The use of toltrazuril for the prevention of coccidiosis in piglets before weaning

SUMMARY: To determine the efficacy of toltrazuril as a prophylactic treatment for coccidiosis in piglets caused by Isospora suis (I suis) , a single 1.0 mL dose of toltrazuril was administered orally to 1056 piglets between 3 and 6 days of age, in 5 piggeries. Prophylactic treatment of piglets reduced the occurrence of coccidiosis in litters from 71% to 22%. The number of antibacterial treatments given and the number of piglets affected per litter were also significantly reduced, resulting in some improvement in growth rates to weaning. The severity of diarrhoea was significantly reduced, as was the amount of oocyst excretion. The number of days that piglets excreted oocysts in the faeces was reduced from 4.9 days to 2.5 days. The detection of J suis in piglets with diarrhoea was reduced from 84% in the untreated piglets to 6% in the piglets given the prophylactic treatment.     

Amprolium and furazolidone as preventive treatment for intestinal coccidiosis of piglets

Two coccidiostats, amprolium and furazolidone, were used as preventive treatments for intestinal coccidiosis in three-day-old piglets experimentally infected with 50,000 sporulated oocysts of Isospora suis.

All infected piglets, treated or not, displayed clinical signs compatible with coccidiosis. Diarrhea and anorexia appeared around five days postinoculation in the non-treated and in the amprolium-treated groups; these signs were delayed to days 7 and 8 postinoculation in the furazolidone-treated group. The treatments did not prevent growth retardation. Amprolium seemed to reduce oocyst shedding whereas furazolidone had no effect. Villous atrophy was present in all infected piglets.

     

Occurrence of Isospora suis in Germany, Switzerland and Austria

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

Coccidiosis in swine

It is clear that although the clinical history, pathologic lesions, and endogenous stage life cycle of I. suis are well understood, the epidemiology of this parasite is not understood or is misunderstood. Consequently, treatment of individual piglets and prophylactic use of coccidiostats in sows have not been consistently rewarding. The best control at present is achieved through use of extensive sanitation, particularly steam cleaning. The incidence of clinical coccidiosis in piglets continues to be a major component (approximately 20 per cent) in the differential etiology of scours in baby pigs.     

仔猪等孢球虫与等孢球虫病研究进展

仔猪等孢球虫病是由猪等孢球虫寄生在哺乳期及新近断奶仔猪小肠上皮细胞所引起的一种寄生性原虫病，呈世界性分布，给养猪场造成严重的经济损失。本文对猪等孢球虫病的病原分类、虫体形态和生活史、致病性、流行病学特点、临床症状、病理变化、诊断、防治等方面的目前研究状况进行了综述，为猪等孢球虫病的有效防制提供参考。     

Role of acquired immunity and natural age resistance on course of Isospora suis coccidiosis in nursing piglets.

Thirty-two piglets from three litters were experimentally inoculated with 200000 sporulated oocysts of Isospora suis at 3 days of age and/or rechallenged at 19 days of age or primary inoculated at 19 days of age, to compare the role of acquired immunity and natural age resistance on the course of coccidiosis. Twelve piglets were not inoculated and served as a control. Following challenge, the signs of coccidiosis characterised by clinical symptoms, oocysts shedding and weekly weights were similar to those which occurred in piglets primary inoculated at 19 days of age. This comparison suggests that maturation of non-specific components of the immune system plays a more important role in the resistance of neonatal piglets to I. suis infection than specific immune mechanisms.     

Experimental transmission of intestinal coccidiosis to piglets: clinical, parasitological and pathological findings.

Twenty-eight piglets coming from a "specific pathogen free" herd were inoculated at three days of age with 50 000 or 100 000 sporulated oocysts of Isospora suis. Fecal samples were examined for oocyst shedding daily and several clinical parameters were recorded. Ten piglets were used as normal controls. Groups of piglets were euthanized from three days to 12 days postinoculation and routine necropsies were performed. Bacteriological, virological, parasitological and histopathological examinations were made on the intestinal tracts. The incubation period was four to five days. Clinical signs and microscopic intestinal lesions observed in the experimentally infected animals were similar to those reported in spontaneous cases of porcine neonatal coccidiosis. Lesions of villous atrophy in the small intestine seemed to result from the destruction of villous epithelial cells mainly during the peak of asexual reproduction which occurred around four to five days postinoculation. Intracellular coccidial organisms were difficult to find during the late atrophic and villous regrowth stages of the intestinal lesions. The prepatent period varied from four to seven days and the most common was five days. Eighty percent of the piglets kept alive more than four days postinoculation have shed oocysts. Piglets dosed with old sporulated oocysts (ten months old) shed many more oocysts than those infected with a fresh inoculum (less than two months old). The patent period was not determined precisely with the design of the experiment but some of the infected piglets shed oocysts for at least five days.     

