Development of a capture ELISA for the detection of antibodies to enteropathogenic Escherichia coli (EPEC) in rabbit flocks using intimin-specific monoclonal antibodies

A capture enzyme-linked immunosorbent assay (cELISA) was developed using intimin-specific monoclonal antibodies to detect specific antibody in rabbits that have been in contact with enteropathogenic Escherichia coli (EPEC). Sera from 121 EPEC-negative, minimum-disease-level (MDL) rabbits were used for negative controls, and sera from 25 MDL rabbits, experimentally infected with EPEC of bio-/serotype 3-/O15, for positive controls. These were used to determine a cut-off value for a positive cELISA result. The value selected gave the test a sensitivity of 80.0% and a specificity of 98.4% on an individual level. At this value, a flock level sensitivity and specificity of 79.2 and 85.2%, respectively were calculated for a flock with a prevalence of seven per cent, if 40 animals were tested, and a minimum of two reactors were obtained. The test characteristics improve with increasing prevalence. To evaluate the diagnostic potential of the cELISA, sera from 40 to 50 slaughter rabbits per flock from 25 rabbit flocks with bacteriologically determined EPEC status were tested. The results demonstrated that this test can be a useful tool to determine the EPEC status of a rabbitry, provided that it is used at regular intervals.

Disinfection of wooden structures contaminated with Paenibacillus larvae subsp. larvae spores

AIMS

The aim of the study is to examine the disinfection of wood contaminated with Paenibacillus larvae subsp. larvae spores, in order to find a practical decontamination method for hive materials.

METHODS AND RESULTS

The number of viable spores recovered after the treatment, on the surface by swabbing, and in the deeper parts of the wood by scraping, was used to test the efficiency of the disinfection. Our results indicate that chemical disinfection is only complete when high concentrations (> 50%) of the disinfectant are used. Heat treatment in general was found to be very effective. The scorching of wood was not satisfactory as it only killed spores at the surface.

CONCLUSION

Complete disinfection is only possible with some heat treatments or by using high concentrations of chemical disinfectants.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study puts forward some methods that can provide complete decontamination, which is necessary for an effective control of American foulbrood disease.

A review of the importance of cryptosporidiosis in farm animals

Cryptosporidium species are coccidian parasites with a large capacity to reproduce and to disseminate. Several species are known to infect farm animals, although the economic importance of cryptosporidiosis is highly host species dependent. This paper reviews the impact of cryptosporidial infections in livestock and poultry. For different farm animals, the Cryptosporidium spp. that occur, as well as their clinical and pathological features, and their interactions with other pathogens, are described. In addition, data concerning the prevalence, the transmission and the epidemiology of the disease are mentioned and a description of the economic losses associated with cryptosporidiosis in each of the hosts is given. Cryptosporidiosis seems to be mainly a problem in neonatal ruminants. Cryptosporidium parvum is considered to be an important agent in the aetiology of the neonatal diarrhoea syndrome of calves, lambs and goat kids, causing considerable direct and indirect economic losses. Avian cryptosporidiosis is an emerging health problem in poultry, associated with respiratory disease in chickens and other Galliformes, and with intestinal disease in turkeys and quails. Because of limited availability of effective drugs, the control of cryptosporidiosis relies mainly on hygienic measures and good management.

A Cryptosporidium parvum oocyst low molecular mass fraction evokes a CD4+ T-cell-dependent IFN-gamma response in bovine peripheral blood mononuclear cell cultures

T-Cell antigens that induce the in-vitro interferon-gamma response during Cryptosporidium parvum infection of neonatal calves were identified. A total oocyst extract was separated into a high and a low Mr fraction by a microfiltration technique. Both the high and low Mr fractions evoked an in-vitro interferon-gamma response in naturally infected animals, although strong individual differences between the hosts were observed. Using a complement-mediated technique CD4+ T-cells or WC1+gammadelta T-cells were depleted, whereupon the remaining lymphocyte cultures were stimulated with the different antigen preparations. It was shown that the in-vitro interferon-gamma response of Cryptosporidium-infected calves is CD4+ T-cell-dependent.

