Gaffkemia of Lobsters


Category 2 (In Canada and of Regional Concern)

Common, generally accepted names of the organism or disease agent

Gaffkemia, Red tail disease.

Scientific name or taxonomic affiliation

Aerococcus viridans var homari (=Gaffkya homari).

Geographic distribution

Enzootic in feral and captive, larval, postlarval, juvenile and adult lobsters, as well as other decapods from both sides of the North Atlantic Ocean. Prevalence in cultured lobsters in California was low.

Host species

Homarus americanus, and Homarus gammarus (=vulgaris). Observed in low prevalences in Libinia emarginata, Carcinus maenas, Cancer borealis, Cancer irroratus, and Penaeus aztecus. Experimentally transmitted to Panulirus interruptus, Pandalus platyceros, Cancer irroratus, Cancer magister, Geryon quiquedens, Chionoecetes opilio, Callinectes sapidus.

Impact on the host

Transmitted through puncture wounds or lesions. Infection usually results in a depression in haemocyte counts, an increase in haemolymph clotting time and often causes fatal septicemic disease in lobsters. The impaired clotting mechanism was a result of the drastic reduction in circulating haemocyte numbers (Stewart et al. 1969a). Less than ten A. viridans cells /kg body weight of lobster is sufficient to cause fatal bacteremia. The mean time to death for infected lobsters increases as the temperature is decreased (Stewart and Rabin 1970). Gaffkemia was interpreted as a wasting type of disease produced by A. viridans, which is resistant to the intrinsic defense mechanisms of lobsters (Stewart et al. 1969a). From laboratory exposure experiments, Robohm et al. (2005) determined that at 19.5 °C (peak, summer, bottom-water temperatures in Long Island Sound, USA) relatively moderate levels of hypoxia as well as sulfide in the absence of hypoxia may accelerate death in lobsters infected by A. viridans var homari.

In the four years prior to 1966, haemolymph samples from 2035 lobsters from five areas off the Canadian Atlantic coast revealed a 2 to 40% prevalence of A. viridans in wild stocks. Evidence suggested that a high natural prevalence of infection could lead to an epizootic during live-storage of captive lobsters (Stewart et al. 1966), Although A. viridans is widely distributed and can infect other species of crustacea, it has not been identified as the cause of epizootics in species other than Homarus spp. (Stewart and Rabin 1970). Lobsters vaccinated with formaldehyde killed A. viridans from broth cultures had a several fold increase in haemolymph bactericidal activity but this vaccine provided no measurable protection against challenge with A. viridans (Stewart and Zwicker 1972).

Diagnostic techniques

Gross Observations: Rapid and significant increase in mortality among impounded lobsters, particularly after stress. Heavily infected specimens may have slightly reddish discolouration visible through the integument of the underside of the abdomen. Haemolymph is thin and pinkish with a drastic reduction in number of circulating haemocytes and clotting time may be prolonged to absent in late infections.

Smears: Microscopic examination of Gram stained haemolymph reveals numerous typical Gram positive tetrad-forming coccal bacteria (0.8-1.1 µm).

Immunological Assay: Confirmation by Flourescent Antibody Test (FAT) using conjugated anti­A. viridans var homari antiserum.

Culture: Culture characteristics are non-motile, catalase negative, beta-haemolytic, facultative anaerobic, tetrad-forming coccal bacteria that often appear as grayish-white raised colonies on agar plates. Light infections can be detected by inoculating 0.5 ml haemolymph into phenethyl selective broth medium, incubate at 28 °C for 24 hr. Lobster haemolymph in vitro forms an excellent medium for growth. Confirm positive tubes by FAT. Preparation of the selective medium can be made less costly by replacing the glucose with food-grade sucrose (table sugar) and the sodium chloride with iodized table salt.

Methods of control

Temporary reduction in mortality rate may be obtained by lowering temperature, which reduces proliferation rate of the bacterium (i.e., time-to-death increased from 2 days at 20 °C to at least 250 days at 1 °C; Stewart et al. (1969b)). Avoid wounding and crowding lobsters. Maintain proper husbandry and system hygiene. Protection may be conferred by vaccines (Keith et al. 1992).


