[Update on toxoplasmosis in poultry farming]

INTRODUCTION

Toxoplasmosis is a worldwide occurring zoonosis caused by the obligate intracellular parasite Toxoplasma gondii (T. gondii). All warm-blooded species, including humans, serve as intermediate hosts. Definitive hosts are exclusively cats. Farm poultry can become infected with oocysts from contaminated feed or directly from the ground, or by pecking of e.g. infected rodents. Outdoor or free-range housing of poultry increases the risk of infection with length of time. Poulty meat must be seen as a potential source of infection for humans with the increasing popularity of humane animal husbandry practices in poultry farming. This short literature review attempts to assess the current epidemiological situation in farmed poultry and to assess the possible relevance of toxoplasmosis of poultry meat and poultry meat products for human consumption.

Bovine Cryptosporidium parvum field isolates differ in cytopathogenicity in HCT-8 monolayers

Suckling calves are prone to Cryptosporidium infection. The variable degree of clinical disease is influenced by keeping conditions and immune status of the host, but diversity of isolate virulence may also contribute. The aim of the current study was to evaluate the cytopathogenic effects of 26 C. parvum field isolates by using a MTT assay in HCT-8 cell monolayers. Cell viability of monolayers inoculated with oocysts of the field isolates varied considerably with values of 17.7% (± 5.1%) to 99.5% (± 7.1%). A standard deviation of 18.6% was detected for cell viability of the in house reference strain, which were tested alongside in every assay. Field isolates were grouped in three categories of cytopathogenicity. Probably the length of storage has an effect on the level of the cell destruction category detected post infection in vitro. The applied tool may help to better understand the variable course of cryptosporidiosis in the field.

Host-pathogen interaction in Toxoplasma gondii-infected mixed chicken blood cell cultures

Toxoplasma gondii has the ability to infect various nucleated cell types in different hosts. The aim of the present study was to investigate which chicken blood cells were targeted by T. gondii in a mixed blood cell culture similar to in vivo conditions and to evaluate parasite-host cell interactions. The study consisted of two subsequent experiments. In experiment 1, we applied T. gondii tachyzoites (ME49) at a multiplicity of infection of 1 tachyzoite per blood cell and examined parasite replication, cytokine, and inducible nitric oxide synthase (iNOS) mRNA expression between 1 h and 48 h post-infection (p.i.) by quantitative PCR. By using T. gondii RH-GFP tachyzoites expressing the green fluorescent protein (GFP) in experiment 2, we aimed for visualizing infected cells by confocal laser scanning microscopy (CLSM) and flow cytometric analysis at 24 h p.i. The parasite replication curve showed a massive decrease of parasite stages until 24 h p.i. followed by an approximately plateau phase. We observed mainly significantly increased iNOS mRNA expression levels in T. gondii-infected culture compared to uninfected cells. Flow cytometry and CLSM data confirmed monocytes/macrophages as main target cells for T. gondii. Moreover, different lymphocytes like B cells and cytotoxic T cells seem to be targeted to a low extent. Our findings indicate that monocytes/macrophages play a key role during T. gondii infection in chicken as host cells and triggering of immune response. To the best of our knowledge, this is the first report of a mixed chicken blood cell culture experimentally infected with T. gondii.

Distribution of Cryptosporidium parvum gp60 subtypes in calf herds of Saxony, Germany

Cryptosporidiosis is a common protozoan parasitic infection that causes diarrhoea in neonatal calves. The high shedding of environmentally resistant oocysts facilitates outbreaks of cryptosporidiosis in humans. In total, 58 farms (512 calves) in Germany (Saxony and Brandenburg) were visited three times each. Faecal samples of pre-weaned calves were microscopically examined for oocysts of Cryptosporidium spp. using Heine staining and were scored with regard to their consistency. Overall, 88.9% of calves tested microscopically positive for Cryptosporidium spp. in at least one sample, and the excretion of oocysts was significantly (P < 0.01) associated with a higher faecal score (diarrhoea). After DNA extraction from pooled farm isolates, 47 samples were successfully subtyped by sequence analysis of the 60 kDa glycoprotein gene (gp60). All isolates belonged to subtype family IIa. IIaA15G2R1 was the most common subtype (present on 66% of the farms), followed by IIaA16G3R1 (13%). Subtypes IIaA14G1R1, IIaA14G2R1, IIaA1612R1, IIaA16G2R1, IIaA17G1R1, IIaA17G2R1, IIaA17G4R1 and IIaA19G2R1 were found sporadically. This is the first description of gp60 subtype IIaA17G4R1 in cattle in Germany.

Dirofilaria-repens-Befall in einem Schlittenhunde-Rudel im Land Brandenburg

Gegenstand und Ziel: In den letzten Jahren hat Dirofilaria (D.) repens erheblich an Bedeutung gewonnen. Infolge der globalen Erwärmung und des zunehmenden internationalen Haustierverkehrs ist eine weitere Ausbreitung des vektorgebundenen Parasiten aus seinen angestammten Habitaten Richtung Nordeuropa denkbar. Bei einem Tier aus einem Rudel von 29 Schlittenhunden wurden bei einer Routineuntersuchung Mikrofilarien im Blut festgestellt. Dies gab Anlass zur Untersuchung des ganzen Rudels. Ziele waren Art-diagnose der Filarien, Darstellung des Vorkommens der Filariose im Rudel und Prüfung einer neuen filariziden Behandlungsstrategie. Material und Methoden: Neben der Untersuchung auf Filarien erfolgte eine hämatologische Untersuchung. Zur Detektion der Mikrofilarien diente der Knott-Test. Aus den Proben der positiven Tiere wurde eine PCR zur Artdiagnose durchgeführt. Die für Mikrofilarien positiven Hunde wurden mit Doxycyclin und Ivermectin behandelt. Ergebnisse: Fünf von 29 Tieren waren mit D. repens infiziert. Ein Patient zeigte Hautveränderungen, die anderen Hunde präsentierten sich klinisch unauffällig. Bei den hämatologischen Parametern wiesen sie jedoch signifikante Abweichungen auf. Vier und 19 Wochen nach Abschluss der 6-wöchigen Behandlung waren mittels Knott-Test keine Mikrofilarien mehr nachweisbar. Schlussfolgerung und klinische Relevanz: Die kanine kutane Dirofilariose (D. repens) ist in Deutschland nicht mehr als ausschließlich importierte Krankheit anzusehen. Für die Wahl einer adäquaten Therapie hat eine Artdiagnose entscheidende Bedeutung. Die PCR stellt hierfür eine sichere Methode dar. Durch die Kombinationstherapie mit Ivermectin und Doxycyclin kann eine Amikrofilarämie erreicht werden. Da sich ein Befall der Endwirte nur selten klinisch äußert, sind prophylaktische Maßnahmen zur Limitierung einer Ausbreitung des Parasiten in potenziellen Risikogebieten zu diskutieren. Bei Hunden mit pruriginösen, nodulären Dermatitiden sollte D. repens differenzialdiagnostisch in Erwägung gezogen werden.

