Nicolas Antoine-Moussiaux

Contributions of experimental mouse models to the understanding of African trypanosomiasis.

African trypanosomiasis is the collective name for a wide variety of trypanosome infections that affect humans and livestock. In recent years, experimental mice infection models have provided new insights into both human and animal trypanosomiasis. Mouse models seem to be a valuable and versatile tool in trypanosomiasis-associated pathology and immunology research and highlight the variety shown by African trypanosomiases. Indeed, inbred mouse strains have enabled the study of genetic determinants of susceptibility and of the roles of anti-parasite antibodies, inflammatory mediators and anti-inflammatory mediators for each trypanosome species. Remarkable advances relating to the encephalitic stage of sleeping sickness have also been achieved thanks to murine models. The different contributions of murine models to the African trypanosomiases knowledge are presented here. Future search directions are finally proposed, with respect to mouse model opportunities and limitations.

Host-Parasite Interactions in Trypanosomiasis: on the Way to an Antidisease Strategy

African trypanosomiasis (AT) is a family of parasitic conditions affecting both humans and livestock, impairing development in sub-Saharan Africa, throughout the 10 million-km2 habitat zone of the common vector, Glossina spp. According to the WHOs estimations ([2][1]), 300,000 to 500,000 people are

Tuareg ethnoveterinary treatments of camel diseases in Agadez area (Niger)

For generations, nomadic herders have been learning to manage herd health, particularly in dromedaries because of their great value. Owing to the unavailability of veterinary services, camel herders in remote areas have been developing their own pharmacopoeia and veterinary techniques. The bleeding of sick animals is a common treatment, as Tuareg herders believe that ‘tainted blood’ (izni) is the cause of many conditions. Several surgical techniques are also used, such as excision of calcified sublingual cord. The remedies mentioned in this survey are derived from Maerua crassifolia, Boscia senegalensis, Acacia raddiana, Cucumis prophetarum, Calotropis procera, Ricinus communis, Citrullus colocynthis, green tea, millet, tobacco and onions. Artificial elements are also used for treatment of animals: Powders collected from batteries, various haircare or skincare creams, crushed glass, insecticides or motor oil belong to their pharmacopoeia. This broadmindedness allows the introduction of modern veterinary medicine. Factors such as the lack of real production objectives constitute limits to this progress, however.

A Systematic Scoping Study of the Socio-Economic Impact of Rift Valley Fever: Research Gaps and Needs

Rift Valley fever (RVF) is a severe mosquito‐borne disease affecting humans and domestic ruminants. RVF virus has been reported in most African countries, as well as in the Arabic Peninsula. This paper reviews the different types of socio‐economic impact induced by RVF disease and the attempts to evaluate them. Of the 52 papers selected for this review, 13 types of socio‐economic impact were identified according to the sector impacted, the level and temporal scale of the impact. RVF has a dramatic impact on producers and livestock industries, affecting public and animal health, food security and the livelihood of the pastoralist communities. RVF also has an impact on international trade and other agro‐industries. The risk of introducing RVF into disease‐free countries via the importation of an infected animal or mosquito is real, and the consequent restriction of access to export markets may induce dramatic economic consequences for national and local economies. Despite the important threat of RVF, few studies have been conducted to assess the socio‐economic impact of the disease. The 17 studies identified for quantitative analysis in this review relied only on partial cost analysis, with limited reference to mid‐ and long‐term impact, public health or risk mitigation measures. However, the estimated impacts were high (ranging from

Immune depression of the SJL/J mouse, a radioresistant and immunologically atypical inbred strain

5 to

A Non-Cytosolic Protein of Trypanosoma evansi Induces CD45-Dependent Lymphocyte Death

470 million USD losses). To reduce the impact of RVF, early detection and rapid response should be implemented. Comprehensive disease impact studies are required to provide decision‐makers with science‐based information on the best intervention measure to implement ensuring efficient resource allocation. Through the analysis of RVF socio‐economic impact, this scoping study proposes insights into the mechanisms underpinning its often‐underestimated importance. This study highlights the need for comparative socio‐economic studies to help decision‐makers with their choices related to RVF disease management.

The Perceived Value of Passive Animal Health Surveillance: The Case of Highly Pathogenic Avian Influenza in Vietnam

