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Au sein des élevages avicoles, les oiseaux sauvages sont souvent suspectés de transmettre des agents pathogènes, en particulier les espèces péridomestiques qui peuvent jouer un rôle particulier en tant qu’hôtes relais. Dans cette étude, nous avons exploré le rôle de plusieurs de ces espèces dans l’épidémiologie des virus de l’influenza aviaire et de la maladie de Newcastle sur deux sites d’élevage conservatoire d’outardes Houbara aux Emirats Arabes Unis. Nous avons mis en place une approche multiaxiale et multi-méthodologique afin de caractériser le risque d’introduction et de transmission de ces virus et de formuler une stratégie de gestion sanitaire de ce risque. Dans un premier temps, nous avons décrit les communautés d’oiseaux sauvages présentes sur les sites d’élevages et dans l’environnement proche, afin d’en apprécier richesse et densité mais aussi d’en identifier les espèces dominantes. Nous avons aussi décrit les mouvements de ces espèces dominantes entre les sites d’élevage et les sites avoisinants, afin de caractériser les échanges entre ces différentes entités. Nous avons enfin décrit les mouvements des espèces dominantes à l’intérieur des sites d’élevage dans les zones de volières extérieurs et leurs contacts avec les outardes captives. Parallèlement, nous avons évalué la prévalence des virus étudiés au sein des espèces dominantes et analysé leur dynamique au sein des sites d’élevage. Ensuite, en croisant toutes les données obtenues, nous avons analysé le risque épidémiologique représenté par les espèces dominantes pour les outardes captives en termes d’introduction et de transmission de ces virus. Enfin, en s’appuyant sur les résultats obtenus dans chacun de ces axes, nous avons formulé une stratégie de gestion sanitaire du risque de transmission d’agents pathogènes aux outardes captives par l’avifaune sauvage, répondant ainsi à l’objectif de notre étude.

Newcastle disease (ND) is endemic in West Africa, which has also experienced outbreaks of highly pathogenic avian influenza (AI) H5N1 since 2006. We aimed to estimate the prevalence and incidence of AI and ND in village poultry in Mali and to identify associated risk factors. A longitudinal serologic study was conducted between November 2009 and February 2011 using ELISA commercial kits to detect antibodies. Sera (5963) were collected from 4890 different poultry. AI was rare, with a seroprevalence of 2.9% (95% confidence interval [CI] 2.3-3.5) and a seroincidence rate of 0.7 birds per 100 bird-months at risk (95% CI 0.4-1.0). AI antibodies were short lived, with a seroreversion rate of 25.4 birds per 100 bird-months at risk (95% CI 19.0-31.7). Risk factors for AI were limited: temporal variation occurred, but proximity to a water body was a risk factor only when large populations of wild waterbirds were present. ND was very common, with seroprevalence of 68.9% (95% CI 61.9-76.0) and a seroincidence rate of 15.9 birds per 100 bird-months at risk (95% CI 11.9-19.8). ND seroreversion rate was 6.2 birds per 100 bird-months at risk (95% CI 3.6-8.9). Regarding risk factors for ND, temporal variations occurred, and ND was more likely to be present in the Sudanian agro-ecological zone than in the Sahelian zone, in chickens than in other species, in flocks with higher numbers of Guinea fowl, and in flocks that had access to a waterbody. Control efforts would benefit from further increasing the ND vaccination coverage of village poultry, although this was already quite high (54.9%) for an African country. Seroconversion seemed satisfactory in vaccinated poultry, since 90.0% (95% CI 87.6-92.4) of these had ND antibodies. Further research should investigate the apparent lack of an epidemiologic role of domestic ducks for AI in Mali (unlike in Southeast Asia) and the potential role of Guinea fowl as a reservoir for ND.

