Ovine coccidiosis: heavy infection in young lambs increases resistance without causing disease

Seven groups of twin lambs, kept with their dams on pasture, were given single oral inoculations of 10,000 oocysts of Eimeria ovinoidalis and 10,000 E crandallis at one, two, four, seven, 14, 21 or 28 days after birth, respectively. All were then challenged with 100,000 of each species at 42 days of age. An eighth group was challenged without having received the earlier 'immunising' inoculum, and a ninth group was not inoculated at all. Bodyweights, faecal consistency, oocyst output, and serum coccidial antibody levels were monitored up to 12 weeks of age. No clinical response was detected to inoculation up to four days of age. Loosening of faeces and a slight setback in weight-gain occurred in lambs inoculated seven, 14 and 21 days after birth; inoculation 28 days after birth caused severe diarrhoea and weight loss. Challenge at 42 days caused severe coccidiosis with 50 per cent mortality in the 'unimmunised' group. In those that had received 'immunising' inoculations, the challenge at 42 days caused some diarrhoea and some weight loss, but much less than in the 'unimmunised' lambs. The later the 'immunisation', the less severe was the disease attributable to the challenge at 42 days. Serum antibody levels correlated fairly closely with resistance to the disease. It was concluded that very young lambs were resistant to the pathogenic effects of some coccidia, but were able to respond to them immunologically.     

Effects of leucocyte extract, levamisole and sulphadimidine on natural coccidial infections (Eimeria spp.) in young lambs

The efficacy of leucocyte extract (LE) and sulphadimidine in preventing coccidiosis in naturally infected lambs on pasture was evaluated in 3 separate experiments, whereas the prophylactic effect of levamisole was studied in 1 of the experiments. LE prepared from ewes immune to coccidia (Eimeria spp.) was administered either intravenously or intraperitoneally to young lambs 7, 5, or 2 days before they were turned out on pastures contaminated with coccidia. In all experiments, LE failed to transfer protective immunity to the lambs against the first coccidial infection on pasture. The LE preparations used apparently had an immunosuppressive effect, which resulted in more severe clinical signs of coccidiosis in the recipients. The lambs given LE showed a higher incidence of diarrhoea, a poorer weight gain, a higher mortality, and a higher oocyst output than the untreated control lambs. In lambs treated with sulphadimidine at 200 mg/kg on days 12, 13, and 14 after turnout there was a reduced severity of the coccidial infections in all experiments. The sulphadimidine-treated lambs had better weight gains and passed fewer oocysts than the controls during the third and fourth week after turnout, but some of them developed diarrhoea. Lambs treated with levamisole at 2 mg/kg 2 days before turnout, at turnout, and 2 days after turnout were more severely affected by the first coccidial infection on pasture than the controls.To study the lambs’ immunity against a heavy challenge infection with coccidia as compared with their immunity against the natural reinfection on pasture, some of the lambs from the original groups (untreated, sulphadimidine-treated, LE-treated) were each inoculated with 2 mill. Eimeria spp. oocysts about 6 weeks after turnout. The oocyst counts of the challenged lambs, except the LE-treated lambs, increased to a new peak 19–20 days after challenge. The challenge infection caused a softening of the faeces and a marked depression in weight gain in all challenged groups of lambs, mainly between days 10 and 17 after challenge. The lambs were thus only partially immune to coccidia after the first coccidial infection on pasture. The lambs treated with either LE or sulphadimidine in connection with the first coccidial infection on pasture were not appreciably more susceptible to the challenge infection than the untreated lambs.     

Interaction between coccidia and Nematodirus battus in lambs on pasture

Five thousand oocysts of each of two species of coccidia, Eimeria crandallis and E ovinoidalis or 30,000 infective larvae of Nematodirus battus, given as single infections to three- to five-week-old lambs, caused only transient diarrhoea and had no effect on growth. Lambs infected first with coccidia and two weeks later with N battus suffered severe diarrhoea, weight loss and some deaths. Simultaneous administration of the coccidia and the nematodes increased the clinical severity of the syndrome and increased the numbers of nematode eggs produced.     