Specific interferon-gamma, IgA and IgM responses after experimental infection of neonatal calves with Cryptosporidium parvum

The in vitro interferon-gamma production by peripheral blood mononuclear cells and the local antibody build up was monitored in neonatal calves experimentally infected with Cryptosporidium parvum and in negative controls of the same age. From day 6 p.i. on, an infection-induced interferon-gamma response was observed in lymphocyte cultures after stimulation with Cryptosporidium oocyst antigen preparation. Only the Cryptosporidium-infected calves developed local IgA and IgM responses from day 6 p.i. on, with peak values at day 10 p.i. These antibodies disappeared quickly, perhaps due to the strict hygienic measures and consequently the absence of a continuous antigenic stimulation.

Complete development of Cryptosporidium parvum in MDBK cells

Sporozoites of Cryptosporidium parvum excysted in vitro from bovine oocysts were incubated with monolayers of Madin-Darby bovine kidney cells. The extent of parasite colonisation was monitored by light microscopy and immunofluorescence. Electron microscopy confirmed the complete development and replication of C. parvum within Madin-Darby bovine kidney cells.

Sensitivity of avian Eimeria spp. to seven chemical and five ionophore anticoccidials in five Belgian integrated broiler operations

Coccidia were isolated from 122 Belgian broiler farms without clinical coccidiosis. Shuttle programs including robenidin or nicarbazine in the starter (7-14 days) followed by an ionophore or diclazuril in the grower ration were most commonly used. Out of 215 coccidiosis-positive groups, 146 Eimeria acervulina, 65 E. maxima, and 88 E. tenella isolates were tested without further laboratory propagation in 17 sensitivity profiles. For each profile, oocytes were pooled from 9 +/- 4 farms (mean +/- SD) that used the same anticoccidial program and that belonged to the same integrated broiler operation. Each suspension contained an equal number of isolates and oocyst numbers from each farm tested. Each profile included an unmedicated uninfected group, an unmedicated infected group, and 11 medicated infected groups, consisting each of three replicates of three Ross chicks. Medication started at 8 days of age, and each inoculated bird received 50,000 sporulated oocysts at 10 days. Results were related to the anticoccidial program that had been in use. Chemical drugs showed the highest activity against Eimeria, whereas ionophores were less efficacious. Of the latter, monensin (110 ppm) was least active; narasin (70 ppm), salinomycin (60 ppm), and maduramicin (5 ppm) took an intermediate position, and lasalocid (90 ppm) was most active. A 50% improvement in weight gain was obtained in 7 to 10 out of 17 profiles with 100 + 8.35 ppm clopidol/methylbenzoquate (10), 125 ppm nicarbazin (9), 3 ppm halofuginone (8), and 1 ppm diclazuril (7). A 50% improvement in feed conversion was obtained in 7 to 11 profiles with nicarbazin (11), halofuginone (10), diclazuril (9), 33 ppm robenidine (9), clopidol/methylbenzoquate (7), and lasalocid (7). Based on relative oocyst output, the highest activity against E. acervulina was obtained with clopidol/methylbenzoquate (8/16); the highest activity against E. maxima was obtained with lasalocid (6/6), diclazuril (5/6), and halofuginone (5/6); and the highest activity against E. tenella was obtained with diclazuril (8/8), amprolium/ethopabate (5/8), halofuginone (4/8), maduramicin (4/8), and nicarbazin (4/8).