Field study of coccidial and rotaviral diarrhoea in unweaned piglets

A study of diarrhoea in unweaned piglets was carried out in nine herds, with special reference to the enteropathogenic agents which could be demonstrated. Coccidial (Isospora suis) and rotaviral infections were both identified, either singly or in combination. More extensive studies of I suis infection were undertaken in two of the herds and it was found that diarrhoea occurred most commonly in five- to 14-day-old piglets. Piglets with I suis infection were not necessarily diarrhoeic but grew poorly compared to uninfected piglets. I suis infection in litters correlated with oocyst excretion in sows. In herds with I suis infection, amprolium and monensin were used in the sow ration to achieve control, and in one herd oral dosing of piglets with amprolium in the first three or four days of life was carried out.     

猪等孢球虫检测及防控研究进展

猪等孢球虫是一种危害仔猪生长的专性寄生性原虫,感染该寄生虫的仔猪生长缓慢,且常表现出腹泻症状,甚至死亡,对养猪业造成极大危害。本文综合了国内外研究成果,从流行病学特征、形态特征、生活史、检测方法及防控措施等方面对仔猪等孢球虫进行了综述,并对猪等孢球虫的防控手段、内生发育史、基因组学等生物学特性以及与肠道菌群的相互作用等问题进行了展望,以期为猪等孢球虫的病原鉴定及有效防控提供科学依据。     

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

Porcine coccidiosis caused by Isospora suis is one of the leading causes of neonatal diarrhea in suckling piglets. Currently the only registered drug for metaphylaxis is toltrazuril. To evaluate the effect of treatment on piglets from 7 Austrian farms without and 8 Austrian farms with toltrazuril application we examined oocyst excretion (including determination of oocysts per gram of feces; OPG), diarrhea (fecal score FS 1-4 with 3 and 4 being diarrhea), and general health (health score HS 1-4 with 3 and 4 describing poor health). Both groups included farms with different levels of hygiene. Samples from 265 litters without treatment, comprising 1588 individual samples, and 1548 samples from 258 treated litters were taken twice (around the 14th and the 21st day of life, respectively), examined by autofluorescence and, if positive, by McMaster counting. In both groups animals had less diarrhea and lower health scores during the second sampling but the treated piglets were always significantly healthier and had less diarrhea. The percentage of weaned piglets was higher in treated animals although this was not significant (p=0.052). In the first round of sampling 17.8% of the individual samples from untreated piglets were positive for oocysts (with a maximum prevalence on the 12-15th day of life) while in the treated piglets only 0.4% shed oocysts p<0.001). At the second sampling only 2.1% of the untreated animals and none of treated piglets excreted I. suis (p=0.083). Positive animals shed up to 8 × 10(3)OPG. There was an increased risk for infected piglets to develop diarrhea (odds ratio, OR 4.73) and poor health (OR 5.05) in untreated piglets, and poor hygiene without disinfection was identified as a risk factor for poor health (OR 1.90), diarrhea (OR 1.42) and oocyst excretion (OR 1.73). The risk of poor health (OR 2.89) and diarrhea (OR 1.44) was also increased for piglets under poor hygienic conditions receiving toltrazuril, so both metaphylaxis of coccidiosis and good hygiene are necessary to effectively control neonatal diarrhea. The costs of treatment are considerably lower than the estimated financial production losses. Therefore, treatment is recommended for farms where clinical coccidiosis is diagnosed.     

