Fecal Oocyst Output Research Articles

Effects of Artemisia annua and Foeniculum vulgare on chickens highly infected with Eimeria tenella (phylum Apicomplexa).

BackgroundIntensive poultry production systems depend on chemoprophylaxis with anticoccidial drugs to combat infection. A floor-pen study was conducted to evaluate the anticoccidial effect of Artemisia annua and Foeniculum vulgare on Eimeria tenella infection. Five experimental groups were established: negative control (untreated, unchallenged); positive control (untreated, challenged); a group medicated with 125 ppm lasalocid and challenged; a group medicated with A. annua leaf powder at 1.5% in feed and challenged; and a group treated with the mixed oils of A. annua and Foeniculum vulgare in equal parts, 7.5% in water and challenged. The effects of A. annua and oil extract of A. annua + F. vulgare on E. tenella infection were assessed by clinical signs, mortality, fecal oocyst output, faeces, lesion score, weight gain, and feed conversion.ResultsClinical signs were noticed only in three chickens from the lasalocid group, six from the A. annua group, and nine from the A. annua + F. vulgare group, but were present in 19 infected chickens from the positive control group. Bloody diarrhea was registered in only two chickens from A. annua group, but in 17 chickens from the positive control group. Mortality also occurred in the positive control group (7/20). Chickens treated with A. annua had a significant reduction in faecal oocysts (95.6%; P = 0.027) and in lesion score (56.3%; P = 0.005) when compared to the positive control. At the end of experiment, chickens treated with A. annua leaf powder had the highest body weight gain (68.2 g/day), after the negative control group, and the best feed conversion (1.85) among all experimental groups.ConclusionsOur results suggest that A. annua leaf powder (Aa-p), at 1.5% of the daily diet post-infection, can be a valuable alternative for synthetic coccidiostats, such as lasalocid.

Immunization with recombinant 3-1E protein in AbISCO®-300 adjuvant induced protective immunity against Eimeria acervulina infection in chickens

Immunostimulating complexes (ISCOMs), a kind of novel antigen presenting system, could enhance immune protection by antigen presentation. AbISCO®-300 comprising purified saponin, cholesterol and phosphatidyl choline is an effective ISCOM adjuvant. To evaluate the immune protection of recombinant 3-1E protein against Eimeria acervulina infection, chickens were immunized with recombinant 3-1E protein in combination with AbISCO®-300 or recombinant 3-1E protein alone in this study. The protective immunity was assessed with body weight gain, fecal oocyst output, detection of intestinal IgA positive cells and percentages of CD3+, CD4+ or CD8+ intestinal intraepithelial lymphocytes (IELs). Chickens vaccinated with different doses of recombinant 3-1E protein plus AbISCO®-300 showed higher percentages of CD3+, CD4+, and CD8+ intestinal IELs, increased positive expression rate of intestinal IgA, increased body weight gains and decreased oocyst shedding compared with recombinant 3-1E protein-only vaccinated groups. The results showed that immunization with various doses of the recombinant 3-1E protein in AbISCO®-300 adjuvant enhanced immune protection against avian coccidiosis.

Pharmacodynamic evaluation of a reference and a generic toltrazuril preparation in broilers experimentally infected with Eimeria tenella or E. acervulina

1. The aim of this study was to investigate the effects on pigmentation, faecal oocyst output, immune responsiveness and reactive oxygen species (ROS) generation following treatment with either the reference toltrazuril (Baycox) or a generic preparation (gen-TTZ), during an experimental Eimeria tenella (Et) or E. acervulina (Ea) infection of 210 Ross broiler chickens.2. Results showed a significant difference on the anticoccidial efficacy 6 d after treating infected animals with Baycox (Et: 99.69% and Ea: 99.52%) or gen-TTZ (Et:85.71% and Ea 81.81%).3. Gen-TTZ-treated animals were less strongly carotenoid-pigmented than Baycox-treated broilers. Mean plasma carotenoid concentrations were significantly higher in groups treated with Baycox than in broilers given gen-TTZ.4. Treatment of animals with Baycox led to a significant decrease in ability of the peripheral blood mononuclear cells to produce ROS in contrast to gen-TTZ-treated groups. Baycox, but not generic toltrazuril, increased IL-10 and decreased tumour necrosis factor alpha (TNF-α) concentrations in chickens infected with E. tenella and E. acervulina.5. It is suggested that differences in anticoccidial efficacy may be observed when using a generic toltrazuril product. Hence, in addition to plasma profiles of drugs, standardised clinical control tests may be necessary for generic formulations, particularly if other parameters are important to achieve a better control of coccidiosis.

