Outbreak of clinical listeriosis in sheep: evaluation from possible contamination routes from feed to raw produce and humans

We report the results of clinical and microbiological investigations on Listeria monocytogenes infections in a flock of 55 sheep and describe the implications for the safety of the raw milk and raw-milk cheeses produced in the on-farm dairy. The outbreak was caused by feeding grass silage, which was contaminated with 5 log10 CFU L. monocytogenes/g. Clinically, although having been fed from the same batch of silage, abortive (nine ewes), encephalitic (one ewe) and septicaemic (four ewes) forms of listeriosis were observed during the outbreak phase. As the starting point of feeding the contaminated silage was known we could calculate an incubation period of 18+/-2 and 26 days for the abortive and the encephalitic form of listeriosis, respectively. Pathologically, the septicaemic cases suffered from Listeria accumulation at comparable numbers in visceral organs but not in the brain. Only a single ewe developed central nervous symptoms and a rhomb-encephalitis was immunohistologically confirmed. In this case the infection proceeded from the nasal mucosa into the brain, with no infections of the liver, spleen and other visceral organs. Sampling of the cheese production chain, the farm environment and the persons living at the farm revealed the exposure of a farm-worker to an isolate genetically indistinguishable from the outbreak clone, obviously through the consumption of faecally contaminated bovine raw milk. The cheese under processing was free of Listeria because, as a result of intensive consultations, the farmer ensured a proper acidification of the cheese. The epidemiological findings suggest that food safety matters should be assessed in any case where infection of food-producing animals with potential human pathogens is observed.     

Poultry, pig and the risk of BSE following the feed ban in France--a spatial analysis

A spatial analysis was carried out in order to analyse the reason why the risk of Bovine Spongiform Encephalopathy (BSE) was spatially heterogeneous in France, during the period following the feed ban of Meat and Bone Meal to cattle. The hypothesis of cross-contamination between cattle feedstuff and monogastric feedstuff, which was strongly suggested from previous investigations, was assessed, with the assumption that the higher the pig or poultry density is in a given area, the higher the risk of cross-contamination and cattle infection might be. The data concerned the 467 BSE cases born in France after the ban of meat and bone meal (July 1990) and detected between July 1st, 2001 and December 31, 2003, when the surveillance system was optimal and not spatially biased. The disease mapping models were elaborated with the Bayesian graphical modelling methods and based on a Poisson distribution with spatial smoothing (hierarchical approach) and covariates. The parameters were estimated by a Markov Chain Monte Carlo simulation method. The main result was that the poultry density did not significantly influence the risk of BSE whereas the pig density was significantly associated with an increase in the risk of 2.4% per 10 000 pigs. The areas with a significant pig effect were located in regions with a high pig density as well as a high ratio of pigs to cattle. Despite the absence of a global effect of poultry density on the BSE risk, some areas had a significant poultry effect and the risk was better explained in some others when considering both pig and poultry densities. These findings were in agreement with the hypothesis of cross-contamination, which could take place at the feedstuff factory, during the shipment of food or on the farm. Further studies are needed to more precisely explore how the cross-contamination happened.     

Identification, Chromosome Location, and Diagnostic Markers for a New Gene (YrCN19) for Resistance to Wheat Stripe Rust

ABSTRACT Several wheat lines and cultivars of wheat (Triticum aestivum) originating from the southwestern region of China were found to be highly resistant to stripe rust by inoculation with the prevalent races (CYR30, CYR31, and CYR32) and newly emerged races (H46-4, SY11-4 and SY11-14) of the pathogen. An inheritance study of the resistance to stripe rust was carried out by crossing resistant AIM6 with susceptible BeiZ76. Results indicated that the resistance to stripe rust was controlled by a single dominant gene. The 112 F(2) plants chosen from the cross BeiZ76/ AIM6 were analyzed with 218 pairs of microsatellite primers to determine the map location of the resistance gene. A simple sequence repeat marker on chromosome arm 2BS, Xgwm410, showed polymorphism and co-segregation between stripe rust resistant and susceptible plants. From the pedigree, inheritance, molecular marker, and resistance response, it is concluded that the stripe rust resistance gene in wheat cv. Chuan-nong19 (CN19) and wheat lines AIM5 and AIM6 is a novel gene, designated YrCN19. The microsatellite primer Xgwm410 is a diagnostic marker of the resistance gene YrCN19, which has potential for application in the marker-assisted breeding of wheat.     

Detection of the Pinewood Nematode, Bursaphelenchus xylophilus, Using a Real-Time Polymerase Chain Reaction Assay

ABSTRACT The pinewood nematode, Bursaphelenchus xylophilus, has caused significant damage to pine plantations both in East Asia and North America and is an important quarantine organism. A real-time polymerase chain reaction (PCR) assay was developed to detect B. xylophilus. A set of primers and probe specific for B. xylophilus was designed to target the ribosomal DNA internal transcribed spacer region. Optimal primer concentration, Mg(2+) concentration, and extension temperature were 400 nM, 3.0 mM, and 60 degrees C, respectively. The assay was highly specific and sensitive, detecting as little as 0.01 ng of B. xylophilus DNA. The real-time PCR assay also successfully detected B. xylophilus in field samples, and it should be very useful for quarantine purposes.     