中草药与抗菌药对产毒性大肠杆菌抑菌作用和对仔猪黄、白痢疗效的比较

采用纸片扩散法和试管两倍稀释法观察了一种中草药注射液和三种抗菌药物对产毒性大肠杆菌的抑菌作用并比较了它们对仔猪黄、白痢的疗效。大肠杆菌对抗菌药物呈中度或高度敏感,中草药注射液几乎没有抑菌作用。但中草药注射液对仔猪黄、白痢的疗效却极显著地优于抗菌药物（Ｐ＜０．００５）。实验结果表明,该中草药注射液对仔猪黄、白痢的疗效并不依赖其抑菌作用。     

Chemoprophylaxis of coccidiosis in lambs with a single oral dose of toltrazuril

The prophylactic efficacy of a single oral dose of toltrazuril against coccidiosis (mixed Eimeria infections) in naturally infected lambs was evaluated in two experiments. Toltrazuril at 20 mg kg-1, given on Day 7 or Day 10 after turnout on pasture, proved to be highly efficacious in preventing clinical coccidiosis under Norwegian conditions. Toltrazuril reduced the oocyst output to very low levels, prevented the development of diarrhoea and improved weight gain during the first 4-5 weeks after treatment. Treatment on Day 7 was superior to treatment on Day 10 with respect to improving weight gain and preventing the development of soft faeces. Lambs treated with toltrazuril on Day 7 seemed to be as immune as untreated lambs to natural reinfections with coccidia later in the grazing season. In one of the experiments, natural infections with the nematode Nematodirus battus produced a coccidiosis-like disease in some lambs simultaneously with the outbreak of coccidiosis.     

Studies on coccidiosis in goats in Poland

The study was carried out in a flock consisting of 110 goats. Nine species of coccidia were found: Eimeria christenseni, E. arloingi, E. jolchijev, E. ninakohlyakimovae, E. alijevi, E. apsheronica, E. caprina, E. caprovina and E. hirci. Eighty-one percent of adults and 100% of kids were infected. Number of oocysts per gram of feces in kids ranged form 1200 to 202000. Clinical symptoms in about 50% of kids were observed. Toltrazuril (Baycox, Bayer), 20 mg/kg of body weight was highly efficacious in therapy of goat coccidiosis.     

Porcine neonatal coccidiosis: evaluation of monensin as preventive therapy

In this study, we evaluated the efficacy of monensin as a preventive therapy for porcine neonatal coccidiosis. Fifteen three-day-old piglets were given 50,000 sporulated oocysts of Isospora suis and eight of them received 15 mg/kg of monensin orally every other day. Seven piglets served as normal controls. Fecal samples were collected and checked for oocyst shedding. At 18 days of age, piglets were euthanized and necropsied.

The onset of clinical signs was delayed in the treated group, but all inoculated piglets displayed anorexia, soft stool, or diarrheic feces. Treated piglets shed large numbers of oocysts in their feces (up to 201,200 oocysts per gram of feces). All infected piglets had lesions of villous atrophy in the jejunum and most of them were in the late atrophic or villous regrowth stages.

The results of this study suggest that monensin does not prevent clinical signs, oocyst shedding, and intestinal lesions caused by I. suis in neonatal piglets.

     

Control of Isospora suis-induced coccidiosis on a swine farm

Results of a program designed to control neonatal porcine coccidiosis on a total confinement, farrow-to-finish swine farm are reported. The control program consisted of washing, phenol disinfection, and steam cleaning of farrowing houses and treatment of sows with amprolium HCl before and after farrowing. Before initiation of the control program, 88.9% of the sows examined in the farrowing house were negative for coccidian oocysts, 9.9% were positive for Eimeria spp, and 1.2% were positive for Isospora suis. Most pigs nursing on sows before initiation of the control program had diarrhea at 5 to 10 days of age, which led to dehydration and weight loss. Morbidity was high, and mortality was moderate. Composite fecal samples from these litters were all positive (100%) for I suis. After initiation of the control program, 99.6% of the sows examined in the farrowing house were negative for coccidian oocysts and 0.4% were positive for Eimeria spp. Clinical signs of coccidiosis were rarely present in nursing pigs examined after the control program was initiated; however, I suis was still present in 19.8% of the composite fecal samples from pigs examined. An association between oocyst production in sows and I suis infections in pigs was not found in the present study. Oocysts of Eimeria spp were not found in the feces from the pigs.     

