Immunopathology of 8‐week‐old ring‐necked pheasants (Phasianus colchicus) exposed to malathion

Brad L. Day, Mary M. Walser, Jagdev M. Sharma, David E. Andersen

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


In addition to their acute neurotoxic effects, some organophosphorus compounds have been shown to have immunotoxic properties. Alterations in the immune system may lead to chronic morbidity and/or mortality that is not readily apparent at the time of initial exposure. Because it often inhabits land that is intensely farmed, the ring‐necked pheasant (Phasianus colchicus) may be a suitable biomonitor of agroecosystems, especially those used in the production of corn. We examined immunopathologic effects of a widely used organophosphate insecticide, malathion, on 8‐week‐old, cage‐reared ring‐necked pheasants 3 d after a single oral dose. No differences were seen in hematologic parameters, body weight, or weight of the bursa of Fabricius. Birds given a high dose of malathion (230 mg/kg) displayed significant decreases in absolute and relative thymic and splenic weights (p ± 0.05). Significant changes were also seen in thymic and splenic histomorphometry (p ± 0.05). The high‐dose group and, in some cases, the low‐dose group (92 mg/kg) displayed significant histologic lesions. These findings indicate that a single dose of malathion, at the LD50 level (230 mg/kg) and occasionally at 40% of the LD50 level (92 mg/kg), is capable of inducing quantitative and qualitative changes in the lymphoid organs of the ring‐necked pheasant that may affect immune function.

Original languageEnglish (US)
Pages (from-to)1719-1726
Number of pages8
JournalEnvironmental Toxicology and Chemistry
Issue number10
StatePublished - Oct 1995


  • Biomonitor
  • Chronic
  • Immunopathology
  • Malathion
  • Ring‐necked pheasant

ASJC Scopus subject areas

  • Environmental Chemistry
  • Health, Toxicology and Mutagenesis


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