Eimeria maxima: efficacy of recombinant Mycobacterium bovis BCG expressing apical membrane antigen1 against homologous infection

Coccidiosis is one of the most important protozoan diseases and inflicts severe economic losses on the poultry industry. The aim of this study was to evaluate the capacity of Bacillus Calmette-Guerin (BCG) to deliver apical membrane antigen1 (AMA1) of Eimeria maxima to stimulate specific cellular and humoral immune responses in chickens. Day-old birds were immunized twice with rBCG/pMV261-AMA1, rBCG/pMV361-AMA1, or BCG via oral, intranasal, and subcutaneous routes and then orally challenged with homologous E. maxima sporulated oocysts. Gain of body weight, fecal oocyst output, lesion scores, serum antibody responses, numbers of splenocyte CD4(+) and CD8(+) T cells, and gut cytokine transcript levels were assessed as measures of protective immunity. Challenge experiments demonstrated that rBCG vaccination via intranasal or subcutaneous routes could increase weight gain, decrease intestinal lesions, and reduce fecal oocyst shedding, and the subcutaneous and intranasal routes were superior to the oral route based on the immune effects. Furthermore, intranasal rBCG immunization could also lead to a significant increase in serum antibody, the percentage of CD4+ and CD8+ T lymphocyte cells, and the levels of IL-1β, IFN-γ, IL-15, and IL-10 mRNAs compared with the control group. These results suggested that intranasal rBCG immunization could induce a strong humoral and cellular response directed against homologous E. maxima infection. This study provides data for the use of rBCG to develop a prophylactic vaccine against coccidiosis.

Effects of dietary supplementation with a herbal extract on the performance of broilers infected with a mixture of Eimeria species

1. A herbal extract containing a blend of three essential oils, derived from oregano, laurel leaf and lavender, was investigated as a feed additive alternative to the conventional anticoccidial sodium monensin. 2. Broilers were infected with a mixture of Eimeria species or left uninfected. Both infected and uninfected broilers were provided with diets containing either herbal extract (HEX), monensin (MON) or without these supplements (CON). The HEX group had 50 mg herbal extract/kg diet and the MON group 100 mg monensin/kg diet. 3. All of the uninfected broilers exhibited higher body weight gain and better feed conversion when compared with their infected counterparts at d 28 and 42 of age. Both HEX and MON supplements caused significant improvements in performance in the infected broilers, but failed to have any effect on uninfected broilers. 4. Faecal oocyst output measured daily by sampling excreta, and expressed on a per bird basis, was lower in the HEX and MON groups than in the CON group. However, the herbal extract was not as effective as monensin in reducing oocyst excretion. Coccidial infection caused a significant increase in total intestinal length and caecal weight, but the dietary treatments did not influence these measurements. 5. These results indicate that providing a herbal extract in the diet was not as effective as monensin in protecting broilers exposed to a coccidial challenge.

Mucosal immunity against Eimeria acervulina infection in broiler chickens following oral immunization with profilin in Montanide™ adjuvants

