Cystoisospora suis Control in Europe Is Not Always Effective

Simultaneous Use of Iron/Anticoccidial Treatment and Vaccination against Oedema Disease: Impact on the Development of Serum-Neutralising Antibodies, Hematinic and Anticoccidial Activities in Piglets

Oedema disease (OD) in weaned piglets is caused by shigatoxigenic Escherichia coli (STEC), which produces the Stx2e toxin. The disease is controlled by early vaccination (for example, with Ecoporc Shiga®). Iron-deficiency anaemia (IDA) and cystoisosporosis are the most common clinical conditions in piglets. These conditions are managed mainly by the intramuscular injection of iron and application of toltrazuril (for example, Forceris®). In the present study, we sought to evaluate any effect on the efficacy of OD vaccination and iron/anticoccidial treatment resulting from a simultaneous application. An evaluation was carried out by measuring the development of neutralising antibodies against the Stx2e toxin, hematinic indices and oocysts shedding. Six litters from Stx2e-antibody-negative sows were included in the study, with 12 piglets in each litter. The piglets were randomly allocated into two groups on their second day of life (DOL): (T1) iron/anticoccidial treatment and vaccine were administered on different days, and (T2) products were administered simultaneously. Blood samples were collected to determine the levels of serum-neutralising antibodies, haemoglobin and haematocrit. Faecal matter was examined for the presence of oocysts of Cystoisospora suis. No differences were found between the two groups in terms of the development of neutralising antibodies. The levels of haemoglobin and haematocrit were lower (p < 0.05 and p = 0.08, respectively) when iron/anticoccidial treatment and vaccine were applied simultaneously but within the optimal range, based on current interpretive criteria for IDA. Oocysts were not detected in the faecal samples from the animals in either group. In conclusion, we found that, under the conditions of our study, the efficacy of OD vaccination and iron/anticoccidial treatment was not affected by the simultaneous use.

Epidemiology and distribution of gastrointestinal parasites in fattening pig farms in northern Italy

In Italy, pig breeding is characterised by intensive farms in which parasitic diseases often present a subclinical pattern, while being responsible for decreased animal welfare and great economic losses. The present study aimed to assess the prevalence of major parasites in pigs, and, for this purpose, 880 faecal samples of fattening pigs raised in 22 intensive farms located in northern Italy were collected in two different sampling sessions, at the beginning and end of the fattening cycle. For the detection of helminth eggs and coccidian oocysts, a quantitative flotation technique was used, whereas a conventional PCR was performed to confirm the identification of cestode eggs found by copromicroscopic analysis. Moreover, data regarding herd management were collected to assess risk factors for parasite occurrence. A total of 95 samples were positive for at least one parasitic taxon (10.8%); the most detected parasite was Ascaris suum (7.6%), followed by Trichuris suis (1.7%) and Cystoisospora suis (0.9%). Further, eggs with morphometric features compatible with those of Hymenolepis diminuta were detected in 16 samples (1.8%), and the analysis of sequences confirmed the identification of cestode eggs. Statistical analysis showed that large farms and those applying the all-in/all-out system were associated with a lower risk of nematode infection. This study provided data on prevalence and burden of gastrointestinal parasites in two different times of the fattening cycle. It was evidenced that endoparasites are persistent, albeit with low prevalences, and would need specific measures to reduce their effects on both animal health and productivity.