International audience; Newcastle disease (ND), caused by virulent class II avian paramyxovirus 1 (Newcastle disease virus, NDV), occurs sporadically in poultry despite their having been immunized with commercial vaccines. These vaccines were all derived from NDV strains isolated around 70 years ago. Since then, class II NDV strains have evolved into 18 genotypes. Whether the vaccination failure results from genotype mismatches between the currently used vaccine strains and field-circulating velogenic strains or from an impaired immune response in the vaccination remains unclear. To test the first hypothesis, we performed a heterologous genotype II vaccine/genotype XI challenge in one-day old specific pathogen free (SPF) chicks and reproduced viral shedding. We then produced two attenuated strains of genotype II and XI by reverse genetics and used them to immunize two-week old SPF chickens that were subsequently challenged with velogenic strains of genotypes II, VII and XI. We found that both vaccines could induce antibodies with hemagglutination inhibition titers higher than 6.5 log(2). Vaccination also completely prevented disease, viral shedding in swabs, and blocked viral replication in tissues from different genotypes in contrast to unvaccinated chickens that died shortly after challenge. Taken together, our results support the hypothesis that, in immunocompetent poultry, genotype mismatch is not the main reason for vaccination failure.

International audience; We sampled 417 swallows in a wetland ecosystem of Zimbabwe in February 2010 and October 2011. RT-PCR tests revealed circulation of avian paramyxovirus type I, avian influenza and West Nile disease viruses in these populations. We discuss the relevance of these findings in relation to what is known on the epidemiology of these viruses in these hosts and in relation to the host ecology. We conclude with recommendations to focus more research on Passeriformes in disease ecology and in particular on the hirundinidae family.

La maladie de Newcastle est une maladie virale des oiseaux, très contagieuse et présente partout dans le monde. Sa présentation clinique est variable. Elle se manifeste généralement par des signes respiratoires mais le tableau clinique peut être dominé par un abattement, des symptômes nerveux ou des diarrhées. Historiquement, la maladie a été découverte en Indonésie en 1926 (Kraneveld, 1926). Mais elle a tiré son nom de la ville de Newcastle-on-Tyne en Angleterre, où elle est apparue en 1927 (Doyle, 1927). Cette maladie constatée dans le monde entier, est actuellement maitrisée au Canada, aux Etats-Unis d'Amérique et dans certains pays de l'Europe occidentale. Elle persiste dans différentes régions d'Afrique, d'Asie et d'Amérique du Sud. Toutefois, étant donné que les oiseaux sauvages peuvent parfois être porteurs du virus sans contracter la maladie, des foyers peuvent apparaître partout où existent des élevages de volailles (OIE, 2016). A Madagascar, elle constitue la cause la plus importante des mortalités aviaires, notamment chez les animaux non vaccinés. De nombreuses mesures de lutte s'imposent pour une meilleure production avicole.

International audience; 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, NOV 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

Our survey aimed to investigate avian influenza (AI) and Newcastle disease (ND) prevalence and risk factors in three areas of Mali at risk for occurrence of H5N1 highly pathogenic avian influenza. Blood samples and cloacal and oropharyngeal swabs were collected from 1470 birds between February 2007 and May 2008 and were tested by commercial enzyme-linked immunosorbent assay to detect antibodies and real-time reverse-transcription (rRT)-PCR to detect virus. Risk factors associated with seropositivity or positive rRT-PCR were identified by random effect logistic regression. AI seroprevalence was significantly lower in birds from commercial farms (0%) than in village backyard birds (3.1%). For backyard birds, no individual risk factors (species, age, sex) were identified, but birds in the Mopti area in the Sahelian zone, where millions of wild birds migrate, were more seropositive than in the Sikasso area in the Sudano-Guinean zone (odds ratio [OR] ?=? 2.0, P ?=? 0.051). Among backyard birds nonvaccinated against ND, ND seroprevalence was 58.4%, and the odds of seropositivity was 2.0 higher in chickens than in ducks, 1.7 higher in females than in males, 3.1 higher in adults than in young birds, and 3.0 higher in poultry from the Sikasso area than from the Mopti area (P < 0.01 in all cases). Prevalence established by rRT-PCR was low for both AI virus (1.1%) and ND virus (2.6%) and was associated with no risk factors for AI but was higher in chickens than in ducks (OR ?=? 5.3, P ?=? 0.05) and in the Sikasso area than in the Mopti area (OR ?=? 3.4, P ?=? 0.027) for ND. For AI and ND, prevalence assessed by serology or rRT-PCR varied over time, although seasonal and interannual variation could not be clearly distinguished. The intracluster correlation coefficient for serologic data was low for AI (0.014) and higher for ND (0.222). These results are useful to optimize surveillance and control strategy for notifiable avian diseases in African countries with similar agroecological and resource-limited contexts.