Demonstration of antibodies to Eimeria species in lambs by an enzyme-linked immunosorbent assay

Soluble extracts were prepared from sporulated oocysts, unsporulated oocysts and merozoites of Eimeria crandallis, E faurei and E ovinoidalis. They were assessed for antigenicity and specificity by ELISA using rabbit antisera to sporulated oocysts or merozoites. Antibody levels were examined in sera from colostrum-deprived coccidia-free lambs, conventionally reared lambs and lambs which had received experimental infections. Maternal antibody was demonstrated in colostrum and in serum taken at 24 hours from all conventionally reared animals but not colostrum-deprived animals. Antibody levels in conventional animals dropped over the first five weeks of life and rose again during the next five weeks. Antibody was not detected in coccidia-free animals. Monospecific infections of E faurei or E ovinoidalis demonstrated antibody responses to primary and secondary infections. Some specificity of response was suggested with E faurei infection. The antigen preparations showed considerable cross-reactions between species. These serum antibody responses, although appearing too late for individual diagnosis, may assist diagnosis on a flock basis.     

Efficacy of toltrazuril in the prevention of coccidiosis in naturally infected lambs on pasture

The efficacy of toltrazuril (Bay Vi 9142) in preventing ovine coccidiosis due to an infection acquired immediately after turnout on pasture was evaluated by comparing the faecal consistency, weight gain, and oocyst output of treated and untreated lambs in 3 trials. The lambs were either given a single treatment with toltrazuril at 15 or 20 mg/kg, or they were given a dose of 10 mg/kg on 2 separate days. A single treatment with toltrazuril at 20 mg/kg on day 10 after turnout on pasture almost completely prevented coccidiosis in 2 trials. In a third trial the acute phase of a severe Nematodirus battus infection coincided with the outbreak of coccidiosis, and thus partly masked the clinical effect of the anticoccidial treatment. In lambs treated with toltrazuril at 15 mg/kg on day 10 after turnout, the coccidial infection caused a softening of the faeces, but the lambs were not severely affected by the coccidia. In lambs given a dose of 10 mg/kg of toltrazuril twice, either on days 10 and 11 after turnout, or on days 10 and 20, the coccidial infection caused a softening af the faeces, including some cases of diarrhoea. Oocyst production due to the initial coccidial infection on pasture was markedly reduced by all treatments with toltrazuril. The reduction was most pronounced after a dose of 20 mg/kg. Lambs treated with single doses of 15 or 20 mg/kg of toltrazuril had a better weight gain than the untreated controls in 2 of the trials. Lambs treated with toltrazuril on day 10 after turnout were partially resistant to the coccidial reinfection acquired immediately after treatment, and they had a similar level of immunity as the untreated controls to the subsequent reinfection on pasture.     

Economic benefits of prophylaxis with diclazuril against subclinical coccidiosis in lambs reared indoors.

One hundred and twenty weaned male lambs, naturally infected with Eimeria species, were used to assess the economic benefits of the prophylactic administration of diclazuril. They were randomly divided into four groups of 30 lambs on the basis of their bodyweight and output of oocysts. The groups were either left untreated (group 1), treated orally with a simple dose of diclazuril at 1 mg/kg (group 2), with two doses two weeks apart (group 3), or with sulphadimethoxine at 50 mg/kg for five consecutive days (group 4). No clinical signs of coccidiosis were observed in any of the groups. The output of oocysts was significantly reduced on day 7 after treatment in group 2, on days 7, 14 and 28 in group 3 and on days 7 and 14 in group 4. No significant differences were found between the treated and untreated groups for bodyweight, carcase weight and carcase classification. The mean fattening period was shorter for the treated lambs (52 and 55 days) than for the untreated controls (60 days). The average growth rate of the lambs treated twice with diclazuril and with sulphadimethoxine was improved and the feed conversion rates of the lambs treated once or twice with diclazuril were 7 per cent and 16 per cent better than that of the untreated lambs.     

