Post harvest epidemioilogy of Salmonella enterica in pork: Prevalence in the environment, carcasses and by-products in two slaughterhouses in Greece (1996-1998)

In this study our objective was to estimate the prevalence of Salmonella enterica in the environment, on the pork carcasses and on several by-products in 2 industrial slaughterhouses over a 2-year period. In the period from 1/7/96 until 1/8/98, 1874 samples were obtained from the slaughterhouse environment (from the floor, the worker\u27s hands and their knives), product samples (from pork carcasses) and by products (livers and plucks). The prevalence of infection in pigs slaughtered at the sampling dates was estimated by testing samples from mesenteric lymph nodes and caecal content. Environmental samples were collected before the onset of slaughter. After the onset of slaughter and for every 50 pigs, a round of samplings of all sources mentioned above was repeated. Salmonella isolation and identification was carried out by standard cultural method. In total, based on the isolation method, 178/1874 (9.5%) samples were positive. The mean prevalence on floors, workers\u27 hands. workers\u27 knives, pork carcasses and by-products were 19.6% (range: 0%-100%), 5.2% (0%-50%), 3.1% (0%-37.5%), .3% (0%-88.9), 6.6% (0%-90%), respectively. The average prevalence of infection in pigs slaughtered at the sampling dates was 20.7% based on mesenteric lymph nodes and 15.2% based on caecal contents. Before the onset of slaughter, 37.5%, 6.3% and 8.7% of samples obtained from floors, worker hands and knives harbored Salmonella. This may reflect an inadequate plant hygiene. The frequent presence of Salmonella in the caecal contents and the lymph nodes may contribute to significant environmental contamination, including inspectors hands, eventually leading to final product contamination. The isolated salmonellae belonged to 22 serotypes. Among those, S. Derby and S. London were the most frequent representing 25.8% and 15.2% respectively. In conclusion, the frequent presence of Salmonella spp. in the lymph nodes, may indicate infection in the herd. Furthermore, the moderate prevalence of Salmonella on carcasses and by-products calls for further identification and institution of postharvest control options

Development of a LAMP assay for detection of Leishmania infantum infection in dogs using conjunctival swab samples

Background: Leishmania infantum infections in dogs play a crucial role in the transmission of pathogens causing visceral leishmaniasis to humans in the Gansu province, northwest China. To be able to control zoonotic transmission of the parasite to humans, a non-invasive loop-mediated isothermal amplification (LAMP) assay to specifically detect L. infantum infections in dogs was developed. Methods: The primers used in the LAMP assay were designed to target kinetoplast DNA minicircle sequences of the L. infantum isolate MCAN/CN/90/SC and tested using DNA isolated from promastigotes of different Leishmania species. The LAMP assay was evaluated with conjunctional swab samples obtained from 111 and 33 dogs living in an endemic and a non-endemic region of zoonotic visceral leishmaniasis in the Gansu province, respectively. The LAMP assay was also compared with conventional PCR, ELISA and microscopy using conjunctional swab, serum and bone marrow samples from the dogs, respectively. Results: The LAMP assay detected 1 fg of L. infantum DNA purified from cultured promastigotes which was 10-fold more sensitive than a conventional PCR test using Leishmania genus-specific primers. No cross reaction was observed with DNA isolated from promastigotes of L. donovani, L. major, L. tropica, and L. braziliensis, and the L. infantum reference strain MHOM/TN/80/IPT1. The L. infantum-positive rates obtained for field-collected samples were 61.3%, 58.6%, 40.5% and 10.8% by LAMP, PCR, ELISA and microscopy, respectively. As only one out of the 33 samples from control dogs from the non-endemic region of zoonotic visceral leishmaniasis was positive by the LAMP assay and the PCR test, the observed true negative rate (specificity) was 97% for both methods. Conclusion: This study has shown that the non-invasive, conjunctional swab-based LAMP assay developed was more sensitive in the detection of leishmaniasis in dogs than PCR, ELISA and microscopy. The findings indicate that the LAMP assay is a sensitive and specific method for the field surveillance of domestic dogs, particularly of asymptomatic canines, in ZVL-endemic areas in western China

