What is it?
Milky haemolymph disease of spiny lobster, also known as milky haemolymph syndrome (MHS), is caused by a rickettsia-like bacterium.
Four distinct rickettsia-like bacteria have been found, one of which is known to be
associated with the disease. The disease affects black tiger prawn, European shore crab and Tropical spiny lobsters.
When and where might it occur?
The disease affects three-month-old or older juveniles and adult lobsters.
It is suspected that horizontal transmission occurs by direct contact with infected lobsters in the same net-pens, or indirectly by contaminated water from adjacent net-pens.
The disease has been experimentally transmitted among lobsters by cohabitation and by injection of unfiltered haemolymph from diseased lobsters into healthy lobsters. It is suspected that fresh foods (fishery bycatch, molluscs and decapod crustaceans) fed to net-pen-reared lobsters in Vietnam are the source of the rickettsia-like bacterial agent of the disease.
Signs of the disease are often lethargy, anorexia or cessation of feeding and mortality soon after clinical and gross pathological signs appear.
Gross pathological signs are:
- milky haemolymph exuding from wounds or visible under swollen abdominal pleura of the exoskeleton (visible on the ventral side; if drawn into a syringe, may appear turbid or milky in severely affected specimens)
- white hypertrophied connective tissues of all major organs and tissues
Microscopic pathological signs are:
- basophilic cytoplasmic masse
Control and treatment
Injection of oxytetracycline has been effective in treating and preventing the disease.
Source: Australian Government, Department of Agriculture, Fisheries and Forestry