Coccidial infections in housed lambs: oocyst excretion, antibody levels and genetic influences on the infection

Faecal Eimeria oocyst excretion, body weights, humoral antibodies against E. ovinoidalis sporozoite antigen and related heritabilities were determined in housed Merinoland sheep lambs throughout a period of 100 days after birth in Germany. Altogether 10-11 Eimeria spp. were found. Cumulative incidences of E. ovinoidalis and E. weybridgensis/crandallis increased rapidly resulting in almost 100% incidence in 8 weeks old lambs. In the other species, the cumulative incidence increased more continuously. Except for E. granulosa oocysts of all species had been excreted at last once until day 30. By far the highest oocyst counts (OpG) were observed with E. ovinoidalis, followed by E. weybridgensis/crandallis. High counts were limited to the period of 5-8 weeks after birth. In the other Eimeria species oocyst counts persisted at comparatively low levels until the end of the observation period although their proportion of the total counts increased with age of the lambs. Time courses of oocyst excretion suggest an early onset of effective immunity to the major Eimeria spp., which differed for the minor species. Mean and maximum oocyst counts and body weights of the lambs were inversely correlated suggesting negative effects of the infection on the lamb's performance. High mean antibody levels on day 7 after birth dropped until day 40 and increased subsequently again. There were no indications that maternal antibodies were protective. Antibody levels on day 40 after birth were positively correlated with oocyst counts in the faeces whereas those determined on day 80 were independent of infection parameters. Heritabilities of log(10)OpG were not significantly different from 0 up to an age of 60 days. Later estimated values were between 0.54 and 0.79 suggesting that immune protective effects rather than innate effects determining disease susceptibility are under genetic influence.     

Species of coccidia occurring in lambs in S?o Paulo State, Brazil.

The purpose of this experiment was to characterize the species of Eimeria affecting lambs and their infection pattern. Faecal samples were collected from each animal at 14-day intervals, beginning when lambs were 2 weeks old and ending when they were 32 weeks old. The oocysts were counted and identified as E. intricata, E. parva, E. pallida, E. crandallis, E. bakuensis, E. weybridgensis, E. ahsata and E. ovinoidalis. The highest oocyst counts were observed when the lambs were 4-8 weeks old.     

Naturally acquired coccidia infection in lambs in Otago

The development of a naturally acquired coccidia infection in lambs in Otago is described using data derived from faecal oocyst counts and specific differentiation of the oocysts. Oocysts first appeared in faeces of lambs 19–37 days after birth. Oocyst production reached a mean peak of 250 000 oocysts per gram when lambs were 40–50 days old and slowly declined with increasing age of lambs. Coccidial infections did not appear to have any obvious effect on weight gain. The numerically most numerous species of coccidia were Eimeria ovina, E. crandallis, E. ninakohlyakimovae, E. parva and E. weybridgensis.     

Survey of Eimeria spp. oocysts in feces from Louisiana State University ewes.

The prevalence and identification of Eimeria spp. in the Louisiana State University ewe flock were determined from 109 fecal samples. Unsporulated oocysts were recovered from 94 of the samples and 1208 oocysts representing ten species of Eimeria were identified: E. ahsata, E. crandallis, E. Faurei, E. granulosa, E. intricata, E. ovina, E. ovinoidalis, E. pallida, E. parava and E. punctata. Eimeria ovinoidalis, which is probably the most pathogenic, was the species common to the most number of samples (59.6%); however, E. granulosa, which is non-pathogenic, was the most numerous species (23.7% of the total identified). The prevalence and identification of oocysts from ewes may be useful to evaluate infection potential when considering control programs, especially for lambs.     

绵羊球虫感染情况和种类调查

应用饱和蔗糖溶液漂浮法对河南、山东和东北等地的1052只绵羊球虫感染情况及种类进行了调查,结果表明球虫总感染率为94.8%,对968份阳性样本中的球虫卵囊进行形态学鉴定,共检出12种艾美耳球虫,分别为阿撒他艾美耳球虫、巴库艾美耳球虫、小型艾美耳球虫、贡氏艾美耳球虫、类绵羊艾美耳球虫、颗粒艾美耳球虫、苍白艾美耳球虫、马耳西卡艾美耳球虫、温布里吉艾美耳球虫、错乱艾美耳球虫、槌形艾美耳球虫和浮氏艾美耳球虫。调查结果发现绵羊最多可同时感染9种球虫,多数为2~5种,混合感染率为71.8%;1岁以下和1岁以上绵羊球虫感染率分别为99.4%和86.0%,平均OPG值分别为7907.36和3263.89;舍饲和放牧绵羊球虫感染率分别为97.0%和89.0%;夏、秋季为球虫主要流行季节。     

