Influence of toltrazuril treatment on parasitological parameters and health performance of piglets in the field – An Austrian experience

The effect of an injectable toltrazuril - gleptoferron (Forceris®) on Cystoisospora suis oocyst excretion and growth of neonatal piglets pre- and post-weaning

In this study the efficacy of an intramuscular formulation of toltrazuril combined with gleptoferron for the control of porcine cystoisosporosis caused by Cystoisospora suis was investigated. The study was carried out on three Belgian farms with a confirmed history of C. suis infections. As none of the farms implemented a standardized toltrazuril treatment regimen for their piglets, the presence of resistant C. suis strains seems improbable. In total 90 litters, representing 1249 piglets, were included in the study and randomly allocated to either the treatment or control group. Piglets in the treatment group received a single intramuscular injection, containing 45 mg toltrazuril and 200 mg gleptoferron, between 1 and 3 days of age. Piglets in the control group received a single injection with only 200 mg gleptoferron. The effect of treatment on oocyst excretion, expressed in oocysts per gram of feces (OPG), average daily weight gain (ADG) and mortality was determined both pre- and post-weaning. A significant decrease in OPG as well as a decrease in the number of litters (pre-weaning) and pens (post-weaning) that tested positive for cystoisosporosis, was observed in the treated animals compared to the controls. Furthermore, treatment resulted in an increased ADG during the period from day 1 to day 21 (p-value: 0.03881). There was no significant difference in mortality observed between the treatment group to the control group (p-value: 0.2167). To our knowledge, this is the first report on the effect of toltrazuril on oocyst excretion after weaning. This finding highlights the potential long-term benefits of the treatment beyond the initial administration.

Cystoisospora spp. infection at a dog breeding facility in the Madrid region: Infection rate and clinical management based on toltrazuril metaphylaxis

Canine coccidiosis caused by Cystoisospora canis and Cystoisospora ohioensis-complex is common in kennels. While often underestimated, coccidiosis may cause severe clinical signs in puppies and sometimes even lead to death, so preventative measures are important. This study examines Cystoisospora spp. infection at a Labrador retriever breeding facility in Madrid, Spain. To identify environmental factors associated with infection, dams were examined throughout a reproductive cycle (from oestrus to 60 days postpartum) and their puppies during their first 60 days of life. Also assessed was the efficacy of combined treatment with emodepside (0.9 mg/ml) and toltrazuril (18 mg/ml) at a dose of 0.5 ml/kg of weight, equivalent to 0.45 mg/kg and 9 mg/kg, respectively, in puppies on day 35 of life. Oocyst shedding was detected in 4.6-18.6% of 45 dams examined and in 2.2-9.1% of their litters (315 puppies). In both cases, peak opg elimination was recorded on day 30 postpartum/of life. The species of Cystoisospora detected were C. canis (91.3%) and C. ohioensis-complex (8.7%). While in both dams and puppies opg counts were higher in autumn when rainfall was at its highest, correlation between opg and rainfall emerged as significant only in puppies (p = 0.031). The treatment of 35 day-old puppies with toltrazuril was 100% effective in controlling this infection in the kennel. Our findings therefore suggest the need for a strict hygiene regime and the use of toltrazuril as blanket treatment to reduce Cystoisospora transmission in dog breeding facilities.

On the efficacy of preventive toltrazuril treatments and the diagnosis of Cystoisospora suis infections in intensively raised piglets in farms from southeast Spain

This study investigated the presence and abundance of Cystoisospora suis oocysts in faecal samples from 131 one- to three-week-old pig litters belonging to eight intensively raised, indoor herds in Spain. Seven herds used preventive anticoccidial toltrazuril treatments administered orally or by intramuscular injection, and one did not use preventive anticoccidial treatments. The diagnosis was performed using two oocyst flotation-concentration methods, Bailenger's method in every herd and the more recent Joachim's method in four herds. Oocysts were detected in every farm, the proportion of oocyst-positive samples was higher with Bailenger's technique, and the estimated overall prevalence (95% confidence interval) was 40 (32-49)%, including 47 (29-65)% in non-medicated litters, 52 (38-67)% in orally medicated litters and 28 (16-40)% in intramuscularly medicated litters (p < 0.05). However, mixed logistic regression models indicated that the risk of infection was not significantly associated with preventive anticoccidial treatments (p > 0.05), and increased with age, was higher in herds with partially compared to fully slatted dung floors in farrowing pens and in litters with pigs with diarrhoea (p < 0.05). The median (range) oocysts per gram of faeces (OpG) in infected litters by Bailenger's method was 623 (35-49048) and mixed negative binomial models revealed no significant association between infection intensity in positive litters and pen's floor type and piglets age, faecal consistency and treatment status (p > 0.05). The apparent low efficacy of Toltrazuril suggests treatment administration failures, reduced residual efficacy or low susceptibility of C. suis strains in study farms and needs further investigation.

