Undergraduate Research and Creativity

URECA

2007-2008

Prevalence of Mycobacteriosis in Striped Bass and Bluefish populations:
A New York Perspective

Michael Taddeo, Mark Sokolowksi, and Mark D. Fast
Marine Animal Disease Laboratory
School of Marine and Atmospheric Sciences

Several members of the bacterial genus Mycobacterium are piscine pathogens. Infection generally results in chronic disease, which may or may not manifest itself externally. Attention was called to the Chesapeake Bay system in the mid 1990’s after high levels of overt infection were reported in striped bass (Morone saxatilis). Extensive and continuing investigation into the epizootic has resulted in a greater understanding of the disease, improved diagnostics, and an estimation of prevalence within the population. Although the Chesapeake Bay and Hudson River stocks intermingle, little to nothing is known about the prevalence of mycobacteriosis in the Hudson River or New York State’s marine district as a whole. Additionally, we have only anecdotal evidence of the occurrence and prevalence of mycobacterial infection in bluefish (Pomatomus saltatrix), another important game fish species. Our study aims to estimate the prevalence of mycobacteriosis in striped bass and bluefish in the Long Island Sound and New York Bight using physical examination, nested PCR, nucleotide sequencing, and histology.

Striped bass and bluefish were collected from several Bays (Jamaica Bay, Little Neck and Manhasset Bays, Cold Spring Harbor, Oyster Bay, and the Lower Hudson River) using shore seining gear, as well as from trawls through the New York Bight. Tissue samples (spleen, anterior kidney, liver, and heart) were then taken from the individuals for use in direct PCR and histological preparation. PCR was performed on tissue homogenates with primers targeting the 16S rRNA gene; nested PCR was then performed with primers specific to the 16S gene of Mycobacterium genus members. Analysis of the PCR results is ongoing, and prevalence data will soon be compiled. PCR products are currently being sequencing to confirm the diagnosis. Additionally, histological examination is being performed on the excised tissues; mycobacteriosis often results in the formation of granulomatous lesions, which are indicative of the disease.

Characterization of piscine mycobacteriosis is important not only because of its effect on finfish populations, but because of its zoonotic potential. Contact with infected fish can result in fish handler’s disease, causing ulcerative dermatitis in humans. In addition, some piscine mycobacteria have been shown to harbor toxic mycolactone-encoding plasmids, which can then be acquired and expressed by other mycobacteria. Consequently, the zoonotic significance of piscine mycobacteria may be augmented by their potential to act as reservoirs of virulence-increasing factors.

This work has been funded by an MOU from the New York State Department of Environmental Conservation and the Marine Animal Disease Lab at SoMAS, Stony Brook.