of great value to this relatively poor population.

TRAINING


We are involved in teaching at the USS and the USTM. These last two years we were invited as trainers to the Malaria Workshop of the Pasteur Institute in Madagascar and the Third Annual Workshop of the Global View of Food Allergy (GLOFAL), in Lambaréné, Gabon; We also reviewed four articles.

COLLABORATIONS


University of Tours (France): Education and collaboration under the project on the development of diagnostics via the exchange of samples, use of the electron microscope available in Tours

 

University of Glasgow (United Kingdom): Collaboration under the project funded by the Wellcome Trust consisting of using the Merion / Brugia pahangi model)

 

University of Liverpool (United Kingdom): Education, exchange of information under the project on the transmission, immunity and means of control or eradication of filariasis

 

MedBiotech (Uganda): Exchange of biological material, collaboration with students and researchers under the project on the diagnosis of Loa loa

 

PUBLICATIONS 2009/2010


Touré-Ndouo F. 2009. Relationship between in vivo synchronicity of Plasmodium falciparum and allelic diversity. Parasitology International. Parint 00683.

Azzibrouck GB, Akue JP, Lenoble DR. Production and immunological characterization of a recombinant subunit of a Loa loa polyprotein antigen. Parasitology. 2010 Jun; 137(7):1119-28. Epub 2010 May 5. PMID: 20441677

Mengome LE, Akue JP, Souza A, Feuya Tchoua GR, Nsi Emvo E. In vitro activities of plant extracts on human Loa loa isolates and cytotoxicity for eukaryotic cells. Parasitol Res. 2010 May 22. [Epub ahead of print] PMID: 20495930 [PubMed - as supplied by publisher]

Mpiga Mickoto B, Akue JP, Bisvigou U, Mayi Tsonga S, Nkoghe D. [Serological study on toxoplasmosis among pregnant women from Franceville, Gabon.] Bull Soc Pathol Exot. 2010 Jan 8. [Epub ahead of print]. PMID: 20084487