Anticholinesterase poisoning of birds: Field monitoring and diagnosis of acute poisoning

Abstract

Organophosphorus and carbamate pesticides are cholinesterase (ChE) inhibiting chemicals that have been responsible for avian die‐offs. Identification of chemicals implicated in these die‐offs is difficult and sometimes conclusions are solely circumstantial. However, when marked depression (inhibition) of brain ChE activity accompanies organophosphorus or carbamate residues in body tissues or ingesta, cause‐effect diagnosis is enhanced. To achieve this end, normal brain ChE activity is estimated for controls of the affected species and then die‐off specimens are individually evaluated for evidence of ChE inhibition. This approach to evaluation of antiChE poisoning may also be used to monitor exposure of vertebrates to field application of organophosphorus or carbamate pesticides. Problems associated with this kind of evaluation, and the main topic of this report, include variability of brain ChE activity among species, postmortem influences of ambient conditions (storage or field) on ChE activity, and differential patterns of ChE activity when inhibited by organophosphorus or carbamate compounds. Other topics discussed are the ChE assay procedure, example case reports and interpretation, and research needed for improving the diagnostic utility of ChE activity in a field situation.

Pathology and Virus Detection in Tissues of Nestling House Sparrows Naturally Infected With Buggy Creek Virus (Togaviridae)

“…Inoculated plates were incubated at 36 C for 48 hr and bacterial isolates were identified using standard methods. Brain cholinesterase activity was evaluated in a subset of nestlings using methods previously reported (Hill and Fleming, 1982).…”

DEVELOPMENT OF REFERENCE RANGES FOR PLASMA TOTAL CHOLINESTERASE AND BRAIN ACETYLCHOLINESTERASE ACTIVITY IN FREE-RANGING CARNABY'S BLACK-COCKATOOS (CALYPTORHYNCHUS LATIROSTRIS)

“…More recently, the measurement of blood or tissue ChE activity has been used to diagnose OP or carbamate insecticide toxicosis in animals (Fairbrother et al 1991;Fairbrother 1996;Fildes et al 2006Fildes et al , 2009Shimsoni et al 2012). If brain AChE activity is inhibited by 20% from normal, exposure to an anticholinesterase compound is considered likely; however, the accepted diagnostic convention is that whole-brain AChE inhibition .50% is indicative of anti-ChE toxicosis (Ludke et al 1975;Hill and Fleming 1982).…”

Factors affecting cholinesterase activity in aquatic animals

“…Excess mucous was wiped from the exterior of the fish with paper towels and fish wet weight was detemiined to the Hill and Fleming, 1982;Gard and Hooper. 1993 (SAS, 1993).…”

“…1961;Hill & Fleming, 1982;Gard & Hooper, 1993 Reactions were optimized at 30°C (maintained by an incubator in the miaoplate reader) and 7.94 x 10^ M acetylthiocholine for C. riparius. The reaction mixture was kept at pH 8.0 by Tris buffer; this pH has been found to be optimal for hydrolyzing acetylthiocholine by C. riparius ChE …”

“…A spectrophotometric assay using a plate reader is used to detemnine ChE activity in fish brain tissue (Ellman etal., 1961;Hill and Fleming, 1982;Corvallis Environmental Research Laboratory, 1987; The Institute for Wildlife and Environmental Toxicology, 1991). ChE activity is determined from the result of two reactions occurring in the assay solution: acetylthiocholine hydrolysis and reaction of the thiocholine product with a colorimetric reagent.…”