Martina Ludewig

Prevalence of specific IgG-antibodies against Toxoplasma gondii in domestic turkeys determined by kinetic ELISA based on recombinant GRA7 and GRA8.

The protozoan parasite Toxoplasma (T.) gondii is one of the most common zoonotic infectious agents worldwide. Besides its sexual reproduction in cats, T. gondii can also infect a wide spectrum of other warm-blooded animals. These include animals used for human consumption such as pigs or chickens. Nevertheless, the role of turkeys for the epidemiology of T. gondii infections has not been studied thoroughly. We have established a kinetic ELISA (KELA) for the detection of T. gondii-specific IgG antibodies in turkey serum samples. The test is based on the recombinant dense granule antigens GRA7 and GRA8. These proteins were used as an antigen mixture at a concentration of 0.13 μg per well. The overall sensitivity of the assay was between 92.6% and 100% and the specificity ranged from 78.1% to 100%, depending on the method used to calculate these parameters. Using this KELA we examined 1913 turkey serum samples from 14 turkey farms from different areas of Germany. From these sera, 387 produced a signal in the KELA, corresponding to a true seroprevalence of up to 20.2%. The seropositivity rate in individual fattening cycles at individual farms ranged from 0.0% to 77.1%, whereas the rates were highly variable within the individual farms and individual fattening cycles. Consequently, conditions of animal husbandry could not be associated with particular seroprevalence rates. Although seropositivity cannot be linked directly to infectious tissue cysts in the muscle tissue of commercially produced turkey meat, we state that there is a potential risk of being infected by consuming turkey meat products that were not heat treated.

Experimental Toxoplasma gondii oocyst infections in turkeys (Meleagris gallopavo)

Toxoplasma (T.) gondii is a protozoan parasite with a broad range of intermediate hosts. Humans are often infected by ingestion of tissue cysts in raw or undercooked meat or meat products. Turkeys as food-producing animals can also serve as intermediate hosts. The aim of the present study was to investigate occurrence and predilection sites of T. gondii infection in turkeys after oral infection with oocysts. Experimental infections with different doses of T. gondii oocysts were performed in 36 turkeys to mimic natural infection. Systemic distribution of parasitic stages was investigated by screening 14 different tissues including the edible tissues heart, liver, thigh, breast and drumstick muscle. Parasite detection was based on a conventional nested polymerase chain reaction (PCR). Animals were sacrificed 6-12 weeks after infection. Results demonstrated parasite spreading over the whole organism after oral infection by oocysts. Most frequently affected tissues were brain (47.2% of all brains were positive for T. gondii) and thigh muscle (25.0% positive samples). Other muscles were regularly T. gondii-positive, all other sampled tissues were positive at least once. Thus, edible tissues are one of the predilection sites of T. gondii in turkeys which renders raw or undercooked turkey meat a potential risk for parasite transmission to humans. Data were compared to results from previous parenteral turkey infections with tachyzoites. With the exception of brain, liver and breast muscle affection, no significant differences were observed between both infection routes. Both infection models could be used for research purposes with certain advantages and disadvantages.

Examinations on the prevalence of footpad lesions and breast skin lesions in B.U.T. Big 6 fattening turkeys in Germany. Part II: Prevalence of breast skin lesions (breast buttons and breast blisters)

This project involves the prevalence of breast skin alterations (breast buttons, blisters, purulent bursitis) in male and female fattened turkeys (British United Turkeys Big 6) from conventional intensive farming. In this case, 24 turkey farms across Germany and 11,860 turkeys (5,740 toms, 6,120 hens) were clinically examined, and 16,200 birds (8,400 hens, 7,800 toms) were evaluated on slaughter lines at 7 turkey abattoirs. Each turkey farm included examination of at least 3 consecutive fattening cycles. Especially in the meat examinations, breast skin alterations were a frequent discovery, particularly in the form of breast buttons. The turkey toms exhibited a prevalence of 27.15%, and the toms were affected significantly more frequently (P < 0.001) by these variations than the turkey hens (7.77%). It is possible that the higher BW of the male specimens leads to increased lying times and is therefore connected with more severe strain on the breast region. The increased fattening period of the turkey toms (slaughtering at wk 21 to 22 of life) vs. the female specimens (slaughtering at wk 15 to 17 of life) must be discussed as a cause. Breast blisters and bursitis sternalis were discovered with a prevalence of 7.36 and 1.24% in toms and more seldom in hens, at 0.30% and 0.15%. Large differences in prevalence were partially recognizable between individual farms as well as between the 3 fattening cycles on a farm. Breast buttons and breast blisters are pathological skin variations for which the etiology is multifactorial. Clear correlations between the prevalence of breast skin alterations and the manner of rearing the birds were not able to be determined. An improvement in this situation, which is considered very problematic from the perspective of bird protection and economics, may be achieved only via cooperation to achieve optimized rearing methods, management, and breeding practices.

