Hansen D E, McCoy R D, Hedstrom O R, Snyder S P, Ballerstedt P B
Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Oregon State University, Corvallis 97331.
J Am Vet Med Assoc. 1994 May 15;204(10):1668-71.
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.
在俄勒冈州西部一片秋季灌溉牧场上的一群羔羊中，观察到了光敏反应的流行。症状包括鼻孔、嘴唇和耳朵周围皮肤以及颊部黏膜出现结痂、坏死和脱落。对牧场植物材料进行显微镜检查发现了稻梨孢菌的孢子。在世界其他地区，这种真菌已被证明是绵羊和牛光敏反应（面部湿疹）的致病因素。未发现可能导致羔羊出现临床症状的感染因子或其他植物材料。放牧期间的天气和湿度条件非常适合真菌生长，在疫情发生之前和期间都检测到大量这种真菌。尽管美国西北部此前未报告过面部湿疹，但我们认为围绕此次疫情的情况足以做出这样的诊断。