Cystoisospora suis infection in suckling piglets in Brazil: Prevalence and associated factors

Piglet coccidiosis is a parasitic disease caused by the protozoan Cystoisospora suis, which is regarded as the most prevalent gastrointestinal parasite in intensive pig farms. Despite the availability of highly effective chemo-metaphylaxis (toltrazuril), coccidiosis is still prevalent in European and other countries. We conducted a cross-sectional study on swine farms in Brazil, to assess the prevalence of Cystoisospora suis in fecal samples and determined the associated factors. In total, 666 litters from 50 farms were sampled twice within one week between samplings (mean age at sampling: 10.75 and 17.7 days). Of 666 litters, 225 (33.8%) were positive at least once, and the expected within farm prevalence of C. suis oocysts was 32.9% (25.4-41.3%; 95% confidence interval). Oocysts were more prevalent in fecal samples collected from farms with diarrhea (odds ratio = 6.75). The room temperature was also positively associated with oocyst detection; a one-degree increase in room temperature increased the chance of a litter being positive by 23.2%. Up-to-date, this is the most comprehensive technical evidence of factors associated with C. suis infection in Brazilian industrial piglet farms.

The strong influence of management factors on coccidian infections in smallholder pig farms and the first molecular identification of Cystoisospora suis in Myanmar

A cross-sectional study was conducted to investigate coccidian infection and associated factors in smallholder pigs, and to identify Cystoisospora oocysts by PCR. A total of 500 pig faecal samples from 330 smallholder farms were collected in Nay Pyi Taw, Myanmar. The faecal flotation method was used to identify Eimeria and Cystoisospora species, and oocyst counts per gram (OPG) of faeces were recorded. Oocysts were differentiated after sporulation. Oocyst DNA was subjected to ITS1-targeted Cystoisospora-specific PCR. The overall coccidian oocyst detection rate by microscopic was 89.0% (445/500). Among the studied samples, 74.0% (370/500) and 70.6% (353/500), were found to be positive with Eimeria spp. and Cystoisospora suis oocysts, respectively. The sequences of C. suis detected were 100% identical to those of C. suis reported from Japan, and had 99.5% resemblance to sequences from Australia and China. Weaner pigs showed the significantly highest (p < 0.05) OPG when compared to other age groups. The highest intensity of coccidian infection (p < 0.05) was found in pigs fed local feed, pigs raised on earthen floors and pigs under poor hygienic conditions. Factors such as age, breed, feed type, and housing floors were found to be significantly associated with coccidian infection (p < 0.05). Age, as well as management factors including floor type, feed type, and hygiene practices on the farm, had a strong influence on the occurrence of coccidian infection in pigs. This is the first study in Myanmar on coccidian infection in pigs and molecular detection of C. suis.

Piglet coccidiosis in Belgium and the Netherlands: Prevalence, management and potential risk factors

Piglet coccidiosis caused by Cystoisospora suis is one of the most important causes of diarrhea in suckling piglets. The parasite has a fast development and multiplies quickly and effectively under the conditions of a farrowing unit. Control measures include cleaning and disinfection and anticoccidial treatment. In Europe, toltrazuril-based products are authorized for this purpose and are applied to piglets on affected farms in the first week of life. To observe the effect of treatment and disinfection on the control of piglet coccidiosis in the field, 23 farms (11 from Belgium, 12 from the Netherlands, mean number of sows = 1413) were sampled twice by litter in the second and third week of life and fecal scores and the presence of C. suis oocysts were determined. A questionnaire was used to collect data on farm sizes, management and hygiene measures as well as treatment (product, dose and piglet age). Thirteen farms regularly treated with toltrazuril (treatment age: 1-6 days, mean 4.3 days) and 19 applied disinfection. Parasite excretion was documented on 60.9% and diarrhea on 78.3% of farms and in 34.3%/15.7% of the litters. Only 2.4% of the litters showed both, so subclinical infection appeared to be common. No significant differences between farms that did not treat against coccidiosis and farms that applied toltrazuril was observed with regard to C. suis oocysts shedding and/or diarrhea. However, in litters that were treated within the first three days of life, oocyst excretion was significantly less often observed than in litters with later treatment (p = 0.033). No significant effect of disinfection could be shown, but most farms applied disinfectants that have no proven effect against coccidia (oxygen-releasing agents or glutaraldehyde + ammonia) while the only farm that used chlorocresols (which are effective against coccidia) did not show oocyst shedding. Current control measures thus appear to be insufficient on most of the examined farms. It is therefore recommended to treat piglets timely and to apply effective disinfectants to reduce C. suis infections. Furthermore, regular evaluation of sustained efficacy of all implemented measures are necessary.

Reduced treatment frequencies with bumped kinase inhibitor 1369 are effective against porcine cystoisosporosis

Bumped kinase inhibitors (BKIs) are a new class of antiprotozoal drugs that target calcium-dependent protein kinase 1 (CDPK1) in various apicomplexan parasites. A multiple dose regimen of BKI 1369 has been shown to be highly effective against Cystoisospora suis (syn. Isospora suis), the causative agent of neonatal porcine coccidiosis. However, multiple dosing may not be widely applicable in the field. The present study aimed to determine the efficacy of reduced treatment frequencies with BKI 1369 against porcine cystoisosporosis in vitro and in vivo. Pre-incubation of sporozoites with BKI 1369 completely failed to inhibit the infection in vitro unless treatment was prolonged post-infection. Notably, a single treatment of infected cell cultures 2 days post-infection (dpi) resulted in a significant reduction of merozoite replication. In an experimental infection model, treatment of suckling piglets experimentally infected with C. suis 2 and 4 dpi with 20 mg BKI 1369/kg body weight completely suppressed oocyst excretion. A single treatment on the day of infection or 2 dpi suppressed oocyst excretion in 50% and 82% of the piglets and reduced the quantitative excretion in those that shed oocysts by 95.2% and 98.4%, respectively. Moreover, a significant increase in body weight gain and reduced number of diarrhea days were observed in BKI 1369 treated piglets compared to the control piglets, irrespective of time points and frequencies of treatment. Given that reduced treatment frequencies with BKI 1369 are comparable in efficacy to repeated applications without any adverse effects, this could be considered as a practical therapeutic alternative against porcine cystoisosporosis.

