Fungi, including Pithomyces chartarum cause facial eczema and inflammation in grazing sheep in Western China

Facial eczema is often found in flocks of grazing sheep in China. To investigate fungi species those cause disease and pathological roles. Forage and soil samples were collected during the pathogenic season and cultured. Samples were collected from regions with and without facial eczema affected sheep. Fungal isolation and identification, statistical analysis of fungal species and distribution were performed. Pathological changes, biochemical parameters of serum liver function and protection of inflammatory factors that tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-12 (IL-12) were observed. Fungal cultivation and identification showed that separation rate of Alternaria, Pithomyces chartarum, Fusarium and Aspergillus were higher, particularly, Pithomyces chartarum was significantly identical. Pathological anatomy and histology indicated that the disease likely attacked merino ewes with the age of 6 months old. The clinical manifestations were characterized by inflammational edema in face (ears and eyelids) and mandibular area. Postmortem examination of dead lambs showed enlargement of liver with yellow white patchs of necrotic lesion and tuberous sclerosis and fibrosis on section. Histologic examination of liver showed extravasated blood, severe lesion of liver cells and bile duct, and fatty degeneration. In sheep, fungal toxin induced the secretion of TNF-α, IL-6 and IL-12. These results revealed that Pithomyces chartarum maybe caused facial eczema and inflammation in sheep. The facial eczema was allergic eczema caused by hepatic dysfunction and hepatonecrosis.

An observational study on the relationship between zinc concentrations in bulk tank milk and in serum and farmer-reported zinc supplementation of dairy cattle for facial eczema prophylaxis

AIMS

To describe the concentration of Zn in bulk tank milk (BTM) in a sample of New Zealand dairy farms, investigate the association between the method of Zn administration for facial eczema prophylaxis and Zn concentrations in BTM and investigate the relationship between the concentration of Zn in serum and that in BTM.

METHODS

Multiple BTM samples (n = 3,330) collected during milk pick-up by the milk tanker driver were stored and tested for 121 farms, in Northland (n = 50), Waikato (n = 51) and Southland (n = 20) from February to May 2017. Enrolled farms provided retrospective information on the type of Zn supplementation (if any) used for the prevention of facial eczema and the timeframe over which supplementation occurred. In addition, the concentration of Zn in serum was measured in blood samples collected from ≥15 cattle per farm for 22 farms from Northland (n = 11) and Waikato (n = 11), and compared against the concentrations of Zn in BTM on the day of blood sampling. A linear mixed model was used to model log Zn concentrations in BTM using method of Zn supplementation, region, milk fat and protein percentage, volume of milk, and frequency of milk pick-up as risk factors. A mixed logistic regression model was used to assess the relationship between Zn concentrations in BTM and the presence of cows with a concentration of Zn in serum of ≥20 µmol/L.

RESULTS

The median Zn concentration in BTM was 67.9 (min 38.9, max 146.6) µmol/L. The median range of Zn concentrations for repeated samples of BTM within farm was 22.6 µmol/L. In comparison to farms that did not use any form of Zn supplementation, farms that supplemented Zn through a slow-release capsule, oral drench, in feed or a combination of in-feed and water were associated with increased concentrations of Zn in BTM (p < 0.001). There was no difference in Zn concentrations in BTM between farms that administered Zn through the water only and farms that did not administer Zn (p = 0.22). Every 15.3 μmol/L increase in Zn concentration in BTM was associated with 2.2 times (95% CI=1.7-2.9) the odds of a cow having Zn concentration in serum ≥20 μmol/L.

CONCLUSION AND CLINICAL RELEVANCE

Zn concentration in BTM is highly variable between farms, days and Zn administration method. Zn concentration in BTM content has modest potential as a way to signal whether a herd has achieved the high Zn status considered to be protective against FE.