Ovine coccidiosis: effect of the antibiotic monensin against Eimeria ninakohlyakimovae and other naturally occurring coccidia of sheep

Sixteen female and 16 male lambs were used in 4 groups to determine the effect of monensin on naturally occurring and experimentally induced coccidiosis. Determinations of numbers of oocysts discharged, quantities of feces discharged, feed consumption, and weight gain were made for female and male lambs in each group. The effect of experimentally induced and naturally occurring coccidiosis on the performance of each group was compared. Nonmedicated lambs, experimentally inoculated with Eimeria ninakohlyakimovae, gained the least weight. Lambs naturally infected with coccidia gained next best and inoculated lambs, in 2 groups medicated with 10 or 20 ppm of monensin in the feed, gained best. The average net gain for the 4 groups was 7.8, 9.7, 13.7, and 13.7 kg. The medicated lambs required less feed/kilogram of weight gain than did the nonmedicated lambs. In general, female lambs were more severely affected by the coccidia, consumed more feed, produced more fecal material, and gained less weight than did male lambs.     

Ovine coccidia in Papua New Guinea

Eimeria oocysts were found in 89% of fecal samples collected from the rectum of 75 sheep from 3 locations in Papua New Guinea. Eighty five percent of the hosts which were positive for coccidia had multiple infections with up to 6 different species of Eimeria. In order of decreasing predominance in the 67 Eimeria-positive samples the species were: E. ovina (72%); E. parva (58%); E. ovinoidalis (48%); E. ahsata (45%); E. crandallis (39%); E. faurei (28%); E. intricata (24%); E. granulosa (4%). Fecal oocyst counts showed the highest mean of 1252 oocysts per gram (o.p.g.) for E. parva and a maximum of 8000 for E. ovina.     

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.     

Control of coccidia in young calves using lasalocid

SUMMARY Thirty-six, 2- to 4-day-old Friesian bull calves were divided into 4 groups and fed milk replacer and calf starter pellets ad libitum in separate pens. Four treatments were applied; lasalocid in milk (1 mg/kg body weight/day) (M), lasalocid in starter (F), lasalocid in both milk and starter (M+F) and untreated (C). When the calves were about 2 weeks old they were each dosed orally with 550 000 sporulated Eimeria sp oocysts, mainly E zurneii and E bovis. The infection, detected by faecal excretion of oocysts, was suppressed in the M+F and M groups. There was significant excretion of oocysts in the F group but these calves did not show any clinical signs of coccidiosis. Untreated calves were affected with diarrhoea containing blood on the 24th day after inoculation. Body weight gain and intake of starter pellets was also depressed in the untreated calves during the time they were clinically affected. It is concluded that mixing lasalocid in milk replacer (or fresh milk) is an effective method of protecting young calves against early infection with coccidia.     

Differentiation of Eimeria species infecting sheep during the grazing season on permanent and new pastures under Norwegian conditions

The total and differential oocyst counts of the different Eimeria species in the faeces of Norwegian ewes and lambs were investigated at weekly intervals during the grazing period on permanent and new pastures. The total oocyst counts of lambs on permanent pastures were significantly higher than those on new pastures 3–6 weeks after the beginning of the grazing period. This demonstrates that the oocysts had survived the winter in the pasture.Species differentiation indicated that E. ahsata, E. arlongi, E. crandallis, E. ninakohlyakimovae, E. faurei and E. parva are able to survive the winter in the pasture. E. crandallis occurred in the greatest numbers, and this species might be an important contributor to the clinical symptoms which are frequently observed in Norwegian lambs about 2–3 weeks after the beginning of the grazing period. There were on the other hand, indications that E. pallida has little ability to survive the winter in the pasture. The results were generally similar for most of the species during 2 successive years.The total number of oocysts in the faeces of ewes was low on new as well as on permanent pastures, and the species differentiation showed negligible differences. Consequently, it was concluded that the ewes could not be the source of the high oocyst numbers in lambs on the permanent pastures.     