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BKI 1369 does not target host cell invasion by C. suis sporozoites but replication of merozoites.

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Single treatment with BKI 1369 in parallel with experimental infection is not effective for the control of cystoisosporosis.

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Two doses of BKI 1369 at 2 and 4 dpi completely suppressed oocyst excretion in piglets experimentally infected with C. suis.

Prevalence and Risk Factors of Intestinal Parasite Infections in Greek Swine Farrow-To-Finish Farms

Intestinal parasites, helminths, and protozoa challenge health and welfare of pigs and deteriorate the sustainability of swine farms leading to monetary losses. A multicentric survey was conducted for approximately one year. Overall, 1150 fecal samples were collected from eight intensive farms in Greece at regular intervals and examined by flotation and Ziehl-Neelsen techniques. Age, season, and time of last recorded antiparasitic treatment were assessed as possible risk factors using binary regression models. The overall prevalence of intestinal parasitism in pigs was 44.7%. The most frequently detected parasites in the studied population were the protozoa Balantidium coli (37.8%), followed by Entamoeba spp. (8.3%), Cystoisospora suis (6.0%), and the nematodes Ascaris suum (3.7%), Trichuris suis (2.5%), and Oesophagostomum spp. (1.4%). Distribution of intestinal parasites in different age groups was as expected. In autumn, the prevalence of Balantidium coli infection enhanced whereas the prevalence of Entamoeba spp. and Cystoisospora suis infections increased in spring. Time of last recorded antiparasitic treatment influenced Balantidium coli and Trichuris suis infection levels. Our results demonstrated that swine intestinal parasitism in intensive farms of Greece seems to be relatively common and highlighted the importance of proper laboratory examinations, as well as the need for tailored made control programs.

Cystoisospora suis Control in Europe Is Not Always Effective

After introduction of the anticoccidial toltrazuril for the metaphylactic treatment of suckling piglet coccidiosis, only few field evaluations on the effect of treatment against the causative agent, Cystoisospora suis, were performed. In 2018, a field study was conducted to detect the presence of the parasite on pig farms in four different European countries, and to evaluate management parameters possibly associated with infection and disease. A total of 49 farms from Austria, the Czech Republic, Germany and Spain were included. Repeated pooled fecal samples from 603 litters were taken in the 2nd and 3rd week of life. Samples were examined by autofluorescence for the presence of C. suis, and fecal consistency was scored. For each farm a questionnaire was provided to document management and treatment history. Feces scored as diarrhoeic were not significantly more often positive for C. suis than non-diarrhoeic feces but samples from litters with previously reported occurrence of diarrhea were significantly more often positive (p = 0.000). Pasty feces were significantly more often positive than those of other consistency (p = 0.005). Overall, 71.4% of the farms and 50.1% of the litters were positive for C. suis at least once. The prevalence on the farms reached up to 100%. Diarrhea was seen in samples from 53.1% of the farms (9.6% of the litters). Cystoisospora suis was diagnosed on 80.8% of the farms with vs. 60.8% of those without diarrhea. Toltrazuril was applied on 30 farms, and of these 53.3% had diarrhoeic samples and 66.7% were positive for C. suis vs. 19 farms that did not use toltrazuril with 52.6% diarrhoeic and 79.0% C. suis positive samples (p > 0.05). Only on two farms a disinfectant with activity against coccidia was used, and C. suis was not detected there. Current control of C. suis appears to be insufficient on the majority of the examined farms. These findings highlight the importance of correct application of medication, and an effective hygiene management. To maintain effective parasite control, efficacy monitoring of the control measures should be implemented.

Determination of ethanamizuril, a novel triazine coccidiostat, in rat plasma by ultra-performance liquid chromatography system-tandem mass spectrometry and its application in a toxicological study

Ethanamizuril is a new triazine compound that has the potential to be a novel anticoccidial drug. Toxicological studies in experimental rats were performed to understand the safety profile of ethanamizuril for drug product development. In this study, a novel, selective and accurate ultra-performance liquid chromatography tandem mass spectrometry method has been developed for the determination of ethanamizuril concentrations in rat plasma. With 4-nitro-o-cresol as an internal standard, sample pretreatment involved a one-step extraction with acetonitrile of 100 μL plasma. The detection was carried out by electrospray ionization mass spectrometry in negative ion mode with selected ion recording. The standard curves were linear (r²  ≥ 0.999) over the concentration range of 0.1-100 μg/mL. The relative standard deviations of intra- and inter-day precisions were less than 8.4 and 8.87%, respectively. The mean extraction recovery of ethanamizuril from rat plasma was 97.68-102.57%. The method was fully validated and successfully applied to monitor plasma concentrations of ethanamizuril in a short-term toxicity study and two-generation reproduction toxicity study. The result of the study confirmed that the elimination of ethanamizuril in rats is slow.

