Foot-pad dermatitis and experimentally induced coccidiosis in young turkeys fed a diet without anticoccidia.

Foot-pad dermatitis (FPD) is a widespread challenge to turkey production. This study aimed at evaluating the effects of using floor heating and exposure to litter with critical moisture content (35%) under experimental infection with Eimeria. adenoeides on the severity of FPD in turkeys. Two trials were done; in each trial, 4 groups of 2-wk-old female turkeys were reared over 4 wk. At the start of the experiment (d 14), each bird had normal foot pads. All birds were fed ad libitum on identical pelleted diets without any anticoccidial additive. The first 2 groups were kept on dry wood shavings with or without floor heating; the other 2 groups were housed on wet wood shavings of 35% moisture with or without floor heating. Two birds in each of the 4 groups were experimentally infected with E. adenoeides via crop intubation (~50,000 oocysts/bird). Foot pads were assessed weekly for external scoring and at d 42 of life for histopathological scoring. The number of oocysts eliminated via excreta was determined. In both trials, using floor heating resulted in significantly decreased FPD scores (2.06 ± 0.735; 1.47 ± 0.734, trials 1 and 2, respectively) compared with groups housed without floor heating (3.88 ± 0.812; 2.73 ± 1.25, trials 1 and 2, respectively). Birds continuously exposed to wet litter (35% moisture) showed significantly increased FPD scores (3.41 ± 1.23; 2.69 ± 1.34, trials 1 and 2, respectively) compared with the group not exposed to wet litter (2.53 ± 1.00; 1.53 ± 0.683, trials 1 and 2, respectively). The coccidial infection in both trials resulted in markedly lowered DM contents of excreta (14.8 and 15.1%, trials 1 and 2, respectively) and litter (58.0 and 57.6%, trials 1 and 2, respectively) in the groups exposed to wet litter without using floor heating. In both trials, using floor heating resulted in the highest mean DM content of litter (85.1 and 85.0%, trials 1 and 2, respectively) and the highest BW (2,693 and 2,559 g, trials 1 and 2, respectively). The results suggest that induced diarrhea caused by coccidial infection led to poor litter quality, and hence, increased the severity of FPD, which can be overcome by using floor heating.

Eimeria involved in a case of coccidiosis in farmed red-legged partridges (Alectoris rufa) in France: oocyst isolation and gross lesion description after experimental infection.

The aim of the present work was, after a coccidiosis outbreak in a farm rearing red-legged partridges (Alectoris rufa) in Brittany (France), to identify the Eimeria species and describe gross lesions induced by three of them (Eimeria kofoidi, Eimeria caucasica and Eimeria legionensis) after experimental infection. E. kofoidi oocysts measured 19.3 µm × 16.3 µm on average; neither micropyle nor oocyst residuum were present, but one, two or more small polar granules were visible. After inoculation of 300,000 oocysts per partridge, severe gross lesions were observed in the duodenum and jejunum, characterized by thickened oedematous mucosa and lumen filled with thick mucus, gas and sometimes false-membrane due to sloughed epithelium. E. caucasica oocysts were on average 29.8 µm × 19.5 µm in size; no oocyst residuum was observed, but a large granule was well visible. E. caucasica also invaded both the duodenum and jejunum, causing haemorrhagic points on the serosal surface, as well as mucoid duodenitis and catarrhal enteritis when 30,000 oocysts were inoculated per bird. E. legionensis oocysts measured 22.6 µm × 14.9 µm on average; they presented a clear micropyle beneath which one or two granulations were present. E. legionensis mainly invaded the caeca; low mortality was observed at the dosage of 200,000 oocysts per bird. Caecal walls were thickened and caseous material was condensed into off-white cheesy cores. For each species, oocyst shedding started 5 days post inoculation, peaked at 9, 8 and 6 days post inoculation for E. kofoidi, E. caucasica and E. legionensis, respectively, then decreased and persisted until 15 days post inoculation (end of examinations).

Comparison of the humoral and cellular immune responses to two preparations of Cryptosporidium parvum CP15/60 recombinant protein.