Specific serum and local antibody responses against Cryptosporidium parvum during medication of calves with halofuginone lactate

Fecal and serum anti-Cryptosporidium parvum immunoglobulin A (IgA), IgM, and IgG were monitored by an enzyme immunoassay in C. parvum-infected calves after medication with halofuginone lactate. In a first experiment, four groups of five 1-day-old colostrum-fed calves were inoculated with 10(6) oocysts of C. parvum. They were medicated with 0, 30, 60, or 120 micrograms of halofuginone lactate per kg from days 2 to 8 postinfection (p.i.). Unmedicated calves passed large numbers of oocysts between 3 and 14 days p.i. Treatment with 30 micrograms/kg did not completely inhibit oocyst output during medication, whereas 60 and 120 micrograms/kg did. The latter groups passed only a reduced number of oocysts when the drug was withdrawn. In a second experiment, 3- to 6-day-old colostrum-fed calves were divided into three groups of 16 or 17 animals each. All animals had acquired C. parvum infection before arrival at the fattening unit. They were medicated with 0, 60, or 120 micrograms/kg for 7 days beginning on the day of arrival. Unmedicated calves passed large numbers of oocysts from 0 to 21 days. Medication stopped oocyst output at day 7, but some of the calves again passed low numbers of oocysts 7 days after withdrawal of the drug. Experimental infection of unmedicated calves was followed by a rise in local anti-C. parvum IgA and IgM titers. Rising coproantibody levels coincided with falling oocyst output. In halofuginone-medicated and experimentally infected calves, only specific anti-C. parvum IgM levels rose during the first 5 days p.i. Specific IgA levels increased in association with oocyst output after withdrawal of the drug in the 60- and 120-micrograms/kg groups. In naturally infected calves, on the other hand, both specific IgA and IgM levels rose further during medication. Although titers were lower than in unmedicated controls, no significant differences were observed. Both medicated and unmedicated calves were equally protected from a challenge with 10(7) oocysts 16 weeks after the first contact with the parasite.

Identification of eae sequences in enteropathogenic Escherichia coli strains from rabbits

DNA sequences coding for attachment and for verotoxin production were investigated in a collection of enteropathogenic Escherichia coli strains from rabbits. All of the strains produced diarrhea after experimental infection, attached to the brush borders of the intestinal lining, and possessed homology to the eae probe, whereas strains isolated from healthy rabbits did not. Sequences homologous to the AF/R1 fimbriae of strain RDEC-1 were not found. One strain reacted with the probe for the Shiga-like toxin type I gene.

The effect of halofuginone lactate on experimental Cryptosporidium parvum infections in calves

The chemoprophylactic effects of halofuginone lactate were tested against calf experimental cryptosporidiosis. Twenty 2-day-old calves, divided into four groups, were orally inoculated with 1 x 10(6) oocysts of Cryptosporidium parvum. The infected control group was unmedicated whereas the three other groups were medicated with the drug at 30, 60 and 120 micrograms kg-1 day-1, respectively, for 7 days, from Day (D) 2 to D8 post-inoculation (D 0 was inoculation day). The calves were weighed twice weekly and disease development and drug efficacy were assessed daily from D0 to D30 from consistency of feces, shedding of oocysts and mortality. Experimental C. parvum infection caused a severe clinical disease with profuse watery diarrhea, high oocyst shedding and mortality (3 out of 5) in the unmedicated group. The results clearly demonstrated the efficacy of halofuginone lactate in reducing the severity of clinical cryptosporidiosis. This efficacy was dose-dependent. The lowest dose (30 micrograms kg-1 day-1) was not able to prevent clinical disease and mortality (3 out of 5). No clinical signs were observed with the 60 and 120 micrograms kg-1 day-1 doses, but the animals shed oocysts after drug withdrawal. This shedding was more delayed the higher the dose of drug administered, but the delayed shedding had no effect on the growth of the animals.

Cryptosporidium parvum in calves: kinetics and immunoblot analysis of specific serum and local antibody responses (immunoglobulin A [IgA], IgG, and IgM) after natural and experimental infections