Anticoccidial drugs of the livestock industry

Coccidiosis is a parasitic disease of a wide variety of animals caused by coccidian protozoa. The coccidia are responsible for major economic losses of the livestock industry. For example, the annual cost due to coccidiosis to the global poultry industry has been estimated to exceed US$ 3 billion annually. Currently available drugs for the control of this disease are either polyether ionophorous antibiotics that are derived from fermentation products, or synthetic compounds, produced by chemical synthesis. Unfortunately, no new drugs in either category have been approved for use for decades. Resistance has been documented for all those of the drugs currently employed and therefore the discovery of novel drugs with unique modes of action is imperative if chemotherapy is to remain the principal means to control this disease. This chapter aims to give an overview of the efficacy and mode of action of the current compounds used to control coccidiosis in livestock and provides a brief outlook of research needs for the future.

Efficacy of an injectable toltrazuril - gleptoferron (Forceris®) to control coccidiosis (Cystoisospora suis) in comparison with iron supplemented piglets without anticoccidial treatment

The efficacy and safety of an injectable combination product containing toltrazuril and gleptoferron (Forceris® - CEVA) for the control of coccidiosis due to Cystoisospora suis was investigated in neonatal piglets. The study was carried out on five European commercial pig farms in France, Germany and Spain and 122 litters consisting of 1508 piglets were selected and randomly allocated to one of two treatment groups. The first group received a single intramuscular injection per piglet of the test product, containing 45 mg toltrazuril and 200 mg iron and this was compared with a control group, which was administered a single intramuscular treatment of iron at 200 mg per piglet only. Body weights, faecal scores and oocysts counts, recorded as oocysts per gram of faeces, (OPG) were observed for 21 days. Only 1138 piglets were actually exposed to coccidiosis and data sets of these animals were selected for statistical analysis. The efficacy of the test product in the control of coccidiosis was shown in higher body weight gains, a lower percentage of animals with diarrhoea, fewer samples with positive oocysts counts as well as a lower excretion peak and a reduced area under the curve of OPG from study day (SD) 4 - SD 21. The combination product of toltrazuril and gleptoferron provided an effective alternative approach to current conventional separate treatment for the prevention of iron deficiency anaemia and coccidiosis in neonatal piglets. It reduced the numbers of potentially stressful interventions and work time.

Microsatellite Analysis of Geographically Close Isolates of Cystoisospora suis

Microsatellites are short repetitive DNA sequences of 2–6 repeats interspersed in the genome that display a rapid mutation rate and consequently show high variation between individuals or populations. They have been used to characterize population diversity and structure and the level of variation between different isolates of a number of different organisms, including apicomplexan protozoa. Currently nothing is known about the genetic variability and population structure of Cystoisospora suis (Apicomplexa: Coccidia), the causative agent of piglet coccidiosis, and we made use of the recently available genome of C. suis (strain Wien-I) to amplify microsatellite regions (ca. 300–550 bp) and evaluate the applicability of fluorescence-labeled primers to investigate amplicon length variation at high resolution using capillary electrophoresis (CE). Two phenotypically characterized isolates (Wien-I, toltrazuril susceptible; Holl 1 toltrazuril resistant) and six field isolates from Europe were compared by conventional PCR followed by agar-gel electrophoresis, Sanger sequencing, and CE (fluorescence labeling and fragment length analysis) to evaluate the applicability of the method. Four primer pairs could be identified that amplified bands of the expected size and were labeled for CE analysis. High resolution CE for size determination of PCR amplicons proved to be a reliable and simple method. It revealed high diversity of the analyzed strains, with marked differences even between two strains from neighboring swine farms. In follow-up studies, adaptation of the PCR assay to multiplexing and amplification of small DNA quantities will provide a cost-effective tool to analyse field strains to reveal geographic diversity that could be mapped to phenotypic traits.

Rotavirus and Cystoisospora suis in piglets during the suckling and early post weaning period, in systems with solid floors and age segregated rearing

Background

Piglet diarrhoea is considered a worldwide problem resulting in animal welfare problems and financial losses for pig farmers. Porcine rotavirus and the coccidian parasite Cystoisospora suis (C. suis) are considered two important pathogens associated with diarrhoea in piglets during the suckling and early post weaning periods. To obtain an overview on the prevalence of porcine rotavirus and C. suis in piglet producing herds with solid floors and age segregated rearing, faecal sampling of 791 litters in 81 farms was performed.

Results

For porcine rotavirus, faecal samples were analysed using a sandwich ELISA. The overall prevalence of rotavirus in the examined herds was 11.4 ± 17.7% at 2 weeks, 56.8 ± 30.7% at 4 weeks and 71.1 ± 29.1% at 6 weeks of age and the accumulated prevalence was 49, 97 and 100%. To detect C. suis, faecal samples were analysed using sedimentation. The overall prevalence of C. suis in the examined herds was 11.9 ± 15.1% at 2 weeks of age, 10.7 ± 16.7% at 4 weeks and 8.7 ± 15.3% at 6 weeks of age and the accumulated prevalence was 56, 76 and 85%. The number of empty days between farrowing batches did influence the shedding of rotavirus at 2 weeks of age but not later. Regarding C. suis, no difference in prevalence was correlated to the number of days between consecutive farrowing batches.