Brock, J.A. and D.V. Lightner. 1990. Diseases of Crustacea. Diseases caused by microorganisms. In: O. Kinne (ed.). Diseases of Marine Animals. Volume III: Introduction, Cephalopoda, Annelida, Crustacea, Chaetognatha, Echinodermata, Urochordata. Biologische Anstalt Helgoland, Hamburg, p. 319-325.

Keith, I.R., Paterson, W.D., Airdrie, D. and L.D. Boston. 1992. Defense mechanisms of the American lobster (Homarus americanus): Vaccination provided protection against gaffkemia infections in laboratory and field trials. Fish and Shellfish Immunology 2: 109-119.

Loughlin, M.B., R.C. Bayer and D.L. Prince. 1994. Low cost selective media to detect gaffkemia, Aerococcus viridans. Journal of Applied Aquaculture 4: 89-92.

Robohm, R.A., A.F.J. Draxler, D. Wieczorek, D. Kapareiko and S. Pitchford. 2005. Effects of environmental stressors on disease susceptibility in American lobsters: a controlled laboratory study. Journal of Shellfish Research 24: 773-779.

Stewart, J.E. 1972. The detection of Gaffkya homari, the bacterium pathogenic to lobsters (genus Homarus). Journal of the Fisheries Research Board of Canada, New Series Circular No. 43, 5p.

Stewart, J.E. 1975. Gaffkemia, the fatal infection of lobsters (genus Homarus) caused by Aerococcus viridans (var.) homari: a review. Marine Fisheries Review 37: 20-24.

Stewart, J.E. and B. Arie. 1973. Paradoxical effects of salinity reductions on lobsters (Homarus americanus) infected with Gaffkya homari. Comparative Biochemistry and Physiology 45A: 717-730.

Stewart, J.E. and J.W. Cornick. 1967. In vitro susceptibilities of the lobster pathogen Gaffkya homari to various disinfectants and antibiotics. Journal of the Fisheries Research Board of Canada 24: 2623-2626.

Stewart, J.E. and H. Rabin. 1970. Gaffkemia, a bacterial disease of lobsters (Genus Homarus). American Fisheries Society Special Publication 5, Part II: 431-439.

Stewart, J.E. and B.M. Zwicker. 1972. Natural and induced bactericidal activities in the hemolymph of the lobster, Homarus americanus: products of hemocyte-plasma interaction. Canadian Journal of Microbiology 18: 1499-1509.

Stewart, J.E. and B.M. Zwicker. 1974. Comparison of various vaccines for inducing resistance in the lobster Homarus americanus to the bacterial infection, gaffkemia. Journal of the Fisheries Research Board of Canada 31: 1887-1892.

Stewart, J.E., J.W. Cornick, D.I. Spears and D.W. McLeese. 1966. Incidence of Gaffkya homari in natural lobster (Homarus americanus) populations of the Atlantic region of Canada. Journal of the Fisheries Research Board of Canada 23: 1325-1330.

Stewart, J.E., B. Arie, B.M. Zwicker and J.R. Dingle. 1969a. Gaffkemia, a bacterial disease of the lobster, Homarus americanus: effects of the pathogen, Gaffkya homari, on the physiology of the host. Canadian Journal of Microbiology 15: 925-932.

Stewart, J.E., J.W. Cornick and B.M. Zwicker. 1969b. Influence of temperature on gaffkemia, a bacterial disease of the lobster Homarus americanus. Journal of the Fisheries Research Board of Canada 26: 2503-2510.

Stewart, J.E., D.M. Foley and R.G. Ackman. 1969c. Characteristics of Gaffkya homari, the causative agent of the lobster disease gaffkemia. Journal of the Fisheries Research Board of Canada 26: 1385-1389.

Citation Information

Bower, S.M. (2007): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Gaffkemia of Lobsters.

Date last revised: September 2007
Comments to Susan Bower

Date modified: