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International audience; In the Mekong Delta region of Vietnam, small-scale chicken farming is common. However, high levels of disease or mortality in such flocks impair eco- nomic development and challenge the livelihoods of many rural households. We investigated 61 diseased small-scale flocks (122 chickens) for evidence of infec- tion with 5 bacteria, 4 viruses, and helminths. Sero- logical profiles (ELISA) were also determined against 6 of these pathogens. The aims of this study were the following: (1) to investigate the prevalence of different pathogens and to compare the probability of detection of bacterial pathogens using PCR and culture; (2) to investigate the relationship between detection of or- ganisms in birds’ tissues and the observed morbidity and mortality, as well as their antibody profile; and (3) to characterize risk factors for infection with specific viral or bacterial pathogens. We used PCR to test for viral (viruses causing infectious bronchitis [IB], highly pathogenic avian influenza [HPAI], Newcastle disease, and infectious bursal disease [IBD]) and bacterial pathogens (Mycoplasma gallisepticum, Pas- teurella multocida, Avibacterium paragallinarum, and Ornithobacterium rhinotracheale [ORT]). The latter two were also investigated in respiratory tissues by conventional culture. Colisepticemic Escherichia coli was investigated by liver or spleen culture. In 49 of 61 (80.3%) flocks, at least one bacterial or viral pathogen was detected, and in 29 (47.5%) flocks, more than one pathogen was detected. A. paragallinarum was detected in 62.3% flocks, followed by M. gallisepticum (26.2%), viruses causing IBD (24.6%) and IB (21.3%), septicemic E. coli (14.8%), ORT (13.1%), and HPAI viruses (4.9%). Of all flocks, 67.2% flocks were colonized by helminths. Mortality was highest among flocks infected with HPAI (100%, interquartile range [IQR]: 81.6– 100%) and lowest with flocks infected with ORT (5.3%, IQR: 1.1–9.0%). The results indicated slight agreement (kappa 0.167) between detection by PCR and culture for both A. paragallinarum and ORT, as well as be- tween the presence of cestodes and ORT infection (kappa 5 0.317). Control of A. paragallinarum, viruses causing HPAI, IBD, and IB, M. gallisepticum, and gastrointestinal helminths should be a priority in small- scale flocks.

Excessive antimicrobial usage and deficiencies in hygiene in meat production systems may result in undesirable human health hazards, such as the presence of antimicrobial drug residues and non-typhoidal Salmonella (NTS), including antimicrobial resistant (AMR) NTS. Recently, Vietnam has witnessed the emergence of integrated intensive animal production systems, coexisting with more traditional, locally-sourced wet markets. To date no systematic studies have been carried out to compare health hazards in beef, pork and chicken in different production systems. We aimed to: (1) estimate the prevalence of antimicrobial residues in beef, pork and chicken meat; (2) investigate the prevalence and levels of NTS contamination; and (3) investigate serovar distribution and AMR against critically important antimicrobials by animal species and type of retail (wet market vs. supermarket) in Vietnam. Fresh pork, beef and chicken meat samples (N = 357) sourced from wet markets and supermarkets in Ho Chi Minh City (HCMC), Hanoi and Dong Thap were screened for antimicrobial residues by PremiTest, and were further investigated by Charm II. Samples from HCMC (N = 113) were cultured using ISO 6579:2002/Amd 1:2007. NTS bacteria were quantified using a minimum probable number (MPN) technique. NTS isolates were assigned to serovar by Multilocus Sequence Typing (MLST), and were investigated for their phenotypic susceptibility against 32 antimicrobials. A total of 26 (7.3%) samples tested positive by PremiTest (9.5% beef, 4.1% pork and 8.4% chicken meat). Sulfonamides, tetracyclines and macrolides were detected by Charm in 3.1%, 2.8% and 2.0% samples, respectively. Overall, meat samples from wet markets had a higher prevalence of residues than those from supermarkets (9.6% vs. 2.6%) (p = 0.016). NTS were isolated from 68.4% samples from HCMC. Chicken samples from wet markets had by far the highest NTS counts (median 3.2 log MPN/g). NTS isolates displayed high levels of resistance against quinolones (52.2%) and β-lactams (49.6%), but low levels against 3rd generation cephalosporins (4.4%) and aminoglycosides (0.8%). The highest adjusted prevalence of multidrug resistance (MDR) corresponded to isolates from chicken meat and pork (OR 8.3 and 1.8, respectively) (baseline = beef). S. Kentucky was the most common serovar identified (11 from chicken, 1 from beef) and 91.7% isolates was MDR. 11/12 isolates corresponded to ST198, a worldwide-disseminated multi-resistant NTS clone. We recommend stepping up policy measures to promote responsible antimicrobial use in animal production, as well as awareness about withdrawal periods to limit the hazard of residues in animal products, and improving slaughtering/hygiene procedures to limit cross-contamination with NTS, particularly in poultry wet markets., Highlights • Antimicrobial residues were found in 7.3% meat samples (9.6% in meat from wet markets and 2.6% in meat from supermarkets). • Over two thirds (68.4%) of meat samples were contaminated with non-typhoidal Salmonella; 52.2% of isolates were multidrug resistant. • Chicken meat from wet markets had the highest loads of contamination with non-typhoidal Salmonella (median 3.2 log MPN/g in positive samples). • Multidrug resistance was highest in Salmonella from chicken meat, and lowest in beef; the type of retail was not linked to increased resistance. • The most commonly identified serovar was multidrug resistant Salmonella Kentucky ST198, with high levels resistance against β-lactams and quinolones.

Resume Les auteurs introduisent la simulation des conditions aux limites et interfaciales dans les calculateurs a reseau electrique avec des elements classiques et pathologiques (dipoles et quadripoles), traduisant les conditions mathematiques ou physiques imposees. A titre d'exemple, deux equations differentielles simples, l'une homogene et l'autre non homogene, sont etudiees; les resultats peuvent etre etendus aux equations aux derivees partielles.

The authors consider the use of electrical network computers (including anlogue circuits) for the study of eigenvalues of matrix and of differential and differential partial equations. These problems are studied by introducing pathological elements. One shows that the two types of problems are the same. They are generalized within pathological conception.

On precise les conditions theoriques de stabilite, qui montrent l'existence de zones stables et instables suivant les valeurs des resistances negatives, celles-ci devant eventuellement etre <

L'instabilite des calculateurs a reseau utilisant des resistances negatives est eliminee par l'emploi de sources auxiliaires. On precise leur nombre et leur position ainsi que leur realisation. Des exemples sont cites.

Les auteurs passent en revue divers montages d'amplificateurs operationnels accompagnes de leurs circuits de reaction elabores en vue de realiser des resistances negatives. Ils en etudient les proprietes, les conditions de stabilite et elaborent pour certains de ceux-ci les circuits correcteurs en modifiant la transmittance de la boucle ouverte.

The authors study the extension of the use of resistance network computers by employing a.c. supply, for the resolution of problems such as study of progressive waves or determination of complex solutions. This extension is realized by taking into account the phase shifts obtained with a.c. signals; eventually one must use pathological elements to supply the network.

Les auteurs presentent un procede de calcul utilisant la methode des differences finies, qui met en oeuvre un reseau electrique compose uniquement de resistances. La resolution de l'equation de Schrodinger necessite dans certains cas l'utilisation d'une resistance negative obtenue a l'aide d'un montage faisant intervenin un amplificateur operationnel. Les auteurs donnent quelques resultats obtenus grace a l'emploi systematique du reseau de resistances.