Conclusions

Our study confirmed that rotavirus should be regarded as an ubiquitous virus that can be expected to be present in almost every pig herd in Sweden. The study also demonstrated that the number of infected litters increased from birth to 6 weeks of age. Secondly, it showed that C. suis frequently occurred in pig herds and that the number of infected litters was rather stable from two to 6 weeks of age. Consequently, both rotavirus and C. suis may play a role in intestinal disturbances in piglets during the suckling and post weaning periods despite age segregated rearing, at least in systems with solid floors. However, as this study was carried out in herds without reported problems with diarrhoea or poor weight gain, the role of these pathogens should not be overestimated.

Comparison of an injectable toltrazuril-gleptoferron (Forceris®) and an oral toltrazuril (Baycox®) + injectable iron dextran for the control of experimentally induced piglet cystoisosporosis

BACKGROUND

Cystoisospora suis causes diarrhoeal disease and reduced weight gain in suckling piglets, and a toltrazuril-based oral suspension is available for treatment. Recently a combinatorial product with toltrazuril plus iron has been developed for parenteral application. In this study we compared the efficacy of the injectable product with the oral suspension against experimentally induced piglet cystoisosporosis.

METHODS

In a randomised controlled study, three groups of piglets (n = 10-13) were treated either with a fixed dose of 45 mg toltrazuril + 200 mg gleptoferron i.m. per piglet (Forceris®) on the second day of life (study day 2; SD 2) or with 20 mg toltrazuril/kg body weight as an oral suspension (Baycox® 5%) on SD 4 or left untreated (Control group). The Baycox® and the Control group received 200 mg of iron dextran/piglet on SD 2. All piglets were infected with 1000 sporulated C. suis oocysts on SD 3. Faecal samples were taken daily from SD 7 to SD 20 to determine faecal consistency, oocyst shedding and other diarrhoeal pathogens. Body weight was recorded on SD 1 and then weekly until SD 29. Animals were observed daily for general health and after treatment for possible adverse events.

RESULTS

In the Control group all animals shed oocysts for 3.1 days on average and all animals showed diarrhoea for an average of five days. Excretion peaked on SD 9 (max. 48,618 oocysts per gram of faeces). Treatment with Forceris® completely suppressed oocyst excretion. In the Baycox® group, low levels of excretion could be detected. Diarrhoea was reduced to single piglets in the treated groups. Body weight development was reduced in the Control group compared to the treated groups. Enteropathogenic bacteria (Escherichia coli, Clostridium perfringens) could be detected. All parameters related to oocyst excretion, faecal consistency and weight gain were significantly improved in the treated groups compared to the Control group without significant differences between the treated groups. Both products were safe to use.

CONCLUSIONS

Treatment with both the injectable (Forceris®) and the oral (Baycox®) formulation of toltrazuril in the prepatent period were safe and highly effective against experimental infection with C. suis in newborn piglets.

Endoparasites in domestic animals surrounding an Atlantic Forest remnant, in São Paulo State, Brazil

Morro do Diabo State Park (MDSP) is a significant remnant of the Atlantic Rain Forest in Brazil and is surrounded by rural properties. In that area, wild and domestic animals and humans are in close contact, which facilitates the two-way flow of infectious diseases among them. We assessed endoparasites in domestic livestock from all rural properties surrounding MDSP. There were sampled 197 cattle, 37 horses, 11 sheep, 25 swine, 21 dogs, one cat and 62 groups of chickens from 10 large private properties and 75 rural settlements. Eimeria spp. was present in almost all hosts, excepted in horses, dogs and cats. Giardia cysts were present only in cattle. Nematodes were found in swine, ruminants and horses in high prevalence. Ancylostoma, Toxocara and Sarcocystis were found in dogs. Chickens were found with coccidia, Ascaridida and Capillaria spp.. These parasites can cause malnutrition and reproductive disorders for their hosts. Strategies to prevent and control the spread of endoparasites can improve wildlife, animal and human health in this area.

Clinical cystoisosporosis associated to porcine cytomegalovirus (PCMV, Suid herpesvirus 2) infection in fattening pigs

Cystoisospora (syn. Isospora) suis is the causative agent of neonatal porcine coccidiosis and one of the main causes of diarrhoea in suckling piglets worldwide. Infection with porcine cytomegalovirus (PCMV, Suid herpesvirus 2) causes inclusion body rhinitis in pigs. In a Swiss pig herd (n = 2 boars, 7 sows, 2 gilts, 18 finishing pigs, 30 fattening pigs, 54 suckling piglets), an outbreak of PCMV infection with high morbidity in all age categories, characterized by fever, anorexia, reduced general condition, respiratory signs and increased piglet mortality, was diagnosed by histopathology and molecular methods. Five fattening pigs (age ~ 17 weeks) additionally showed diarrhoea, not typical for PCMV infections, and one fattener had to be euthanized due to poor condition. Histopathologically, severe fibrinopurulent jejunoileitis with extensive atrophy and fusion of intestinal villi, loss of goblet cells and crypt abscesses associated to C. suis infection were present. In the liver, herpesvirus intranuclear inclusion bodies were observed and PCMV was confirmed by PCR/sequencing. No further infectious causes of diarrhoea (i.e. Rotavirus A; TGEV; PEDV; PCV-2; enterotoxigenic Escherichia coli or Lawsonia intracellularis) were detected in the euthanized fattener. Coproscopically, C. suis oocysts were identified in the faeces from further fatteners with diarrhoea. While C. suis usually produces disease only in suckling piglets, its association with severe intestinal lesions and diarrhoea in ~ 17-week-old fatteners was surprising. It is supposed that the underlying PCMV infection might have contributed to the presentation of clinical cystoisosporosis in fattening pigs. The interaction mechanisms between these two pathogens are unknown.