Experimental Toxoplasma gondii and Eimeria tenella co-infection in chickens

The widespread apicomplexan parasites Toxoplasma gondii (T. gondii) and Eimeria tenella (E. tenella) are important pathogens with high prevalence in poultry. The aim of our study was the investigation of mutual influences in co-infected chickens, focusing on immune response and course of infection. Two separate trials were performed using in total 96 1-day-old chickens, divided into four study groups: group NC (negative control, uninfected), group PC-T (oral or intramuscular infection with T. gondii oocysts (trial 1) or tachyzoites (trial 2), respectively), group PC-E (oral infection with E. tenella (trial 1) or E. tenella and Eimeria acervulina (trial 2)), and group TE (co-infection). T. gondii and Eimeria infections were validated by different parameters, and cytokine expression in the gut and spleen was investigated. T. gondii-specific antibodies were detected earliest 4 days post infection (p.i.) by immunoblot and direct DNA detection was possible in 22.1% of all tissue samples from infected chickens. Eimeria spp. merogony seemed to be enhanced by co-infection with T. gondii, interestingly without marked differences in oocyst excretion between co-infected and Eimeria spp. mono-infected chickens. An increase of messenger RNA (mRNA) expression of Th1- (IFN-γ, IL-12, TNF-α) and Th2-related cytokines (IL-10) mainly in groups PC-E and TE was observed, however, without statistically significant differences between co-infection and single infection with Eimeria. In conclusion, most of the measurable immune response could be attributed to Eimeria infection. To the best of our knowledge, this is the first report on co-infection experiments of T. gondii with Eimeria spp. in chickens.

Co-infection of Trypanosoma pestanai and Anaplasma phagocytophilum in a dog from Germany

Infections with arthropod-borne pathogens are an increasing threat world-wide that requires heightened vigilance from veterinary and medical practitioners, especially when they involve new or unusual organisms. A dog was presented to a local veterinary clinic in Germany with malaise, pale mucous membranes and stiff joints. Clinical assessment revealed pyrexia, leukopenia and thrombocytopenia. On suspicion of a tick-borne infection, blood samples were examined for clinical and biochemical parameters and subjected to a Anaplasma phagocytophilum-, Borrelia spp.- and Ehrlichia canis-specific real-time PCR. Additionally, a sample of the pre-therapeutic buffy coat was co-cultured with the Ixodes scapularis cell-line ISE6 for 20days. Only the PCR specific for A. phagocytophilum DNA yielded a positive result, and furthermore, Anaplasma morulae were visible in granulocytes and tick cells. After co-culturing, extracellular trypomastigote and epimastigote stages of Trypanosoma sp. with an average length of 29.7μm were observed, featuring a pointed posterior end. Sequence analysis of a 2080bp fragment of the 18S rRNA gene showed 99% identity to the 18S rRNA gene of Trypanosoma pestanai, previously described from a European badger (Meles meles) in France. The dog's condition improved rapidly in response to doxycycline treatment for three weeks. The clinical status normalized and clinical blood parameters were found to be within the reference ranges. To our knowledge this is the first description of T. pestanai infection in a dog, the first detection of T. pestanai in Germany and the first documented co-infection with these two pathogens. Co-infections with unusual opportunistic vector-borne pathogens should be considered, if acute canine granulocytic anaplasmosis is evident.

[Dirofilaria repens-infection in a dog in central Germany without any history of travel]

A mixed breed dog was presented with dyspnoea and fever. In the purulent thorax aspirate, a nematode larva was found during the cytological examination. Subsequent diagnostic tests revealed an infection with Dirofilaria repens, which was probably acquired autochthonously in central Germany. Moxidectin was administered every 4 weeks for 6 months and shown to be effective as indicated by subsequent blood examinations. This case report shows that infection with Dirofilaria repens is possible in Germany and can be treated successfully.

Climate suitability for the transmission of Dirofilaria immitis and D. repens in Germany

Recently concerns are increasing that dirofilarial nematodes may spread from endemic areas in southern, eastern and central Europe to countries in northern regions of Europe. The increasing number of autochthonous cases of canine Dirofilaria repens infections in Germany indicates that worms of this genus may invade new areas, and climate change may be a key factor in this scenario. Thus analysis of long term development of regional temperature is a pivotal factor in risk analysis related to transmission of these worms. Such information is important for suggestions of counteracting strategies, such as definition of periods of increased transmission risk and, consequently, time slots most suited for preventative measures. In this study, mean daily temperature data from 34 geographical clustered weather stations representing all parts of Germany were analyzed. It is concluded that the increasing trend for average daily temperatures observed in the period from 1984 to 2013 has led to climatic conditions that allow the completion of dirofilarial life cycles in large parts of Germany between May and October. Autochthonous infection with D. repens is already established in some regions and targeted diagnosis and medical prophylaxis is advisable for dogs assumedly exposed during risk of transmission periods. It appears likely that global warming will support further spread of D. repens. Furthermore for the population of dogs the spread of the more pathogenic species D. immitis in hitherto non-endemic Germany is a potential risk if mean temperatures rise to a level suitable for parasite development in the abundant vector mosquitoes during the warmer seasons.

Necrotic enteritis in chickens: development of a straightforward disease model system

The interaction between Eimeria species and Clostridium perfringens was investigated in two different necrotic enteritis (NE) models: 120-day-old broilers were used in two separate experiments consisting of six groups (n=10) each. Besides controls, chickens were infected with coccidia on study day (SD) 18 (Eimeria maxima and Eimeria acervulina (experiment 1) or Eimeria tenella and Eimeria brunetti (experiment 2) and/or a NetB toxin positive C perfringens strain (both experiments: SD 14 or SD 22, respectively)). Body weight, feed intake, mortality rate, clinical disease, Eimeria species oocyst excretion and C perfringens counts were recorded. NE and coccidiosis specific lesion scores were assessed (SD 24 and SD 30). In coinfected groups, NE-typical clinical signs occurred. Coccidiosis-specific lesions were most severe in coinfected groups (significant for E tenella, P<0.05). Most pronounced NE lesions occurred in coinfected chickens compared with C perfringens monoinfected groups (experiment 2, C perfringens infections on SD 22: P<0.05). In experiment 2, E tenella antibody levels were (non-significantly) higher in coinfected groups than in Eimeria species monoinfected groups. Thus, infection with E tenella and Eimeria brunetti followed by C perfringens inoculation is regarded as an easy to handle and suitable model for investigations into NE of chickens.