Examination of rearing standards and health status in turkeys in Germany.

Within the framework of a cooperative research project, sponsored by the Federal Ministry of Food, Agriculture and Consumer Protection in Germany (BMELV), turkey health as well as numerous aspects of animal welfare in various intensive commercial farms with varying rearing forms were examined. For this purpose extensive documentation of flock management and health status information was conducted over the past two years at the farms. Additional information was ascertained from the carcasses at the slaughterhouse. The first results of this study, which look at flock management, will be presented here. Upon reviewing the questionnaires, it is clear that on one hand almost all farmers orientate there stocking rate upon the allowed limits, on the other hand, however, when considering national general requirements, which are very important parameters thatargely influence animal health (i. e. litter quality and care of sick/injured animals) farmer compliance lacks. Especially the litter quality, which, among other parameters, plays a very important role in food pad health, proved to be unsatisfactory. Unfortunately, no instruments are available that measure the litter quality, yet. The status of footpad health was a major problem in all the rearing systems. However, the prevalence of epithelial necrosis and deep skin lesions varied immensely among different flocks of the same age.

Impact of Selected Factors on the Occurrence of Contact Dermatitis in Turkeys on Commercial Farms in Germany.

Simple Summary In two extensive field studies in Germany, the influence of husbandry on health and fitness of fattening turkeys was investigated in living animals of various ages as well as carcasses shortly after slaughter. Already in the early rearing phase, contact dermatitis of foot pads was observed as a relevant problem in turkey farming. Litter quality and condition as well as management must be coordinated at all rearing stages of turkeys to prevent the appearance of high litter moisture values in order to minimize the prevalence of foot pad dermatitis. Abstract In a long term research project in Germany the influence of husbandry on the health of fattening turkeys (Study 1) as well as the influence of practiced rearing conditions on the health of turkey poults (Study 2) was examined in 24 farms and at the meat processing plant. In all examined rearing farms, litter samples for the determination of litter moisture were taken. This paper summarizes the results obtained by our working group from 2007 until 2012. The results elucidate the universal problem of foot pad dermatitis (FPD). Nearly 100% of the observed turkeys showed a clinically apparent FPD at the meat processing plant. Furthermore, skin lesions of the breast, especially breast buttons were diagnosed, particularly at the slaughterhouse. FPD was detected in the first week of the rearing phase. Prevalence and degree showed a progressive development up to the age of 22–35 days, whereas 63.3% of the poults had foot pad alterations. As even mild alterations in the foot pad condition can be indicators for suboptimal design of the rearing environment, especially high litter moisture, it is important to focus on the early rearing phase.

Validation of ISO method 10273 - Detection of pathogenic Yersinia enterocolitica in foods

EN ISO 10273 method for the detection of pathogenic Yersinia enterocolitica in foods was validated in the project Mandate M/381 funded by European Commission. A total of 14 laboratories from five European countries participated in the interlaboratory study (ILS) organized during 2013 and 2014. Before the ILS, the method was revised by an international group of experts and the performance of the revised method was assessed in an ILS study. The results are published as a part of the standard EN ISO 10273 revision. The study included three rounds with different sample types; raw milk, iceberg lettuce and minced meat, inoculated with a low and high level of pathogenic Y. enterocolitica strains representing major pathogenic bioserotypes 4/O:3 and 2/O:9. The homogeneity and stability of the samples were verified before dispatching them to the laboratories. The results demonstrated the method sensitivity of 96% in raw milk, 97% in minced meat, and 98% in lettuce at high inoculation level of pathogenic Y. enterocolitica. The specificity was 100% in raw milk, 96% in minced meat, and 98% in lettuce. The level of detection, LOD50, varied between study rounds, being 9.4 CFU/25 ml in raw milk, 9.9 CFU/25 g in minced meat and 63 CFU/25 g in lettuce samples. During the study, confirmation by using real-time PCR method ISO/TS 18867 together with pyrazinamidase testing was also validated, as alternative to conventional biochemical confirmation. When comparing different isolation steps used in the revised method during the study rounds, PSB enrichment and plating on CIN after alkaline (KOH) treatment showed the highest sensitivity (52-92%) in raw milk and minced meat samples. In lettuce samples, however, ITC with KOH treatment before plating on CIN showed higher sensitivity (64% at low level; 82% at high level) than plating on CIN from PSB with KOH treatment (44% at low level; 74% at high level). Statistical analysis of different isolation steps supported the use of two enrichment media, PSB and ITC, in the revised method. Recovery of pathogenic Y. enterocolitica on CIN was most efficient after KOH treatment and, based on the analysis, plating on CIN agar without KOH treatment could be left as optional procedure in the method.