Genomic Tools for the Identification of Loci Associated with Facial Eczema in New Zealand Sheep

Facial eczema (FE) is a significant metabolic disease that affects New Zealand ruminants. Ingestion of the mycotoxin sporidesmin leads to liver and bile duct damage, which can result in photosensitisation, reduced productivity and death. Strategies used to manage the incidence and severity of the disease include breeding. In sheep, there is considerable genetic variation in the response to FE. A commercial testing program is available for ram breeders who aim to increase tolerance, determined by the concentration of the serum enzyme, gamma-glutamyltransferase 21 days after a measured sporidesmin challenge (GGT21). Genome-wide association studies were carried out to determine regions of the genome associated with GGT21. Two regions on chromosomes 15 and 24 are reported, which explain 5% and 1% of the phenotypic variance in the response to FE, respectively. The region on chromosome 15 contains the β-globin locus. Of the significant SNPs in the region, one is a missense variant within the haemoglobin subunit β (HBB) gene. Mass spectrometry of haemoglobin from animals with differing genotypes at this locus indicated that genotypes are associated with different forms of adult β-globin. Haemoglobin haplotypes have previously been associated with variation in several health-related traits in sheep and warrant further investigation regarding their role in tolerance to FE in sheep. We show a strategic approach to the identification of regions of importance for commercial breeding programs with a combination of discovery, statistical and biological validation. This study highlights the power of using increased density genotyping for the identification of influential genomic regions, combined with subsequent inclusion on lower density genotyping platforms.

Cloning, mapping and association studies of the ovine ABCG2 gene with facial eczema disease in sheep

Facial eczema (FE) is a hepatogenous mycotoxicosis in sheep caused by the fungal toxin sporidesmin. Resistance to FE is a multigenic trait. To identify QTL associated with this trait, a scan of ovine chromosomes was implemented. In addition, ABCG2 was investigated as a possible positional candidate gene because of its sequence homology to the yeast PDR5 protein and its functional role as a xenobiotic transporter. The sequence of ovine ABCG2 cDNA was obtained from liver mRNA by RT-PCR and 5' and 3' RACE. The predicted protein sequence shares >80% identity with other mammalian ABCG2 proteins. SNPs were identified within exon 6, exon 9 and intron 4. The intron 4 SNP was used to map ABCG2 to ovine chromosome 6 (OAR6), about 2 cM distal to microsatellite marker OarAE101. Interestingly, this chromosomal region contains weak evidence for a FE QTL detected in a previous genome-scan experiment. To further investigate the association of ABCG2 with FE, allele frequencies for the three SNPs plus three neighbouring microsatellite markers were tested for differences in sheep selected for and against FE. Significant differences were detected in the allele frequencies of the intronic SNP marker among the resistant, susceptible and control lines. No difference in the levels of ABCG2 expression between the resistant and susceptible animals was detected by Northern hybridisation of liver RNA samples. However, significantly higher expression was observed in sporidesmin-dosed sheep compared with naïve animals. Our inference is that the ABCG2 gene may play a minor role in FE sensitivity in sheep, at least within these selection lines.

[First case of pithomycotoxicosis (facial eczema) in the Netherlands]

Between mid September and the beginning of November 2005, the Animal Health Service (AHS) received thirteen reports offarms on which several animals showed severe symptoms of solar eczema. Blood chemistry showed very high levels of GOT/AST and GGT indicative of severe liver damage. Farm visits to eight farms showed that the animals--previous to the start of the symptoms--had been grazing 24 hours/day and received no additional feed. Ingestion of poisonous plants or medications was considered unlikely to have caused the liver damage, and liver fluke infections were present on only two farms. Microscopic examination of specimens of grass revealed the presence of spores of Pithomyces chartarum in samples taken from six of nine farms. This fungus produces the mycotoxin sporidesmin, which causes severe liver damage and pithomycotoxicosis (facial eczema). This article is the first to describe Pithomyces chartarum in cattle in mainland Europe. Further research on the distribution and re-occurrence of Pithomyces chartarum infection and sporidesmin survival in grass silage is recommended.