Effects of pH, sodium chloride, and curing salt on the infectivity of Toxoplasma gondii tissue cysts

Toxoplasma gondii is one of the most common zoonotic parasites in the world. The parasite causes no or mild symptoms in immunocompetent humans. However, a high potential hazard exists for seronegative pregnant women and immunocompromised patients. The consumption of meat containing tissue cysts or oocyst-contaminated vegetables and fruits or the handling of cat feces poses a high risk of infection with T. gondii. It is known that raw minced meat, raw fresh sausages, and locally produced raw meat products are possible causes of T. gondii infection. The infectivity of T. gondii tissue cysts in meat products depends, among other factors, on the pH and the salt concentration. Therefore, the impact of these two factors on the tissue cysts was examined. For this purpose, dissected musculature and brain from experimentally infected mice (donor mice) were placed in a cell culture medium (RPMI 1640). The medium was adjusted to different pH values (pH 5, 6, and 7) with lactic acid and to different salt concentrations (2.0, 2.5, and 3.0%) with sodium chloride (NaCl) or nitrite-enriched curing salt (NCS) for the various tests. After storage at 4°C for different time periods, the materials were fed to bioassay mice. Later, the brains were examined for presence of T. gondii to assess the infectivity. The data show that T. gondii tissue cysts have a high pH tolerance. Cysts were infectious in the muscle for up to 26 days (pH 5). In contrast to their tolerance to pH, cysts were very sensitive to salt. Muscle cysts survived at an NaCl concentration of up to 2.0% only, and for no longer than 8 days. At NaCl concentrations of 2.5 and 3.0%, the cysts lost their infectivity after 1 day. When NCS instead of NaCl was used under the same conditions, T. gondii muscle cysts retained infectivity for only 4 days at 2.0%. Consequently, NCS (NaCl plus 0.5% nitrite) has a stronger effect on T. gondii cysts than does common table salt. Sausages produced with low NaCl concentration and short contact times pose a potential risk for susceptible individuals.

Einfluss der Verteilung von Strongyliden- und Ascarideneiern in Pferdekotproben auf den Nachweis mit einem kombinierten Sedimentations-Flotations-Verfahren

Gegenstand und Ziel: Werden zur parasitologischen Diagnostik Aliquote derselben Kotproben an verschiedene Labore geschickt, differieren gelegentlich die Untersuchungsergebnisse. Eine mögliche Erklärung ist eine inhomogene Verteilung der ausgeschiedenen Eier in einer Pferdekotprobe. Daher wurde Kot aus verschiedenen Lokalisationen von zur Routinediagnostik eingesandten Pferdekotproben untersucht und geprüft, ob die Homogenisierung einer größeren Kotmenge (mindestens 40 g) vor der Probennahme (10 g Kot) zur Durchführung des kombinierten Sedimentations-Flotations-Verfahrens (KSFV) einheitlichere Untersuchungsergebnisse erbringt. Material und Methoden: Es wurden 51 Pferdekotproben jeweils dreimal parallel mit dem KSFV untersucht, wobei die Aliquote aus der Randregion (R), dem Inneren (I) oder beiden Lokalisationen (G) stammten. Ferner wurde dreimal das KSFV mit vorheriger Homogenisierung einer größeren Kotmenge (n = 51) durchgeführt und die Nematoden-Eizahl (Strongyliden- und Ascarideneier) bestimmt. Ergebnisse: Die Untersuchung der Proben der verschiedenen Lokalisationen erbrachte ähnliche Ergebnisse und maximale sowie minimale Anzahl der Nematodeneier lagen nahe dem Medianwert. Die Homogenisierung einer größeren Kotmenge vor Entnahme des Aliquots konnte diese Resultate nicht verbessern. Schlussfolgerung und klinische Relevanz: Nematoden sind häufige pathogene Endoparasiten des Pferdes und eine zuverlässige Beurteilung der Ei-Ausscheidung ist bedeutend für die Planung von Bekämpfungsmaßnahmen. Bei der Untersuchung von 10 g Kot mittels KSFV spielt die Verteilung der in dieser Studie nachgewiesenen Nematodeneier (Strongyliden- und Ascarideneier) in Pferdekotproben keine wesentliche Rolle, sodass auf die Homogenisierung einer größeren Kotmenge vor der Aliquotierung verzichtet werden kann. Bei Einsendung hinreichend großer Probenmengen (ca. 50 g) ist mit repräsentativen Laborergebnissen zu rechnen.

[Effect of distribution of eggs of strongyles and Parascaris equorum in faecal samples of horses on detection with a combined sedimentation-flotation method]

OBJECTIVE

Results of parasitological examination of faecal aliquots may vary between diagnostic laboratories. To examine whether inhomogeneous distribution of worm eggs in faecal samples is responsible for this observation, horse faeces provided for routine diagnosis of helminth infection were examined. Distribution of worm eggs was assessed by examining aliquots taken from different locations of the faecal sample by a combined sedimentation-flotation method (KSFV). In addition, it was tested, whether the homogenization of a larger amount (minimum of 40 g) of faeces before performing KSFV improved reproducibility of the method.

MATERIAL AND METHODS

51 faecal samples of horses were examined three times in parallel by KSFV with ZnSO4 solution. 10 g aliquots were taken from the margin (R), from inside (I) and from both locations (G). The remaining amount of faeces was weighed, suspended with water 1:1 and homogenized. Subsequently, three subsamples, each consisting of 20 g of this suspension, were taken and examined by KSFV.

RESULTS

The egg numbers of the nematodes (strongyles and Parascaris equorum ) found in samples that originated from different locations were similar and variation was low. The homogenization of a larger amount of faeces had no relevant impact on egg counts of these nematodes.

CONCLUSION AND CLINICAL RELEVANCE

Nematode infections are relevant and frequently occurring in the horse, and reliable assessment of worm egg excretion is a critical aspect for rational planning of control measures. It could be shown that the distribution of nematode eggs (strongyles and Parascaris equorum ) in horse faeces is quite even and results are in principle reproducible if 10 g faeces are examined by KSFV. The homogenization of a larger amount of faeces does not improve the sensitivity or reproducibility of KSFV, and is thus dispensable. For diagnostic purposes, it is advisable to ship approximately 50g of horse faeces to the laboratory.