Fecal and serum anti-Cryptosporidium parvum immunoglobulin A (IgA), IgM, and IgG were monitored by an enzyme-linked immunosorbent assay after experimental and natural infection of calves with C. parvum. Although all experimentally infected calves showed high levels of colostral antibodies in the feces, they acquired C. parvum infection. Three of five animals died. Calves which acquired natural infection showed only diarrhea. Levels of colostral coproantibodies dropped quickly. Experimental infection was followed by a rise in local anti-C. parvum IgM levels from day 5 postinfection (p.i.). IgM peaked at day 14 p.i. and then disappeared quickly. Anti-C. parvum IgA levels rose between days 7 and 14 p.i. and decreased slowly. Rising levels of coproantibodies coincided with falling oocyst output. Fecal anti-C. parvum IgG levels rose slightly during oocyst output, and IgG disappeared 3 weeks p.i. Similar kinetics were established in naturally infected calves. Although fecal anti-C. parvum IgA levels declined slowly, reinfections were established 5, 7, and 14 weeks after the primary contact. Serum anti-C. parvum IgG levels rose during maximal oocyst excretion, whereas serum anti-C. parvum IgA levels peaked later than did local IgA levels. Challenge reinfection of naturally infected calves at day 112 was not followed by clinical signs or oocyst output or by a secondary antibody response. Sequential Western immunoblotting with fecal extracts revealed up to 32 different parasite antigens. Convalescent-phase sera recognized up to 23 antigens. Fecal IgA reacted intensely with antigens with relative molecular weights (M(r)) of approximately 11,000 and 15,000. These antigens were not recognized by convalescent-phase serum IgG. Both local IgA and serum IgG also showed strong reactions with 23,000- and 44,000-M(r) antigens and with several antigens of between 66,200 and 200,000 M(r). Most bands remained detectable for at least 16 weeks p.i.

Efficacy of halofuginone lactate against Cryptosporidium parvum in calves

The efficacy of halofuginone lactate against natural Cryptosporidium parvum infection in 150 neonatal market calves of a mixed Belgian breed was tested. The drug was administered orally in the milk replacer over a period of 3 to 14 days at doses ranging from 30 to 500 micrograms/kg of body weight. Over a period of 4 weeks, the animals were examined twice a week for shedding of C. parvum oocysts and were scored semiquantitatively for diarrhea. Weight gain was assessed after 2 and 4 weeks. Subclinical infections by rota-, corona-, and bovine picobirnaviruses were equally distributed in the different groups. In total, 93% of the unmedicated calves eliminated C. parvum within 10 days after arrival at the rearing unit and 62% of them showed diarrhea. Immediately after treatment with halofuginone was started, no more signs of Cryptosporidium-associated diarrhea were established. From the level of 60 micrograms/kg on, oocysts were no longer detected in 98% of animals 5 to 6 days after the start of treatment. Animals remained negative for at least 7 days after withdrawal of the drug. From 7 to 10 days after withdrawal, some animals excreted oocysts again. The number of shedders was closely linked with increasing doses of the drug, which indicates that lower doses do not interrupt infection completely and allow development of immunity. In this respect, a dose of 60 to 125 micrograms/kg over a period of 7 days seems most appropriate in practice. Toxic side effects were noticed only at 500 micrograms/kg.

Effect of disinfection of drinking water with ozone or chlorine dioxide on survival of Cryptosporidium parvum oocysts

Demineralized water was seeded with controlled numbers of oocysts of Cryptosporidium parvum purified from fresh calf feces and subjected to different treatments with ozone or chlorine dioxide. The disinfectants were neutralized by sodium thiosulfate, and neonatal mice were inoculated intragastrically and sacrificed 7 days later for enumeration of oocyst production. Preliminary trials indicated that a minimum infection level of 1,000 oocysts (0.1-ml inoculum) per mouse was necessary to induce 100% infection. Treatment of water containing 10(4) oocysts per ml with 1.11 mg of ozone per liter (concentration at time zero [C0]) for 6 min totally eliminated the infectivity of the oocysts for neonatal mice. A level of 2.27 mg of ozone per liter (C0) was necessary to inactivate water containing 5 x 10(5) oocysts per ml within 8 min. Also, 0.4 mg of chlorine dioxide per liter (C0) significantly reduced infectivity within 15 min of contact, although some oocysts remained viable.

