Equine viral arteritis
Encyclopedia
Equine viral arteritis is a disease of horses caused by an RNA virus
of the genus Arterivirus
. The virus which causes EVA was first isolated from horses in Ohio
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
, but there is no breed “immunity”. In the UK, it is a notifiable disease
. There is no known human hazard.
es are small, enveloped, animal viruses
with an icosahedral
core containing a positive-sense RNA
genome. The family includes Equine arteritis virus (EAV), porcine reproductive and respiratory syndrome virus (PRRSV), lactate dehydrogenase elevating virus
(LDV) of mice and simian haemorrhagic fever virus (SHFV).
Some horses show no symptoms.
of the virus. The most frequent is the respiratory route. The virus can also be spread by the venereal route, including by artificial insemination. Stallions may become carriers
.
(PCR), and detection of antibodies by ELISA
and virus neutralisation
tests.
available in the UK and Europe
, 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.
RNA virus
An RNA virus is a virus that has RNA as its genetic material. This nucleic acid is usually single-stranded RNA but may be double-stranded RNA...
of the genus Arterivirus
Arterivirus
Arterivirus is a genus of virus, with type species equine arteritis virus. In 1996, the family Arteriviridae was included within the order Nidovirales. Arteriviruses are small, enveloped, animal viruses with an icosahedral core containing a positive-sense RNA genome...
. The virus which causes EVA was first isolated from horses in Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
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
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, but there is no breed “immunity”. In the UK, it is a notifiable disease
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. Many governments have enacted regulations for reporting of both human...
. There is no known human hazard.
Equine Arteritis Virus
The virus which causes EVA is the Equine Arteritis Virus (EAV). ArterivirusArterivirus
Arterivirus is a genus of virus, with type species equine arteritis virus. In 1996, the family Arteriviridae was included within the order Nidovirales. Arteriviruses are small, enveloped, animal viruses with an icosahedral core containing a positive-sense RNA genome...
es are small, enveloped, animal viruses
Animal virology
The study of animal viruses is important from a veterinary viewpoint and many of these viruses cause diseases that are economically devastating. Many animal viruses are also important from a human medical perspective...
with an icosahedral
Icosahedron
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is one of the five Platonic solids....
core containing a positive-sense RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
genome. The family includes Equine arteritis virus (EAV), porcine reproductive and respiratory syndrome virus (PRRSV), lactate dehydrogenase elevating virus
Lactate dehydrogenase elevating virus
Lactate dehydrogenase elevating virus, or LDV for short, belongs to part of the arteriviridae family and the nidovirales order. Also included in the nidovirales order are the coronaviridae. The arteriviridae infect macrophages in animals and cause a variety of diseases...
(LDV) of mice and simian haemorrhagic fever virus (SHFV).
Symptoms
Infected horses show variable symptoms including:- FeverFeverFever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, peaking at up to 41 C - DepressionDepression (mood)Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...
- OedemaEdemaEdema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
- ConjunctivitisConjunctivitisConjunctivitis refers to inflammation of the conjunctiva...
or "pink eye" - AbortionAbortionAbortion is defined as the termination of pregnancy by the removal or expulsion from the uterus of a fetus or embryo prior to viability. An abortion can occur spontaneously, in which case it is usually called a miscarriage, or it can be purposely induced...
in pregnant mares - Nasal discharge
Some horses show no symptoms.
Transmission
There are a number of routes of transmissionTransmission (medicine)
In medicine and biology, transmission is the passing of a communicable disease from an infected host individual or group to a conspecific individual or group, regardless of whether the other individual was previously infected...
of the virus. The most frequent is the respiratory route. The virus can also be spread by the venereal route, including by artificial insemination. Stallions may become carriers
Asymptomatic carrier
An asymptomatic carrier is a person or other organism that has contracted an infectious disease, but who displays no symptoms. Although unaffected by the disease themselves, carriers can transmit it to others...
.
Diagnosis
Because of the variablity 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 polymerase chain reactionPolymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
(PCR), and detection of antibodies by ELISA
ELISA
Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...
and virus neutralisation
Neutralisation (immunology)
Neutralisation in the immunological sense refers to the ability of antibodies to block the site on bacteria or viruses that they use to enter their target cell. One example of this within biology is a neutralizing antibody....
tests.
First UK Outbreak
The first outbreak of EVA in the UK was in 1993. The outbreak affected six premesis and around 100 horses were infected. Further spread of the virus was prevented by movement restrictions.Control
There is a vaccineVaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
available in the UK and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, 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.