The present study was conducted to compare aqueous nanoparticle-based Montanide™ IMS 1313 N VG PR (IMS 1313) and oil-based ISA 71 VG (ISA71) adjuvants in combination with an Eimeria subunit protein vaccine on protection against avian coccidiosis. Male broiler chicks were vaccinated twice with an Eimeria recombinant profilin protein alone or in conjunction with IMS 1313 or ISA 71 prior to infection with live, sporulated Eimeria acervulina oocysts. For comparison, chickens were immunized with a commercial live coccidiosis vaccine (Coccivac-B). The following parameters were assessed as measures of protective immunity: body weight gain, fecal oocyst output, profilin-specific intestinal secretary IgA (sIgA) or IgY antibody levels, and percentages of CD4+, CD8+, TCR1+, or TCR2+ intestinal intraepithelial lymphocytes (IELs). Birds vaccinated with profilin plus ISA 71 had increased body weight gains, equivalent to Coccivac-B vaccination, compared with the profilin-only group. Immunization with profilin plus IMS 1313, or with profilin plus ISA 71, reduced fecal oocysts shedding compared with the profilin-only group. Intestinal sIgA levels were greater in the profilin plus IMS 1313 or ISA 71 groups, and IgY levels were greater in the profilin plus ISA 71 group, compared with profilin alone. Birds vaccinated with profilin plus IMS 1313 or ISA 71 had higher percentages of CD4+, CD8+, and TCR1+, but not TCR2+, intestinal IELs compared with the profilin-only vaccinated group. Taken together, these results indicate that immunization of chickens with the recombinant profilin subunit vaccine in conjunction with IMS 1313 or ISA 71 adjuvants increases protective immunity against experimental E. acervulina infection.

Effects of Simple and Disposable Chicken Cages for ExperimentalEimeriaInfections

During experimental Eimeria infections in chickens, facilities are often contaminated by fecal oocysts known to be highly resistant to both chemical and enzymatic treatments. Thus, studies using experimental Eimeria infections have been limited due to the difficulty of complete elimination of residual oocysts from both cages and facilities. To overcome this limitation, simple, inexpensive, and disposable cages were constructed from cardboard boxes and tested during experimental Eimeria maxima infections. The cages were used in animal rooms with only a 1.7% evidence of coccidia contamination between adjacent cages. No significant differences in fecal oocyst output and body weight gain were noted between animals housed in disposable cages and animals housed in wire control cages. This cage design is a useful means for preventing oocyst contamination during experimental conditions, suggesting that this disposable cage design could be used for other avian infectious disease studies.

Dose–response effects of diclazuril against pathogenic species of ovine coccidia and the development of protective immunity

Twin lambs at pasture with their ewes, were divided into seven groups of 10 lambs. One group of 10 lambs served as a non-infected, untreated control. Five groups of 10 lambs were infected with 10,000 oocysts of Eimeria crandallis and 10,000 oocysts of Eimeria ovinoidalis when they were 3 weeks old (day 21 of the study). This produced a good level of infection with high oocysts production and diarrhoea in the lambs.Fourteen days after the primary, artificial challenge (day 35) four of these groups were treated with oral diclazuril at 0.25, 1.0, 2.0 or 4.0mg/kg. Diclazuril treatment was highly effective, dramatically reducing symptoms of diarrhoea and reducing faecal oocyst output by 79.7%, 97.3%, 99.4% and 99.5% respectively in the treated groups within four days.Two weeks post-treatment, and 28 days after the primary coccidial challenge (day 49 of the study), five groups of lambs were re-challenged with 100,000 oocysts of E. crandallis and 100,000 oocysts of E. ovinoidalis (secondary challenge). A group of lambs which had received neither the primary coccidia infection, nor drug treatment (susceptible controls) were also given the secondary challenge. All lambs given the secondary challenge produced high numbers of coccidia and exhibited varying degrees of diarrhoeic faeces. The lambs, which had previously received the higher doses of diclazuril at 2.0 and 4.0mg/kg, developed clinical signs of coccidiosis. These lambs were completely susceptible despite having received the early primary immunising infection of coccidia on day 21. The effects of the secondary challenge were more severe in the groups dosed with the two highest levels of diclazuril than in the susceptible control lambs, which had presumably been exposed to continued low levels of pasture contamination and had acquired a limited degree of immunity from this exposure. It would appear that treatment at the higher dose levels not only eliminated most of the oocysts from the primary challenge but also adventitious infection derived from the grazing paddocks. In contrast, lambs which had received the two lower drug levels of diclazuril (0.25 and 1.0mg/kg) whilst producing large numbers of oocysts, had only transient diarrhoea following secondary challenge.It was concluded that when used as a metaphylactic treatment, diclazuril works rapidly and is effective within four days of administration. Overall, a single dose of diclazuril at either 0.25–1.0mg/kg appears to be highly effective in the control of coccidiosis in young lambs at pasture whilst allowing the development of protective immunity against subsequent heavy coccidia challenge.