Evolution of coccidial infection in commercial and domestic rabbits between 1982 and 1986

Caecal samples were collected from 751 domestic rabbits of various origin and from 1229 diarrhoeic rabbits issued from 61 commercial rabbitries. They were screened for coccidiosis. In 1982, the year of introduction of the anticoccidial robenidine in commercial rabbit feeds, a dramatic decrease of coccidial infection ratio was detected in commercial rabbitries: only 6% of samples contained greater than 100 oocysts per gram against 85% in 1979, when sulphaquinoxaline/pyrimethamine was used. Only Eimeria magna, E. media and E. perforans were detected, whereas the highly pathogenic species E. flavescens and E. intestinalis had disappeared from commercial units. After 4 years of continuous use of robenidine, infection ratio rose progressively, although still far below the 1979 levels. Most of the other species reappeared, but only in very low proportions (1-4% of samples). The percentage occurrence of E. magna, E. media and E. perforans on the contrary rose progressively to 25, 26 and 34%, respectively, suggesting drug resistance. In domestic rabbitries, the incidence of coccidial infection was markedly higher and all nine species of Eimeria were detected. Eimeria magna, E. media and E. perforans were very common, E. flavescens, E. intestinalis, E. piriformis and E. stiedai were less common, whereas E. irresidua and E. coecicola were relatively rare. Notwithstanding the lower activity of robenidine against E. stiedai, no rise of hepatic coccidiosis became evident.

Biotype, serotype, and pathogenicity of attaching and effacing enteropathogenic Escherichia coli strains isolated from diarrheic commercial rabbits

A total of 568 strains of Escherichia coli isolated from healthy and diarrheic rabbits were separated into 11 different biotypes according to the fermentation patterns of four carbohydrates. Strains belonging to biotypes 1 to 3, 6, and 8 induced lesions characteristic for attaching and effacing E. coli (AEEC). They attached to the intestinal epithelium of the terminal small intestine and the large intestine of 5-week-old rabbits after experimental infection and caused effacement of the microvillous brush border. However, pathogenicity for weaned rabbits, as judged by diarrhea score, anorexia, and reduced weight gain, varied according to the biotypes of the strains. Strains belonging to biotypes 1 and 6 produced only discrete clinical signs, strains belonging to biotypes 2 and 3+ (motile) induced diarrhea and growth depression, whereas strains belonging to biotypes 3- (immotile) and 8 caused severe clinical signs and high mortality. This confirms evidence from the field. Biotypes 3- and 8, accounting for 35.5 and 7.1% of AEEC strains in weaned diarrheic rabbits, respectively, were not detected in weaned healthy rabbits, while biotype 2 was the predominant strain in weaned healthy rabbits (62.3%). Finally, serotyping showed a close relationship between biotype and serotype of the AEEC examined. Most strains of biotypes 1+ and 2+ tested were O109:K-:H2 and O132:K-:H2, respectively, whereas all strains tested of biotype 3- were O15:K-:H- and those of biotype 8 were O103:K-:H2. These data indicate that specific clones of AEEC might be involved in juvenile rabbit enteritis. It was concluded that determination of biotypes allows the screening of highly pathogenic AEEC in weaned rabbits (biotypes 3- and 8).

Efficacy of toltrazuril against intestinal and hepatic coccidiosis in rabbits

The anticoccidial effect of toltrazuril (Bay Vi 9142) against Eimeria flavescens, E. intestinalis, E. magna, E. perforans and E. stiedai was tested in experimentally-infected rabbits. Continuous administration of 10-15 p.p.m. of the drug in the drinking water was highly effective in reducing oocyst output of all five species and in preventing clinical signs and macroscopic lesions. Sporulation of excreted oocysts was not affected. After 5 weeks of medication, no negative influence was noted on zootechnic performance of growing healthy rabbits. Medication of rabbits with 25 p.p.m. only during schizogony or gamogony (2 days of treatment, repeated after 5 days) quickly reduced clinical signs and oocyst output. When administered during late schizogony or gamogony, toltrazuril allowed development of immunity against reinfection with homologous species.