An invasion record for the swimbladder nematode Anguillicoloides crassus in European eel Anguilla anguilla in a deep warm-monomictic [corrected] lake, from invasion to steady state

This study is the first account of the establishment and development of the neozoic nematode parasite Anguillicoloides crassus in its host, the European eel Anguilla anguilla, in a deep, warm-monomictic [corrected] lake. A 21 year study of A. crassus took place in Upper Lake Constance (ULC), Europe's second largest pre-alpine lake. The study included two extensive surveys, one in 1991 during the initial parasite invasion phase and the second in 2006 when the infection was well established. The subtropical swimbladder nematode A. crassus was first recorded in A. anguilla in ULC in 1989. Prevalence reached 60% in 1992 and remained at this level until 2007. In 2008, prevalence decreased to 48%. Infection intensity peaked in 1993 at a mean value of 16 adult parasites per host fish. Around 90% of all A. anguilla examined displayed swimbladder lesions, with a significant trend to increasing severity over time. Moreover, heavy swimbladder lesions were seen in c. 10% of A. anguilla ready to migrate to their spawning habitat. Both ruffe Gymnocephalus cernuus and sunfish Lepomis gibbosus serve as paratenic hosts for A. crassus in ULC. Gymnocephalus cernuus seems to be the main vector, and infection is especially frequent in spring possibly caused by reduced immune system efficacy of G. cernuus during winter. In 1991, hypochromic anaemia was prevalent in ULC A. anguilla acutely infected with A. crassus, whereas in 2006 blood values were indicative of chronic infection. The growth and survival rates of A. anguilla during their continental phase were not noticeably altered in infected fish, but damage to the swimbladder probably impairs migration potential and thus the subsequent breeding success of the oceanic phase.

Effects of curcumin on Cryptosporidium parvum in vitro

Cryptosporidium parvum is a zoonotic protozoan parasite having peculiarities among the apicomplexa that could be responsible for its resistance to some drugs and disinfectants against coccidia. The awareness of Cryptosporidium as a health problem in man and animal is increasing and potent drugs are urgently needed. Curcumin, a natural polyphenolic compound, has been found to be active against a variety of diseases including anticarcinogenic, antimicrobial, and antiprotozoal effects. We investigated the effects of curcumin on infectivity and development of C. parvum in a recently established in vitro system combining infection of human ileocecal adenocarcinoma cell cultures with quantification of intracellular parasites by quantitative polymerase chain reaction. Curcumin was found to be effective (>95% inhibition of parasite growth) at 50 microM for 24 h when infected cultures were exposed for more than 12 h. Withdrawal of curcumin after 24 h of exposure did not result in a significant resumption of C. parvum growth. The invasion of host cells by sporozoites (infectivity) was found to be inhibited at least 65% in the presence of 200 microM curcumin. No significant reduction of viability of C. parvum oocysts after incubation with curcumin was recorded. Altogether, curcumin showed promising anticryptosporidial effects under in vitro conditions and deserves further exploration.

The effect of a metaphylactic treatment with diclazuril (Vecoxan®) on the oocyst excretion and growth performance of calves exposed to a natural Eimeria infection

A multicenter field efficacy study was performed in six farms located in Belgium, France and Germany with a history of suspected coccidiosis outbreaks and the proven presence of Eimeria bovis and/or Eimeria zuernii. At each of these trial sites the calves were randomly allocated to two groups (T, treated; C, control) of similar size. In total, 231 calves were included in the study. Group T calves (n=116) were drenched with a single dose of diclazuril (Vecoxan, 1mg/kg body weight) close to the time of expected outbreak of coccidiosis (day 1 of the study period), group C calves (n=115) served as placebo-treated controls. Although E. bovis and/or E. zuernii were identified at all trial sites, clinical coccidiosis was only noted in 16% of the group C calves. At day 5 of the study period (4 days after treatment), faecal oocyst counts (opg, oocysts per gram) were substantially lower in group T ("short-term effect") compared to group C. At four trial sites, the respective values of groups T and C were significantly different (P=0.0132 to P=0.0001) in favour of group T. For the pooled data of all trial sites, this effect was highly significant (P<0.0001). The overall faecal oocyst counts from day 3 until day 21 of the study period ("Area Under the Curve") was significantly reduced in group T by 87.2-99.5% ("long-term effect") at five trial sites (P=0.0139 to P<0.0001). The pooled data revealed a highly significant effect of treatment on oocyst excretion over the observation period (P<0.0001). On five of the six trial sites, the average weight gain was higher in group T than in group C. On those trial sites, the average weight gain of group T calves exceeded that of the controls by 95-268g/day and by 2.0-6.0kg over the study period. This effect was statistically significant (P<0.01) at one trial site. Altogether the calves of group T gained on average 129g more weight daily than the controls (+2.7kg over the study period). For these pooled data, statistical analysis confirmed the positive effect of treatment of calves exposed to coccidiosis on growth performance (P=0.003). In conclusion, metaphylactic treatment with diclazuril efficiently controls coccidiosis in calves thus reducing environmental contamination with oocysts and preventing negative effects of natural exposure to coccidiosis on growth performance of calves.

Influence of experimental Eimeria zuernii infection on clinical blood chemistry in calves

Coccidiosis, often caused by Eimeria zuernii infection, is an important diarrhoeal disease in calves [Fitzgerald, P.R., 1980. The economic impact of coccidiosis in domestic animals. Adv. Vet. Sci. Comp. Med. 24, 121-143]. Infection trials were performed to investigate the effects of experimental E. zuernii coccidiosis on clinical blood chemistry in calves. Three groups of calves were formed: group 1 (n=14) served as uninfected control group, group 2 (n=11) was infected with 150,000 sporulated E. zuernii oocysts per calf, and group 3 (n=16) was infected with 250,000 sporulated E. zuernii oocysts per calf. Measurements throughout the prepatent and the patent period revealed a marked influence of E. zuernii infection on the following parameters: total protein, albumin, urea, bilirubin, creatine kinase, free fatty acid concentration, and cholesterol. Aberrances in these were most pronounced in group 3. No significant and/or distinct changes after infection could be detected in blood glucose concentration. E. zuernii infection impairs intestinal function and induces catabolic metabolism in affected calves. Bilirubin, urea and cholesterol concentration, and creatine kinase activity were particularly affected indicating catabolism of protein and lipids.

Influence of experimental Eimeria zuernii infection in calves on electrolyte concentrations, acid–base balance and blood gases

Coccidiosis, often caused by Eimeria zuernii, is an important disease in calf rearing and is clinically mainly associated with diarrhoea (PR Fitzgerald in Adv Vet Sci Comp Med, 24:121-143, 1980). Calves were experimentally infected with E. zuernii oocysts to investigate the effects of artificial E. zuernii coccidiosis on electrolyte concentrations, acid-base balance and blood gases. Therefore, animals were assigned to three groups: group 1 (n = 14) served as uninfected control group, group 2 (n = 11) was infected with 150,000 sporulated E. zuernii oocysts per calf, and group 3 (n = 16) was infected with 250,000 sporulated E. zuernii oocysts per calf. Aberrances which were attributed to coccidiosis were observed in the following parameters: sodium and chloride concentrations, pH (only high-dose infected group 3), base excess, standard bicarbonate, total carbon dioxide and partial pressure of carbon dioxide. Alterations were most pronounced in the high-dose infected group 3. Anion gap and oxygen saturation did not show significant differences between the groups. Due to diarrhoea and malabsorption in coccidiosis-affected calves, there is a distinct loss not only of fluid and blood but also of electrolytes and alkaline buffer substances which provokes the development of an acidosis. This is counteracted by metabolism and respiration but cannot be compensated in severely affected and moribund calves.