Experimental Isospora suis infections in miniature swine

Clinical responses to experimental Isospora suis infections were compared in Sinclair miniature pigs and cross-bred conventional pigs. Pre-patent periods, fecal consistencies, oocyst excretion dynamics, trends in surviving pig weights and lesions were similar in infected miniature and conventional pigs. The results indicate that the susceptibility of miniature pigs to I. suis is similar to that of conventional pigs. These findings should encourage their use as models for the study of neonatal coccidiosis.     

Epidemiology of porcine neonatal steatorrhoea in Sweden. 1. Prevalence and clinical significance of coccidal and rotaviral infections

A study of neonatal steatorrhoea in unweaned piglets was carried out in randomly visited herds. Isospora suis and rotavirus were shown to be incriminated in this type of enteric disease and these agents may be considered important enteropathogens for 1-3-week-old piglets in Sweden. More extensive studies of I. suis were undertaken in one large herd. It was found that steatorrhoea may appear in 4-day-old piglets but oocysts were not detected until some days latter. Piglets that were shedding I. suis were not necessarily steatorrhoeic but oocysts were more frequently found in steatorrhoeic faeces than in faeces of normal consistency. The earliest oocyst output was detected at 5 days of age, the average litterage at first appearance being 12.8 +/- 4.0 days. The occurrence of I. suis oocysts in piglets did not correlate with the oocyst output in sows, which almost exclusively included genus Eimeria. Repeated parasitological and virological examination of steatorrhoeic faecal samples from 5-10 litters per herd at an age of 1-3 weeks would be helpful for making a herd diagnosis.     

Endoparasites in swine in different age groups and management systems

In different age groups endoparasites are of varying importance. Sows are predominantly infected with gastrointestinal strongyles (mainly Oesophagostomum spp.), Ascaris suum and Eimeriae, to a lesset extent with Trichuris suis, Hyostrongylus rubidus, Strongyloides ransomi or Isospora suis, while in suckling piglets I. suis and occasionally S. ransomi frequently occur. Weaners and fatteners are infected with coccidia and gastrointestinal strongyles, later with A. suum. Whipworms are also found occasionally. I suis causes diarrhoea in suckling piglets, while in older animals the infection is not correlated with disease. Damage induced by helminths is mainly due to reduced performance, in the case of ascarosis to reduced carcass value. Therefore planned antiparasitic measures should be taken at all stages of pig keeping. Hygienic measures can reduce infection pressure; however parasite elimination is difficult to obtain under conventional management conditions. Consequently the control of parasitic infection at the early stage of piglet production is desirable.     

Porcine coccidia in Papua New Guinea

Faecal samples from 232 domestic pigs raised on concrete, 98 free-ranging village pigs, and five wild boar showed 46.6 (108/232), 54 (53/98) and 80% (4/5) prevalence of coccidian oocysts, respectively. Eight species of Eimeria, and Isospora suis, were recovered. In their descending order of predominance in the pigs raised on concrete, the species of coccidia were E. debliecki (26.7%), E. scabra (22.4%), E. neodebliecki (19.8%), E. porci (15.5%), E. suis (11.6%), E. polita (8.6%), E. perminuta (7%), E. spinosa (5.6%) and I. suis (3.9%). The first five species listed above predominated in the village pigs as well. E. polita, E. spinosa and I. suis were not found in the wild boar. I. suis oocysts prevailed in 8.3% of the 36 sows on concrete, and in 11.1% (3/27) of those which were positive for coccidia. Isosporoid oocysts were absent in the village sows. Of the 125 less than 24-day-old piglets, 29.6% were diarrhoeic, and of these, 43.2% were positive for coccidia. Four of the 16 (25%) coccidia-positive, diarrhoeic piglets, and four of the 37 (10.8%) coccidia-positive non-diarrhoeic piglets shed I. suis oocysts, an observation which seems to weaken the present contention that I. suis is the primary causative agent of neonatal porcine coccidiosis. The highest mean number of oocysts per gram faeces (23,550) was recorded from the diarrhoeic farm piglets on concrete, and the lowest of 6,100 from the gestating farm sows. Mean opg data revealed very little significant quantitative variation between the corresponding age groups of the free-ranging village pigs and the commercially-farmed ones. One of the most interesting findings in the study was that the sows were more frequently infected than all other age groups.     

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

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