Equine viral arteritis (EVA) is a disease of horses caused by a virus of the species ''Alphaarterivirus equid'', an

RNA virus An RNA virus is a virusother than a retrovirusthat has ribonucleic acid (RNA) as its genetic material. The nucleic acid is usually single-stranded RNA ( ssRNA) but it may be double-stranded (dsRNA). Notable human diseases caused by RNA viruse ...

. It is the only species in the genus ''Alphaarterivirus'', and that is the only genus in the ''Equarterivirinae'' subfamily. The virus which causes EVA was first isolated in 1953, but the disease has afflicted equine animals worldwide for centuries. It has been more common in some breeds of horses in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

, but there is no breed "immunity". In the UK, it is a

notifiable disease A notifiable disease is any disease that is required by law to be reported to government authorities. The collation of information allows the authorities to monitor the disease, and provides early warning of possible outbreaks. In the case of live ...

. There is no known human hazard.

Signs

The signs shown depend on the horse's age, the strain of the infecting virus, the condition of the horse and the route by which it was infected. Most horses with EVA infection do not show any signs; if a horse does show signs, these can vary greatly in severity. Following infection, the first sign is

fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

, peaking at , followed by various signs such as

lethargy Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overwor ...

, nasal discharge, "pink eye" (

conjunctivitis Conjunctivitis, also known as pink eye, is inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness, or itchiness may occur. The ...

), swelling over the eye (supraorbital

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...

urticaria Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and does not leave any long-lasti ...

, and swelling of the limbs and under the belly (the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

abdomen) which may extend to the udder in mares or the scrotum of male horses. More unusual signs include

spontaneous abortion Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical l ...

in pregnant mares, and, most likely in foals, severe respiratory distress and death.

Cause

EVA is caused by an arterivirus called equine arteritis virus (EAV). Arteriviruses are small, enveloped,

animal viruses Veterinary virology is the study of viruses in non-human animals. It is an important branch of veterinary medicine. Rhabdoviruses Rhabdoviruses are a diverse family of single stranded, negative sense RNA viruses that infect a wide range of hos ...

with an

icosahedral In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrica ...

core containing a positive-sense

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

genome. As well as equine arteritis virus the Arterivirus family includes

porcine reproductive and respiratory syndrome virus ''Betaarterivirus suid 1'', formerly ''Porcine reproductive and respiratory syndrome virus'' (PRRSV), is a virus that causes a disease of pigs, called porcine reproductive and respiratory syndrome (PRRS), also known as blue-ear pig disease (in C ...

(PRRSV),

lactate dehydrogenase elevating virus Lactate dehydrogenase elevating virus (LDV) constitutes the species ''Gamamaarterivirus lacdeh'' which is part of the family ''Arteriviridae'' and order ''Nidovirales''. The order ''Nidovirales'' also includes the family of coronaviruses. Arteriv ...

(LDV) of mice and

simian haemorrhagic fever virus ''Deltaarterivirus hemfev'', formerly ''Simian hemorrhagic fever virus'' or ''simian haemorrhagic fever virus'' (SHFV), is a highly pathogenic virus in monkeys. It is a positive-stranded RNA virus classified in the family ''Arteriviridae''. It i ...

(SHFV). There are a number of routes of

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...

of the virus. The most frequent is the

respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gre ...

route. Virions can also be shed into the semen, and the disease has been spread by artificial insemination. Stallions may become carriers.

Diagnosis

Because of the variability of symptoms, diagnosis is by laboratory testing. Blood samples, nasal swabs and semen can be used for isolation of the virus, detection of the viral RNA by

reverse transcriptase A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, ...

polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) ...

and detection of antibodies by

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...

tests.

Prevention

vaccine A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. ...

is available in the UK and

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

, however in laboratory tests it is not possible to distinguish between antibodies produced as a result of vaccination and those produced in response to infection with the virus. Management also plays an important part in the prevention of EVA.

Research

Zinc

ionophore In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as ...

s show antiviral activity against Equine viral arteritis.

History

The virus causing EVA was first identified following an outbreak of respiratory disease and spontaneous abortion on a horse farm in

Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...

in 1953. The first outbreak of EVA in the UK was in 1993. The outbreak affected six premises and around 100 horses were infected. Further spread of the virus was prevented by movement restrictions.

References

External links

* {{Taxonbar, from=Q57758308, from2=Q18844364, from3=Q57753807, from4=Q57751690 Horse diseases Animal viral diseases