Central nervous signs, blindness and cerebral vermicosis in free-ranging peregrine falcons (Falco peregrinus) associated with aberrant larval migrations

Four free-ranging peregrine falcons (Falco peregrinus) were submitted with a history of unilateral or bilateral blindness and central nervous signs to a veterinary clinic in Germany. There were no indications of trauma or ocular disease. Likewise, other differential diagnoses for CNS signs were ruled out within the diagnostic process. The clinical diagnostic panel in live falcons included general examination, radiography, endoscopy, hematology, ophthalmoscopy and parasitological examination of the feces, blood gas analysis and blood chemistry as well as computed tomography, and magnetic resonance imaging (MRI). A complete pathological and histopathological examination was performed post-mortem. The only common finding in all birds was an infection with the nematode parasite Serratospiculum tendo. The parasite was confirmed morphologically and via PCR. In two falcons intracerebral vermicoses was suspected in MRI and confirmed in subsequent histopathology, but molecular biological identification of the parasite species failed from brain tissue. Until today, S. tendo had been reported to affect the respiratory system, the liver and different parts of the gastrointestinal tract and to cause cachexia, inappetence, regurgitation, dyspnea and general signs of illness such as lethargy, poor plumage, and reduced reproduction. Our findings indicate that aberrant migration should be considered as cause for CNS signs in falcons. As S. tendo might be a possible cause for this, CNS signs might be included in the list of clinical signs of serratospiculiasis in falcons.

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.

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.

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.

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.

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.

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.