Embryo vaccination of chickens using a novel adjuvant formulation stimulates protective immunity against Eimeria maxima infection

Our previous study demonstrated that chickens immunized subcutaneously with an Eimeria recombinant profilin protein vaccine emulsified in a Quil A/cholesterol/DDA/Carbopol (QCDC) adjuvant developed partial protection against experimental avian coccidiosis compared with animals immunized with profilin alone. Because in ovo vaccination is presently used in commercial applications worldwide throughout the poultry industry, the current study was undertaken to investigate chicken embryo vaccination with profilin plus QCDC adjuvant. Eighteen day-old embryos were immunized with isotonic saline (control), profilin alone, QCDC alone, or profilin plus QCDC, and orally challenged with live Eimeria maxima at 7 days post-hatch. Body weight gain, fecal oocyst output, and intestinal cytokine transcript levels were assessed as measures of protective immunity. While immunization with profilin alone or QCDC alone did not alter body weight gain of infected chickens compared with the saline control group, vaccination with profilin plus QCDC increased body weight gain such that it was equal to the uninfected controls. Immunization with profilin plus QCDC also reduced fecal oocyst shedding compared with unimmunized controls, although in this case QCDC failed to provide an adjuvant effect since no difference was observed between the profilin-only and profilin/QCDC groups. Finally, increased levels of transcripts encoding IL-1β, IL-15, and IFN-γ were seen in the intestinal tissues of animals given profilin plus QCDC compared with the profilin-only or QCDC-only groups. In summary, this study demonstrates an adjuvant effect of QCDC on body weight gain and intestinal cytokine responses following in ovo vaccination of chickens with an Eimeria profilin vaccine.

Eimeria maxima recombinant Gam82 gametocyte antigen vaccine protects against coccidiosis and augments humoral and cell-mediated immunity (46.19)

Abstract Intestinal infection with Eimeria, the etiologic agent of avian coccidiosis, stimulates protective immunity to subsequent colonization by the homologous parasite, whilst cross-protection against heterologous species is poor. This study was designed to assess a purified recombinant protein from E. maxima gametocytes (Gam82) in stimulating immunity against experimental infection with live parasites. Following Gam82 intramuscular immunization and oral parasite challenge, body weight gain, fecal oocyst output, gut lesions, serum antibody response, cytokine production, and lymphoproliferation were assessed to evaluate vaccination efficacy. Animals vaccinated with Gam82 and challenged with E. maxima showed lower oocyst shedding and reduced intestinal pathology compared with non-vaccinated and parasite-challenged animals. Gam82 vaccination also stimulated the production of antigen-specific serum antibodies, induced greater levels of IL-2 and IL-15 mRNAs, and increased splenic lymphoproliferation compared with non-vaccinated controls. These results demonstrate that the Gam82 recombinant protein protects against coccidiosis and augments humoral and cell-mediated immunity.

Eimeria maxima recombinant Gam82 gametocyte antigen vaccine protects against coccidiosis and augments humoral and cell-mediated immunity

Intestinal infection with Eimeria, the etiologic agent of avian coccidiosis, stimulates protective immunity to subsequent colonization by the homologous parasite, while cross-protection against heterologous species is poor. As a first step toward the development of a broad specificity Eimeria vaccine, this study was designed to assess a purified recombinant protein from Eimeria maxima gametocytes (Gam82) in stimulating immunity against experimental infection with live parasites. Following Gam82 intramuscular immunization and oral parasite challenge, body weight gain, fecal oocyst output, lesion scores, serum antibody response, and cytokine production were assessed to evaluate vaccination efficacy. Animals vaccinated with Gam82 and challenged with E. maxima showed lower oocyst shedding and reduced intestinal pathology compared with non-vaccinated and parasite-challenged animals. Gam82 vaccination also stimulated the production of antigen-specific serum antibodies and induced greater levels of IL-2 and IL-15 mRNAs compared with non-vaccinated controls. These results demonstrate that the Gam82 recombinant protein protects against E. maxima and augments humoral and cell-mediated immunity.

