Estudo de alguns constituintes sanguíneos de bovinos intoxicados naturalmente pela micotoxina esporidesmina / Study of some haematologycal constituents of cattle naturally poisoning by sporidesmin mycotoxin

Determinaram-se o hemograma, o proteinograma sérico, os níveis séricos de gamaglutamiltransferase e de bilirrubina e o tempo médio de excreçäo de bromossulfaleína de bovinos acometidos pelas formas subclínicas, subaguda e crônica da intoxicaçäo pela micotoxina esporidesmina. A intoxicaçäo subclínica näo influenciou os parâmetros sanguíneos analisados. Bovinos portadores da forma subaguda e, principalmente, da forma crônica apresentaram, ao menos em algum momento da doença, alteraçöes significativas como elevaçäo dos níveis sanguíneos de gamaglutamiltransferase (até 521,80 mais ou menos 137,20 UI/L), de bilirrubina conjugada (até 1,73 mais ou menos 0,37 mg/100 ml), de bilirrubina livre (até 0,35 mais ou menos 0,22 mg/100 ml) e do tempo médio de excreçäo de bromossulfaleína (até 0,35 mais ou menos 0,22 mg/100 ml) e do tempo médio de excreçäo de bromossulfaleína (até 6,44 mais ou menos 0,65 minutos), além de hipoalbuminemia (2,38 mais ou menos 0,12 g/100 ml) e anemia normocítica normocrômica (4,52 mais ou menos 3,28 hemácias/ul x 10 elevado à sexta potência).

Intoxicaçäo natural de bovinos pela micotoxina esporidesmina. I. Aspectos epidemiológicos / Natural poisoning of cattle by sporidesmin mycotoxin. I. Epidemiological aspects

Verificaram-se os principais aspectos epidemiológicos relacionados à intoxicaçäo natural de bovinos pela micotoxina esporidesmina. Constatou-se que a enfermidade foi de maior ocorrência em animais de sete a 12 meses de idade, independente do sexo. A taxa de prevalência variou de 10,32 a 17,70 por cento e a de letalidade de 25,00 a 31,99 por cento. A doença ocorreu em todas as épocas do ano. Embora a temperatura ambiente elevada tenha sido a característica climática que mais favoreceu a produçäo de esporos de P. chartarum, a umidade relativa do ar e a precipitaçäo pluviométrica, associadas ao excedente de pastagens secas no solo, também contribuíram para o desenvolvimento do fungo

Intoxicaçäo natural de bovinos pela micotoxina esporidesmina. II. Aspectos clínicos / Natural poisoning of cattle by sporidesmin mycotoxin. II. Clinical aspects

O presente estudo foi realizado em 30 propriedades rurais, sendo 10 de cria de bovinos de corte, 10 de engorda de gado de corte e 10 de bovinos leiteiros, num total de 798 casos clínicos. Os principais sintomas foram lesöes cutâneas nas orelhas, barbela, base da cauda e regiöes glútea e do flanco, além de emagrecimento e icterícia. Verificaram-se três formas clínicas da doença: aguda, crônica moderada e crônica grave. O retorno dos animais à pastagem contaminada, após sua cura, mostrou que foi comum a recorrência da enfermidade. Notaram-se indícios da existência de animais geneticamente susceptíveis à açäo da esporidesmina, da possibilidade de transferência da toxina pelo leite e de possível hipersensibilidade cutânea induzida pela esporidesmina

Intoxicaçäo natural de bovinos pela micotoxina esporidesmina. III. Desenvolvimento ponderal de bovinos intoxicados / Natural poisoning of cattle by sporidesmin mycotoxin. III. Weight gain of poisoned cattle

Analisou-se o desenvolvimento ponderal de bovinos que sobreviveram à intoxicaçäo natural pela esporidesmina. As pesagens foram realizadas em animais portadores das formas subclínica, crônica moderada e crônica grave da doença, durante 360 dias após a cura clínica. Os percentuais de perda de peso foram 2,52 por cento, 28,01 por cento e 39,28 por cento para as formas subclínica, crônica moderada e crônica grave, respectivamente. Tais perdas foram decorrentes, provavelmente, da disfunçäo hepática e suas consequências metabólicas, da baixa ingestäo de alimentos e/ou da perda de elementos plasmáticos pela exsudaçäo cutânea

Parenchymal injury and biliary obstruction in relation to photosensitization in sporidesmin-intoxicated lambs.