Significance of Clostridium spiroforme in the enteritis-complex of commercial rabbits

Commercial rabbits showing clinical signs of enteritis-complex were examined for the presence of Clostridium spiroforme and its iota-like toxin. The bacterium was detected by Gram stain in 52.4% of 149 cecal samples and iota-like toxin in 7.4%. From 29 strains of C. spiroforme tested, 26 were toxigenic, originating from 24 of 29 rabbitries. In 13.4% of the samples, C. spiroforme was present as the only known disease agent. Gross and microscopic lesions were similar to those described in the literature. In the other samples, C. spiroforme was associated with attaching effacing Escherichia coli (29.5%), Bacillus piliformis (10.3%), rotaviruses (25.6%), coronavirus (2.6%), Eimeria spp. (44.9%) and cryptosporidia (6.4%). In 33.3% of C. spiroforme-containing samples, more than one of these agents was present. There was no significant difference between the presence of these organisms in C. spiroforme-positive and negative samples. On the basis of these results as well as that of previous data, we suggest that C. spiroforme-mediated diarrhea is favoured by maldigestion, initiated by infectious agents and/or nutritional factors.

Scanning and transmission electron microscopy of attaching effacing Escherichia coli in weanling rabbits

A strain of an enteropathogenic Escherichia coli, originally isolated from diarrheic weaned rabbits, produced diarrhea in five-week-old New Zealand white rabbits. Sequential examination of the intestines by scanning and transmission electron microscopy revealed that the strain attaches first to the Peyer's patch dome epithelium and later to the enterocytes of distal small intestine, cecum, and colon. Colonized cells became rounded and detached. The colibacilli were intimately associated with the apical cell membrane. Both absorptive and goblet cells were affected. The strain caused effacement of the microvillous border of colonized epithelial cells. Colibacilli were regularly seen in the partially evacuated cavities of goblet cells, but not in absorptive epithelial cells.

Pathogenicity of attaching effacing enteropathogenic Escherichia coli isolated from diarrheic suckling and weanling rabbits for newborn rabbits

The pathogenicity of six strains of Escherichia coli originating from different commercial rabbitries was tested in neonatal rabbits. Two strains isolated from healthy weaned rabbits (O7:H6 and O9:H?) did not induce any clinical sign or lesion. Two strains (O109:H2) isolated from diarrheic suckling rabbits caused yellow diarrhea 36 to 60 h after inoculation and high mortality between 60 and 72 h after infection. At 12 h after infection, light and electron microscopy showed attachment to epithelial cells and effacement of microvilli from proximal small intestine to colon. Bacteria were often present in the apical cytoplasm of epithelial cells. The two strains isolated from diarrheic weanling rabbits (O109:H2 and O15:H-) did not induce any clinical sign. Attachment to epithelial cells and effacement of microvilli was observed 48 h after inoculation in distal small intestine, cecum, and colon. These data are further evidence for the existence of two groups of attaching effacing enteropathogenic E. coli in rabbits, showing different preferences for age group and intestinal compartment.

Experimental Escherichia coli enteropathy in weanling rabbits: clinical manifestations and pathological findings

Diarrhoea was reproduced by inoculating 5-week-old New Zealand White rabbits orally with 2 X 10(6) CFU of E. coli 0.15:H-. The strain produced diarrhoea in all the dosed rabbits 6.25 +/- 2.71 (mean +/- S.D.) days after infection (p.i.). Mortality was high. Sequential examination of the intestines by light microscopy showed the strain to attach first to the tips of the lymphoid follicle epithelium of Peyer's patches 24 h p.i., but not to other sites until 3 days p.i. From 3 to 14 days p.i. the strain caused an acute intestinal inflammatory response and large numbers of E. coli adhered to the enterocytes of ileum, caecum and colon. Colonized cells became rounded and were desquamated. Severe oedema of the caecal lamina propria was often present. Colonization of the intestine, as shown by rectal swab cultures, reached a maximum 4 to 7 days p.i. and did not decrease until 14 days p.i.