Survival of Toxoplasma gondii tachyzoites in simulated gastric fluid and cow’s milk

The protozoan parasite Toxoplasma gondii is one of the most important food-related pathogens worldwide. Besides contact to oocysts or ingestion of tissue cysts mainly by consumption of raw or undercooked meat from infected animals, raw milk is considered to be a risk factor and possible route of transmission for tachyzoites. This stage of the parasite is usually very sensitive to acidic pH and, therefore, considered unlikely to survive stomach passage. However, tachyzoites were shown to survive for several days in milk and there are also reports on transmission of toxoplasmosis via milk. Thus, the aim of the study was to examine retention of infectivity of tachyzoites in simulated gastric fluid (SGF) of different acidity and to elucidate whether addition of different shares of milk would affect survival of the parasites. Tachyzoites were exposed to SGF of pH 2.0 through 6.0 and their remaining infectivity was examined by cell culture. Furthermore, the impact on survival was investigated in different admixtures of milk to the SGF (25, 50, 75%) as well as in pure milk. Tachyzoites were shown to retain infectivity in SGF of pH 5.0 and 6.0 for at least 90min while they were more sensitive to lower pH values. Admixture of milk resulted in extension of survival. The results support the hypothesis of tachyzoites to survive stomach passage and their retention of infectivity.

Toxoplasma gondii – Seroprävalenz in Mastschweinebeständen Ergebnisse aus einer deutschlandweiten Studie

Es kann davon ausgegangen werden, dass die Toxoplasmose eine der häufigsten Lebensmittel übertragenen parasitären Zoonosen ist. Toxoplasma gondii ist ein Protozoon, das alle warmblütigen Säugetiere, einschließlich des Menschen infizieren kann. Die Infektion des Menschen erfolgt durch die orale Aufnahme infektionsfähiger Oozysten aus der Umwelt oder infektionsfähiger Gewebezysten aus rohem Fleisch bzw. nicht thermisch behandelten Fleischerzeugnissen. In Abhängigkeit von der Häufigkeit des Verzehrs kommt dem Schweinefleisch in Deutschland dabei die größte Bedeutung zu. Der Pro-Kopf-Verzehr an Schweinefleisch lag im Jahr 2005 bei 39,5 kg/Jahr (Anonymus, 2006b). Vor allem daraus hergestellte Produkte wie rohes Hackfleisch (Hackepeter) oder nicht thermisch behandelte Fleischerzeugnisse (frische Mettund Knackwurst, Zwiebelmettwurst, kurz gepökelte und geräucherte Schinken) stellen ein nicht unerhebliches Infektionsrisiko dar (Tenter u. Fehlhaber, 2002). Bei Menschen mit einem intakten Immunsystem verläuft die Infektion in der Regel symptomlos. Komplikationen können allerdings bei der erstmaligen Infektion einer Schwangeren auftreten. In Folge dieser pränatalen Infektion kann es in Abhängigkeit vom Übertragungszeitpunkt zu schweren Missbildungen des Fetus kommen (Anonymus, 1999). In Deutschland wurden im Jahr 2006 10 Fälle und im Jahr 2005 18 Fälle konnataler Toxoplasmose registriert (Anonymus, 2005 und 2006a). In diesem Zusammenhang ist herauszustellen, dass lediglich konnatale Toxoplasma-Fälle erfasst werden, die mit Symptomen einhergehen. Nach einer Veröffentlichung von Janitschke (1999) ist bei ungefähr 90 % der während der Schwangerschaft stattfindenden Toxoplasma-Infektionen die Erkrankung nicht erkennbar, so dass nach Meinung des Autors die Anzahl der tatsächlichen Erkrankungsfälle wesentlich über den gemeldeten liegen dürfte. Problematisch ist die Infektion außerdem für Personen, deren Immunsystem geschwächt ist, z. B. bei AIDS, Hodgin Krankheit, nach Chemotherapie bzw. Organtransplantation (Tenter et al. 2000). Nach Angaben aus der Literatur gingen in Deutschland die T.-Seroprävalenzen in den Schweinebeständen von teilweise über 90 % in den Jahren 1962 bis 1964 (Boch et al., 1964) auf weit unter 1 % (Seinecke 1996) zurück. Eigene Untersuchungen zur Toxoplasma-Seroprävalenz von Mastschweinen aus Sachsen, Anhaltinischen und Brandenburgischen Betrieben ergaben mit 20,4 bzw. 5,6 % deutlich höhere Prävalenzen (Fehlhaber et al. , 2003; Schulzig u. Fehlhaber, 2005).