Genetic resistance to Sarcocystis miescheriana in pigs following experimental infection

Clinical and parasitological traits of Sarcocystis miescheriana differ in Pietrain and Meishan pigs. For further description and characterization of the genetic basis of this variation a F(2) family based on Pietrain boars and Meishan sows as founders was generated. One hundred and thirty-nine F(2) pigs were challenged orally at an age of 100 days with 50,000 sporozysts to produce the typical clinical picture of a moderate dose Sarcocystis infection. Heritabilities were estimated for clinical and clinical-chemical traits, for specific antibody responses to the infection and for bradyzoite numbers found in skeletal (Musculus longissimus dorsi: M.l.d.) and heart muscles at necropsy 70 days post-infection (p.i.) Apart from several low to moderate heritabilities, high heritabilities were observed for bradyzoite numbers in the M.l.d. (0.68), IgM antibody levels (0.74) during the acute (14 days p.i.) and titres of specific IgG antibodies (0.42) in the early stage of cyst formation (42 days p.i.). Marked heritabilities of these traits, which are basic for acute phase of the disease (14 days p.i.) or chronic Sarcocystosis presume genes that explain sufficient shares of variance (QTL). The model is considered valuable for screening of gene variants associated with resistance/susceptibility to Sarcocystis infection. Such gene variants could then be used in susceptibility-scoring or selection programs in the future.

Parasitological and clinical parameters of experimental Eimeria zuernii infection in calves and influence on weight gain and haemogram

Infection trials were performed to characterize experimental Eimeria zuernii coccidiosis parasitologically and clinically and to investigate the effects on weight gain and haemotologic parameters in affected calves. Three groups of calves were formed: Group 1 (n = 14) served as uninfected control group, group 2 (n = 11) was infected with 150,000 sporulated E. zuernii oocysts per calf, and group 3 (n = 16) was infected with 250,000 sporulated E. zuernii oocysts per calf. All infected animals shed oocysts and showed diarrhoea; a positive correlation could be shown between quantified oocyst excretion and faecal consistency. Measurements throughout the prepatent and the patent period revealed a marked influence of E. zuernii infection on weight gain, leukocyte concentration, haemoglobin, haematocrit, and mean cellular volume. Aberrations in these parameters were most pronounced in the highly infected group. The results of this study confirm that acute sublethal E. zuernii coccidiosis causes distinct loss of fluid and blood via intestine. This dominates also the haematological picture of the disease, which is mainly characterized by haemoconcentration. Leukocyte concentration was depressed during the early patent period, whereas it increased markedly from day 24 after infection on.

Development and validation of a cell culture based assay for in vitro assessment of anticryptosporidial compounds

In vitro culture of Cryptosporidium parvum oocysts in HCT-8 cells was combined with immunofluorescent labelling and digital image analysis to quantify the development of the parasite by detecting and measuring the labelled area in the respective cell cultures. The number of inoculated oocysts and the labelled area correlated reliably and significantly (R (2), 0.98-0.99). The effects of various concentrations of halofuginone bromide (0.00039 to 50 microM) and monensin (0.00225 to 0.144 microM) on in vitro parasite development were determined in further trials in cultures inoculated each with 10(5) oocysts. Monensin reduced the detected area in a dose-dependant manner. In comparison to the untreated controls, the area positive for C. parvum in the cultures treated with 0.144 to 0.009 microM monensin reached a maximum of 17%, and inhibition of 40% was observed at 0.0045 microM. Halofuginone bromide also efficiently inhibited parasite in vitro reproduction, albeit at higher concentrations. At 12.5 microM or more, inhibition was at least 90%; 0.05 microM still yielded 80% inhibition, whereas at concentrations below 0.00625 microM, labelled areas abruptly increased. Both drugs appeared efficient under in vitro conditions; the applied system is suited to screen drugs for their anti-cryptosporidial capacity.

Efficacy of various anticoccidials against experimental porcine neonatal isosporosis

The efficacies of 20 mg/kg body weight (BW) of toltrazuril (Toltra) 2 days post-infection (dpi), 2 mg/kg BW of diclazuril 2 and 3 dpi and 200 mg/kg BW of sulphadimidine 2, 3 and 4 dpi were compared in a model for piglet isosporosis. Weight gain (first 4 weeks of life) and diarrhoea and oocyst excretion from 4 to 11 dpi were evaluated (10-12 piglets/group). Additionally, animals were killed and examined for pathohistological changes of the small intestines 5, 7, 11 and 14 dpi (n = 3 per group and time point) and lengths of the intestinal villi. Diarrhoea (semi-liquid or liquid faeces) was seen from 5 dpi in all groups except Toltra, and the differences in prevalence and intensity of diarrhoea were statistically significant (p < 0.05) between Toltra and the other groups, which were similar (trial 1). Oocyst excretion was greatly reduced in the Toltra group, which was also statistically significant for the mean and median excretion rates and the percentage of excreting piglets between Toltra and the other groups (p < 0.05). Weight gain was highest in Toltra (p < 0.05). Histopathology revealed mostly villous necrosis and atrophy in the small intestines except the duodenum, which peaked at 7 dpi, in all groups except Toltra. Between 5 and 11 dpi, the Toltra group had significantly longer villi than the other groups. Reduced weight gain and diarrhoea caused by Isospora suis was controlled by a single application of Toltra in the pre-patent period, while neither diclazuril nor sulphadimidine improved the clinical picture of isosporosis.

World association for the advancement of veterinary parasitology (WAAVP): Second edition of guidelines for evaluating the efficacy of anthelmintics in swine

Guidelines are provided for evaluating the efficacy of anthelmintics in swine which, in conjunction with other sets of guidance such as those of the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products (VICH GL7 and VICH GL16), should encourage the adoption of uniform registration requirements globally. Testing of efficacy should be carried out according to the principles of "Good Clinical Practice" (VICH GL9, 2000). Data obtained according to these guidelines should be internationally acceptable for the registration of anthelmintics for swine. Further, the use of the guidelines should expedite development, government review, and approval of anthelmintics for swine, as well as contribute towards reducing costs and the number of experimental animals used for drug testing.