Prevalence and pathology of ectoparasites of Mediterranean sea bream and sea bass reared under different environmental and aquaculture conditions

Sea bream, Sparus aurata L., and sea bass, Dicentrarchus labrax L., were sampled from an off- shore cage farm in eastern Greece, an inshore cage fish farm in southern Greece, and a lagoon in northern Greece. The prevalence and intensity of Metazoan parasites and factors associated with the prevalence were investigated. In Farm 1 (eastern Greece), ectoparasite prevalence in sea bream and sea bass was 61.5% and 76.9% for Monogenea, none for Isopoda, and 0 and 23% for Copepoda. In Farm 2 the prevalence was 13.3% and 26.3% for Monogenea, 13.7% and 20% for Isopoda, and 0 and 13.6% for Copepoda. In the lagoon, the prevalence of ectoparasites was 100% and 21.9% for Monogenea and Copepoda, respectively. The lagoon had the highest prevalence of parasites among the studied ecosystems, however, the variety did not significant- ly affect the health of the infected fish. In Sparidae, gill lesions were due to monogeneans while skin and eye lesions were due to larvae of the isopod Ceratothoa oestroides that caused severe pathology. Furnestinia echeneis and Diplectanum aequans were host specific to sea bream and sea bass, respectively, and persisted in all aquaculture systems. Lernanthropus kroyeri was host specific and detected only in sea bass from the cage farms

Factors associated with the serological prevalence of Salmonella enterica in Greek finishing swineherds

Blood samples were taken from 50 finishing pigs at 90-105 kg in each of 59 randomly selected farrow-to-finish herds. The sera were tested for antibodies to Salmonella enterica by the Danish mix-ELISA. Samples with an optical density of >10% were considered to be positive. Associations between the odds of seropositivity of pigs and possible risk factors were evaluated in multivariable logistic regression models. The results of the analysis indicated that pigs fed non-pelleted dry or wet ration had I I (P=0.0004) or 9 (P=0.02) times, respectively, lower odds of seropositivity than those fed pelleted ration. The risk of seropositivity was 4 (P=0.0006) times higher in pigs fed a combination of chlortetracycline, procaine penicillin and sulphamethazine during, fattening than in those fed an approved growth promoter or a probiotic

Effect of toltrazuril treatment in nursing piglets naturally infected with Isospora suis

Isospora suis is an important parasitic infection in intensive pig production worldwide responsible for significant economic losses In this study the efficacy of toltrazuril treatment against isosporosis was evaluated under field conditions and throughout the nursing period in reducing (i) the mean time to onset of diarrhoea and oocyst excretion (ii) the odds of diarrhoea and (iii) the odds and level of oocyst excretion adjusting for the heterogeneity of! suss infection among litters and across time In a 300-sow farrow-to-finish commercial operation twenty-five litters were randomly allocated to receive toltrazuril (thirteen litters) or no treatment (twelve litters) The course of infection was followed in all piglets by coprological examination from day 6 after farrowing until weaning Parametric shared frailty models generalised linear mixed models and a two-part random effects model were used in the analyses Treated piglets had longer mean time to onset of oocyst excretion lower odds of excreting oocysts and lower mean amount of excreted oocysts on any day during the nursing period Diarrhoea was less likely to occur in treated piglets Variance partition coefficients revealed that almost half of the variation in the odds of oocyst excretion and diarrhoea was ascribed to unknown or unmeasured factors that operate at higher than the piglet levels of aggregation Thus beyond toltrazuril treatment control of isosporosis in commercial pig farms can be improved by identification and quantification of these factors (C) 2010 Elsevier B V All rights reserve