As the inbred mouse strain SJL/J displays increased resistance to several pathogens and as its immune system shows multiple specificities, it is tempting to infer a causal link between these observations. The first question that comes to mind is whether adaptive immunity plays a role, and a way to answer this question is to see if the resistance phenotype persists when adaptive immunity is depressed. Although it has long been known that irradiation causes repression of leukopoiesis in mice, the technical data available in the literature are of no help in the case of strain SJL/J, because it displays exceptional radioresistance. Here we show that exposure of SJL/J to ∼9Gy, an intensity corresponding to the lethal dose 50 for the species Mus musculus, leads to serious but reversible alteration of leukopoiesis. This conclusion stems from an examination of the effects, 1-11 days post-exposure, of whole-body gamma-ray irradiation on leukocyte populations in the thymus and peripheral blood of young adult females. Immunodepression was most severe 4 days post-exposure. As in other strains, leukocyte populations displayed differential radiosensitivity, B (CD19(+)) cells being most sensitive, T (CD4(+)/CD8(+)) cells moderately sensitive, and natural killer (NK1.1(+)) cells most resistant. Surprisingly, however, the helper/inducer T lymphocytes proved more resistant than the cytotoxic/suppressor T lymphocytes, contrarily to what is observed in other strains. The procedure described will make it possible to refute or establish reliably the existence of causal links between SJL-specific phenotypic traits and immune aberrations and to elucidate further the respective roles of innate and acquired immunity in determining the resistance of this strain to an array of viral diseases.

Applying participatory approaches in the evaluation of surveillance systems: A pilot study on African swine fever surveillance in Corsica

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present study was designed to establish whether there is a direct causal link between the parasite load during its exponential phase of growth and the disappearance of peripheral blood leukocytes. In vitro experiments performed with trypanosomes and purified peripheral blood mononucleated cells revealed the existence of a lymphotoxin embedded in the T. evansi membrane: a protein sensitive to serine proteases, with a molecular mass of less than 30 kDa. Lymphocytes death induced by this protein was found to depend on the intervention of a lymphocytic protein tyrosine phosphatase. When lymphocytes were exposed to increasing quantities of a monoclonal antibody raised against the extracellular portion of CD45, a transmembrane protein tyrosine phosphatase covering over 10% of the lymphocyte surface, T. evansi membrane extracts showed a dose-dependent decrease in cytotoxicity. As the regulatory functions of CD45 concern not only the fate of lymphocytes but also the activation threshold of the TCR-dependent signal and the amplitude and nature of cytokinic effects, this demonstration of its involvement in T. evansi-dependent lymphotoxicity suggests that T. evansi might manipulate, via CD45, the hosts cytokinic and adaptive responses.

When private actors matter: Information-sharing network and surveillance of Highly Pathogenic Avian Influenza in Vietnam

Economic evaluations are critical for the assessment of the efficiency and sustainability of animal health surveillance systems and the improvement of their efficiency. Methods identifying and quantifying costs and benefits incurred by public and private actors of passive surveillance systems (i.e. actors of veterinary authorities and private actors who may report clinical signs) are needed. This study presents the evaluation of perceived costs and benefits of highly pathogenic avian influenza (HPAI) passive surveillance in Vietnam. Surveys based on participatory epidemiology methods were conducted in three provinces in Vietnam to collect data on costs and benefits resulting from the reporting of HPAI suspicions to veterinary authorities. A quantitative tool based on stated preference methods and participatory techniques was developed and applied to assess the non‐monetary costs and benefits. The study showed that poultry farmers are facing several options regarding the management of HPAI suspicions, besides reporting the following: treatment, sale or destruction of animals. The option of reporting was associated with uncertain outcome and transaction costs. Besides, actors anticipated the release of health information to cause a drop of markets prices. This cost was relevant at all levels, including farmers, veterinary authorities and private actors of the upstream sector (feed, chicks and medicine supply). One benefit associated with passive surveillance was the intervention of public services to clean farms and the environment to limit the disease spread. Private actors of the poultry sector valued information on HPAI suspicions (perceived as a non‐monetary benefit) which was mainly obtained from other private actors and media.

Flow cytometric enumeration of parasitaemia and haematologic changes in trypanosoma-infected mice

The implementation of regular and relevant evaluations of surveillance systems is critical in improving their effectiveness and their relevance whilst limiting their cost. The complex nature of these systems and the variable contexts in which they are implemented call for the development of flexible evaluation tools. Within this scope, participatory tools have been developed and implemented for the African swine fever (ASF) surveillance system in Corsica (France). The objectives of this pilot study were, firstly, to assess the applicability of participatory approaches within a developed environment involving various stakeholders and, secondly, to define and test methods developed to assess evaluation attributes. Two evaluation attributes were targeted: the acceptability of the surveillance system and its the non-monetary benefits. Individual semi-structured interviews and focus groups were implemented with representatives from every level of the system. Diagramming and scoring tools were used to assess the different elements that compose the definition of acceptability. A contingent valuation method, associated with proportional piling, was used to assess the non-monetary benefits, i.e., the value of sanitary information. Sixteen stakeholders were involved in the process, through 3 focus groups and 8 individual semi-structured interviews. Stakeholders were selected according to their role in the system and to their availability. Results highlighted a moderate acceptability of the system for farmers and hunters and a high acceptability for other representatives (e.g., private veterinarians, local laboratories). Out of the 5 farmers involved in assessing the non-monetary benefits, 3 were interested in sanitary information on ASF. The data collected via participatory approaches enable relevant recommendations to be made, based on the Corsican context, to improve the current surveillance system.