Changes in weight gain, faecal oocyst count and packed cell volume of Eimeria tenella-infected broilers treated with a wild mushroom (Ganoderma lucidum) aqueous extract : article

An experiment was conducted to study the effect of a wild Ganoderma lucidum aqueous extract in coccidian-infected broilers. At 6 weeks of age the birds were randomly allocated to 6 treatment groups of 20 Ross broilers each in wire cages. Groups A, B and C were infected with Eimeria tenella Houghton strain at the rate of 36 250 sporulated oocysts/ml per bird. The remaining 3 groups D, E and F were uninfected controls. At 7 weeks the birds in group A were treated with G. lucidum aqueous extract and those in B with amprolium in drinking water ad libitum at the rate of 200 mg/ml each for 7 days consecutively. Body weight gain, feed intake, faecal oocyst output and some haematological parameters were monitored. The result showed that all the infected birds in groups A, B and C had clinical signs of weakness and reduced appetite on day 4 post-infection. By the 5th day post-infection their faeces became bloody and watery, and large numbers of E. tenella oocysts were present in the faeces. On day 3 after treatment the oocysts detected were considerably reduced in both treated groups A and B and slightly higher in the untreated group C. The faeces of the uninfected control groups were normal and free of coccidial oocysts. After treatment for 7 days no coccidial oocysts were found in faeces of the birds that had been treated. Infected, untreated birds showed a slight drop in feed intake and weight gain from 7 to 8 weeks of age. The final mean weight gain recorded in the treated groups A and B was comparable to that of the uninfected birds in the 3 control groups, while it was lower in the untreated group C. The feed to gain ratio was higher in C than in the other groups. A slight drop in packed cell volume was observed in groups A, B and C at 7 weeks of age, 1 week after infection. This study showed that treatment with G. lucidum results in a marked reduction in the number of E. tenella oocysts shed in the faeces, leading to improved weight gain and decreased weight loss. The results confirmed the virulence of the Houghton strain of E. tenella and the effectiveness of both amprolium and G. lucidum extract against E. tenella.

Toltrazuril and sulphonamide treatment against naturally Isospora suis infected suckling piglets: Is there an actual profit?

A study was carried out to assess the efficacy and the economic profit of prophylactic treatment against Isopsora suis with toltrazuril or with a sulfamethazine/trimethoprim combination in piglets from an intensive pig farm. Thirty-one litters were included in study. Eight litters were treated once with toltrazuril (20 mg/kg b.w.) at 3 days of age (Toltra group); 8 litters were treated with the sulphonamide combination (sodium sulfamethazine 35 mg and trimethoprim 7 mg/kg b.w.) for 3 consecutive days starting at 3 days of age (Sulfa group), and 15 litters were untreated (control group). Counts of oocyst per gram on pooled feces sampled from each litter were carried out on Days 7, 14, 21 and 28 and diarrhea was registered daily from pooled samples. Piglets were weighed on Days 1, 7 and 28 and mean weight gain (WG) and daily weight gain (DWG) were evaluated. The economic profit of treatment was evaluated comparing the WG of piglets of each treatment group from the day of birth to Day 28. On Days 14, 21 and 28, toltrazuril showed a better efficacy in controlling fecal oocyst output, diarrhea and weight gain compared with sulphamidic treatment ( P < 0.001). The budgeting analysis showed a return of economic benefit of € 0.915 per toltrazuril-treated piglets and an additional cost of € 1.155 per sulphonamide-treated piglets.

Protective effect of hyperimmune egg yolk IgY antibodies against Eimeria tenella and Eimeria maxima infections

Avian coccidiosis is caused by several distinct species of Eimeria protozoa and is the major parasitic disease of poultry of economic importance. As an alternative strategy to control avian coccidiosis without using prophylactic medications, we have investigated the efficacy of inducing passive immunity against coccidiosis by orally feeding hyperimmune IgY antibodies. In this study, a commercially available egg yolk powder, Supracox® (SC), a purified IgY fraction of egg yolk prepared from hens hyperimmunized with three major species of Eimeria oocysts, were continuously fed to young chicks from hatch. Upon orally infecting these broiler chicks with Eimeria tenella and Eimeria maxima oocysts at 1 week of age, they showed significantly higher body weight gains (P<0.05) compared to the untreated controls. Furthermore, SC-fed chicks showed significantly less intestinal lesions and reduced fecal oocyst output compared to the untreated controls following oral infections with E. tenella and E. maxima. These results provide clear evidence that passive immunization of chicks with hyperimmune egg yolk IgY antibodies provide significant protection against E. tenella or E. maxima infections.