Ovine coccidiosis: studies on the pathogenicity of Eimeria ovinoidalis and E. crandallis in conventionally-reared lambs, including possible effects of passive immunity

No pathogenic effect was detected in lambs when 10(4) oocyts of each species were inoculated before 72 h of age. At 4 weeks of age the combined inoculum caused diarrhoea and weight loss, the severity being roughly proportional to the size of the inoculum. Even 1000 oocysts of each species caused diarrhoea; the pathogenic effect was attributable mainly to E. ovinoidalis. Hyperimmunization of ewes during pregnancy (by repeated inoculation of massive doses of oocysts) reduced the effects of oocyst inoculation in their progeny. Levamisole administration during pregnancy increased the birthweight of lambs.     

Winter resistant oocysts in the pasture as a source of coccidial infection in lambs

Lambs born in pens with slatted floor were brought out at 2–5 weeks of age on pastures heavily grazed by sheep the previous years. About 16 days later the oocyst output of the lambs rapidly increased to high levels. Lambs on pastures which never had been grazed by sheep earlier, had moderate oocyst counts.Between 11 and 25 days after the beginning of grazing there were significantly more lambs with diarrhoea on permanent pastures compared with pastures never grazed by sheep earlier.It was found that lambs were heavily infected during the first 2 days on permanent pastures.Thirteen housed lambs were given 10–50 g of soil from a permanent pasture as a water suspension by a stomach tube. Fifteen days later there was a steep rise in the oocyst output in most of them, and 11 of the 13 lambs developed diarrhoea and 2 died. None of 10 lambs given uninfected soil and none of 12 untreated controls showed diarrhoea and the oocyst output remained on a moderate level.It is concluded that oocysts which have survived the winter in the pasture are the main source of infection with Eimeria spp. in lambs with this kind of management. Soil-eating is the most likely source of infection during the first days on pasture.     

Diversity and seasonal occurrence of Eimeria species in a mixed flock of communally reared sheep and goats in Mafikeng in the North West Province, South Africa

Diversity and seasonal occurrence of coccidia in a communally reared mixed flock of sheep and goats at Mafikeng, North West Province, South Africa, was determined between March 2008 and February 2009. Faecal specimens were collected directly from the rectum of the animals and the number of oocysts per gram of faeces (opg) determined. The mean monthly opg for goats was significantly higher than that for sheep. Higher oocyst counts were observed during the hot, rainy season than during the cold, dry season. The highest mean values for both the sheep (862.5 opg) and goats (1200 opg) were recorded during March. Six species (Eimeria crandallis, E. bakuensis, E. weybridgensis, E. ahsata, E. intricata, and E. ovinoidalis) were recovered from sheep, with E. crandallis and E. bakuensis occurring most frequently. The last 2 species, together with E. ahsata, are considered among the most pathogenic species in sheep. In goats, 7 species (E. arloingi, E. jolchijevi, E. caprina, E. alijevi, E. caprovina, E. christenseni and E. hirci) were recovered, with E. arloingi and E. jolchijevi occurring most frequently. Up to 5 Eimeria species were recovered from individual specimens in goats while up to 4 were recovered in sheep. No cross-infections between goats and sheep were recorded and no clinical coccidiosis was noted during the study. It is increasingly becoming evident that the pathogenic E. arloingi is one of the most commonly occurring Eimeria species in goats in South Africa.     

The coccidia of sheep and goats in Senegal

A survey of the coccidia in domestic sheep and goats was undertaken to ascertain the type of Eimeria species and the number of different coccidial species in individual faecal samples. Simultaneously the prevalence and the oocyst output was investigated in 2234 sheep and 577 goats during a 12-month period. Eight Eimeria species were encountered in sheep: E. ahsata, E. crandallis, E. faurei, E. intricata, E. ovina, E. ovinoidalis, E. pallida and E. parva.

In goats the following species were found: E. ahsata, E. arloingi, E. christenseni, E. crandallis, E. faurei, E. intricata, E. ninakohlyakimovae and E. parva.

The prevalence in sheep was 94% and in goats 85%, multiple parasitism was the rule. No seasonal fluctuation was observed in the prevalence or oocyst output. The sheep and goats' oocyst output was moderate, the mean for both being in the range of 1000–5000 oocysts/g of faeces.