First report of Eimeria leuckarti infection in a horse in New Zealand

The protozoan parasite, Eimeria leuckarti was present in the ileal mucosa of a 7-month-old Thoroughbred filly which was destroyed with acute peritonitis resulting from perforation of the rectum. The parasite was considered to be of no clinical significance and the signs of colic noted prior to the rectal rupture were related to the vascular lesions caused by infection with Delafondia vulgaris.     

First report of Eimeria leuckarti infection in a horse in New Zealand

The protozoan parasite, Eimeria leuckarti was present in the ileal mucosa of a 7-month-old Thoroughbred filly which was destroyed with acute peritonitis resulting from perforation of the rectum. The parasite was considered to be of no clinical significance and the signs of colic noted prior to the rectal rupture were related to the vascular lesions caused by infection with Delafondia vulgaris.     

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.     

Natural infection with Dictyocaulus arnfieldi in pony and donkey foals

From June to October 1978 four pony mares and foals and two donkey mares and foals grazed a paddock contaminated with Dictyocaulus arnfieldi larvae. No signs of respiratory disease were seen in the foals but within 11 weeks of exposure to the paddock all six developed patent lungworm infections. In October 1978 one donkey and two pony foals were killed. At post mortem examination parasites in various stages of development and measuring up to 8 cm in length were found in the lungs. At this time the three surviving foals were stabled for the remainder of the experiment. Two of these ceased passing D arnfieldi larvae during the winter months but in one pony foal patency persisted until the study ended in August 1979. Patent lungworm infections were not seen in the pony mares, although two started to cough four to six weeks after starting to graze the infected paddock. One of the affected mares was killed in October 1978 when seven small (less than 7 mm) D arnfieldi were recovered. The other continued to cough until the end of the study over a year later.     

Prevalence of oocysts of Isospora suis and Eimeria spp from sows on farms with and without a history of neonatal coccidiosis

Oocysts of Isospora suis were not found in any of 77 fecal samples from sows on farms with a history of neonatal coccidiosis. Oocysts of Isospora suis were found in 1 of 172 fecal samples from farms without a history of neonatal coccidiosis. Oocysts of Eimeria spp were found in 81.8% of the sows from farms with a history of neonatal coccidiosis and in 94.8% of the sows from farms without a history of neonatal coccidiosis. Oocysts of Isospora spp from birds were encountered as a pseudoparasite in several fecal samples.     

Natural infection of a horse with Fascioloides magna.

A 25-year-old Quarterhorse mare was euthanized for a variety of medical reasons. At necropsy, 7 liver flukes, identified as Fascioloides magna, were recovered from the liver. This is the first report of F. magna in a horse.     

Association of soil concentrations of Rhodococcus equi and incidence of pneumonia attributable to Rhodococcus equi in foals on farms in central Kentucky

OBJECTIVE: To determine whether soil concentrations of total or virulent Rhodococcus equi differed among breeding farms with and without foals with pneumonia caused by R equi. SAMPLE POPULATION: 37 farms in central Kentucky. Procedures-During January, March, and July 2006, the total concentration of R equi and concentration of virulent R equi were determined by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively, in soil specimens obtained from farms. Differences in concentrations and proportion of virulent isolates within and among time points were compared among farms. RESULTS: Soil concentrations of total or virulent R equi did not vary among farms at any time point. Virulent R equi were identified in soil samples from all farms. Greater density of mares and foals was significantly associated with farms having foals with pneumonia attributable to R equi. Among farms with affected foals, there was a significant association of increased incidence of pneumonia attributable to R equi with an increase in the proportion of virulent bacteria between samples collected in March and July. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that virulent R equi were commonly recovered from soil of horse breeding farms in central Kentucky, regardless of the status of foals with pneumonia attributable to R equi on each farm. The incidence of foals with pneumonia attributable to R equi can be expected to be higher at farms with a greater density of mares and foals.     

Transmission of endoparasites in horse foals born on the same pasture on a farm in central Kentucky (1996-1999)

Research carried out during the last 4 years (1996-1999) of an 11-year study of the prevalence of internal parasites naturally transmitted to horse foals born on the same pasture on a farm in central Kentucky is presented here. Horses in this herd were not treated with any antiparasitic compound for over 20 years except for a replacement stallion in 1994. A total of 22 species, including 12 species of small strongyles, were recovered in the 4-year period. Transmission patterns of all species (n=35) of endoparasites recovered are compared for the 11-year study. Some of the changes were an increase in number of Thelazia lacrymalis and Anoplocephala perfoliata and a decrease in Gasterophilus intestinalis, Parascaris equorum, and Strongylus vulgaris. Clinical problems associated with parasitism were not observed in any of the 92 foals in the long-term investigation.     