Monitoring and treatment of Fascioloides magna in semi-farm red deer husbandry in Croatia

The presence of American liver fluke (Fascioloides magna) in Croatian wild ruminant species was detected for the first time in January 2000. At the same time, the problem of adequate parasitological monitoring and treatment appeared in the captive deer population. Quarantine and health screening protocols, as well as migration and transportation influence had to be evaluated in red deer husbandry. Non-invasive methods were introduced to estimate the prevalence of F. magna in the semi-farm rearing system. Coprological analysis has been performed on 264 faecal samples. The most effective antiparasitic treatment was implemented on herd and individual treatment. Treatment was extended to the free-ranging population of deer in the same region.     

Cutaneous Melanocytoma in a Llama (Lama glama)

Veterinary Research Communications -     

Populational dynamics of Stomoxys calcitrans (Linneaus) (Diptera: Muscidae) in three biocenosis, Minas Gerais, Brazil

Populational flux of the adult phase of Stomoxys calcitrans was observed in the municipal district of Pedro Leopoldo, Minas Gerais, Brazil. Three biocenoses were selected for the study: stable agrobiocenosis, pastural agrobiocenosis and eubiocenosis. The occurrence and the populational flux of the insects, using the Magoon trap for their capture, were established. For each trap located in different biocenoses, a crossbred calf (Bos taurus × Bos indicus) approximately 6-month-old was used as “live bait,” exposed weekly for 48 h in the traps. Of the three agrobiocenoses studied, the stable agrobiocenosis contributed the greatest number of specimens of. S. calcitrans captured, corresponding to 96.9% of the total flies of this species collected. S. calcitrans shows seasonal behavior for approximately 6 months (spring and summer being the rainiest months of the year). The population peaked during the months of November and December. During the months of July and August, there was no capture of flies.     

Analysis of BoLA class II microsatellites in cattle infested with Boophilus microplus ticks: class II is probably associated with susceptibility

The aim of this study was to determine the role of certain bovine lymphocyte antigens (BoLA) regions in the resistance or susceptibility to Boophilus microplus tick infestation in two different breeds of cattle. The breeds were maintained, one in natural conditions and the second one in an experimental setting at the research station in Martinez de la Torre, Veracruz, Mexico. The study took place from June to August 2001 (natural infestation) using 33 crossbreed steers (crossbreed is here defined as 3/4 European = 1/2 Simmenthal x 1/4 Holstein x 1/4 Zebu, a cross resulting from F1 x Simmenthal), ranging from 15 to 20 months old. Fifty-nine F1 cows (1/2 Holstein x 1/2 Zebu) were included in the experimental setting, infested and followed during 25 days in November 2001 and 2002. Experiment A included thirty-one 2-7-year-old F1 cows, and experiment B included twenty-eight 18-24-month-old F1 heifers. Both groups were analysed separately and were not comparable because of the different infestation methods and genetic background. All ticks > or =4mm long were counted on the total body of F1 animals and on one side of the 3/4 European steers. In this case, susceptible animals were defined when having ticks = X + 1S.D. (29 +/- 16). In the experimental setting susceptibility was defined when the number of ticks was over the 75 percentile (> or =79). DNA was extracted from peripheral blood samples of all animals. The BoLA DRB3, DRBP1, RM185 and BM1815 microsatellite loci were amplified using a PCR method. Genescan software was used for analysis in an ABI sequencer. The SPSS statistical program was used and the comparisons were assessed using the Fisher's exact test. In the naturally infested animals, DRB3-184 was found positively associated with tick infestation (P = 0.018; Pc = NS; OR = 5; EF = 28%). DRBP1-128 was also found to be increased (P = 0.03; Pc = NS; OR = 6; EF = 42%). In the experimentally infested animals, two more loci were found to be associated, BM1815-152 (P = 0.01; Pc = NS; OR = 15; EF = 74%) and DRBP1-130 (P = 0.05; Pc = NS; OR = 4; EF = 77%). None of them remained significant after correction, indicating that a larger sample size is needed to confirm the results. This is the first study showing MHC genes associated with tick infestation based on class II microsatellite polymorphisms. Further studies are needed to confirm the susceptibility traits and to determine haplotype segregation in families.     

First record of Trichinella pseudospiralis in the Slovak Republic found in domestic focus

Infection of Trichinella spp. is widespread among wildlife in Slovakia and the red fox (Vulpes vulpes) is the main reservoir of Trichinella britovi. Trichinella spiralis has been rarely documented in sylvatic and domestic animals of this country. During routine examination of domestic pigs at the slaughter, Trichinella larvae were detected by artificial digestion in a domestic pig of a large-scale breeding farm in Eastern Slovakia. The parasite has been identified by molecular (PCR) and biochemical (allozymes) analyses and by the morphology of the nurse cell as the non-encapsulated species Trichinella pseudospiralis infecting both mammals and birds. The epidemiological investigation carried out at the farm level revealed the presence of the same parasite species in other three pigs of 192 examined (2.1%), in 3 of 14 (21.4%) examined synanthropic rats (Rattus norvegicus) and in a domestic cat. The farm was characterized by inadequate sanitary conditions, insufficient nutrition, cannibalism and the presence of rat population. A different profile has been observed at the phosphoglucomutase locus in T. pseudospiralis isolates from Slovakia in comparison with the T. pseudospiralis reference isolate from the Palearctic region. This is the first documented focus of T. pseudospiralis from Central Europe. The detection in domestic pigs of a non-encapsulated parasite infecting both mammals and birds stresses the need to avoid the use of trichinelloscopy to detect this infection at the slaughterhouse.     

The susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis

Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.