Eimeria stiedae: Experimental infection in rabbits and the effect of treatment with toltrazuril and ivermectin

The aim of this study was to investigate the clinical, haematological, biochemical, lipid peroxidation, ultrasonographic and pathologic findings in hepatic coccidiosis induced by Eimeria stiedae in rabbits, and also to compare the treatment effects of both toltrazuril and ivermectin separately and in combination. In this study, 56 rabbits were divided into eight groups. The first group was designated as healthy control group. Rabbits were infected with 40.000 sporulated oocysts of E. stiedae. Groups 2, 3, 4, 5, 6, 7 and 8 were allocated as the infected control group, infected+toltrazuril-treated group, infected+ivermectin-treated group, infected+toltrazuril+ivermectin-treated group, non-infected+toltrazuril-treated group, non-infected+ivermectin-treated group, non-infected+toltrazuril+ivermectin-treated group, respectively. Haematocrit, Haemoglobin and MCV values as well as percentage of lymphocyte decreased in Groups 2 and 4 whereas leucocyte counts and percentage of granulocyte leucocyte increased. Serum GGT, ALT and AST activities increased but albumin value decreased. Plasma MDA concentrations increased whereas erythrocyte CAT, GSH-Px, and SOD activities decreased. Mean oocyst numbers in per gram faeces (epg values) increased in both groups during the study. Ultrasonographic examination revealed that the liver was enlarged and had hyperechogenic parenchyma. Bile ducts were dilated and hyperechogenic and the gall bladder was dilated. The livers of these animals were enlarged and typical macroscopic and microscopic findings of coccidiosis were present. Treatment with toltrazuril and toltrazuril+ivermectin combination were highly effective in reducing faecal oocyst output in infected rabbits. Haematological, biochemical and lipid peroxidation parameters and, ultrasonographic findings of the liver were close to control values for Groups 3 and 5. Necropsy of these animals showed no visible lesions related to hepatic coccidiosis although a few oocysts were detected in the bile duct epithelial cells.

Infectivity of Cryptosporidium parvum isolated from asymptomatic adult goats to mice and goat kids

An experimental study was carried out in neonatal goat kids to examine the infectivity of Cryptosporidium oocysts, pattern of oocyst shedding and morphological changes in the intestine during the infection. Cryptosporidium oocysts isolated from adult asymptomatic goats, and identified as C. parvum by polymerase chain reaction (PCR) were used in this study. Of three 4-day-old goat kids, two were orally infected with C. parvum oocysts (10 5 oocysts in 10 ml PBS/kid). One goat kid given 10 ml PBS only by the oral route served as a control. Cryptosporidium oocysts were detected in the faeces of one infected kid on day 3 post-inoculation (pi) whereas in the other 6 days pi. The faecal oocyst counts gradually increased and the peak counts in the two kids were 2×10 6 g −1 (on day 12 pi) and 3.2×10 6 g −1 (on day 14 pi). The increase in faecal oocyst output coincided with diarrhoea in an infected kid from days 10–17 pi. Although the oocyst excretion declined gradually after the peak, both infected kids excreted oocysts until euthanized on days 20 and 22 pi. Light and scanning electron microscopic investigations of the ileum revealed the endogenous stages on the brush border of the enterocytes, infiltration of neutrophils and mononuclear cells into the lamina propria, atrophy, stunting and fusion of villi. For purposes of comparison, goat Cryptosporidium oocysts were inoculated orally (10 3 oocysts/mouse) to eight, 1-week-old mice. All experimental mice excreted oocysts from day 3 pi, and four infected mice continued to excrete oocysts up to day 42 pi. The experimental infection described in goat kids resembled the natural disease in terms of oocyst excretion, clinical signs and intestinal pathology. The ability of oocysts excreted by asymptomatic goats, to infect goat kids and mice is likely to have a major impact on the epidemiology of cryptosporidiosis in livestock and man.