Pathogenic properties of Escherichia coli strains isolated from diarrheic commercial rabbits

Thirty-two different strains of Escherichia coli isolated from diarrheic commercial rabbits showing intestinal attachment of bacilli were studied. None of the strains produced thermostable or thermolabile enterotoxins, and none was invasive. Strains isolated from suckling rabbits attached in vitro to the brush borders of intestinal villi, whereas strains from weanling rabbits did not. After experimental infection of 5-week-old rabbits, the 26 strains isolated from weaned diarrheic rabbits attached to the epithelium of ileum, cecum, and colon, whereas only slight attachment was found after infection with the six strains isolated from suckling diarrheic rabbits. The former strains induced diarrhea in 87% of the rabbits, whereas the latter induced diarrhea in only 9% of inoculated rabbits. E. coli isolated from healthy rabbits did not cause diarrhea. Strains isolated from diarrheic suckling rabbits all belonged to serotype O109:K-:H2, whereas strains from diarrheic weaned rabbits belonged to at least eight different serogroups. It is suggested that two different mechanisms of E. coli enteropathy might exist in rabbits.

Immunity and effect of clopidol/methyl benzoquate and robenidine before and after weaning on rabbit coccidiosis in the field

For 15 months the anticoccidial effect of 200 ppm clopidol/methyl benzoquate and of 50 ppm robenidine, and the development of immunity against five different species of Eimeria were followed in a closed rabbit population. In unmedicated rabbits, oocyst output decreased progressively with increasing age to a very low level in animals older than four months, but none of the species present disappeared completely in adult animals. No clinical symptoms nor mortality from coccidiosis was noted in reproduction stock. In field conditions E magna and E perforans seemed to induce the weakest resistance, whereas a more marked resistance has been found for E intestinalis and E irresidua. E media appeared to have an intermediate position. Robenidine reduced oocyst output of E magna, E intestinalis, E irresidua, E media and E perforans significantly, whereas clopidol/methyl benzoquate reduced oocyst output of the latter four species only and was least active against E magna. Both drugs also reduced coccidiosis-induced mortality significantly. Medication only before weaning had no distinct influence on coccidial infection, or on mortality by coccidiosis after weaning; nor did those parameters differ significantly between continuously medicated rabbits and rabbits medicated after weaning only. As reproductive stock is protected by immunity, this makes the necessity of medicating does and bucks with anticoccidials questionable in intensive or semi-intensive reproduction systems.

Efficacy of narasin against hepatic and intestinal coccidiosis in rabbits

The anticoccidial effect of narasin against Eimeria flavescens, E. intestinalis, E. magna, E. perforans and E. stiedai was tested in experimentally infected rabbits. The drug was highly effective in reducing oocyst output and in preventing clinical signs. Maximum activity as measured by oocyst discharge was achieved with feed levels from 12 to 24 p.p.m.; there was no influence on oocyst sporulation. Optimal weight gain and food consumption were obtained with levels between 8 and 12 p.p.m.; at higher levels there was an adverse effect on growth, food intake, relative liver and heart weights and on serum potassium and glucose.

Coccidiosis in rabbits: a field study

During a survey 1052 faecal samples were examined in commercial and domestic rabbitries in Belgium. Nine different species of Eimeria were recognised. E magna, E media and E perforans were very common in both production methods. E flavescens, E intestinalis and E stiedai occurred more commonly in traditionally reared rabbits. E stiedai was not recorded in commercial rabbitries. E coecicola, E irresidua and E piriformis were less common. Oocyst output was suppressed in increasing efficacy by clopidol, sulphaquinoxaline/pyrimethamine (10:1), sulphadimidine and robenidine (P less than 0.01). The use of a droppings pit reduced the level of coccidial infection significantly compared with a sledge type of cleaning mechanism (P less than 0.001).

Robenidine treatment of rabbits naturally infected with coccidia

New Zealand White rabbits naturally infected with Eimeria intestinalis, E. magna, E. media and E. perforans and fed 100 parts/10(6) robenidine in their diet for 70 days ceased to excrete oocysts in their faeces after 19 days of treatment.