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A Porcine Cytomegalovirus (PCMV) outbreak was diagnosed in a Swiss pig herd

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Cystoisospora suis caused diarrhoea in 17 week-old fattening pigs co-infected with PCMV

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PCMV infection may produce immunosuppression in pigs

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PCMV may have contributed to presentation of clinical cystoisosporosis in fattening pigs

Review of triazine antiprotozoal drugs used in veterinary medicine

Triazines are relatively new antiprotozoal drugs that have successfully controlled coccidiosis and equine protozoal myeloencephalitis. These drugs have favorably treated other protozoal diseases such as neosporosis and toxoplasmosis. In this article, we discuss the pharmacological characteristics of five triazines, toltrazuril, ponazuril, clazuril, diclazuril, and nitromezuril which are used in veterinary medicine to control protozoal diseases which include coccidiosis, equine protozoal myeloencephalitis, neosporosis, and toxoplasmosis.

Experimentally confirmed toltrazuril resistance in a field isolate of Cystoisospora suis

Background

Constant treatment regimens with toltrazuril against Cystoisospora suis infection in piglets are being applied in the intensive production systems for the last two decades, but the possibility of resistance development has not been addressed so far despite limited availability of treatment alternatives. Recently, a pig producer in The Netherlands who routinely used toltrazuril complained about diarrhea in suckling piglets in the absence of bacterial and viral pathogens, and oocysts of C. suis could be isolated from feces of affected litters.

Methods

Piglets from two litters were infected with a field isolate of C. suis, Holland-I, and treated with 0 (Holl-Ctrl), 20 (Holl-20) or 30 (Holl-30) mg/kg of body weight (BW) of toltrazuril (Baycox®). The efficacy of toltrazuril was measured by assessment of oocyst excretion, fecal consistency and BW gain. A separate litter was infected with a toltrazuril-susceptible strain of C. suis, Wien-I, and treated with 0 (Wien-Ctrl) or 20 (Wien-20) mg/kg BW of toltrazuril for comparison.

Results

Treatment with the recommended (20 mg/kg) dose of toltrazuril completely suppressed oocyst shedding and diarrhea in group Wien-20. The prevalence of oocyst excretion was 100% in the groups infected with Holland-I and 80% in the group Wien-Ctrl. Most days with diarrhea were observed in group Holl-20 with an average of 6.40%, followed by 5.71% in Wien-Ctrl, while in Holl-Ctrl and Holl-30 diarrhea was only seen in 1.79% of the samples (n = 14/piglet). Oocyst excretion, fecal consistency and BW gain did not differ significantly among groups infected with Holland-I, indicating loss of efficacy to toltrazuril.

Conclusion

Experimental infections and treatment confirmed toltrazuril resistance against the field isolate even at increased dosage. Such isolates are a potential threat to pig production as no other effective and economically sustainable alternative treatment is currently available. In the absence of a standardized protocol for resistance testing in C. suis, regular parasitological examination and, if possible, experimental confirmation should be considered to evaluate the extent and consequences of toltrazuril resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2257-7) contains supplementary material, which is available to authorized users.

Cloning, expression and molecular characterization of a Cystoisospora suis specific uncharacterized merozoite protein

Background

The genome of the apicomplexan parasite Cystoisospora suis (syn. Isospora suis) has recently been sequenced and annotated, opening the possibility for the identification of novel therapeutic targets against cystoisosporosis. It was previously proposed that a 42 kDa uncharacterized merozoite protein, encoded by gene CSUI_005805, might be a relevant vaccine candidate due to its high immunogenic score, high expression level and species-specificity as determined in silico.

Methods

The 1170 bp coding sequence of the CSUI_005805 gene was PCR amplified and cloned into the bacterial expression vector pQE-31. The specificity of the expressed recombinant protein was evaluated in an immunoblot, and relative levels of expression in different developmental stages and subcellular localization were determined by quantitative real-time PCR and indirect immunofluorescence assay, respectively.

Results

The CSUI_005805 gene encoded for a 389 amino acid protein containing a histidine-rich region. Quantitative RT-PCR showed that CSUI_005805 was differentially expressed during the early development of C. suis in vitro, with higher transcript levels in merozoites compared to sporozoites. The recombinant protein was specifically recognized by sera from chicken immunized with recombinant CSUI_005805 protein and sera from piglets experimentally infected with C. suis, all of which suggested that despite prokaryotic expression, the recombinant CSUI_005805 protein maintained antigenic determinants and could elicit an immune response in the host. Immunofluorescence labelling and confocal microscopy revealed localization primarily at the surface of the parasite.