Eimeriosis in cattle: current understanding

This report addresses various aspects of the protozoan parasite Eimeria which contribute to their increasing recognition as important protozoal pathogens in cattle. Among others, questions of parasite biology and epidemiology, its impact on host physiology, and control strategies are dealt with. The tenacious oocysts are found ubiquitously in the environment making an infection of calves and young cattle, the most susceptible age group, almost inevitable. Further development, comprising of asexual multiplication, the merogony, and a subsequent sexual stage, the gamogony, takes place within cells of the small and large intestines, after which numerous unsporulated oocysts are formed and shed with the faeces. Of the more than a dozen species, Eimeria bovis and Eimeria zuernii only are made responsible for severe clinical disease characterized by haemorrhagic diarrhoea with sometimes fatal outcome. To a lesser extent, Eimeria alabamensis also can cause clinical disease. Because of the damage inflicted on the intestinal tissue, the digestive process and overall homeostasis can become severely affected, even with absence of clinical disease, with adverse effects on animal welfare and performance. The consequent economic losses for the cattle industry are thus substantial. Active (species specific) immunity, both humoral and cellular, develops rapidly after first antigen contact, its intensity being dependent on the number of oocysts ingested. However, no absolute protection is achieved and even older animals can excrete oocysts, contributing to a state of endemic stability. For efficient control, exact diagnosis of the Eimeria species involved and the evaluation of animal management and husbandry practices are of utmost importance. Mixed infections are the rule and only an occurrence of pathogenic species, together with clinical symptoms, justifies the assumption of a coccidiosis. Proper hygiene regime and ensuring unfavourable conditions for oocyst survival in the environment (cool and dry, disinfection procedures) will help to reduce infection pressure on the herd. Of the various pharmacological compounds used to treat coccidiosis, those which act against the late developmental stages, administered during prepatency (metaphylactically rather than therapeutically), are currently considered most effective.

Isospora suis: an experimental model for mammalian intestinal coccidiosis

Piglets experimentally infected with 10,000 oocysts of Isospora suis in three identical trials (n = 50) were examined clinically and coproscopically from 5 to 11 days post-infection (d.p.i.), weighed in weekly intervals until the fourth week of life and compared to age-matched asymptomatic controls (n = 17). Furthermore, 17 infected piglets were histologically examined on days 5-14 p.i. Infected animals had a significantly lower weight gain than the controls and showed diarrhoea throughout, with maximum prevalence and intensity on 6 d.p.i. Half of the animals had diarrhoea for only 2 days or less. The number of diarrhoea days was negatively correlated with weight gain. Oocyst excretion started on 5 d.p.i. with peak prevalences and declined afterwards; a smaller peak was seen on 10 d.p.i. All animals excreted parasites at least once, and most of them excreted for 5-7 days. Oocyst excretion intensity paralleled the prevalence and ranged from 220 to 251,501 oocysts per gram of faeces (opg). Most samples contained 4 x 10(3) to 4 x 10(4) opg. The opg values were negatively correlated with faecal scores (samples with diarrhoea contained less oocysts) of the same day and the previous day. Histologically, necrosis followed by atrophy of the villi was most pronounced in the early stage of infection throughout the jejunum and ileum but declined thereafter. On 14 d.p.i., villous atrophy was still noticeable in the jejunum. Histology is difficult to quantify and requires large animal numbers, although the effects are visible for some time. Weight gain and faecal score can be affected by other factors than parasite infection. From the compiled data, we conclude that the established model is suitable to study piglet isosporosis with oocyst excretion being the most reliable parameter, although individual variations are considerable. A negative correlation between excretion and diarrhoea may be responsible for the difficulties in the detection of the parasite in field samples.

Pathology and treatment of Eimeria zuernii coccidiosis in calves: investigations in an infection model

Two studies were conducted in the Eimeria zuernii infection model in order to investigate the pathology of E. zuernii coccidiosis and the efficacy of toltrazuril (Baycox 5% suspension) in this infection. For this purpose, a total of 30 calves were infected experimentally with E. zuernii oocysts and faecal samples taken regularly from the rectum and examined for faecal consistency and oocyst excretion. Six of the calves underwent pathological examination at various points in time after infection. Significant macroscopic and microscopic changes were demonstrated and parasitic stages were identified in the intestinal mucosa of infected calves during the late prepatent and patent period. Inflammatory reactions revealed by light microscopy were confirmed by electron microscopical investigations. Treatment of calves with toltrazuril during the late prepatent period resulted in significantly lower frequencies of diarrhoea and levels of oocyst excretion, and weight gain was significantly higher than in shamtreated animals.

Control of clinical coccidiosis of calves due to Eimeria bovis and Eimeria zuernii with toltrazuril under field conditions

The efficacy of metaphylactic treatment with toltrazuril (Baycox 5% suspension) against natural infections with Eimeria bovis and/or Eimeria zuernii in calves was investigated. The study was conducted with 208 calves on five calf-rearing farms in Germany and the Czech Republic. All participating farms had a notable incidence of coccidiosis. Animals were treated 14 days after stabling in the respective facility. One group was treated with 15 mg toltrazuril/kg body weight, and a second group served as the sham-treated control. Assessment of efficacy was based on faecal consistency and oocyst excretion of E. bovis and E. zuernii, both investigated throughout the study. Duration and rate of oocyst excretion as well as number of scour days with E. bovis or E. zuernii oocyst shedding and the severity of diarrhoea were significantly lower in the toltrazuril-treated groups. It is concluded that a single metaphylactic treatment with toltrazuril controls coccidiosis of housed calves under various field conditions.

Occurrence of Isospora suis in Germany, Switzerland and Austria

Nationwide surveys for the occurrence of Isospora suis were carried out in Germany, Austria and Switzerland including a questionnaire regarding herd size, health status and management practices and a coccidiosis sampling kit for pooled faecal samples from litters of suckling piglets. A total of 184 veterinary practices participated in the survey and returned 1745 samples (331 kits) from 324 farms in the north (n = 98), south (n = 84), centre/east (n = 42) and west (n = 10) of Germany, Austria (n = 61) and Switzerland (n = 29) with larger farms in north and centre/east (average number of sows: 270 and 500) and smaller ones in the south (95), Austria (60) and Switzerland (43). Larger farms tended to have better hygienic standards (slatted floors, disinfection of the farrowing units). The majority of the participating farms (93.5%) reported problems with diarrhoea in piglets at 2-3 weeks of age, significantly associated (P < 0.001) with uneven weaning weights (94.9%). Toltrazuril (5%; Baycox) was used only rarely; however, in these farms unevenness of weaning weights was less frequently observed (P = 0.011). A 76.2% of the farms were positive for I. suis (samples contained mostly low or moderate oocyst numbers), especially in the south (P < 0.001). Oocysts were more frequently found in samples from farms with reported diarrhoea (P = 0.011), uneven weight gain (P = 0.019) or in herds of small size (P < 0.001). Disinfection, floor type or treatment with toltrazuril did not affect the frequency of observation of oocysts.

