Yasuko Neagari, Suzue Arii, Mai Udagawa, Manabu Onuma, Yoshiya Odaya, Takeshi Kawasaki, Makio Tenpaku, Hisayo Hayama, Ken-ichi Harada, Masaya Mizukami, Koichi Murata
Journal of Wildlife Diseases 47 (1), 49-55, (1 January 2011) https://doi.org/10.7589/0090-3558-47.1.49
KEYWORDS: Agricultural reservoir, cyanobacteria, egrets, herons, steatitis, vitamin E
More than 70 egrets and herons were found sick or dead at an agricultural water reservoir in Kanagawa Prefecture, Japan between September and October 2008. The birds showed weakness, lethargy, and inability to fly before death. Postmortem findings included large amounts of firm subcutaneous and cavitary fat comprised of necrotic adipose tissues with infiltrates of heterophils and macrophages. The birds were diagnosed with steatitis on the basis of the gross lesions and histopathology. Egrets with steatitis had low blood levels of vitamin E. High counts of cyanobacteria (Microcystis aeruginosa) were found in the reservoir concurrent with the outbreak of steatitis. No microcystin was detected in the reservoir water or the livers from the egrets. This is the first report of steatitis in wild birds in Japan.