R-10-10 Emergency surveillance monitoring for MSX disease

Deborah Bouchard
Animal Health Laboratory
University of Maine

MSX (Happlosporidium neslonii) is a parasite that infects adult oysters, killing as much as 30% in a single oyster bed. Although MSX has been present in Maine before, in 2010 a large-scale outbreak occurred in the Damariscotta River, the heart of Maine’s oyster growing industry. In response, Maine Department of Marine Resources issued an emergency order blocking the transfer of animals from the affected area. With funds from both Maine Sea Grant and the National Sea Grant Office, the industry, the state, the university, and a private laboratory worked together immediately to develop and implement a surveillance program, including testing of oyster operations coastwide. The University of Maine’s Animal Health Laboratory developed a proposed plan for sampling and analysis of present pathogens (PCR and histology) with assistance from epidemiologists from the USDA.

With the exception of Hall Point in the upper Damariscotta River, all natural oyster beds sampled were positive for MSX with varying infection percentages. Subsequent sampling in April of 2011 showed similar prevalence. Results from June/July 2011 confirmed the continued presence of the MSX pathogen within the river. The results of this initial snapshot surveillance program served to ease the concerns of growers outside of the Damariscotta River by confirming that MSX was in fact contained within that one estuary. Additionally, baseline surveillance data for the natural and farmed populations in the Damariscotta River has been established, and University of Maine researchers are continuing to investigate the problem.

Two-year project 2010-2011
Maine Sea Grant Program Development funds $5,000
National Sea Grant funds $15,000