Hemosiderosis is associated with increased susceptibility to Yersinia pseudotuberculosis infection in Seba’s short-tailed bats ( Carollia perspicillata )

Abstract

Yersinia pseudotuberculosis (Yptb) is a gram-negative bacterium that can cause sporadic fatal infections in humans, domestic animals, and wildlife. We describe an outbreak of Yptb in a captive collection of 222 Seba’s short-tailed bats (Carollia perspicillata), 50 of which died of confirmed (39 of 222, 17.6%) or suspected (11 of 222; 5.0%) Yptb infection. Females were more likely to be infected than males (odds ratio: 3.4), and non-pregnant females were more likely to be infected than pregnant females (odds ratio: 13.6). The most common gross lesions were multifocal cream/white discolorations and/or nodules (30 of 39, 77%) in the liver, followed by splenomegaly (23 of 39, 59%) and mesenteric lymphadenomegaly (9 of 39, 23%); 5 of 39 (13%) animals had no gross lesions. Histology was performed on the livers of 33 confirmed Yptb-positive animals, with the most common findings being extramedullary hematopoiesis (27 of 33, 82%) and pyogranulomatous or suppurative hepatitis (20 of 33, 61%). Hemosiderosis was observed in 32 of 33 (97%) cases and in 27 of 27 (100%) control animals that were not infected with Yptb. Solution inductively coupled mass spectrometry showed that infected bats had an average of 1.7× more hepatic iron than uninfected bats (P = .0067); this was corroborated by image analysis of Perl’s stained sections (P < .0001), but laser ablation on a subset of cases was not significant (P = .1051). We hypothesize that hemosiderosis favors the systemic spread of Yptb by limiting the efficacy of hepcidin-mediated iron depletion, and that limiting dietary iron may protect captive wildlife from bacterial infections.