A sero-epidemiological study was conducted in six broiler breeding companies and four broiler breeding laying hen companies, covering most of the poultry breeding farms in Tunisia. The objective was to evaluate the effectiveness of the immune response following the application of vaccination protocols established by the owners and carried out against the viruses of Newcastle disease (NDV), infectious bronchitis (IBV) and infectious bursal disease (IBD). During eight visits per farm, questionnaires were completed and 2000 samples were taken. The samples were submitted to indirect ELISA using CIVTEST AVINDV, -IBV, and -IBD kits. For each date and each disease, the mean specific antibody titers and the coefficient of variation were calculated. These indicators revealed that the chicks were in good health, the kinetics of post-vaccination antibodies generally satisfactory, and the overall immune response sufficiently uniform. However, the vaccination protocol recommended by the National Commission for Avian Diseases was not always applied. This either caused a temporary drop in antibody levels resulting in a high risk of infection, or necessitated interventions resulting in economic losses because of vaccine-related costs. This work shows the need for farmers to have a database for the establishment of an immunoprophylaxis program adapted to the epidemiological conditions of these farms.

We aimed at characterizing commercial and traditional village poultry farming in Mali, with a focus on practices influencing the risk of transmission of avian influenza and Newcastle disease. Surveys were conducted in 2009–2011 in a study area covering approximately 98% of the Malian poultry population. Among the 282 commercial farms investigated, of which 64 had not been known by the government authorities, 83% were located within a 50 km radius from the capitals of the country and regions and 54% had low biosecurity standard. Among the 152 randomly selected village household flocks investigated, characteristics were overall similar to those in other African countries but some differences were notable including a large flock size (median 44 poultry), a low presence of ducks and geese (11% and 1.1% of flocks, respectively), vaccination against Newcastle disease being common (49% of flocks), a low proportion of households selling sick and dead birds (0.7% and 0%, respectively) and limited cohabitation between poultry and humans at night. Our recommendations to limit the risk of disease transmission include (1) for commercial farms, to introduce compulsory farm registration and accreditation, to increase technical proficiency and access to credit for farms with low biosecurity, and to support poultry producer associations; (2) for village poultry, to promote better quarantine and management of sick and dead birds. Such detailed knowledge of country-specific characteristics of poultry production systems is essential to be able to develop more efficient disease risk management policies.

This chapter documents the logics underpinning farmers’ management practices of an emerging disease. In the area of our survey, Vietnamese farmers, who are one of the front lines of the fight against H5N1, are called upon to collaborate to the international fight against the virus. Our study highlights that direct (poultry mortality) and indirect impacts (consequence of the measures imposed by the government to contain the virus, fluctuation of consumers’ demand, etc.) tend to be relatively limited when compared to the permanent state of instability which characterises the context of poultry production in the surveyed village. This instability is mainly related to numerous and regular poultry infectious diseases and market fluctuations. If international community considers H5N1 as a zoonotic risk and a pandemic threat which asks for emergency tools, H5N1 is framed by the farmers of our study as an epizootic problem manageable through routinised measures. These measures aim at minimising the economic impact of the disease rather than preventing poultry and Human from the disease. Consequently, local management of the disease cannot fit with the precautionary approach promoted by the international community.