Endocrine changes in the fowl during infection with Eimeria maxima

Plasma concentrations of thyroxine (T4), triiodothyronine (T3), prolactin, growth hormone and corticosterone were measured in immature domestic fowl which were infected with Eimeria maxima, uninfected but given the same amount of food as those infected (pair-fed) or fed ad libitum. Infection with E maxima caused a decrease in plasma T4 concentration whereas pair feeding caused an increase when food intake was minimal. Plasma T3 concentrations were decreased similarly in both infected and pair-fed birds. Infection caused an increase in plasma prolactin concentration, whereas pair-feeding did not. The plasma concentration of growth hormone was not affected by any of the treatments. Plasma corticosterone concentration was markedly increased on days 5 and 6 in pair-fed birds but was not affected by infection with E maxima.     

The prevalence of Cryptosporidium, and identification of the Cryptosporidium horse genotype in foals in New York State

To date, little is known about the prevalence, genotypes and zoonotic potential of Cryptosporidium spp. affecting horses, especially in North America. A cross-sectional study was conducted in New York, USA between February 25th and May 1st 2009. Fecal samples were collected from three hundred and forty nine 1-10-week-old foals and their dams on 14 different broodmare farms. All fecal samples were screened for Cryptosporidium spp. using a direct immunofluorescence assay (DFA). DNA extraction and PCR-RFLP analysis of the small-subunit (SSU) rRNA gene were performed on all the foal samples. PCR-positive samples were subtyped by DNA sequencing of the 60-kDa glycoprotein (gp60) gene. On DFA, 13/175 (7.4%) foal samples and 3/174 (1.7%) mare samples were designated positive for Cryptosporidium spp., whereas on SSU rRNA-based PCR, 9/175 (5.1%) foal samples were positive. Cryptosporidium PCR-positive foals were significantly older (13-40 days, median age of 28 days) compared with negative foals (4-67 days, median 18 days, p=0.02). The number of foals with diarrhea or soft feces was not significantly different between positive and negative foals (p=0.09). PCR-RFLP analysis of the SSU rRNA gene and DNA sequencing of the gp60 gene identified the parasite as subtype VIaA14G2 of the horse genotype. This is the first report of a group of foals affected with the Cryptosporidium horse genotype, which has recently been detected in humans. As other contemporary molecular studies have identified C. parvum in foals, it seems that equine cryptosporidiosis should be considered a zoonosis.     

Prevalence of benzimidazole resistance on horse farms in Germany

Faecal egg counts (FECs) were made on samples from 1383 horses on 64 farms in northern Germany between August 2000 and November 2001. There were significant differences between the mean FECs in the two years; in 2000, 59.6 per cent of 369 samples were positive and in 2001, 32.6 per cent of 1014 samples were positive for strongyle eggs. The results of a FEC reduction test indicated that resistance to fenbendazole was present on all 10 farms where it had been used, including in 33 of 60 horses tested. In contrast, treatment with ivermectin resulted in the complete elimination of nematode eggs in all the 77 horses tested. The mean LD50 values of the egg hatch test for thiabendazole indicated resistance on all 20 farms investigated and in 94 of 134 samples (70 per cent).     

Hematologic and immunophenotypic factors associated with development of Rhodococcus equi pneumonia of foals at equine breeding farms with endemic infection

Rhodococcus equi causes severe pyogranulomatous pneumonia in foals and in immunocompromised people. In mice, both CD4+ and CD8+ T lymphocytes contribute to host defense against R. equi, but CD4+ T lymphocytes are required for pulmonary clearance of the bacteria. In this prospective study of 208 foals at two equine breeding farms with endemic R. equi infections, we collected peripheral blood samples at 2 and 4 weeks of age and at the time of diagnosis of R. equi pneumonia. Samples were analyzed for concentrations of total and differential leukocytes, EqCD4+ and EqCD8+ T lymphocytes, and B lymphocytes. Thirty (14.4%) foals developed R. equi pneumonia. At the 2nd week of life, affected foals had significantly lower concentrations of white blood cells (WBC) and segmented neutrophils, significantly lower proportions of EqCD4+ T lymphocytes, and significantly higher proportions of EqCD8+ T lymphocytes. The EqCD4:EqCD8 ratio was significantly lower for affected foals. At the 4th week of life, affected foals had significantly lower concentrations of segmented neutrophils and EqCD4+ T lymphocytes than did unaffected foals. The ratio of EqCD4:EqCD8 was significantly lower for affected foals. Two- and 4-week-old foals with ratios of EqCD4:EqCD8<3 were significantly more likely to develop R. equi pneumonia. There was a significant farm effect which diluted our statistical power to detect differences; however; after adjusting for the farm effect, 2-week-old foals with ratios of EqCD4:EqCD8<3 remained significantly more likely to develop R. equi pneumonia. There were no significant differences in immunophenotypic variables between affected foals (at the time of diagnosis) and age-matched control foals. These data suggest that there are hematologic and immunophenotypic differences between affected and unaffected foals during the first 2-4 weeks of life, prior to onset of clinical signs of R. equi pneumonia. These differences may represent important immunologic mechanisms associated with increased susceptibility of individual foals to infection with R. equi. Because there was considerable overlap between values for affected and unaffected foals, we cannot yet recommend immunophenotyping of foals at endemically-infected farms as a clinically useful screening tool to identify foals at increased risk of developing R. equi pneumonia.     