Ecdysis of Oesophagostomum: possible involvement of eicosanoids and development of a bioassay

Bioassays were developed and applied to test the role of eicosanoids and pH changes in ecdysis of Oesophagostomum dentatum. Exsheathment (80-100%) was achieved by subjecting third-stage larvae (L3) either to chlorine (hypochlorite assay) for 5 min or by incubating them in HCl followed by addition of NaHCO3 (pH-change assay) with subsequent cultivation at 38.5 degrees C/10% CO2 for 1 week. Addition of the lipoxygenase (LOX) inhibitor diethylcarbamacine (DEC) to the larvae resulted in a reduction of the exsheathment rates which could be restored by the addition of leukotrienes (LT)B4, LTC4, LTD4 and LTE4. Addition of the cyclooxygenase (COX) inhibitor acetylsalicylic acid (ASA) also resulted in decreased exsheathment rates both in the hypochlorite and in the pH-change assays in a dose-dependent manner. However, the primary COX products (prostaglandins) were not able to reverse this effect, in contrast to LTC4. It was concluded that: (1) both tests are suitable for bioassaying the effect of substances on exsheathment, and (2) eicosanoids involved in the control of exsheathment of L3 of O. dentatum are primarily LT.

[The compatibility of ronidazol in racing pigeons in a controlled clinical study]

Ronidazol is often used in racing pigeons for the treatment of Trichomonas infections and diseases. Therefore, in this study, the compatibility of the drug was examined by oral application over 7 days. For this purpose a randomized blind study was performed using four different groups (control group, 10 mg = therapy-group, 20 mg = double-dose-group and 40 mg = high-dose-group) of pigeons (Columba livia f. domestica) with 6 male and 6 female birds each. All birds were clinically healthy and between 6 and 12 weeks of age. The application of ronidazol at a dose of 10 mg/racing pigeon did show no side-effect within the duration of the study, e.g. no influence could be seen on clinical, haematological, blood-chemical and pathological parameters. Low-to middle-grade clinical alterations of the gastro-intestinal tract occurred in the high-dose group at day 6 and 7 of the application of the drug. Therefore a fourfold overdosing of ronidazol should be avoided.

Endoparasiten des Schweins: Bedeutung und Bekämpfung

Es wird eine kurze Übersicht über den gegenwärtigen Kenntnisstand zum Endoparasitenbefall des Schweins gegeben. Von den gastrointestinalen Nematoden kommen Ascaris suum und Oesophagostomum spp. bei Intensivhaltung relativ häufig vor. Seltener lassen sich Trichuris suis und Strongyloides ransomi diagnostizieren. Andere Helminthen wie Trichinella spiralis oder Finnen von Taenia solium werden extrem selten beim Hausschwein gefunden. Aus der Gruppe der monoxenen Kokzidien treten Eimerien bei Sauen häufig auf, meist ohne eine Erkrankung zu verursachen. Ein wichtiger und häufiger Erreger von Saugferkeldurchfall ist Isospora suis. Zystenbildende Kokzidien wie Toxoplasma gondii oder Sarcocystis spp. haben eine fleischhygienische Relevanz. Für andere beim Hausschwein seltene Endoparasiten stellen Wildschweine ein natürliches Reservoir und eine potenzielle Infektionsquelle bei Weidehaltung dar. Eine effiziente Endoparasitenbekämpfung beim Schwein erfordert neben dem gezielten Einsatz von Medikamenten gute Hygiene und Management.

Prevalence and control of bovine cryptosporidiosis in German dairy herds

In a 5-year survey regarding its prevalence and importance in five German state veterinary laboratories Cryptosporidium was diagnosed annually in 19-36% of faecal samples either submitted to the laboratories or taken post mortem. In approximately half of the cases no other enteropathogens were detected. However, only 73% of 30 laboratories participating in a questionnaire survey routinely tested for this parasite, and the majority of researchers considered cryptosporidiosis to be of minor importance. In a placebo-controlled field study 152 suckling calves were treated daily against cryptosporidiosis either with sulfadimidine or with halofuginone (Halocur, Intervet) over 1 week. Treatment by oral drench started at the onset of diarrhoea in the herd. Oocyst excretion, faecal consistency and health status were recorded five times for a 3-week period. Oocyst excretion peaked 7-14 days in the placebo group after the onset of diarrhoea, and during that period prevalence and intensity of excretion were significantly lower in the halofuginone-treated group compared to the sulfadimidine and the placebo control groups. The health status (diarrhoea, dehydration) declined in all groups but was significantly (P<0.05-0.001) better in the halofuginone group in the first 2 weeks. Halofuginone effectively (P<0.05-0.001) reduced oocyst excretion and improved the health status of the treated animals, while sulfadimidine had no effect against Cryptosporidium.

Comparison of viability assays for Cryptosporidium parvum oocysts after disinfection

In order to test various viability assays for Cryptosporidium parvum oocysts were used to infect HCT-8 cells in vitro or baby mice. Infected cells were either stained with fluorescent anti-Cryptosporidium-antibody or lysed and subjected to C. parvum-specific PCR after 48 h. Titrations with infective oocysts were performed and compared to oocysts disinfected with Neopredisan for 2 h at varying concentrations. Caecal smears and histological sections from infected animals were examined in parallel. The number of foci of parasite development in vitro after immunofluorescent staining correlated well with the infection dose. PCR was less quantifiable and the results were not always reproducible, especially when low infection doses were used. Disinfection resulted in a dose-dependent reduction of oocyst infectivity when compared to the controls in all three assays. The infection of cells cultured in vitro with oocysts of C. parvum provides a suitable tool for the estimation of viability after treatment with chemical disinfectants. Immunofluorescence is easy to perform and gives quantitative results, while PCR-based detection of parasite DNA, although possible, requires the use of more sophisticated tools for quantification.

Fasciola hepatica alters coagulation parameters in sheep plasma in vivo and in vitro

The blood-sucking activities of the liver fluke, Fasciola hepatica, are likely to cause alterations in coagulation during the course of infection; and the effect of F. hepatica on various coagulation parameters was studied during the course of acute and chronic fasciolosis of sheep over a period of 17 weeks. Whole blood and plasma samples from infected sheep (with 800 metacercariae each) and uninfected controls were collected weekly until 17 weeks post-infection (w.p.i.) and the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) were determined. Additionally, adult F. hepatica were recovered from bile ducts, incubated for the production of excretory/secretory products (ESP) or homogenised and the effect of fluke products on APTT, PT and TT was determined. Anaemia was evident in infected sheep from 8 w.p.i. until 17 w.p.i. Plasma APTT was accelerated during 8, 9, 12, 14, 16 and 17 w.p.i., while PT was prolonged at 8-11 w.p.i. and TT at 10, 14 and 17 w.p.i. Addition of worm ESP or homogenate to plasma resulted in an enhancement of the intrinsic pathway (APTT) together with a prolongation of the extrinsic and common pathways (PT, TT) of coagulation. It was concluded that F. hepatica contains and releases substances that may contribute to coagulation changes in vivo. Further characterisation of the active substance(s) in vitro revealed heat inactivation, a size >30 kDa and inhibition by the proteinase inhibitors Complete and EDTA for the APTT-accelerating substance(s). The TT-deceleration, in contrast, was increased after heating.

