A RETROSPECTIVE STUDY OF THE LESIONS ASSOCIATED WITH IRON STORAGE DISEASE IN CAPTIVE EGYPTIAN FRUIT BATS (ROUSETTUS AEGYPTIACUS)

Abstract

Egyptian fruit bats (Rousettus aegyptiacus) are one of many species within zoologic collections that frequently develop iron storage disease. The goals of this retrospective multi-institutional study were to determine the tissue distribution of iron storage in captive adult Egyptian fruit bats and the incidence of intercurrent neoplasia and infection, which may be directly or indirectly related to iron overload. Tissue sections from 83 adult Egyptian fruit bats were histologically evaluated by using tissue sections stained with hematoxylin and eosin, trichrome, and Prussian blue techniques. The liver and spleen consistently had the largest amount of iron, but significant amounts of iron were also detected in the pancreas, kidney, skeletal muscle, and lung. Hepatocellular carcinoma (HCC; 11) was the most common neoplasm, followed by cholangiocarcinoma (4). Extrahepatic neoplasms included bronchioloalveolar adenoma (3), pulmonary carcinosarcoma (1), oral sarcoma (1), renal adenocarcinoma (1), transitional cell carcinoma of the urinary bladder (1), mammary gland adenoma (1), and parathyroid adenoma (1). There were also metastatic neoplasms of undetermined primary origin that included three poorly differentiated carcinomas, a poorly differentiated sarcoma, and a neuroendocrine tumor. Bats with hemochromatosis were significantly more likely to have HCC than bats with hemosiderosis (P = 0.032). Cardiomyopathy was identified in 35/77 bats with evaluable heart tissue, but no direct association was found between cardiac damage and the amount of iron observed within the liver or heart. Hepatic abscesses occurred in multiple bats, although a significant association was not observed between hemochromatosis and bacterial infection. To the authors' knowledge, this is the first publication providing evidence of a positive correlation between hemochromatosis and HCC in any species other than humans.

Chiroptera

“…Hepatocellular carcinoma and cholangiocarcinoma can be seen in R. aegyptiacus with liver damage associated with IO. Myocardial degeneration and/or fibrosis is also common in R. aegyptiacus with IO (occur in about 45% of affected bats) but it is not correlated with the amount of iron present in the liver or heart (Leone et al, 2016). Myocardial fibrosis is also observed in older fruit bats of other species, albeit at a lower rate than R. aegyptiacus.…”

“…Iron overload (IO) has been reported in captive Rousettus aegyptiacus (Crawshaw et al, 1995;Farina et al, 2005;Leone et al, 2016). Overload is likely dietary, although the reason for the susceptibility of this species relative to other species on the same diet is unclear.…”

“…These include hypovitaminosis E in Pteropus spp. (Heard et al, 1996) and iron overload in Rousettus aegyptiacus (Leone et al, 2016); however, not all bats with myocardial fibrosis have these conditions. Further studies into etiologies of myocardial disease in bats are needed.…”

“…Most published case reports of neoplasia represent single neoplasms, with Rousettus aegyptiacus the most common species in these reports. The most commonly reported neoplasms in captive R. aegyptiacus are hepatocellular carcinoma and cholangiocarcinoma, thought to be associated with liver damage from iron overload (Leone et al, 2016).…”

Unacknowledged Potential Factors in Catastrophic Bat Die-off Arising from Coal Fly Ash Geoengineering

“…Egyptian fruit bats (Rousettus aegyptiacus) frequently develop iron storage disease associated with increased infection rates and cancer, including hepatocellular carcinoma [101].…”