This study compares the immune responses produced by immunising mice and rabbits with two preparations of the recombinant 15/60 kDa protein of Cryptosporidium parvum. Genomic C. parvum DNA was amplified and the recombinant protein was synthesized as a fusion protein with glutathione-S-transferase in Escherichia coli and in the eukaryotic system of baculovirus/insect cells. Both recombinant proteins induced similar levels of serum antibodies against the fusion recombinant protein, but the eukaryotic recombinant protein triggered a stronger humoral response to C. parvum. Similarly, increased lymphoproliferation occurred only after stimulation of spleen cells from mice immunised with the eukaryotic recombinant protein. This suggests that the eukaryotic protein is a better candidate for immunological studies on cryptosporidiosis.

A survey of Eimeria species in commercially-reared chickens in France during 1994.

In a survey of chicken coccidia in France during 1994, samples of litter were collected from 41 farms. On 31 of these farms, eimerian oocysts were abundant enough to allow monitoring of their numbers in the litter. Peak total oocyst counts on these farms ranged from 16,200 to 1,254,000/g of litter, but no coccidiosis was observed. The chickens reared without anticoccidial agents in their food (poulets biologiques) produced higher and earlier peak oocyst counts in litter than the chickens given medicated food (poulets labels). The oocysts in litter samples from 22 farms (13 poulet biologique, five poulet label, two standard broiler, one breeder and one layer) of the original 41 were identified. Six of the seven eimerian species known to parasitize chickens were found, using combinations of five methods (oocyst morphology, intestinal lesions, enzyme electrophoresis, growth in embryonating eggs and prepatent time). Multispecific infections predominated (95% of 22 farms), up to six species occurring together. Of farms where oocysts were detected, the percentages with each species were: Eimeria acervulina (100%), E. mitis (82%), E. tenella (77%), E. maxima (73%), E. praecox (45%) and E. brunetti (27%). These appear to be the first definite records of E. mitis and E. praecox for France. Although E. necatrix was not found in this survey, it had recently been detected by other workers in France, so that all seven chicken Eimeria species were known to be contemporaneous.

Chemoprophylaxis of Cryptosporidium parvum infection with paromomycin in kids and immunological study.

The anticryptosporidial activity of paromomycin, a natural antibiotic weakly absorbed when administered per os, was assessed in goat kids experimentally infected once via the oral route with 10(6) Cryptosporidium parvum oocysts. Paromomycin used prophylactically at a dose of 100 mg/kg of body weight per day from day-1 to day 10 (day 0 was the inoculation day) prevented infection during the period of drug administration. A delayed low infection was suggested by an antibody rise, but the infection developed below the microscopic detection limits. This low parasite development induced a partial immunity in kids, which reacted immunologically to a challenge on day 21 without symptoms or detectable oocyst shedding. So, paromomycin is a good candidate for field trials because it is prophylactically effective against experimental C. parvum infection and well tolerated by animals. This drug would be useful in an adapted form as an anticryptosporidial agent for neonatal ruminants.

Analysis of humoral immune response in chickens after inoculation with Cryptosporidium baileyi or Cryptosporidium parvum.

White leghorn chickens aged 14 days were orally inoculated with 1 x 10(6) oocysts of Cryptosporidium baileyi or C. parvum to compare the specific immune responses. Cross-reactions were evaluated using homologous or heterologous antigens in enzyme-linked immunosorbent assay (ELISA) and Western blot to determine the occurrence of an antigenic homology between these two species. Blood, bile, whole intestine, bursa of Fabricius, and feces were collected daily from the day of inoculation (day 0) to day 22 postinoculation (PI). Eight control chickens remained negative up to day 22 PI. Chickens inoculated with C. baileyi did not express clinical symptoms but shed oocysts from days 6 to 21 PI. Chickens inoculated with C. parvum exhibited no clinical signs, no oocysts in feces, and no developmental stages of the parasite. However, a specific immune response to both antigens appeared on day 9 PI. ELISA using homologous or heterologous antigens showed that anti-C. baileyi and anti-C. parvum antibodies in serum or bile were detectable using C. baileyi or C. parvum oocysts as antigen, but the intensity of the response was significantly higher when C. baileyi was used. Cross-reactions in immunoblot analysis confirmed ELISA results, revealing a greater number of bands using C. baileyi as antigen but showing that epitopes recognized on the protein with a molecular weight of 15,000-17,000 were different.

Major antigens of Cryptosporidium parvum recognised by serum antibodies from different infected animal species and man.