Since its first detection in Southern China in 1996, highly pathogenic avian influenza virus (HPAIV) H5N1 has emerged as a major global health threat and spread across three continents. In Africa, Mali was considered a country at high risk and surveillance of HPAIV H5N1 was complicated by the endemicity of another highly lethal poultry virus producing similar symptoms, Newcastle disease virus (NDV). The general aim of this thesis was to improve our understanding of the epidemiology of avian influenza (AI) and Newcastle disease (ND) in Mali and produce recommendations for improving the surveillance and control of these diseases. Prevalence/incidence studies showed: a low circulation of AI viruses (AIVs) -although higher in villages located in the inner delta of the Niger River where large populations of wild water birds migrate- and seemingly no particular epidemiological role of domestic ducks; a high circulation of NDV influenced by seasonal, geographic and flock (number of Guinea fowl, access to a pond) factors. Poultry production and trade studies revealed: a largely informal commercial poultry sector, mainly peri-urban and of low biosecurity level; characteristics of village poultry farming more (free-roaming, inadequate quarantine and sick/dead bird disposal) or less (high ND vaccination coverage, low palmipeds' density) favourable for AIVs and NDV transmission; mainly rudimentary low-biosecurity live poultry markets and a hierarchical structure of poultry trade network to/from the Sikasso district with four hubs identified based on network centrality measures. Evaluation of HPAI and ND surveillance found: a well-organised surveillance network but functioning only moderately satisfactorily, lack of targeting of active surveillance and largely insufficient sensitivity of passive surveillance. Specific strengths (laboratory diagnostic, information dissemination) were identified, as well as weaknesses some of which are easily correctable (data management, efficiency follow-up) while others require significant funding or commitment (resources for field work, involvement of private animal health professionals).

International audience; Background: Newcastle disease is still a serious disease of poultry especially in backyard free-range production systems despite the availability of cross protective vaccines. Healthy-looking poultry from live bird markets have been suspected as a major source of disease spread although limited studies have been conducted to ascertain the presence of the virulent strains in the markets and to understand how they are related to outbreak strains. Methods: This study evaluated the occurrence of Newcastle disease virus in samples collected from poultry in live bird markets across Uganda. The isolates were pathoyped using standard methods (mean death time (MDT), intracelebral pathogenicity index (ICPI), and sequencing of the fusion protein cleavage site motif) and also phylogenetically analysed after sequencing of the full fusion and hemagglutin-neuraminidase genes. The isolates were classified into genotypes and subgenotypes based on the full fusion protein gene classification system and compared with other strains in the region and world-wide. Results: Virulent avian paramyxovirus type I (APMV-1) (Newcastle disease virus) was isolated in healthy-looking poultry in live bird markets. The viruses belonged to a new subgenotype, Vd, in genotype V, and clustered together with Tanzania and Kenya strains. They harbored low genetic diversity. Conclusion: The occurrence of virulent AMPV-1 strains in live bird markets may serve as sources of Newcastle disease outbreaks in non-commercial farms.

La maladie de Newcastle (MN) grève lourdement les productions aviaires malgaches, essentielles à l'alimentation et à l'économie familiales. La MN est une dominante pathologique en l'absence de vaccination généralisée. L'objectif de cette thèse est la modélisation, la validation et l'analyse mathématique de modèles de transmission de transmission du virus de la MN (VMN) dans les systèmes avicoles villageois en général et à Madagascar en particulier. Nous proposons de nouveaux modèles basés sur les connaissances actuelles de l'histoire naturelle de la transmission du VMN. Ainsi, nous présentons deux modèles mathématiques à compartiments de la transmission du VMN dans une population de poules : un premier modèle avec transmission environnementale et un deuxième modèle où la vaccination contre la maladie est prise en compte. Nous présentons une analyse complète de la stabilité de ces modèles à l'aide des techniques de Lyapunov suivant la valeur du taux de reproduction de base R0. Le travail s'est appuyé sur des enquêtes de terrain pour comprendre les pratiques de vaccination actuelles à Madagascar.