Conclusions

The results suggest that CSUI_005805 is highly expressed in merozoites and might thus be critical for their survival and establishment inside host cells. Owing to its specificity, localization and expression pattern, CSUI_005805 could be exploited as an attractive candidate for alternative control strategies against C. suis such as vaccines.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2003-1) contains supplementary material, which is available to authorized users.

Vaccination against parasites - status quo and the way forward

Although vaccination against various pathogens is integral to health management of swine, vaccines against parasites have not yet been commercialized for the use in pigs. The incentive to develop and commercialize anti-parasitic vaccines in swine are twofold; on the one hand parasitic diseases which are economically important, such as ascarosis and neonatal coccidiosis, could be controlled in a sustainable manner; on the other hand, the transmission of zoonotic parasites, such as Toxoplasma gondii or Cysticercus cellulosae, could be effectively interrupted. Although experimental research indicates that vaccination against a number of porcine parasites is feasible, development and commercialization of potential vaccines so far has been very slow, as our knowledge on the host-parasite interplay in porcine parasitic infections is still very limited. In the light of growing concerns regarding consumer health and antiparasitic drug resistance, however, it is timely to re-direct R&D efforts to the development of biological control options.

Cystoisospora suis - A Model of Mammalian Cystoisosporosis

Cystoisospora suis is a coccidian species that typically affects suckling piglets. Infections occur by oral uptake of oocysts and are characterized by non-hemorrhagic transient diarrhea, resulting in poor weight gain. Apparently, primary immune responses to C. suis cannot readily be mounted by neonates, which contributes to the establishment and rapid development of the parasite, while in older pigs age-resistance prevents disease development. However, the presence of extraintestinal stages, although not unequivocally demonstrated, is suspected to enable parasite persistence together with the induction and maintenance of immune response in older pigs, which in turn may facilitate the transfer of C. suis-specific factors from sow to offspring. It is assumed that neonates are particularly prone to clinical disease because infections with C. suis interfere with the establishment of the gut microbiome. Clostridia have been especially inferred to profit from the altered intestinal environment during parasite infection. New tools, particularly in the area of genomics, might illustrate the interactions between C. suis and its host and pave the way for the development of new control methods not only for porcine cystoisosporosis but also for other mammalian Cystoisospora infections. The first reference genome for C. suis is under way and will be a fertile ground to discover new drugs and vaccines. At the same time, the establishment and refinement of an in vivo model and an in vitro culture system, supporting the complete life cycle of C. suis, will underpin the functional characterization of the parasite and shed light on its biology and control.

Safety evaluation of a triazine compound nitromezuril by assessing bacterial reverse mutation, sperm abnormalities, micronucleus and chromosomal aberration

Nitromezuril (NZL) is a novel triazine compound that exhibits remarkable anticoccidial activity. However, mutagenicity and genotoxicity of NZL have not been evaluated to date. This study evaluated the potential risks of NZL by testing for bacterial reverse mutation (Ames), mouse sperm abnormality (SA), bone marrow micronucleus (MN) and chromosomal aberration (CA). Mice were orally administered with NZL at 385, 192 and 96 mg/kg, corresponding to 0.5 ×, 0.25 × and 0.125 × the LD50 of NZL, respectively. No significant increases in SA and CA were found in mice treated with NZL for 5d and 3d, respectively (P>0.05). NZL at 96-385 mg/kg did not have significant influence on micronucleated polychromatic erythrocyte counts (P>0.05). These results suggest that NZL is not genotoxic. However, Ames test results were positive both with and without the S9 system for Salmonella typhimurium TA98 and TA100, suggesting that NZL may be mutagenic. The mutagenic effects of NZL were different in in vitro and in vivo assays. Further studies should be conducted to confirm the safety of using and developing NZL as a novel anticoccidial drug.

Superinfection of sows with Cystoisospora suis ante partum leads to a milder course of cystoisosporosis in suckling piglets

Cystoisospora (syn. Isospora) suis is a leading cause of diarrheal disease in neonatal piglets. To address the possibility of maternal immunization against C. suis infection six non-naïve pregnant sows were superinfected with 100,000 oocysts 2 weeks ante partum and compared to non-superinfected animals. Their piglets were infected with 1000 oocysts on the third day of life. Clinical and parasitological parameters as well as antibody titers in colostrum/milk and blood of sows and in the blood of piglets were evaluated by IFAT against sporozoites and merozoites from 2 weeks ante partum until the 35th day after birth. For IFAT two different invasive stages of C. suis were used to find possible differences between the immune response against the initially infectious stages (sporozoites) and later occurring asexual developmental stages (merozoites), which might be responsible for persisting/extraintestinal infections. IFN-γ production of PBMC and piglet splenocytes was determined by ELISPOT. Maternal superinfection resulted in increased titers of IgA, IgM and IgG in colostrum and milk as well as in the blood of sows and their piglets. Oocyst shedding and diarrhea were observed in the offspring of both groups, but piglets of superinfected sows showed significantly reduced oocyst shedding and less diarrhea. This protective effect was correlated with increased titers of antibodies, especially IgA, in colostrum, milk and blood serum of sows and piglets, and with the reactivity of splenocytes to parasite antigen. Superinfection of sows ante partum could partially protect piglets against the clinical outcome of experimental infection. Both colostrum and milk contain maternal protective substances as the effect of protection was highly correlated with antibody titers during the first 2 weeks of life. IgA in different substrates may serve as a marker for the level of protection against clinical cystoisosporosis.

