Equine infectious anemia
S0064 - Ultrasensitive qualitative detection of equine infectious
anemia proviral DNA by real time polymerase chain reaction.
infectious anemia (EIA), also known as Swamp Fever, is a viral
disease known to occur in all members of equidae, including
horses, mules and donkeys. Equine infectious anemia virus (EIAV)
is a member of the genus Lentivirus of the family Retroviridae.
EIAV is unique among the lentiviruses in that the initial acute
febrile response and associated viremia are followed by
recurrent cycles of the disease and, finally, a prolonged
experience fever and hemorrhaging 7-30 days post infection. Very
few horses with this initial fever are detected by owners.
Chronic infection is marked by episodes of fever, weight loss,
depression, progressive weakness, anemia and edema. These signs
occur every two weeks in recurring cycles.
symptoms that may occur during the course of the disease include
loss of appetite, frequent urination, diarrhea, weakness,
paralysis of the hindquarters, paleness of the mucous membranes,
yellowish discoloration of the conjunctiva, small pinpoint
hemorrhages beneath the tongue, rapid breathing and accelerated
pulse. Pregnant mares may abort.
The onset of
these signs is often associated with stresses such as hard work,
hot weather, racing, pregnancy or use of steroid drugs. Some
animals show no clinical signs associated with the infection and
may go undetected. These apparently healthy carriers harboring
the virus are a constant reservoir of infection.
currently no effective vaccine to prevent EIAV infection.
Routine serological testing and removal of seropositive reactors
limits the spread of this disease. However, the utility of
serological tests depends on the length of time it takes for an
animal to mount an immune response and on the test’s sensitivity
and sensitivity of antibody detection. Currently, the agar gel
immunodiffusion assay (the Coggins test) is widely accepted and
used for serodetection of EIAV group specific antigen p26.
Competitive enzyme-linked immunosorbent assay (c-ELISA) and
synthetic antigen ELISA (SA-ELISA) have also been used for the
serological detection of EIA specific antibodies. A fluorescent
polarization-based diagnostic assay for detection of EIAV
antibodies has also been reported ( Tencza et al., 2000).
Besides serological assays, virus isolation can be used but it
is not practical because it is time consuming, laborious and
requires specialized technical skills to maintain primary horse
macrophage cultures for the replication of pathogenic strains of
EIAV. The high cost and slowness of virus isolation make it
unsuitable for routine monitoring.
EIAV proviral DNA in blood cells by PCR has been shown to be
more sensitive and specific than serological assays not only in
identifying subclinical EIAV-infected horses, but also recently
infected horses still in the process of mounting an immune
response (Spyrou, et al., 2003).
Help confirm the disease causing agent
Shorten the time required to confirm a clinical
diagnosis of EIA virus infection.
Help ensure that horse populations are free of EIA virus
Early prevention of spread of the virus
Minimize personnel exposure to the virus
Safety monitoring of biological products that derive
Spyrou, V., Papanastassopoulou, M., Psychas, V., Billinis, C.H,
Koumbati, M., Vlemmas, J. and Koptopoulos, G. (2003). Equine
infectious anemia in mules: virus isolation and pathogenicity
studies. Vet Microbiol. 95:49-59.
Tencza, S.B., Islam, K.R.,
Kalia, V., Nasir, M.S., Jolley, M.E. and Montelaro, R.C. (2000).
Development of a fluorescence polarization-based diagnostic
assay for equine infectious anemia virus. J. Clin. Microbiol.
Specimen requirements: 0.2 ml whole blood in EDTA (purple top) or ACD (yellow top)
tube, or 0.2 ml fresh, frozen or fixed tissue.
types other than those listed here, please call to confirm
specimen acceptability and shipping instructions.
specimen types, if there will be a delay in shipping, or during
very warm weather, refrigerate specimens until shipped and ship
with a cold pack unless more stringent shipping requirements are
specified. Frozen specimens should be shipped so as to remain
frozen in transit. See shipping
instructions for more information.
2 business days
Qualitative real time PCR