IgE and IgG antibodies in skin allergy of the horse

In horses, allergies have been characterized by clinical signs and/or intradermal (i.d.) allergen testing. Our aim was to find the first direct evidence that immunoglobulin E (IgE) mediates equine allergy. In addition, we tested the hypothesis that immediate skin reactions in horses can also be mediated by IgG. Anti-IgE affinity columns were used to purify IgE from serum of one healthy horse and three horses affected with summer eczema, an allergic dermatitis which is believed to be induced by Culicoides midges. A modified Prausnitz-Küstner experiment was performed in four clinical healthy horses by i.d. injection of the purified serum IgE antibodies. The following day, Culicoides allergen was injected at the same sites. Skin reactions were not observed in response to allergen alone, and in two horses after stimulation at any previous IgE injection site. However, the other two horses showed an immediate skin reaction at the previous injection sites of IgE obtained from allergic horses. In addition, purified monoclonal antibodies to various equine immunoglobulin isotypes were injected i.d. into six healthy horses. Immediate skin reactions were observed in response to anti-IgE (6/6 horses) and anti-IgG(T) injections (5/6 horses). The specificities of both antibodies for IgE and IgG(T), respectively, were confirmed by enzyme linked immunosorbent assays. The results provide the first direct evidence that IgE mediates classical Type-I allergy in horses and plays a major role in the pathogenesis of summer eczema. The data also suggest that IgG(T) can bind to skin mast cells and might contribute to clinical allergy.

Summer eczema in exported Icelandic horses: influence of environmental and genetic factors

A cross sectional study was designed to estimate the prevalence of summer eczema (a chronic, recurrent seasonal dermatitis) in exported Icelandic horses and the influence of environmental and genetic factors on the development of the disease.

Among 330 horses, which had been exported to Germany, Denmark and Sweden, 114 (34.5%) were found to have clinical signs of summer eczema. The prevalence was highest 2 years after export and the exposure to the biting midges Culicoides spp., was found to be the main risk factor for developing the disease. Genetic influence on the sensitivity for the disease was not established.

It was concluded that exported Icelandic horses are predisposed for summer dermatitis and the fact that they are not introduced to the antigens of the biting midges early in live, due to it's absence in Iceland, is likely to explain the high prevalence of the disease after export.

Pithomycotoxicosis (facial eczema) in ruminants in the Azores, Portugal

Outbreaks of pithomycotoxicosis (facial eczema), a hepatogenous photosensitisation caused by the mycotoxin sporidesmin, have affected ruminants in the Azores Islands of Portugal after warm, humid periods during late summer and autumn. Twenty-two outbreaks were recorded in cattle between 1999 and 2001, affecting 11.4 per cent of the animals in the affected herds, and in 2000 there was an outbreak in one sheep flock in which more than 20 per cent of the sheep died. The clinical signs included decreases in milk production, weight loss, photosensitisation and its sequelae, including death. The animals had high activities of gamma glutamyltransferase in their serum, and icterus and severe liver disease, including biliary hyperplasia and fibrosis, were found postmortem. The characteristic spores of the toxigenic saprophytic fungus Pithomyces chartarum were found on grass; all 381 isolates of the fungus were toxigenic for sporidesmin by elisa, and the results were confirmed by high-performance liquid chromatography analysis. Cattle from farms at greatest risk of pithomycotoxicosis were protected by supplementing their concentrate feed with zinc oxide, or using a slow-release intraruminal zinc bolus.

Catalase gene is associated with facial eczema disease resistance in sheep

Facial eczema (FE) is a hepatogenous photosensitization disease of ruminant animals, particularly in sheep which vary widely in their susceptibility to the disease. The liver damage is caused by the mycotoxin, sporidesmin. There is evidence that the toxicity of sporidesmin is due to its ability to generate 'active oxygen' species. We evaluated the catalase gene, which encodes an enzyme with antioxidant functions, as a candidate for determining the susceptibility of sheep to the disease. Two microsatellite markers, OarSHP3 and OarSHP4, which flank the sheep catalase gene, were isolated from a Yeast Artificial Chromosome (YAC) clone. These markers mapped the catalase locus by linkage to ovine chromosome 15. Eleven informative markers spaced throughout chromosome 15, inclusive of the catalase marker OarSHP4, gave no significant linkage with the disease traits when analysed in four outcross resource pedigrees. However, OarSHP3 and OarSHP4 allele frequencies showed significant differences between FE resistant and susceptible selection-lines. Comparison of sequences of catalase cDNAs from sheep of resistant and susceptible lines showed only two silent mutations. A single nucleotide polymorphisms (KP1) in exon 6 of the catalase gene also showed significant differences in allele frequencies between the selection lines. The lack of evidence for linkage in outcross pedigrees, but the significant association in the genetic lines, implies that catalase is involved in determining the susceptibility of sheep to facial eczema, and that the candidate gene's effect is probably recessive or minor.