Plusieurs protocoles de vaccination contre la maladie de Newcastle sont utilises au Senegal sur les poulettes futures pondeuses en elevage moderne. Cependant, chaque annee, cette virose se manifeste par des mortalites ou des chutes de ponte qui grevent le budget des exploitants de la filiere. Afin de determiner l'efficacite de la prophylaxie medicale mise en oeuvre, il a donc ete procede a une comparaison des differents schemas de vaccination dans les conditions reelles de production. Il s'avere que les programmes vaccinaux comportant essentiellement des vaccins vivants fournissent une moins bonne protection que ceux qui ont recours aux vaccins inactives huileux injectables, sans doute a cause du manque de technicite dans l'administration des vaccins vivants. Une primo vaccination associant un vaccin vivant administre individuellement par trempage du bec et une injection de vaccin inactive huileux procure une bonne protection pendant les dix premieres semaines de la vie. Une nouvelle injection a cette periode permet d'assurer une couverture pendant toute la duree de l'elevage de la poulette et ameliore l'effet de la vaccination par injection a l'entree en ponte. Des lors, aucun rappel n'est necessaire jusqu'a la reforme des pondeuses. (Resume d'auteur)

Les possibilités d'utilisation d'anticorps de jaune d'oeuf (IgY) pour la détection des virus de la maladie de Newcastle (NDV), de la bronchite infectieuse (IBDV) et de la maladie de Gumboro (IBDV) par le test d'immunofluorescence directe ont été examinées. Des poules pondeuses ont été immunisées avec différents vaccins commerciaux à NDV, IBV et IBDV inactivés. L'immunisation a donné des titres élevés d'anticorps spécifiques dans le jaune d'oeuf à partir de 4 à 8 semaines après l'immunisation initiale, et ce durant une période d'environ 20 semaines. Les IgY ont été extraites du jaune d'oeuf par précipitation au sulfate d'ammonium, puis purifiées par la méthode de chromatographie d'affinité, donnant 1,46 mg d'IgY spécifique par jaune d'oeuf en moyenne. Après marquage avec l'isothiocyanate de fluorescéine (FITC) la sensibilité et la spécificité des conjugués ont été évaluées sur des cultures cellulaires sur des lamelles couvre-objets. Dans le test d'immunofluorescence directe, les conjugués dilués au 1 : 8 ou au 1 : 4 avec du PBS réagissaient spécifiquement avec l'antigène homologue dans des calques d'organes de poussins infectés expérimentalement et dans des cultures cellulaires sur des lamelles couvre-objets. Aucune réaction n'a été observée avec des antigènes hétérologues. La fluorescence non spécifique était facilement éliminée par une absorption avec de la poudre de foie. En conclusion, ces résultats montrent que les IgY marquées avec FITC peuvent être produites en grandes quantités de manière facile et économique. Pour le diagnostic de NDV, IBV et IBDV, les anticorps de jaune d'oeuf constituent donc une excellente alternative à la production d'anticorps fluorescents à partir du sang de lapins ou de poules, notamment pour les laboratoires ayant des moyens financiers limités.