Hoof lesions and lameness in sows in three Greek swine herds

Objectives: To characterize foot lesions, estimate their frequency and severity, and investigate their association with parity and lameness in three Greek farrow-to-finish swine herds. Materials and methods: The studied sows, which had been individually stalled during previous gestations, were examined for foot lesions upon entry into the lactation facilities. Lesions scored included heel hyperkeratinization, erosions or cracks, and toe and dew claw overgrowths. When exiting the farrowing facilities, the sows were observed while walking along an alley and their degree of lameness was scored. Results: The proportion of sows with at least one lesion on any foot was very high and similar among herds, with 121 of 125 (96.8%), 123 of 125 (98.4%), and 377 of 386 (97.7%) sows affected in herds A, B, and C, respectively. The most frequent lesions were those located on the heel, and overgrown toes and dew claws. For these sites, lesion severity increased with sow parity. The concurrent presence of lesions on more than one foot site, on the same or different feet or both, had a multiplicative effect on the likelihood of lameness. Implications: Under the conditions in the herds participating in this study, sow foot lesions are extremely common, with older sows more likely than younger sows to have lesions on the heel and overgrown toes and dew claws. The degree of lameness may be affected by a causal interface among foot lesions

Factors associated with the occurrence and level of Isospora suis oocyst excretion in nursing piglets of Greek farrow-to-finish herds

Background: Piglet isosporosis is one of the most common parasitic diseases in modern pig production. To prevent clinical disease, prophylactic treatment of piglets with toltrazuril (BAYCOX (R) 5%, Bayer HealthCare, Animal Health, Monheim, Germany) is widely practiced in the past 20 years. There are only very few reports documenting the likely effect of managerial practices, such as hygiene measures, all-in-all-out management of farrowing facilities and piglet manipulations, and/or farm-specific environment - i.e. design and materials of the farrowing pen and room - in the risk of disease occurrence and transmission. Therefore, in this cross-sectional study, we identified litter-and herd-level factors associated with the odds and the level of Isospora suis oocyst excretion in nursing piglets of Greek farrow-to-finish pig herds. Faecal samples were collected from 314 liters of 55 randomly selected herds. Oocyst counts were determined by a modified McMaster technique and possible risk-factor data were collected through a questionnaire. In the analysis, we employed a two-part model that simultaneously assessed the odds and the level of oocyst excretion. Results: Factors associated with lower odds of oocyst excretion were: use of toltrazuril treatment, all-in all-out management of the farrowing rooms, no cross-fostering or fostering during the first 24 hours after farrowing, plastic flooring in the farrowing pens, farrowing rooms with more than fourteen farrowing pens and employment of more than two caretakers in the farrowing section. Factors associated with lower oocyst excretion level were: use of toltrazuril treatment and caretakers averting from entering into farrowing pens. Conclusion: Apart from prophylactic treatment with toltrazuril, the risk and the level of I. suis oocyst excretion from piglets in their second week of life, was associated with managerial and environmental factors. Changes in these factors, which may enhance prevention of piglet isosporosis - either alternatively or supplementary to medical control - are of increasing importance because of the likely development of resistant parasites under the currently widespread use of anticoccidial compounds

A Bayesian Weibull survival model for time to infection data measured with delay

Survival analysis methods can be used to identify factors associated with the time to induction of infection In the absence of a perfect test, detection of infection is generally delayed and depends on the duration of the latent infection period We assess, via simulations, the impact of ignoring the delayed detection of infection on estimated survival times and propose a Bayesian Weibull regression model, which adjusts for the delayed detection of infection The presence of non-differential detection delay seriously biased the baseline hazard and the shape of the hazard function. For differential detection delay, the associated regression coefficients were also biased The extent of bias largely depended on the longevity of the delay. In all considered simulation scenarios our model led to corrected estimates We utilized the proposed model in order to assess the age at natural infection with Mycobacterium avium subsp paratuberculosis (MAP) in Danish dairy cattle from the analysis of available time to milk-seropositivity data that detected infection with delay. The proposed model captured the inverse relationship between the incidence rate of infection and that of seroconversion with time susceptibility to infection decreases with time (shape parameter under the proposed model was rho = 0 56 1. under standard Weibull regression) Cows infected earlier in their lives were more likely to subsequently shed detectable levels of MAP and, hence, be a liability to herd-mates Our approach can be particularly useful in the case of chronic infections with a long latent infection period, which, if ignored, severely affects survival estimates (C) 2010 Elsevier BV All rights reserve