EFFECTS OF MALATHION ON DISEASE SUSCEPTIBILITY IN WOODHOUSE'S TOADS

• Published in: Journal of wildlife diseases Vol. 35; no. 3; pp. 536 - 541
• Main Authors: Taylor, Sharon K, Williams, Elizabeth S, Mills, Ken W
• Format: Journal Article
• Language: English
• Published: United States Wildlife Disease Association 01.07.1999; Wildlife Dis Assoc
• Subjects: Administration, Topical; Aeromonas hydrophila; amphibian; Animals; Brain - enzymology; Bufo woodhousi; Bufo woodhousii; Bufonidae - immunology; Cholinesterase Inhibitors - administration & dosage; Cholinesterase Inhibitors - toxicity; Cholinesterases - analysis; Disease Susceptibility; Dose-Response Relationship, Drug; Gram-Negative Bacterial Infections - immunology; Gram-Negative Bacterial Infections - veterinary; hepatomegaly; Insecticides - administration & dosage; Insecticides - toxicity; malathion; Malathion - administration & dosage; Malathion - toxicity; Male; organophosphorus pesticide; pesticide; Prospective Studies; Random Allocation; s; Woodhouse's toad
• ISSN: 0090-3558; 1943-3700
• DOI: 10.7589/0090-3558-35.3.536

Adult male Woodhouse's toads (Bufo woodhousi) developed clinical disease, hepatomegaly, and died at a higher rate when externally exposed once to either a high or low sublethal dose (0.011 or 0.0011 mg malathion/g toad) of field grade malathion and challenged with a sublethal dose of Aeromonas hydrophila injected intraperintoneally (1.1 × 104 bacteria/g toad) when compared to toads not exposed to malathion but challenged with A. hydrophila (P < 0.007). Toads exposed to malathion (high or low dose) and challenged with A. hydrophila had clinical disease, hepatomegaly, and died at a higher rate [9 (90%) of 10] than toads exposed to malathion alone (P < 0.002). Toads exposed to the high and low doses of malathion had a 22% and 17% decrease in brain cholinesterase levels, respectively, when they were compared to nonmalathion exposed toads (P < 0.025, P < 0.006). It appears that field grade malathion applied externally to adult Woodhouse's toads may cause increased disease susceptibility when challenged with a potentially pathogenic bacteria.