Immune Responses and Resistance to Eimeria acervulina of Chickens Divergently Selected for Antibody Responses to Sheep Red Blood Cells

Resistance to Eimeria acervulina was measured in two lines of chickens that had been divergently selected for high (H line) or low (L line) antibody (Ab) responses to SRBC, and in a randombred control (C) line originating from the same parental stock. Fecal oocyst output of cocks from the three lines from the 17th generation was estimated after primary and secondary infection with 2 × 105 oocysts. In addition, Ab responses to E. acervulina oocyst antigen and cellular immune responses in vitro to E. acervulina antigen were measured after primary and secondary infection with E. acervulina.No significant line differences were found with respect to fecal oocyst output after primary infection. Only at the end of the primary infection period, i.e., Day 15 postprimary infection, was a significantly lower fecal oocyst output found in the H line as compared to the C and L lines. After secondary infection, significantly higher fecal oocyst output was found in the C line. Significantly higher Ab response after primary and secondary infection were found in the H and C lines as compared to the L line. No line differences were found for cellular immune responses to E. acervulina oocyst antigen.These observations imply that selection for enhanced humoral immunity to SRBC did not result in enhanced resistance to E. acervulina in terms of fecal oocyst output. However, the H line might expel E. acervulina more rapidly than the other two lines. The absence of line differences in resistance to Eimeria is discussed with respect to the role of the humoral immune response.

Evaluation of the Association of Parasitism with Mortality of Wild European Rabbits Oryctolagus cuniculus (L.) in Southwestern Australia

Abundances of the parasitic nematodes Trichostrongylus retortaeformis and Passalurus ambiguus, and 8 Eimeria species were estimated by fecal egg and oocyst output in 12 discrete free-ranging populations of wild rabbits (Oryctolagus cuniculus) in southwestern Australia. Comparisons of parasite egg and oocyst counts were made between those rabbits known to have survived at least 2 mo after fecal samples were collected and those rabbits that did not survive. There were significant negative relationships between parasite egg and oocyst counts and survival when all age groups and collection periods were pooled for several species of coccidia and for T. retortaeformis. However, when the same comparisons were made within rabbit age groups and within collection periods, there were very few significant differences even where sample sizes were quite large. The differences indicated by the pooled analysis for coccidia were most likely due to an uneven host age distribution with respect to survival, combined with an uneven distribution of the oocyst counts with rabbit age. The result for T. retortaeformis was similarly affected but by a seasonal pattern. Parasitism by nematodes and coccidia did not appear to be an important mortality factor in these rabbit populations, at least at the range of host densities we examined. This suggests that other factors must have been responsible for the observed pattern of density-dependent regulation in these rabbits.

Variations in oocyst output associated with Cryptosporidium baileyi infections in chickens

Groups of birds, aged 2, 16 and 30 days, were experimentally infected with 400, 20 000 or 1 000 000 oocysts of Cryptosporidium baileyi. The faecal oocyst output for each group was determined by collection of faeces on Days 0, 5, 7 and 13–21 post-infection (p.i.). The duration of patency of infection, as determined by oocyst extrection, declined more drapidly in the older age groups but persisted longer in birds challenged with the lower oocyst numbers.

Preventive treatment of rabbit coccidiosis with α-difluoromethylornithine

The effect of α-difluoromethylornithine (DFMO) administered in drinking water (0.2 and 0.5%) against liver and intestinal coccidioses in experimentally infected rabbits was studied. Zool-technical and clinical parameters were used to assess the efficacy of the compound. In both coccidioses the lower dose not show any important effect. The higher dosage (0.5%) however, reduced the lesions induced by coccidia to an important extent. The animals infected and treated with 0.5% DFMO showed similar weight gain, food intake and relative liver weight figures to the non-infected controls. Serum transaminase levels in the rabbits infected with Eimeria stiedai and treated with 0.5% DFMO were close to those of the non-infected animals. Infected rabbits treated with this dosage also showed reductions (over 80%) in faecal oocyst output.