Serum humoral immune response to Cryptosporidium parvum was evaluated in six species: mouse, rabbit, lamb, calf, pig and man. Electrophoretic and immunoblot analysis showed that specific animal antibody response appeared between Day 4 and Day 15 post inoculation. The two main target antigens had apparent molecular weights of 15-17 and 23 kDa. They were recognised by each species studied. Serum IgA intensively recognised the 15-17 kDa antigen, except in rabbit. This study demonstrates that these two antigens are consistent targets of humoral immune response and can therefore be of great interest in studies of therapy/prophylaxis.

Treatment of experimental ovine cryptosporidiosis with ovine or bovine hyperimmune colostrum.

Ovine or bovine colostrums with different antibody titers were tested for their ability to prevent cryptosporidiosis in five groups of neonatal lambs experimentally infected with 10(6) Cryptosporidium parvum oocysts 2 days after birth (Day 0). In a control group (Group 1), six lambs were deprived of ewe colostrum and exclusively fed with milk replacer. Two groups of six lambs were allowed to suckle their non-hyperimmunized (Group 2) or hyperimmunized (Group 3) dams throughout the experiment. Two groups of seven lambs were separated from their dams at birth before suckling and fed with non-hyperimmune (Group 4) or hyperimmune (Group 5) bovine colostrum; for 7 days they received 50 ml of colostrum completed by milk replacer twice a day, then they were fed with milk replacer exclusively. Control lambs became infected and developed clinical cryptosporidiosis with diarrhea on Days 4-9 post inoculation, oocyst shedding and mortality (2/6). In all the treated groups, the colostrum prevented mortality and clinical cryptosporidiosis. The mortality (5/7) observed in Group 5 was not due to cryptosporidiosis but anemia. In treated groups, specific antibodies were detected on Day 0 after 2 days of colostrum intake and varied little in time for IgM and IgG in spite of the parasite development, whereas they appeared later in the control group, on Day 4 for IgM, Day 11 for IgA and Day 14 for IgG. In all groups, the response which was the most consistent was the IgA response which evolved from Days 11 to 18 in association with the decline of oocyst shedding. Our results show that whatever the serum antibody titers were, the specific C. parvum circulating antibodies have no influence on the control of cryptosporidiosis. The prophylaxis or the treatment of cryptosporidiosis require high titers of specific C. parvum antibodies in the gut lumen during a sufficiently long period.

Humoral antibody response and oocyst shedding after experimental infection of histocompatible newborn and weaned piglets with Cryptosporidium parvum.

Experimental inoculations (mono- and multi-inoculations) with C parvum isolated from a diarrheic child and maintained on calves, were performed on 2 histocompatible miniature (d/d haplotype) weaned 4-week-old piglets and 2 newborn piglets. In each group, 1 piglet received water at the moment of inoculation and served as a negative control. Our results showed that the piglet strain used was resistant to cryptosporidiosis. No clinical sign or oocyst shedding were observed in newborn piglets. A very weak shedding was noticed on day 6 (D6) post-inoculation in inoculated weaned piglets. Using ELISA, inoculated weaned piglets showed a peak of G, M and total antibodies on D10. Specific IgA antibody production peaked on D20. During the experiment on newborn piglets, no peak of specific IgA production was detected. Using immunoblotting, sera of both inoculated weaned piglets and one inoculated newborn piglet were shown to recognize a 14.5-16.5 kDa protein. A 23 kDa antigen was recognized by all 3 uninoculated and inoculated weaned piglets. A difference between mono and multi-inoculations was not clearly demonstrated. Age did not play any role. This pig strain does not seem to be a good model to induce acute cryptosporidiosis.

Immunological characterization of a 17-kDa antigen from Cryptosporidium parvum recognized early by mucosal IgA antibodies.

Cryptosporidium parvum antigens were characterized by immunoblot analysis of sera and intestinal secretions of BALB/c mice orally infected with 10(5) oocysts. A major band at 17 kDa under non-reduced conditions and at 18 kDa under reduced conditions was recognized by anti-C. parvum IgA and IgG in serum and intestinal secretions from day 15 post-infection. This recognition persisted throughout the experiment (day 30). Mouse-serum antibodies raised against the 17-kDa purified antigen (P17) showed no cross-reactivity with other C. parvum antigens. Immunofluorescence study revealed that this antigen is located on the sporozoite. It is suggested that this antigen could be a good candidate for studies of mucosal immune response to C. parvum and for vaccination.