Diarrhetic Shellfish Poisoning, Washington, USA, 2011

Jennifer K. Lloyd

, Jeffrey S. Duchin, Jerry Borchert, Harold Flores Quintana, and Alison Robertson

Author affiliations: Public Health—Seattle & King County, Seattle, Washington, USA (J.K. Lloyd, J.S. Duchin); University of Washington, Seattle (J.S. Duchin); Washington State Department of Health, Tumwater, Washington, USA (J. Borchert); US Food and Drug Administration, Dauphin Island, Alabama, USA (H. Flores Quintana, A. Robertson)

Abstract

Diarrhetic shellfish poisoning is a gastrointestinal illness caused by consumption of bivalves contaminated with dinophysistoxins. We report an illness cluster in the United States in which toxins were confirmed in shellfish from a commercial harvest area, leading to product recall. Ongoing surveillance is needed to prevent similar illness outbreaks.

Diarrhetic shellfish poisoning (DSP) is an acute gastrointestinal illness caused by consumption of bivalve mollusks that have accumulated okadaic acid (OA) or related dinophysistoxins through filter feeding. DSP toxins are produced by several species of marine dinoflagellates from the genera Dinophysis and Prorocentrum (1–4). Symptoms of DSP include nausea, abdominal pain, vomiting, diarrhea, headache, chills, and fever (5). Onset occurs 0.5–4 hours after consumption of contaminated food, and symptoms last up to 72 hours; treatment is supportive. To date, no sequelae have been reported, but speculation has suggested that chronic exposure may increase risk for gastrointestinal cancers (6,7).
The earliest clinical reports of DSP were from the Netherlands in 1961; however, DSP toxins were structurally elucidated >15 years later in Japan (2,8,9). DSP illnesses have since been documented worldwide. In the United States, sporadic DSP-like illnesses have been recorded on the East Coast since 1980, coinciding with detection of toxin-producing dinoflagellates in shellfish beds (2,4). In 2002, shellfish beds in Chesapeake Bay, Virginia, were briefly closed because Dinophysis spp. dinoflagellates were detected, although hazardous DSP toxin levels were not detected and no illnesses were reported (10). More recently, in Texas, harvest areas were closed for >1 month following a large Dinophysis bloom that contaminated oyster beds with OA in excess of the Food and Drug Administration (FDA) regulatory guidance level; no illnesses were reported (11,12).