Transfer of Cystoisospora suis-specific colostral antibodies and their correlation with the course of neonatal porcine cystoisosporosis

Cystoisospora suis is the most pathogenic species of coccidia in suckling piglets, affecting them predominantly within their first three weeks of life. The clinical signs of neonatal cystoisosporosis include watery diarrhea and wasting, leading to significant economic losses for the farmer. Since neonatal piglets have an immature immune system, colostral transfer of maternal factors such as immune cells or antibodies is essential for controlling infections at that age. However, the role of C. suis-specific antibodies transferred from the sow to the piglets and possible correlations between antibody levels in the piglets acquired from colostrum with the clinical outcome of disease are currently not understood. To address this issue, 12 non-infected piglets and 14 piglets experimentally infected with C. suis on the third day of life were examined during their first four weeks of life. IgG, IgA, and IgM titers in the blood serum specific for sporozoites and merozoites of C. suis were evaluated, along with oocyst excretion and fecal consistency. Additionally, the antibody content in the colostrum and milk of three mother sows was determined. A transfer of naturally acquired C. suis-specific antibodies from sows to piglets with the colostrum could be demonstrated. Maternal antibodies in piglets' blood sera did not persist for longer than 14-21 days except for IgG which was present in high titers until the end of the study. Within 2-3 weeks after birth the onset of endogenous antibody production was noticed. Titers in blood serum showed a correlation with the severity of diarrhea which was positive for IgG and IgM (possibly due to increased consumption or loss of these antibodies) and negative for IgA. C. suis-specific mucus antibodies isolated from infected and non-infected piglets (n=6/group) on the 28th day of life were present in both groups, showing significantly higher titers of IgA and IgM in infected piglets. Maternally transferred antibodies acquired by natural infections of sows as observed in this study did not provide protection against the clinical manifestation of disease. The level and effect of transferrable maternal factors necessary for protection still need to be elucidated. However, correlations between antibody titers and fecal consistency in the piglets indicate that C. suis-specific antibodies might be useful markers for the expectable clinical severity of cystoisosporosis.

In-vivo efficacy of toltrazuril on experimentally induced Toxoplasma gondii tissue cysts in lambs: a novel strategy for prevention of human exposure to meat-borne toxoplasmosis

The aim of the present study was to investigate in vivo efficacy of toltrazuril on Toxoplasma gondii tissue cysts following induction of chronic toxoplasmosis in 4-week-old lambs (n=27) by inoculation of 1×10(5) T. gondii ME 49 strain oocysts (day 0). Beginning at the 15th day after inoculation, lambs in Group T20 and Group T40 were given toltrazuril orally 2 times, once every week (Baycox 5%, Bayer Animal Health) at a dose of 20 mg/kg and 40 mg/kg, respectively. Positive control (PC) lambs were not given any therapy, and 2 clinically healthy non-infected lambs were used as negative controls (Group NC). Two out of 9 lambs in PC group (oocyst inoculated but non-treated) were killed on toltrazuril treatment days (day 15 and 22) to evaluate the tissue cyst presence in their muscles. On day 90, the remaining 25 lambs were necropsied, and samples from the brain and 11 different muscle groups were collected. The tissues were examined for the presence of tissue cysts by histopathology, immunohistochemistry, nested-PCR and percoll gradient centrifugation. Anti-T. gondii antibodies were screened by IFAT throughout the experiment. The increased T. gondii seropositivity beginning from the 15th day of inoculation remained steady at Day 45 and Day 90 in Groups PC while it was significantly lower at Day 90 in toltrazuril receiving groups. In toltrazuril treated groups, histopathological findings included degenerative changes in the cyst wall, complete macrophage invasion to the cysts, and reduction or removal of the cysts in toto. Four out of 9 lambs (44.4%) in both toltrazuril treated group (Group T20 and T40) did not contain tissue cyst in any examined tissues while all positive control animals had T. gondii tissue cysts at least in one muscle group. The toltrazuril treatment efficacy on the cyst presence was determined as 44.4%. The number of the cysts in the musculature was significantly different between non-treated and toltrazuril treated lambs (X(2)=6.613; p=0.037). For the total number of cysts, the positive control lambs had higher number of cysts compared to both toltrazuril treated lambs (T20 and T40) (X(2)=5.629; p=0.018 and X(2)=5.629; p=0.018, respectively) while there were no differences between Group T20 and Group T40 (X(2)=0.000; p=1.000). According to PCR results, the brain and M. semitendinosus were positive in all 7 control lambs while 12 out of 18 lambs were positive in toltrazuril treated lambs. In conclusion, the results are promising as the toltrazuril treated lambs had markedly less parasite counts compared to those of untreated lambs. Further research should be conducted to reveal if toltrazuril treatment in sheep could be used as a strategy to minimize the cyst exposure of humans through consumption of raw or undercooked mutton.