Evidence of bromethalin toxicosis in feral San Francisco “Telegraph Hill” conures

Abstract

During 2018, four free-ranging conures, from a naturalized flock in San Francisco, presented with a characteristic set of neurologic signs that had been reported in other individuals from this flock. The cause of morbidity or mortality in historic cases has not been identified. From these four subjects, fresh feces were collected during their initial days of hospitalization and submitted to the University of Georgia Infectious Diseases Laboratory and Center for Applied Isotope Studies for bromethalin and desmethyl-bromethalin quantitation. Using High Performance Liquid Chromatography, the laboratory detected bromethalin, a non-anticoagulant, single-dose rodenticide, in fecal samples from three subjects; half of these samples were also positive for desmethyl-bromethalin, bromethalin’s active metabolite. In three subjects that died, the UGA laboratory screened brain and liver samples and found bromethalin in all samples; desmethyl-bromethalin was detected in all but one brain sample, which was below the detection limit. Our findings suggest the conures are more resistant to bromethalin than are other species in which bromethalin has been studied, and/or that the conures may be ingesting the toxin at a sublethal dose. More data is needed to better assess the long-term effects of bromethalin on animals exposed at the subacute/chronic levels, and also to better understand the compartmentalization of bromethalin and desmethyl-bromethalin in a wider variety of species.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

“…Neither commercial (Dictionary of Natural Products 28.2, SciFinder) nor in-house natural product databases revealed an entry for this elemental composition, which suggests that it is a novel natural product. The fact that the metabolite contains five bromine atoms is notable, as polyhalogenated synthetic compounds, such as bromethalin or hexachlorophene, are known to induce VM-like brain lesions in birds and mammals (1,5,11,30).…”

Neuropathology of feral conures with bromethalin toxicosis

“…In these circusmtances, feces are a good alternative for testing for bromethalin since the molecule and its metabolites are probably excreted through the feces. 16 We showed that birds exposed to bromethalin present with different degrees of vacuolar change and myelinopathy, in particular the white matter tracts of the brainstem and optic system. This characteristic distribution of lesions may be related to higher susceptibility to edema in certain regions of the avian brain.…”

“…in San Francisco, California (“The Telegraph Hill conures”). 16 However, our understanding of the most important diagnostic features of bromethalin toxicosis in free-ranging birds is limited, undermining the prompt recognition of this toxicosis in these species. To address this gap, in this report, we describe the neuropathology of bromethalin toxicosis in a group of feral conures.…”

“…Toxicological analyses for organic compounds were performed in liver, brain, and feces of all animals using ultraviolet high-performance liquid chromatography (HPLC-UV) ( n = 11) or gas chromatography–mass spectrometry (GC-MS) ( n = 3). 16 Zinc and lead levels were measured in the liver, spleen, and pancreas of 3 animals through flame atomic absorption spectroscopy (FAAS). 3 There was between 0.03 and 118.4 µg/g of bromethalin in the feces, liver, and/or brain of 12 animals (Supplemental Table S2).…”

“…In these circusmtances, feces are a good alternative for testing for bromethalin since the molecule and its metabolites are probably excreted through the feces. 16…”