Combined Injection for Control of Iron-Deficiency Anemia and Coccidiosis in Piglets Decreases Stress at Management Time

The aim of the present study was to assess the short-term behavioral and physiological responses of piglets to different treatment protocols for the control of iron-deficiency anemia (IDA) and cystoisosporosis. Piglets were treated with either (1) an injection of iron combined with an oral application of toltrazuril (TLZ) by drenching or (2) a combination injection of TZL + gleptoferron; the behavior of the piglets was then evaluated. For this study, 288 piglets were divided into three experimental groups: 96 piglets were kept untreated (control group); 96 piglets received an oral administration of a generic TZL-based anticoccidial agent (20 mg/kg BW) along with intramuscular administration of iron dextran (200 mg/mL; 1 mL/piglet) at the same handling (oral + parenteral group, O + P); and 96 piglets received an intramuscular application of the combination product (parenteral group, P). For each treated piglet, the total handling time, flight reaction, and the intensity and frequency of vocalizations were determined using the methodology described by Scollo et al. (2020). Piglets in the O + P group were found to emit more screams during treatment administration than animals in the P group (21.05% vs. 8.42% of animals; p < 0.05). Piglets in the O + P group reacted worse to manipulation and oral administration because a higher percentage of animals continued to fidget even after handling (32.63% vs. 12.63%; p < 0.05). Differences in growth performance between the groups were not observed in our study (p > 0.05). In conclusion, the administration of a combination product reduced stress during administration, as indicated by reduced vocalizations and reactions to manipulation.

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.

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.

Pharmacokinetics of toltrazuril and its metabolite, toltrazuril sulfone, in suckling piglets following oral and intramuscular administrations

Toltrazuril (TZR) is currently the only registered chemotherapeutic drug in the European Union for the treatment of Cystoisospora suis. This study investigated the comparative pharmacokinetics and tissue concentration-time profiles of TZR and its active metabolite, toltrazuril sulfone (TZR-SO2 ), after oral (per os, p.o.) and intramuscular (i.m.) administration to suckling piglets. Following a single administration of TZR orally at 50 mg/piglet or intramuscularly at 45 mg/piglet, higher concentrations of TZR and TZR-SO2 were observed in all three investigated tissues after p.o. administration. The mean TZR concentration in serum peaked at 14 μg/mL (34.03 h) and 5.36 μg/mL (120 h), while TZR-SO2 peaked at 14.12 μg/mL (246 h) and 9.92 μg/mL (330 h) after p.o. and i.m. administration, respectively. TZR was undetectable in the liver after p.o. administration (18 days) and in the jejunum (24 days) after i.m. injection, while TZR-SO2 was still detectable in all three tissues after 36 days regardless of administration routes. This study showed that p.o. formulation exhibited faster absorption and higher serum/tissue TZR/TZR-SO2 concentrations than i.m. formulation. Both formulations generated sufficient therapeutic concentrations in the serum and jejunum, and sustained enough time to protect against Cystoisospora suis infection in the piglets.

Cystoisospora suis in Portugal: an observational study of prevalence, management, and risk factors

BACKGROUND

Neonatal coccidiosis is a common and important disease of suckling piglets in modern farming caused by Cystoisospora suis. Prevalence rates are high, namely, in Portugal, although no recent data are available. The metaphylactic administration of a single dose of toltrazuril and hygienic measures are the backbone of control strategies on positive farms. However, several studies have shown that these programs are not always effective, underlining the need to revise the risk factors and control strategies currently applied. The present study evaluated C. suis prevalence on Portuguese farms and assessed the risk factors associated with facilities and farm rearing practices.

RESULTS

From the 27 tested farms, 23 were positive to Cystoisopora suis (85.2%). In total, 258 litters were sampled (accounting for 516 samples-2 samples per litter), with an average of 59.7% of positive litters per positive farm. Faecal pools from litters, in which liquid faeces predominated had a higher probability of containing oocysts than litter pools with mainly solid (Odds Ratio: 9.87; p < 0.0001) or pasty faeces (OR: 7.05; p = 0.001), and samples obtained from younger animals had higher oocyst counts (coefficient: - 0.0720; 95% CI - 0.125; - 0.019). No significant effect of toltrazuril administration was observed on the positivity rate, and none of the tested farms used disinfectants with official claims against parasites and known anticoccidial effects (e.g., cresol-based products).

