An extract of Hydrilla verticillata and associated epiphytes induces avian vacuolar myelinopathy in laboratory mallards

Faith E. Wiley, Michael J. Twiner, Tod A. Leighfield, Susan B. Wilde, Frances M. Van Dolah, John R. Fischer, William W. Bowerman

Research output: Contribution to journalArticle

9 Scopus citations


Avian vacuolar myelinopathy (AVM) is a neurological disease affecting bald eagles (Haliaeetus leucocephalus), American coots (Fulica americana), waterfowl, and other birds in the southeastern United States. The cause of the disease is unknown, but is thought to be a naturally produced toxin. AVMis associated with aquatic macrophytes, most frequently hydrilla (Hydrilla verticillata), and researchers have linked the disease to an epiphytic cyanobacterial species associated with the macrophytes. The goal of this study was to develop an extraction protocol for separating the putative toxin from a hydrilla-cyanobacterial matrix. Hydrilla samples were collected from an AVM-affected reservoir (J. StromThurmond Lake, SC) and confirmed to contain the etiologic agent by mallard (Anas platyrhynchos) bioassay. These samples were then extracted using a solvent series of increasing polarity: hexanes, acetone, and methanol. Control hydrilla samples from a reference reservoir with no history of AVM (Lake Marion, SC) were extracted in parallel. Resulting extracts were administered to mallards by oral gavage. Our findings indicate that the methanol extracts of hydrilla collected from the AVM-affected site induced the disease in laboratorymallards. This study provides the first data documenting for an "extractable" AVM-inducing agent.

Original languageEnglish (US)
Pages (from-to)362-368
Number of pages7
JournalEnvironmental Toxicology
Issue number4
StatePublished - Aug 1 2009



  • AVM
  • Algal toxin
  • American coot
  • Avian vacuolar myelinopathy
  • Bald eagle
  • Cyanobacteria
  • Haliaeetus leucocephalus
  • Mallard

ASJC Scopus subject areas

  • Toxicology
  • Management, Monitoring, Policy and Law
  • Health, Toxicology and Mutagenesis

Cite this

Wiley, F. E., Twiner, M. J., Leighfield, T. A., Wilde, S. B., Van Dolah, F. M., Fischer, J. R., & Bowerman, W. W. (2009). An extract of Hydrilla verticillata and associated epiphytes induces avian vacuolar myelinopathy in laboratory mallards. Environmental Toxicology, 24(4), 362-368.