Risk factors for avian influenza and Newcastle disease in smallholder farming systems, Madagascar highlands.

Newcastle disease (ND) and avian influenza (AI) are issues of interest to avian producers in Madagascar. Newcastle disease virus (NDV) is the major constraint for village aviculture, and avian influenza viruses type A (AIAV) are known to circulate in bird flocks. This study aims at classifying smallholder poultry farms, according to the combination of risk factors potentially associated with NDV and AIAV transmission and to assess the level of infection for each farm class. Two study sites, Lake Alaotra and Grand Antananarivo, were chosen with respect to their differences in terms of agro-ecological features and poultry productions. A typology survey involving 526 farms was performed to identify possible risk factors for (i) within-village, and (ii) between-village virus transmission. A cross-sectional serological study was also carried out in 270 farms to assess sero-prevalences of NDV and AIAV for each farm class and the link between them and risk factor patterns. For within-village transmission, four classes of farms were identified in Grand Antananarivo and five in Lake Alaotra. For between-village virus transmission, four classes of farms were identified for each site. In both sites, NDV sero-prevalence was higher than for AIAV. There was no evidence of the presence of H5 or H7 subtypes of AIAV. Sero-prevalences were significantly higher in Lake Alaotra than in Grand Antananarivo for both viruses (OR=2.4, p=0.02 for NDV, and OR=9.6, p<0.0001 for AIAV). For within-village NDV transmission in Grand Antananarivo, backyard chicken farms (OR=3.6, p<0.001), and chicken farms with biosecurity awareness (OR=3.4, p<0.01) had greater odds of having antibodies against NDV than the others. For between-village virus transmission, farms with multiple external contacts, and farms using many small markets had greater odds of having antibodies against NDV than the others (OR=5.4, p<0.01). For AIAV, there were no differences in sero-prevalences among farm classes. In Lake Alaotra, the observed high density of palmipeds and widespread rice paddies were associated with high sero-prevalences for both viruses, and a homogeneous risk of virus transmission between the different farm classes. In Grand Antananarivo, farm visits by collectors or animal health workers, and farm contacts with several markets were identified as potential risk factors for NDV transmission. Further studies are needed to identify the circulating virus genotypes, model their transmission risk, and provide adapted control measures.

A simple model for simulating immunity rate dynamics in a tropical free-range poultry population after avian influenza vaccination.

In developing countries, vaccination against highly pathogenic avian influenza subtype H5N1 (HPAI) in free-range poultry flocks is usually implemented as periodic campaigns and newborn chicks are generally not vaccinated by farmers between vaccination passes. The demographic population turnover leads to a continuous decrease in the population immunity rate (PIR) over time. We present a simple Leslie matrix model for estimating population turnover and PIR dynamics in a hypothetical small-size vaccinated free-range poultry population. Four different vaccination scenarios were identified assuming necessary procedures to achieve immunity. The results indicate that high levels of population immunity are difficult to sustain. Assuming an animal immunity response of 80% after vaccination and a constant population size, PIR 4 months after vaccination was 30% in all the scenarios. Predictions averaged over time showed mean PIR between 36% and 48%, which is below the population immunity thresholds for eradication approximated from R0 estimates.

[The need for research to support the emergence of alternative animal health systems]. / Nécessité pour la recherche de soutenir l'émergence de systèmes de santé animale non conventionnels.

Animal diseases remain one of the main problems for livestock production in terms of trade development, poverty reduction and public health. Animal health systems are complex because of the diversity of the parties involved and because of various changes in the delivery of veterinary services, such as the redefinition of the roles of the public and private sectors. It is, therefore, often difficult to assess the global performance of animal health systems and sub-systems in terms of their medical, economic and social effectiveness. In addition, the necessary reliability of the health information obtained leads to certification of the status of regions and countries with regard to epizootics, which requires a high degree of standardisation and conformity with international norms. An assessment therefore needs to be made of the advantages of alternative systems compared with conventional systems. An animal health system should be seen as a whole, and when assessing its overall performance several things must be taken into account, e.g. the markets for products and the sometimes contradictory interests of all the different parties involved. There are, therefore, many research needs and avenues to be pursued, including: the methods, data and tools required for assessing the effectiveness of systems, including a definition of what constitutes a reliable indicator; the factors that determine the health of a herd; having a clearer idea of what will affect herd health will make it possible to map risk indicators and animal health care needs; the design and management of realistic and harmonised animal health information systems whose indicators provide reliable measurements of health; the function, organisation and effectiveness of participative surveillance approaches; the definition and effectiveness of animal health contracts, such as health mandates between the State and private veterinarians; the function and role of livestock auxiliaries; the establishment of assessment methods and standards that take into account the specific situation of southern countries that could lead to the certification and accreditation of alternative systems. The efficiency of these systems must then be tested (direct impact, cost-benefit studies) using the above-mentioned indicators, and an implementation 'toolkit' can then be assembled, taking into account the local differences which will affect the suitability of each system for different locations. Research into the assessment of animal health systems is a long-term investment, but it ensures that quality certification is reliable and allows for the safe development of animal product markets.

[Therapeutic efficacy during active phases of multiple sclerosis: gait analysis and comparison with the EDSS score]. / Mesure de l'efficacité thérapeutique au cours d'une poussée de sclérose en plaques par l'analyse de la marche: comparaison avec le score EDSS.

Fifteen patients experiencing a flare-up of multiple sclerosis were given 1 g methylprednosolone per day for 5 days. The EDSS score and gait analysis using spatio-temporal variables were recorded for these patients on days 0, 5 and 45. Both methods evidenced significant improvement but the significance was observed between day 0 and day 5 for the EDSS and between day 5 and 45 for gait speed and between day 0 and 45 for step rate. Gait speed was correlated with the pyramidal scale but not with the other functional scales of the EDSS. These results suggest that EDSS and spatio-temporal gait analysis are different tools for the assessment of therapeutic effect. Gait analysis can provide a precise quantitative assessment of the locomotor handicap as a function of the proposed treatment.

[Spontaneous intracranial hypotension syndrome. A case]. / Syndrome d'hypotension intracrânienne spontanée. Un cas.

We report a 49-year-old woman with spontaneous intra-cranial hypotension. this characteristic syndrome associates postural headache and a low cerebro-spinal fluid pressure. It was confirmed by lumbar puncture and magnetic resonance imagery. We describe the clinical and the cerebro-spinal fluid features, the radiological appearances, and the clinical and radiological course. The interests of this diagnosis are, first, its spontaneous benign course and, second, to avoid unnecessary invasive investigations.

[Brachial diplegia caused by cervical spinal cord ischemia. A case]. / Diplégie brachiale par ischémie médullaire cervicale. Un cas.

We report one case of acute cervical spinal cord infarction characterized by motor impairment of the upper limbs with respect of the lower limbs. It occurs infrequently. The purpose of this paper is to discuss the clinical, neurophysiological and magnetic resonance imaging findings, and to review the presumed mechanisms of spinal cord infarction.