Hemochromatosis refers to excess deposition of iron in tissues resulting in injury to those tissues. It is an important disease of several captive zoological species including toucans, tanagers, birds of paradise, and Egyptian fruit bats (Rousettus aegyptiacus). Currently, liver biopsy is the only antemortem diagnostic technique for this disease. This study was undertaken to evaluate hemosiderosis/hemochromatosis in a captive population of Egyptian fruit bats by determining whether there is a relationship between blood iron values and hepatic iron concentration, and if histologic findings correlate with hepatic iron levels. Twenty-three adult Egyptian fruit bats were used in the study, and six island flying foxes (Pteropus hypomelanus) were used as controls. All were housed in indoor-outdoor enclosures at the Lubee Foundation, a private zoological facility in North Central Florida, and fed the same diet of mixed vegetables, fruits, and a commercial vitamin/mineral supplement. Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron levels, total iron binding capacity, whole blood lead levels, and plasma ferritin assays. Liver samples obtained via laparotomy were divided; one half was placed in formalin, processed for histologic examination, and scored by two blinded observers for iron deposition, necrosis, and fibrosis, and the other half was frozen and submitted for tissue mineral analysis. The Egyptian fruit bats had significantly higher liver iron (mean=3668.89±1822.82 ppm) and lead (mean=8.93±5.77 ppm) levels than the island flying foxes (mean [Fe]=173.89±173.08 ppm, mean [Pb]=1.87±0.50 ppm). The hepatic iron levels were significantly (p<0.001) correlated with tissue lead levels, histologic grading for iron and necrosis, serum iron, and ferritin. Blood lead levels were not elevated, and blood lead levels were negatively correlated (p<0.001) with tissue lead levels. Evaluation of serum iron and ferritin may be useful and less invasive methods for diagnosis of hemochromatosis in Egyptian fruit bats. Elevation of the tissue iron and lead levels could be related to altered intestinal absorption of these ions in Egyptian fruit bats.
This project was funded by a grant from the Lubee Foundation, Inc.