Biological control of sporidesmin-producing strains of Pithomyces chartarum by biocompetitive exclusion

The feasibility of using atoxigenic strains of Pithomyces chartarum for the biological control of toxigenic strains of P. chartarum was examined. Pasture, treated with atoxigenic strains of P. chartarum, contained up to 80% less sporidesmin than found in untreated pasture. Maximum sporidesmin levels of 26 ng g-1 grass in treated pasture and 113 ng g-1 grass in untreated pasture (means of 24 and four plots, respectively) were recorded 14 weeks after treatment, when spore numbers had reached a maximum of 80,000 spores g-1 grass in the untreated plots and 50,000 spores g-1 grass in the treated plots. This trial demonstrated that sporidesmin-producing spores of P. chartarum could be successfully reduced in pasture by the addition of atoxigenic strains, thereby reducing the risk of facial eczema in livestock.

Photosensitization associated with exposure to Pithomyces chartarum in lambs

An epidemic of photosensitization was observed in a group of lambs on irrigated autumn pasture in western Oregon. Signs included crusting, necrosis, and sloughing of the skin over the nostrils, lips, and ears, and of the mucous membranes of the buccal regions. Microscopic examination of plant material from the pasture disclosed spores of Pithomyces chartarum. This fungus has been documented as a causal factor in photosensitization in sheep and cattle (facial eczema) in other parts of the world. An infective agent or other plant material that could have induced the clinical signs in the lambs was not evident. Weather and humidity conditions were ideal for fungal growth during the grazing period, and the fungus was detected in large numbers before and during the epidemic. Even though facial eczema has not been reported previously in northwestern United States, we feel the circumstances surrounding this epidemic warrant such a diagnosis.

Mouse micronucleus assays of sporidesmin, the toxin associated with facial eczema in ruminants

Sporidesmin, a fungal toxin with widespread distribution within New Zealand, was previously shown to be a potent clastogen in Chinese hamster cells in vitro, but not in peripheral blood lymphocytes of sheep in vivo. In mice, massive oral doses led only to slight increases in micronucleus levels in the bone marrow, despite highly significant changes to other toxicological parameters. It would appear that the intact animal is protected in some fashion from the clastogenic effects of sporidesmin, although this substance must still be considered a potential human genotoxic agent.

In vitro and in vivo mutagenicity studies on sporidesmin, the toxin associated with facial eczema in ruminants

Sporidesmin, a fungal toxin with widespread distribution within New Zealand, is thought to exert toxic effects through oxidative damage. The purified chemical was tested for its ability to cause point mutations in four strains of Salmonella typhimurium (TA98, TA100, TA102 and TA1537), in the presence and absence of exogenous metabolic activation. Although toxic effects were seen at concentrations exceeding 400 mu gl/plate, there were no significant increases in revertant colonies. In strain TA102, these results were not modified by the presence of glutathione. In AA8 Chinese hamster cells, sporidesmin acted as a potent clastogen, causing chromosomal breaks at concentrations as low as 3 ng/ml, where there was very little reduction in cell viability. Effects were primarily at the chromatid level, but some chromosomal events were also seen. Following low doses, the most common events were chromatid deletions and induction of double minute chromosomes. Interchange events occurred at concentrations of 10 ng/ml and above. The most common of these events was an incomplete chromatid interchange, although some examples of complete chromatid and chromosomal interchange were seen. These in vitro experiments were subsequently extended to an in vivo study of sporidesmin-induced lymphocytic micronuclei (MN) in sheep. In a double blind experiment, 5 sheep were treated with a single high dose of sporidesmin. Blood samples were taken from these, and from 5 untreated sheep, at various intervals before and after treatment. Peripheral blood lymphocytes cultures were harvested and scored for MN in cytokinesis-blocked cells, as a measure of clastogenic activity of sporidesmin in vivo. Following decoding, statistical analysis of the data revealed no significant differences between the MN levels in peripheral blood lymphocytes of sporidesmin-treated and untreated sheep. Although the possibility still exists that clastogenic effects could occur in other species, the data indicate that sporidesmin is not a clastogen in sheep, even though this species is highly susceptible to the toxic effects of sporidesmin.