Effect of prophylactic administration of hyperimmune plasma to prevent Rhodococcus equi infection on foals from endemically affected farms

The effect on foals of prophylactic administration of hyperimmune plasma to prevent R. equi infection was investigated on three farms at which R. equi infection was endemic. Sixteen foals between 10 and 39 days of age were intravenously given 1-21 of hyperimmune plasma. ELISA antibody titres against R. equi were significantly increased and maintained at high levels for over 30 days in most of the recipient foals. The prevalence of R. equi infection was 6.3% (1/16) in the foals that received the immune plasma, and 26.3% (5/19) in the control foals not given the immune plasma on the three farms. For 2 years before and after this field trial on the three farms, 18 of 64 foals (28.1%) showed clinical signs of respiratory tract infection and four of them died of R. equi pneumonia. Heavy contamination of horses and their environment with virulent R. equi was detected by colony blotting, and plasmid profiles also suggested that foals on the three farms were constantly exposed to virulent R. equi. The results of this field trial support previous observations by some researchers that the administration of hyperimmune plasma to foals in the early days of life promotes prevention of R. equi infection on endemic farms; however, the mechanism of hyperimmune plasma protection remains unclear.     

Absorption and deposition of xanthophylls in broilers challenged with three dosages of Eimeria acervulina oocysts

1. An experiment was designed to evaluate the effect of different doses of oocysts of Eimeria acervulina on intestinal absorption and skin deposition of xanthophylls (XAs) in broilers.

2. A total of 192 broiler chickens were randomly assigned to 4 groups: an uninfected control group and three groups inoculated with either 1 × 10², 1 × 10⁴ or 1 × 10⁵ sporulated oocysts of E. acervulina by gavaging at 21 d. There were 4 replicate pens (2 male and 2 female) per group.

3. Plasma xanthophyll (PX) and skin yellowness (SY) were measured in live birds weekly. At 42 d of age, SY was measured in the breast and abdomen after chilling and in the breast 24 h post-processing on refrigerated carcasses.

4. In general, in all challenged treatments, and for the duration of the study, the average PX decreased by 0.02 μg/ml (R² = 61.6%) for every 1000 inoculated oocysts, whereas PX increased by 1.26 μg/ml/d in uninfected birds.

5. The average SY in live birds from 21 to 42 d of age decreased by 0.019 b*/every 1000 oocysts administered, while SY of uninfected controls increased by 0.57 b*/d. It was also noted that in all treatments females had a greater SY (6.17 b*) than males for the duration of the study. The SY of the breast and abdomen was correlated (r = 0.76) in chilled carcasses. Breast SY in 24 h refrigerated carcasses was greater in the control group and for female birds.

6. Oocyst excretion was different between inoculated treatments only on 7 d post-inoculation (PI). Coccidia lesion scores in the duodenum averaged 1+ in infected birds and 2+ in birds given the highest oocyst dose.     

Characterization of Clostridium perfringens in the feces of adult horses and foals with acute enterocolitis

Up to 60% of cases of equine colitis have no known cause. To improve understanding of the causes of acute colitis in horses, we hypothesized that Clostridium perfringens producing enterotoxin (CPE) and/or beta2 toxin (CPB2) are common and important causes of severe colitis in horses and/or that C. perfringens producing an as-yet-undescribed cytotoxin may also cause colitis in horses. Fecal samples from 55 horses (43 adults, 12 foals) with clinical evidence of colitis were evaluated by culture for the presence of Clostridium difficile, C. perfringens, and Salmonella. Feces were also examined by enzyme-linked immunosorbent assay (ELISA) for C. difficile A/B toxins and C. perfringens alpha toxin (CPA), beta2 toxin (CPB2), and enterotoxin (CPE). Five C. perfringens isolates per sample were genotyped for the following genes: cpa, cpb, cpb2 consensus, cpb2 atypical, cpe (enterotoxin), etx (epsilon toxin), itx (iota toxin), netB (necrotic enteritis toxin B), and tpeL (large C. perfringens cytotoxin). The supernatants of these isolates were also evaluated for toxicity for an equine cell line. All fecal samples were negative for Salmonella. Clostridium perfringens and C. difficile were isolated from 40% and 5.4% of samples, respectively. All fecal samples were negative for CPE. Clostridium perfringens CPA and CPB2 toxins were detected in 14.5% and 7.2% of fecal samples, respectively, all of which were culture-positive for C. perfringens. No isolates were cpe, etx, netB, or tpeL gene-positive. Atypical cpb2 and consensus cpb2 genes were identified in 15 (13.6%) and 4 (3.6%) of 110 isolates, respectively. All equine C. perfringens isolates showed far milder cytotoxicity effects than a CPB-producing positive control, although cpb2-positive isolates were slightly but significantly more cytotoxic than negative isolates. Based on this studied population, we were unable to confirm our hypothesis that CPE and CPB2-producing C. perfringens are common in horses with colitis in Ontario and we failed to identify cytotoxic activity in vitro in the type A isolates recovered.