If spores could be disarmed, they would be unable to infect fish, but further research is needed to find an effective treatment.Some strains of fish are more resistant than others, even within species; using resistant strains may help reduce the incidence and severity of whirling disease in aquaculture. There is also some circumstantial evidence that fish populations can develop resistance to the disease over time. Additionally, aquaculturists may avoid M. cerebralis infections by not using earthen ponds for raising young fish; this keeps them away from possibly infected tubificids and makes it easier to eliminate spores and oligochaetes through filtration, chlorination, and ultraviolet bombardment. To minimise tubificid populations, techniques include periodic disinfection of the hatchery or aquaculture ponds, and the rearing of small trout indoors in pathogen-free water. Smooth-faced concrete or plastic-lined raceways that are kept clean and free of contaminated water keep aquaculture facilities free of the disease.Lastly, some drugs, such as furazolidone, furoxone, benomyl, fumagillin, proguanil and clamoxyquine, have been shown to impede spore development, which reduces infection rates. For example, one study showed that feeding fumagillin to O. mykiss reduced the number of infected fish from between 73% and 100% to between 10% and 20%.
In addition, affected individuals may have abnormally low levels of circulating red blood cells (anemia), a decrease in circulating blood platelets that assist in blood clotting functions (thrombocytopenia), abnormal liver function tests and/or inflammation of the blood vessels (vasculitis). Complications
Recurrent infection
Enlargement of the spleen causing too few red blood cells and platelets in the bloodstream
Enlarged lymph nodes
Skin hyperpigmentation
Cutaneous ulceration

Causes
The cause of Feltys syndrome is unknown, but it has been found to be more common in those with chronic rheumatoid arthritis. Some patients share the HLA-DR4 serotype. This syndrome is mostly present in people having extra articular manifestations of rheumatoid arthritis. People with this syndrome are at risk of infection because they have a low white blood cell count. Mechanism
The underlying pathogenesis of Feltys syndrome is not clear. Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune disease that is characterized by inflammation of the synovial joints due to attack by the bodys own immune system. In this condition, the white blood cells travel through the bloodstream to the synovial joints and release pro-inflammatory cytokines upon arrival. The result of this chemical release causes the synovial cells to release harmful chemicals in response as well as begin the growth of new blood vessels, forming a pannus. The pannus receives blood supply from the newly formed vessels and grows inward, invading the articular cartilage and bone within the joint. The damage to the once healthy tissue causes inflammation and ultimately fluid build-up in the joint.