CONCLUSIONS

The C. suis prevalence on Portuguese swine farms appears to be similar to the prevalence found in other European countries. Repeated sampling of the same litter and the use of autofluorescence microscopy after a modified Ritchie technique seems to have increased sensitivity and consequently the detection rate of positive litters. Finally, despite the common use of oral toltrazuril, C. suis control programs appear to not always be effective (based on the detection of oocysts in faecal samples), suggesting the need to revise the control strategies applied in the field, including management factors and choices of disinfectant products.

Inhibition of sexual stage-specific proteins results in reduced numbers of sexual stages and oocysts of Cystoisospora suis (Apicomplexa: Coccidia) in vitro

Parasites of the order Coccidia (phylum: Alveolata, subphylum: Apicomplexa) have sophisticated life cycles that include a switch from asexual to sexual development, characterised by distinct cell types. During the development of gametes (gamogony), substantial changes occur at the cellular and subcellular levels, leading to cell fusion of micro- and microgametes, and the development of a zygote that forms a protective outer layer for environmental survival as an oocyst, the transmissible stage. Studies on the porcine coccidian Cystoisospora suis already identified changes in transcription profiles during different time points in the parasite's development and identified proteins with potential roles in the sexual development of this parasite. Here, we focus on three proteins that are possibly involved in the sexual development of C. suis. Enkurin and hapless protein 2 (HAP2) play important roles in signal transduction and gamete fusion during the fertilisation process, and oocyst wall forming protein 1 (OWP1) is a homologue of oocyst wall forming proteins of related parasites. We evaluated their locations in the different life cycle stages of C. suis and their inhibition by specific antibodies in vitro. Immunolocalization detected enkurin in merozoites and sporulated oocysts, HAP2 in merozoites and microgamonts, and OWP2 in merozoites, macrogamonts, oocysts and sporozoites. Up to 100% inhibition of the development of sexual stages and oocyst formation with purified chicken immunoglobulin IgY sera against recombinant enkurin, HAP2, and especially OWP1, were demonstrated. We conclude that the three investigated sexual stage-specific proteins constitute targets for in vivo intervention strategies to interrupt parasite development and transmission to susceptible hosts.

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.

Absorption and Distribution of Toltrazuril and Toltrazuril Sulfone in Plasma, Intestinal Tissues and Content of Piglets after Oral or Intramuscular Administration

Piglet coccidiosis due to Cystoisospora suis is a major cause of diarrhea and poor growth worldwide. It can effectively be controlled by application of toltrazuril (TZ), and oral formulations have been licensed for many years. Recently, the first parenteral formulation containing TZ in combination with iron (gleptoferron) was registered in the EU for the prevention of coccidiosis and iron deficiency anemia, conditions in suckling piglets requiring routine preventive measures. This study evaluated the absorption and distribution of TZ and its main metabolite, toltrazuril sulfone (TZ-SO₂), in blood and intestinal tissues after single oral (20 mg/kg) or single intramuscular (45 mg/piglet) application of TZ. Fifty-six piglets were randomly allocated to the two treatment groups. Animals were sacrificed 1-, 5-, 13-, and 24-days post-treatment and TZ and TZ-SO₂ levels were determined in blood, jejunal tissue, ileal tissue, and mixed jejunal and ileal content (IC) by high performance liquid chromatography (HPLC). Intramuscular application resulted in significantly higher and more sustained concentrations of both compounds in plasma, intestinal tissue, and IC. Higher concentrations after oral dosing were only observed one day after application of TZ in jejunum and IC. Toltrazuril was quickly metabolized to TZ-SO₂ with maximum concentrations on day 13 for both applications. Remarkably, TZ and TZ-SO₂ accumulated in the jejunum, the primary predilection site of C. suis, independently of the administration route, which is key to their antiparasitic effect.

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.