Variation in clinical and parasitological traits in Pietrain and Meishan pigs infected with Sarcocystis miescheriana

Future prophylaxis needs new concepts, including natural disease resistance of hosts against infectious agents. Genomic approaches to detect and improve disease resistance in farm animals and the molecular mechanisms involved in host-parasite interactions depend to a high degree on the trait differences between founder breeds, i.e. on the animal model. The present study evaluates differences in susceptibility/resistance against Sarcocystis miescheriana in the European Pietrain (PI) and the Chinese Meishan (ME) pig breeds, based on 25 individuals, infected orally with 5x10(4) sporocysts of S. miescheriana. Significant differences appeared in clinical, serological, haematological and parasitological findings. The major discriminating period post infection (p.i.) was between days 42 and 45. Severity of signs was negatively correlated with specific immunoglobulin titres during the first 3 weeks p.i. and positively with the load of bradyzoites in muscle tissues of the pigs. Loads of bradyzoites in muscle tissues were 20 times higher in PI than in ME. Sarcocystis-specific differences between the two breeds were in the range of 1-2 standard deviations. The study lays the foundation for further experiments to analyse chromosomal regions, candidate genes, and thus the molecular basis of Sarcocystis susceptibility/resistance as a model for host-parasite interaction in protozoan infectious disease.

The role of Isospora suis as a pathogen in conventional piglet production in Germany

In order to evaluate the prevalence of Isospora suis in conventional piglet production in Germany, pooled faecal samples from 327 pig litters from 18 pig production units (20-320 sows each) were examined. At least 10 litters from each farm were investigated. I. suis was present on 83% of the farms and 42.5% of the litters, the infection rate being highest in the third week of age (48.2%). I. suis was found more frequently in samples of diarrhoea than in firm faeces (49.2% compared to 22.2%). Twenty naturally infected piglets from six of these farms underwent examination post mortem, including histology, virology and bacteriology. Histological examination revealed atrophy of the villi in various degrees, mild crypt hyperplasia, fusion of the villi, metaplastic epithelium, erosions and necrosis, especially in the medium and the posterior jejunum and in the ileum. Asexual and sexual developmental stages of the parasite were found in varying numbers in the epithelium of the whole of the small intestine. Bacteria and viruses were mostly excluded as the cause of diarrhoea, and it was concluded that I. suis was the primary pathogen inducing distinct changes and clinical symptoms of diarrhoea.

Development and application of a standardized assay for chemical disinfection of coccidia oocysts

The development and application of a standardized model for testing of anticoccidial disinfectants are described. Due to its economic impact, tenacity of oocysts, and reproducibility of the course of infection Eimeria tenella has been chosen as test organism. Oocysts of the Houghton strain were more susceptible to disinfection with 4% TP4 (Preventol) than oocysts of a field isolate (FI 292/1) as determined by sporulation inhibition and lysis. Scoring of intestinal lesions and of oocyst numbers in mucosal scrapings in chicken infected with various doses of oocysts were found unsuitable for assessment of disinfectants. Because strain differences were observed only Houghton strain oocysts were applied for further testing. Guidelines for standardized in vivo testing of disinfectants have been stipulated by the German Veterinary Society (DVG) on the basis of these studies. When applied for testing of Neopredisan (NP) in two separate laboratories similar results were obtained. Inhibitory activity (IA; proportion of inactivated oocysts) of 92.9 and 90.6% were calculated for 3% NP and of 95.2 and 96.8% for 4% NP after treatment with the disinfectant over 120 min. According to the guidelines IA of at least 95% is required for certification of sufficient disinfecting efficacy by the DVG.

Products of fourth-stage larvae of Oesophagostomum dentatum induce proliferation in naïve porcine mononuclear cells

Infection of pigs with Oesophagostomum dentatum is a major cause of economic losses in pig productions. Whether infection with this nematode results in a protective immunity is still in debate and information about immune-modulating properties of O. dentatum are lacking. The present study investigated the question whether products of O. dentatum larvae modulate the proliferative response of porcine blood mononuclear cells (poMNC) in vitro. The poMNC of naïve and O. dentatum-infected pigs were cultured for 72 h in the presence of products (total homogenates and culture supernates) derived from third- (L3) and fourth-stage larvae (L4) of O. dentatum. Numbers of vital cells and blast-transformed cells were determined flow cytometrically. No larvae product induced an accelerated death of poMNC in vitro. In contrast, products of L4 (but not L3) significantly increased the numbers of vital poMNC in vitro (up to 187%). In addition, L4 products (homogenates and supernates, 0.1-10 microg/ml) but not those of L3 induced significant blastogenesis of poMNC. This was seen with poMNC from naïve and from O. dentatum-infected animals. In spite of these effects, the larvae products were not able to modulate the mitogen-induced (Concanavalin A) poMNC proliferation of naïve and infected animals. In summary, larvae of O. dentatum contain and secrete products with potential immunomodulatory capacity for porcine peripheral blood mononuclear cells. The differential effects of L3 and indicate that the parasite alters its set immunomodulatory substances during its development. This has to be considered in further studies and may help to identify the mediators involved.

Oesophagostomum dentatum: expression patterns of enzymes involved in eicosanoid production

Cytosolic and membrane-bound proteins of various stages of Oesophagostomum dentatum, the nodular worm of pigs, were investigated for the presence of lipoxygenases (LOX) and cyclooxygenases (COX) using polyclonal and monoclonal antibodies. Putative 12-LOX and 15-LOX, but not 5-LOX, were detected in both fractions of all developmental stages in the expected size range of 75 kDa, with an isoelectric point of 6.0-6.5. The protein could be precipitated with 50% ammonium sulfate, as described for mammalian LOX. An antibody directed against both COX isoforms and one against mammalian COX-2 detected proteins of approximately 70 kDa with an isoelectric point of 6.0-6.5 in the membrane-bound fractions of third-stage larvae and adults, but not in the fourth-stage larvae. Anti-COX-1 or more specific anti-COX-2 antibodies failed to detect proteins. The constitutive LOX expression supports the assumption that the metabolites of this enzyme previously detected in O. dentatum serve intrinsic functions, while the production of anti-inflammatory COX-products in the invasive and luminal stages of the parasite implies a possible role in host-parasite interactions.