Chaunocephalosis in a wild population of Asian open-billed storks in Thailand

The most common trematode collected from Asian open-billed storks (Anastomus oscitans) was Chaunocephalus ferox (80% prevalence). The trematode was paired in granulomas in the intestinal wall. Based on histological examination of these capsules, there was degeneration and necrosis of muscle cells in the tunica muscularis. Granulation tissue with hetrophil and lymphocyte infiltration appeared in the granulomas. Intestinal villi were shorter and wider in infected areas than in non-infected areas. Some intestinal glands were dilated. Storks with high intensity of C. ferox appeared ill. The death of storks infected with C. ferox may result from malnutrition due to the loss of absorptive function of the intestine and from the effect of granuloma formation which might interfere with the intestinal peristalsis.