Ferret Aleutian Disease on the Rise Again
By Mary Van Dahm
Note: This article originally appeared in January of 2000. The article discusses an ADV outbreak that occurred in that time period.
Outbreaks of Aleutian Disease Virus (ADV) have struck 5 shelters, a research ferret colony and 7 ferrets at an agricultural show here in the US and two breeders in England. The research facility had used cages that housed ADV infected mink over 2 years previous to housing the ferrets and the ferrets contracted the virus from the contaminated cages. Other sources of the virus are currently not known. A substandard breeder in Michigan who dumped a bunch of ferrets at a Michigan shelter is the suspected source for the disease in that state. Active outbreaks of ADV have also appeared in shelters in Texas, Pennsylvania, and Florida.
Aleutian disease is a parvo virus. Ferret – derived ADV strains are thought to be mutations of the more virulent mink origin ADV strains. There currently is no vaccine for this disease in ferrets so prevention is centered around disinfecting hands, clothes, and shoes after handling ferrets with known cases of the disease. Transmission of the virus may occur by aerosolization, but is usually spread by direct contact with urine, saliva, blood, and feces. The virus can remain active on contaminated surfaces for over two years if proper sanitation is not practiced.
Breeders should test their ferrets for ADV and test all new ferrets before bringing them into their ferretry. Ferret owners with very young or immune depressed ferrets in their household are advised not to get ferrets from mink farms or from known ADV infected ferret sources.
Fortunately most healthy adult ferrets that are exposed to ADV do not develop active cases of the disease. Exposed ferrets will usually live out normal life spans, but can become active if submitted to environmental stress or if they develop other health problems that weaken their immune systems. Unfortunately, ferrets that do become active with ADV usually die from it. Susceptibility to the disease is also thought to be partially genetic. ADV positive ferrets have been known to live with ADV negative ferrets without infecting the negative ferrets. On the other hand, in exposed colonies of related ferrets, up to 60% of the ferrets in the colonies eventually tested positive for ADV.
Symptoms of ADV vary. Some ferrets can die suddenly without any outward clinical signs of the disease. Most often the active form of the disease manifests itself by chronic, progressive weight loss, lethargy, enlarged liver and/or enlarged spleen anemia, rear leg or generalized weakness, neurologic twitching or seizures.and black tarry stool (due to internal hemorrhaging).
Since other health problems can also manifest them selves with these symptoms (hairballs, cancer, etc.) it is strongly recommended that a CEP (counterimmunoelectrophoresis) blood test or an IFA (immunoflourescent antibody) test be done. The CEP test is usually faster and less expensive than the IFA test, but the IFA test is more sensitive and can detect the disease in borderline cases. Many ferrets that test possitive can revert to negative after about 180 days, so retesting is recommended after 6 months.
The hallmark of ADV is hypergammaglobulinemia (the gamma globulin level is generally greater than 20%) usually with concurrent hypoalbuminemia. The most consistent histopathologic finding of ADV in ferrets is liver disease due to infiltration of the liver by plasma cells, lymphocytes, and macrophages. Enlarged lymph glands and lesions throughout the body may also be found in many, but not all, cases. Mink with ADV commonly develope kidney disease, but ferrets do not seem as prone to this development.
ADV is an imunosuppressent disease. Mink that test positive to ADV have also been found to be more susceptible to enteritis and to canine distemper (CD), even though properly vaccinated ADV seems to inhibit the CD vaccine’s ability to stimulate proper anti-body production against the CD virus. If a nonactive ADV positive ferret has been vaccinated for canine distemper, a revaccination is recommended in 6 months or after the ferret has had a negative test reading. In the meantime, keep the ferret indoors and away from possible sources of distemper.
Known cases of ADV positive ferrets should not be taken to places where they may come in contact with other ferrets (shows, fun matches, etc.) They also should not be allowed to run on floors or other areas where other susceptible ferrets or their owners may come in contact with residual traces of the virus from the infected animals.