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Les réseaux d'épidémiosurveillance des maladies animales en Afrique francophone de l'Ouest et du Centre
No full textL’un des objectifs du Programme panafricain de contrôle des épizooties (PACE)
était la mise en place de réseaux d’épidémiosurveillance dans les pays
d’Afrique. Une enquête, sur la base d’un questionnaire écrit, visant à faire un état
des lieux de l’organisation technique et institutionnelle de ces réseaux a été
réalisée dans neuf pays francophones, dont cinq en Afrique de l’Ouest (Sénégal,
Burkina Faso, Côte d’Ivoire, Togo, Guinée) et quatre en Afrique centrale
(Cameroun, République centrafricaine, République démocratique du Congo et
Tchad). Les résultats de cette enquête ont montré qu’il existe plus de similitudes
que de divergences entre ces réseaux. D’une manière générale, ils étaient
techniquement et institutionnellement bien formalisés. Néanmoins, l’insuffisante
capacité de diagnostic des laboratoires ainsi que l’insuffisante opérationnalité
des comités de pilotage constituent deux points faibles de la majorité des
réseaux. La surveillance épidémiologique devrait être une activité régalienne
des Services vétérinaires et elle est déterminante pour assurer la détection
rapide d’une modification du statut sanitaire d’une population animale ;
cependant, la pérennité des réseaux n’est généralement pas garantie en fin de
financement extérieur car, souvent, leur prise en charge n’est pas assurée
convenablement par les États
Fitness inheritance in multiple objective evolutionary algorithms: a test bench and real-world evaluation
No full textIn many real-world applications of evolutionary algorithms, the fitness of an individual has to be derived using complex models and time-consuming computations. Especially in the case of multiple objective optimisation problems, the time needed to evaluate these individuals increases exponentially with the number of objectives due to the ‘curse of dimensionality’ [J. Chen, D.E. Goldberg, S. Ho, K. Sastry, Fitness inheritance in multi-objective optimization, in: W.B. Langdon et al. (Eds.), GECCO 2002: Proceedings of the Genetic and Evolutionary Computation Conference, July 9–13, Morgan Kaufmann Publishers, New York, 2002, pp. 319–326]. This in turn leads to a slower convergence of the evolutionary algorithms. It is not feasible to use time-consuming models with large population sizes unless the time to evaluate the objective functions is reduced. Fitness inheritance is an efficiency enhancement technique that was originally proposed by Smith et al. [R.E. Smith, B.A. Dike, S.A. Stegmann, Fitness inheritance in genetic algorithms, in: Proceedings of the 1995 ACM Symposium on Applied Computing, February 26–28, ACM, Nashville, TN, USA, 1995] to improve the performance of genetic algorithms. Sastry et al. [K. Sastry, D.E. Goldberg, M. Pelikan, Don’t evaluate, inherit, in: L. Spector et al. (Eds.), GECCO 2001: Proceedings of the Genetic and Evolutionary Computation Conference, Morgan Kaufmann Publishers, San Francisco, 2001, pp. 551–558] and Chen et al. [J. Chen, D.E. Goldberg, S. Ho, K. Sastry, Fitness inheritance in multi-objective optimization, in: W.B. Langdon et al. (Eds.), GECCO 2002: Proceedings of the Genetic and Evolutionary Computation Conference, July 9–13, Morgan Kaufmann Publishers, New York, 2002, pp. 319–326] have developed analytical models for fitness inheritance. In this paper, the usefulness of fitness inheritance for a set of popular and separable multiple objective test functions as well as a non-separable real-world problem is evaluated based on unary performance measures testing closeness to the Pareto-optimal front, uniform distribution along and extent of the obtained Pareto front. A statistical evaluation of the performance of an NSGA-II like algorithm on the basis of these unary performance measures suggests that especially for non-convex or non-continuous problems the use of fitness inheritance negatively affects the closeness to the Pareto-optimal front
Influence of diet and photoperiod on development and reproduction of European populations of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
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Epidémiologie de la fièvre catarrhale ovine en Europe: situation actuelle et perspectives
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Nitrate reductase assay for the rapid detection of pyrazinamide resistance in Mycobacterium tuberculosis using nicotinamide
No full textOBJECTIVES: The purpose of this study was to develop the nitrate reductase assay (NRA) for the rapid detection of pyrazinamide resistance in Mycobacterium tuberculosis using nicotinamide resistance as a marker of pyrazinamide resistance in Löwenstein-Jensen (LJ) medium at neutral pH. METHODS: We tested 68 M. tuberculosis isolates using nicotinamide at three different concentrations (1000, 500 and 250 mg/L) by the NRA in LJ medium and compared the results with those obtained with the BACTEC 460-TB or the BACTEC MGIT 960 as reference standard methods. Mutations in the pncA gene were detected by DNA sequencing of the pyrazinamide-resistant isolates. RESULTS: Out of 34 M. tuberculosis pyrazinamide-resistant isolates, 31 were found to be resistant to 1000 and 500 mg/L nicotinamide giving sensitivity and specificity of 91% and 94%, respectively. At 250 mg/L nicotinamide, the sensitivity and specificity decreased to 91% and 71%, respectively. Results were obtained in an average of 10 days. Based on these results, a tentative breakpoint concentration of 500 mg/L nicotinamide was defined. DNA sequencing of the pncA gene detected mutations in 26 out of 34 M. tuberculosis isolates resistant to pyrazinamide. CONCLUSIONS: The NRA using nicotinamide to detect resistance to pyrazinamide in LJ medium is a rapid and accurate method that could be useful in limited-resource countries where the BACTEC 460-TB or the BACTEC MGIT 960 system is not available
Sexual risk reduction needs of adolescents living with HIV in clinical care setting
No full textThis is an electronic version of an article published in AIDS Care. 2008 Apr;20(4):426-33. AIDS Care is available online at informaworldTMAs anti-retroviral therapy becomes increasingly available, young people living with HIV need tailored support to adopt healthy sexual behaviors. There has been a gap in the availability of culturally appropriate techniques for secondary prevention and sexual risk reduction in this target group. This formative study assessed sexual and reproductive health needs and problems, as well as determinants of sexual risk-taking among young people living with HIV aged 11-21 years attending the Paediatric Infectious Disease Clinic in Kampala, Uganda. Theoretical guidance was provided by the Information-Motivation-Behavioral Skills Model. Socio-demographic and selected psychosexual data were assessed using a brief anonymous questionnaire. A total of 75 young people living with HIV participated in eight focus group discussions. In addition, one focus group was conducted with adult key informants (service providers). About a quarter of the young participants reported prior or current sexual experience. The study revealed knowledge gaps relating to reproductive health, HIV transmission, and contraceptive methods. Motivations for protection included hope for the future, good counseling, and fear of the consequences of sexual activity such as unwanted pregnancies. Barriers to adopting preventive behaviors included peer pressure, poverty, HIV-related stigma, ignorance of their partners, alcohol use, and a desire to have children for the older ones. Young sero-positive people in this setting lacked specific behavioral skills, such as disclosure of HIV status to their sexual partners, this being closely linked to fear of rejection and stigma. HIV-positive youths need support in developing the appropriate behavioral skills to adopt healthy sexual behaviors. Interventions in this field need to be developmentally appropriate and tailored to young people's specific needs. Structural interventions should at the same time address and reduce HIV-related stigma and socio-economic needs of young people living with HIV