A serological survey was conducted on rural and intensive poultry production during the 1995 rainy season and 1996 dry season in Senegal Cap-Vert area in order to determine the prevalence of mycoplasmoses, fowl typhoid and pullorum disease, Newcastle, infectious bursal and infectious bronchitis diseases. One-hundred-sixty and 100 rural poultry were sampled during the rainy and dry seasons, respectively, whereas 84 and 88 intensive farm flocks were sampled during the rainy and dry seasons, respectively. Mycoplasma infections were common among rural poultry: 49 and 43% during the rainy and dry seasons, respectively, for Mycoplasma gallisepticum; 50 and 66% during the rainy and dry seasons, respectively, for Mycoplasma synoviae. Salmonella gallinarum pullorum infections were less common (5 and 9% during the rainy and dry seasons, respectively). These infections affected mainly layer hens in intensive farming: during the rainy and dry seasons 4-5% of the flocks were infected with Mycoplasma gallisepticum, 20-28% with Mycoplasma synoviae and 41- 45% with Salmonella gallinarum pullorum. The viral diseases studied here were frequently encountered in rural poultry breeding (infectious bursal disease 76% and infectious bronchitis 89%). A seasonal variation was observed for the Newcastle disease only, as it occurred more frequently during the dry season (98% vs. 84% during the rainy season). In intensive poultry farming this disease was rather rare and tended to occur during the dry season (11% of flocks were infected). Seroprevalences of infectious bursal and infectious bronchitis diseases were high and relatively constant during the study period (69 and 46% during the rainy and dry seasons, respectively, for the infectious bursal disease and 63 and 54% for infectious bronchitis).

Madagascar's 36.5-million-head poultry industry holds a foremost place in its economy and the livelihood of its people. Unfortunately, regular Newcastle disease outbreaks associated with high mortality causes high losses for smallholders and threatens their livelihood. Therefore, Madagascar is seeking concrete, achievable and sustainable methods for the surveillance and the control of Newcastle disease. In this paper, we present and analyze the results of a field study conducted in Madagascar between December 2009 and December 2010. The study area was the Lac Alaotra region, a landlocked area in the north-eastern part of the country's center. Poultry trading is suspected of playing a major role in the spread of avian diseases, especially in developing countries characterized by many live-bird markets and middlemen. Therefore, the goals of our study were to: (i) describe and analyze smallholders’ poultry trading network in the Lake Alaotra region using social network analysis; (ii) assess the role of the network in the spread of Newcastle disease; and (iii) propose the implementation of a targeted disease surveillance based on the characteristics of the poultry trading network. We focused our field study on the harvesting of two data sets. The first is a complete description of the poultry trading network in the landlocked area of Lac Alaotra, including a description of the poultry movements between groups of villages. The second set of data measures the occurrence of outbreaks in the same area by combining a participatory approach with an event-based surveillance method. These data were used to determine the attributes of the network, and to statistically assess the association between the position of nodes and the occurrence of outbreaks. By using social network analysis techniques combined with a classification method and a logistic model, we finally identified 3 nodes (set of villages), of the 387 in the initial network, to focus on for surveillance and control in the Lac Alaotra area. This result is of primary importance in the ongoing efforts to effectively improve the wellbeing of people in the region.

La vaccination contre la maladie de Newcastle par la méthode de distribution des grains de mil enrobés de vaccins thermotolérants LaSota/A300 et V4/276 a été essayée à Ouagadougou, Burkina Faso, sur 298 poulets de chair d'origine européenne pourvus d'anticorps maternels. Des infections opportunistes, comme la colibacillose, ont décimé de 70 à 81 % des effectifs des trois lots vaccinés et aussi 24 % du lot témoin avant d'être éradiquées par une antibiothérapie. L'épreuve virulente avec la souche de virus Hertz 33/56, appliquée aux survivants deux mois après la vaccination, a tué 100 % des témoins, 78 % des poulets vaccinés avec le V4/276, 7 % des vaccinés avec le LaSota/A300, et n'en a tué aucun dans le groupe qui a reçu à la fois le V4/276 et le LaSota/A300 à une semaine d'intervalle. Ces deux derniers groupes possédaient aussi, avant l'épreuve, de hauts titres d'anticorps IHA. Les vaccins lyophilisés LaSota/A300 et V4/276 ont conservé de hauts titres de virus après des expositions de 8 à 34 jours à la température ambiante de la saison fraîche à Ouagadougou.