CAMP-reaction among skin isolates obtained from a dog with an acute squamous eczema

The primary culture of a clinical specimen obtained from a dog with an acute squamous eczema revealed 3 different bacterial cultures. Two of these cultures, a beta-hemolytic Staphylococcus aureus and a group B streptococcal culture, demonstrated synergistic hemolytic activities on this primary culture plate. The group B streptococcus had the serotype surface antigens Ib/c, protein antigen c in its c beta component.

Synergistic hemolytic reactions between staphylococci and Micrococcus lylae

The primary culture of a clinical specimen obtained from a dog with an acute squamous eczema revealed three different bacterial species which demonstrated synergistic hemolytic activities on sheep blood agar plates. The three cultures were identified as beta-hemolytic Staphylococcus intermedius, as a coagulase-negative staphylococcal species, producing a delta-like hemolysin and as non-hemolytic Micrococcus lylae. The coagulase-negative staphylococcal species as well as M. lylae produced synergistically with beta-hemolytic S. intermedius zones of complete hemolysis. The occurrence of three different synergistically active bacterial species from one clinical specimen might be of clinical significance.

Suspected facial eczema in sheep in the central Orange Free State

Facial eczema is known to occur in the Humansdorp district of the Cape Province. During June 1982-January 1984, 5 outbreaks of hepatogenous photosensitivity occurred in sheep in central districts of the Orange Free State. In one of these outbreaks a diagnosis of suspected facial eczema was made histologically.

Photosensitivity in South Africa. V. A comparative study of the pathology of the ovine hepatogenous photosensitivity diseases, facial eczema and geeldikkop (Tribulosis ovis), with special reference to their pathogenesis

The subject of this study was the pathological and scanning electron microscopical changes in the biliary systems of sheep suffering from facial eczema or geeldikkop (Tribulosis ovis), or made photosensitive by ligation of the common bile duct. While an obliterative cholangitis is responsible for the retention of phylloerythrin in facial eczema, the occlusion of bile ducts with crystalloid material (microliths) appear to perform a similar function in geeldikkop. The similarities and differences between the 2 diseases are discussed in the light of their pathogenetic mechanisms.

The pharmacological role of zinc: evidence from clinical studies on animals

Understanding the roles of zinc in the liver is likely to lead to improved therapy of some clinical conditions. Zinc appears to stimulate protein synthesis in the liver where it increases the binding and inhibits the degradation of insulin. Stimulating or maintaining protein synthesis in the liver is crucial to the outcome of parturition, injury or hepatotoxin challenge. A critical liver protein in circulatory collapse is angiotensinogen. This paper describes the observations of animal responses, in a practical farm situation, to zinc medication.

An infected eczematous condition in mice: methods of treatment

Eczematous lesions in VM mice were invariably infected with Staphylococcus pyogenes aureus. A variety of preparations was used in treatment and although most were ineffective, one combining steroid and antibiotic therapy achieved remarkable results.

A study of skin diseases in dogs and cats. III. III. Microflora of the skin of dogs with chronic eczema

The microflora of the skin was studied in 10 dogs with chronic eczema without clinical signs of secondary infection (Table I). The skin surface was swabbed at 7 different sites, making a total of 70 swabs, 25 of which were taken from visibly inflamed areas and 45 from apparently unaffected skin (Table II). Staph. aureus, Staph. epidermidis, micrococci, alpha-hemolytic streptococci, and Acinetobacter spp. were found consistently. Ten different Gram-negative bacteria, 3 different Gram-positive bacteria, and 2 yeasts were found to occur sporadically (Table III). Compared to a group of 10 healthy dogs a more prolific growth of aerobic microorganisms, a greater number of sites carrying Staph. aureus, and a higher recovery of Gram-negative transients were found in dogs with eczema (Table IV--VII). Within the group of dogs with eczema the growth of Staph. aureus was significantly heavier from eczematous skin areas than from clinically normal skin (Table VIII). In dogs with non-infective dermatitides the colonization of the skin by potentially pathogenic microorganisms may have to be considered in the clinical handling of these diseases.