The hepatic changes were compared in lambs photosensitized or not photosensitized after exposure to sporidesmin. Injury to both the parenchyma and the biliary system was more severe in the photosensitized than in the non-photosensitized lambs. The activities of gamma-glutamyltransferase and glutamate dehydrogenase, and the total, conjugated and unconjugated bilirubin concentrations were significantly higher in sera from the photosensitized than from the non-photosensitized lambs. Hepatic glycogen levels were decreased in both the photosensitized and the non-photosensitized lambs, but were significantly lower in the former. Hence it is possible that lesions in hepatocytes contribute to retention of phylloerythrin and so to photosensitization.

Glycogen accumulation and histological changes in the livers of lambs with alveld and experimental sporidesmin intoxication.

Alveld is a hepatogenous photosensitization disease seen in lambs grazing Narthecium ossifragum pastures in Norway. Mycotoxins, possibly sporidesmin, have been suspected to cause the liver damage in alvled as in facial eczema. The histological changes in the liver of alveld cases and in lambs photosensitized after experimental sporidesmin intoxication were compared. The liver damage, characterized by necrosis in single centrilobular hepatocytes, was of the same type in both conditions. Minor to moderate portal fibroplasia and bile duct proliferation were almost always present. Accumulated glycogen was seen in hepatocytes in the centrilobular areas. This was significantly correlated to the enzymatically measured glycogen content and there was good correlation between parenchymal damage and glycogen accumulation. The glucose-6-phosphatase and glycogen phosphorylase activities were normal. These findings indicate that parenchymal damage, rather than obstruction of the bile ducts, caused the retention of phylloerythrin both in alveld cases and in experimentally sporidesmin-intoxicated lambs. The accumulation of glycogen could not be explained.

Clinical biochemistry of sporidesmin natural intoxication (facial eczema) of sheep.

The effects of facial eczema, i.e. intoxication by the mycotoxin sporidesmin, were investigated by extensive biochemical screening of serum in 100 controls (A), 31 clinically ill (B) and 219 apparently healthy (C) Manech ewes under field conditions. Dramatic increases of gamma-glutamyltransferase1), alkaline phosphatases, bilirubin, cholesterol, aspartate and alanine aminotransferases, and lactate dehydrogenase confirmed the severity of liver damage in group B, but they were also observed in slightly more than 50% of group C animals. This demonstrated the true extent of the disease, which could be best assessed by the measurement of serum gamma-glutamyltransferase; but since this enzyme was still elevated one year later, it cannot be used as a reliable prognostic parameter.

Liver enzyme changes in a guinea-pig model of facial eczema (sporidesmiotoxicosis).

Sporidesmin, a hepatotoxin from Pithomyces chartarum, is responsible for facial eczema in ruminants. In an attempt to clarify the biochemical processes supporting sporidesmin toxicity and response of the liver, haematology, plasma biochemistry and liver enzyme changes were monitored for 21 days in a model for facial eczema resulting from a single intraperitoneal injection of 2.8 mg/kg BW sporidesmin to guinea pigs. Most plasma disturbances were observed 8 days after administration and accounted for starvation, liver cytolysis, and cholestasis or liver enzyme induction. Alterations of hepatic enzyme activities were intense with a maximum increase on days 2 for alkaline phosphatases (ALP) and 8 for gamma-glutamyltransferase (GGT), and a maximum decrease on day 21 for aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT). Comparison of liver and plasma enzyme changes indicates that GGT was the most reliable and significant plasma indicator of sporidesmin-associated liver alterations. Moreover, this study points out the validity of the one-dose intoxicated guinea-pig model for research on sporidesmin biochemical toxicity and pathobiology of facial eczema.

Hepatogenous photosensitivity diseases in South Africa.

Various hepatogenous photosensitivity diseases of ruminants in South Africa, caused by plants, fungi and an alga, are described. Information is given on botanical, mycological, toxicological, clinical and pathological aspects of the diseases. The intoxications were grouped according to the primary site of involvement and type of lesions in the liver. The aetiology, pathogenesis, and diagnosis of these conditions received special attention and the most important features are illustrated in colour.

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.

Mycotoxicoses of animals.

Mycotoxicoses are intoxications caused by ingestions of foodstuffs contaminated with mycotoxins, i.e. toxic secondary metabolites of microscopic filamentous fungi (moulds). By field observations and by experimental testing, toxins or toxic strains of more than 100 species of fungi have been encountered. However, causal associations have so far only been established for a small number of mycotoxicoses in farm animals, and the more important mycotoxicoses are aflatoxicosis, facial eczema, mycotoxic nephropathy, and estrogenic syndrome. A full assessment of the impact of mycotoxins on the health of farm animals can hardly be made at present, because the amount of surveillance data from mycotoxicoses is very limited, due mainly to inadequate diagnostic criteria. A new set of criteria for the diagnosis of mycotoxicosis is proposed, which has been successfully applied in the causative study of mycotoxic porcine nephropathy.