Harvey Rabin

Studies on gaffkemia, a bacterial disease of the American lobster, Homarus americanus (Milne-Edwards)☆

A study was made of the local distribution of Gaffkya homari Hitchner and Snieszko and of its host-parasite relationship with the American lobster, Homarus americanus (Milne-Edwards). Of the lobsters from the Marine Biological Laboratory supply, 11.8–32% were found infected and one out of ten lobsters caught off Woods Hole was infected with a Gaffkya-like organism. No isolations were made from lobsters dragged from the edge of the continental shelf nor from lobsters trapped off Marthas Vineyard. G. homari, when inoculated into healthy lobsters, established bacteremia or septcemia on the first or second day after inoculation and induced mortality a few days later. Uninfected lobsters or those pretreated with Vibrio endotoxin did not acquire the disease on contact with the exception of one uninfected contact lobster which developed a slight, temporary bacteremia but survived. Twenty out of 21 lobster sera when tested in vitro stimulated the growth of G. homari while only one out of 21 sera stimulated the growth of Vibrio and seven actually inhibited it. Prior inoculation of heat-killed G. homari did not alter the course of the infection. Such pretreatment also had no influence on the in vitro activity of the serum.

Recent decline in the distribution and abundance of Eurasian milfoil in Chesapeake Bay

Eurasian water milfoil (Myriophyllum spicatum L.) declined significantly in Chesapeake Bay from 1965 to 1967. This decline generally exceeded 95%, and was associated with several pathologic conditions, previously named Northeast disease and Lake Venice disease. We believe that these pathologic conditions have been responsible for the decline. No study of Lake Venice condition has yet been undertaken, but this paper presents evidence that Northeast condition is an infectious disease. Northeast disease symptoms can be transmitted in the laboratory by a bacteriologically sterile filtrate passed through a 0.2 μ filter. This indicates a virus, virus-like particle, or a toxin as the etiologic agent. The primary pathogen is probably a virus, and the evidence for this will be presented in a later paper. Gram-negative bacilli obtained from diseased milfoil probably represent secondary infections.

Studies on host-parasite relationships in gaffkemia.

Abstract Gaffkya homari , the etiologic agent of the bacterial disease of the American lobster, Homarus americanus , known as gaffkemia was found to infect lobsters of ages less than 1 month to over 10 years. G. homari produced infection in the crab Libinia emarginata , though to a lesser degree than in the lobster, and to an even lesser degree in the crab Cancer borealis . Little evidence for infection was found in inoculated horseshoe crabs ( Limulus polyphemus ). Recalcified clotting times and amebocyte counts of gaffkemic and nongaffkemic lobsters were similar. A culture filtrate of G. homari induced casting-off of inoculated chelae and/or hyperactivity in 11 of 19 individual lobsters. A naturally gaffkemic lobster was found to recover from the infection and to possess thereafter a partial resistance to challenge with G. homari . No correlation was found between the degree of stimulation produced by individual lobster sera on the growth of G. homari in vitro and the individual susceptibility of the lobster on direct inoculation. Attempts to transmit the infection by contact with infected lobsters or contaminated water or by feeding were negative.