SUMMARYNewcastle disease (ND) is one of the most important and widespread avian pests. In Africa, backyard poultry production systems are an important source of protein and cash for poor rural livelihoods. ND mortality in these production systems is important and seriously disrupts benefits derived from it. This study undertook an African continental approach of ND epidemiology in backyard poultry. After a systematic literature review of studies published from 1980 to 2009, a meta-analysis of spatio-temporal patterns of serological prevalence and outbreak occurrence was performed. Average ND serological prevalence was estimated at 0·67 [95% confidence interval (CI) 0·58–0·75] in regions characterized by humid ecosystems, high human and poultry densities and low altitudes; 0·36 (95% CI 0·30–0·41) in dry ecosystems at intermediate altitude where human and poultry densities are low and 0·27 (95% CI 0·19–0·38) in mountain ecosystems where human and poultry densities are intermediate. In terms of seasonality, ND outbreaks occur mostly during the dry seasons in Africa, when environmental conditions are likely to be harshest for backyard poultry. In addition, a phylogeographical analysis revealed the regionalization of ND virus strains, their potential to evolve towards a higher pathogenicity from the local viral pool and suggests a risk for vaccine strains to provide new wild strains. These results present for the first time a continent-wide approach to ND epidemiology in Africa. More emphasis is needed for ND management and control in rural African poultry production systems.

Background Poultry represents an important sector in animal production, with backyard flocks representing a huge majority, especially in the developing countries. In these countries, villagers raise poultry to meet household food demands and as additional sources of incomes. Backyard production methods imply low biosecurity measures and high risk of infectious diseases, such as Newcastle disease or zoonosis such as Highly Pathogenic Avian Influenza (HPAI). We reviewed literature on biosecurity practices for prevention of infectious diseases, and published recommendations for backyard poultry and assessed evidence of their impact and feasibility, particularly in developing countries. Documents were sourced from the Food and Agriculture Organization (FAO) website, and from Pubmed and Google databases. Results A total of 62 peer-reviewed and non-referred documents were found, most of which were published recently (after 2004) and focused on HPAI/H5N1-related biosecurity measures (64%). Recommendations addressed measures for flock management, feed and water management, poultry trade and stock change, poultry health management and the risk to humans. Only one general guideline was found for backyard poultry-related biosecurity; the other documents were drawn up for specific developing settings and only engaged their authors (e.g. consultants). These national guidelines written by consultants generated recommendations regarding measures derived from the highest standards of commercial poultry production. Although biosecurity principles of isolation and containment are described in most documents, only a few documents were found on the impact of measures in family poultry settings and none gave any evidence of their feasibility and effectiveness for backyard poultry. Conclusions Given the persistent threat posed by HPAI/H5N1 to humans in developing countries, our findings highlight the importance of encouraging applied research toward identifying sustained and adapted biosecurity measures for smallholder poultry flocks in low-income countries.

Cross-sectional survey for Newcastle disease (ND) were conducted in nonvaccinated household flocks of village chickens to assess serological and virological ND status in households and associated live bird markets. In total, 1,899 sera and 460 pools of cloacal and tracheal swabs were sampled and tested using a commercial enzyme-linked immunosorbent assay (ELISA) and real-time reverse transcriptase polymerase chain reaction (rRT-PCR), respectively. Additionally, paired cloacal and tracheal swabs from 1,269 individual chickens were collected from markets and tested using RT-PCR. The prevalence of households with at least one seropositive chicken was higher during the dry season (27.4 %) than during the wet season (17.4 %) (P = 0.003). Viral genome was detected in 14.2 % of households during the wet season using a fusion (F) gene assay and in 24.2 % of households during the dry season using a polymerase (L) gene assay that targets both class I and class II viruses. At the markets sampled, overall bird level prevalence was 4.9 % for period 1 (F gene assay), and 38.2 % and 27.6 % for periods 2 and 3, respectively (L gene assay). Partial sequencing of the F gene (239 bp) cleavage site indicated that the majority of the circulating strains exhibited motifs specific to virulent strains. Seroepidemiology coupled with molecular analysis can be a useful tool to assess the status of NDV infection. The village chicken population in Ethiopia is endemically infected with virulent NDV that pose a significant threat to emerging small- and medium-scale commercial poultry production.