Management practices related to the control of gastrointestinal parasites on Swedish pig farms

Background

Internal parasites are common in pigs worldwide and may induce clinical disease or subclinical infections with negative effects such as poor weight gain and reduced welfare, which in turn affect productivity. Effective parasite control to reduce the negative impact of parasitic infections demands a combination of antiparasitic drugs as well as various hygiene and biosecurity practices. The aim of this study was to obtain information on current management practices and parasite control routines used on Swedish pig farms using an online questionnaire.

Results

Antiparasitic drugs were used on 69% of the farms routinely and were mainly administered to sows just prior to farrowing. Less than 5% of the herds conducted faecal analysis for parasites. Batchwise, age segregated rearing was common and overall, it was practiced for piglets, growers, and fatteners on 88, 80 and 75% of the farms, respectively. Large and medium sized farms appeared to apply stricter hygiene and biosecurity measures to the growing pigs compared to small farms. Dry sows were mainly housed in groups on deep litter straw beds and cleaning, as well as disinfection, between each group was less common compared to what was practiced for growing pigs. Outdoor access was rare and only occurred on organic and small farms. Most of the farms, 54, 74 and 82% of small, medium, and large sized herds respectively, reported to have less than 5% white spot lesions, caused by migrating A. suum larvae, registered at slaughter.

Conclusion

Several risk factors for parasite infections, such as bedding material, group housing and solid floors, are mandatory requirements by national law. However, it was evident from this study that although strategic hygiene and biosecurity practices appeared common, they were not practiced in all herds and less so for dry sows. Antiparasitic drugs were used frequently and mainly through routine prophylactic treatments without prior testing for parasites. A holistic approach is necessary when designing efficient parasite control programs, and it is essential that management factors and routine monitoring of parasites are given attention. This to achieve efficient parasite control and reduce the risk of unnecessary use of antiparasitic drugs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-021-00193-3.

Cystoisospora suis merozoite development assay for screening of drug efficacy in vitro

Cystoisospora suis is a common diarrheal pathogen of piglets and typically controlled by metaphylactic toltrazuril application. Recently, toltrazuril resistance has been reported in the field; however, both evaluation of toltrazuril efficacy against field isolates and the anticoccidial drug development for pigs is hampered by costs and labor of animal experimentation. Therefore an in vitro merozoite development assay was developed to evaluate the efficacy of compounds against C. suis in vitro. Monolayers of IPEC-1 cells were infected with sporozoites derived from oocysts of defined C. suis laboratory strains and the optimal infection dose as well as concentration, time point and duration of treatment were evaluated by quantitative real-time PCR. Cell cultures were treated with bumped kinase inhibitor (BKI) 1369 at different time points to evaluate the possibility to delineate effects on different developmental stages in vitro during invasion and early infection, and to determine different inhibitory concentrations (IC₅₀, IC₉₅). BKI 1369 had an IC₅₀ of 35 nM and an IC₉₅ of 350 nM. Dose- and duration-dependent efficacy was seen when developing stages were treated with BKI 1369 after infection (days 0-1, 2-3 and 2-5) but not when sporozoites were pre-incubated with BKI 1369 before infection. Efficacies of further BKIs were also evaluated at 200 nM. BKI 1318, 1708, 1748 and 1862 had an efficacy comparable to that of BKI 1369 (which is also effective in vivo). BKI 1862 showed a more pronounced loss of efficacy in lower concentrations than BKI 1369, signifying pharmacokinetic differences of similar compounds detectable in vitro. In addition, the effects of toltrazuril and its metabolites, toltrazuril sulfoxide and toltrazuril sulfone, on a toltrazuril sensitive and a resistant strain of C. suis were evaluated. Inhibition of merozoite growth in vitro by toltrazuril and its metabolites was dose-dependent only for toltrazuril. Clear differences were noted for the effect on a toltrazuril-sensitive vs. a resistant strain, indicating that this in vitro assay has the capacity to delineate susceptible from resistant strains in vitro. It could also be used to evaluate and compare the efficacy of novel compounds against C. suis and support the determination of the optimal time point of treatment in vivo.

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.