''Tremovirus'', also known epidemic tremor, is a

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

genus belonging to the ''

Picornaviridae Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm i ...

'' family. The genus has two species, ''Tremovirus A'', which is also called ''Avian encephalomyelitis virus'', and ''Tremovirus B''. The first avian picornavirus to have its

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

sequenced In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...

, it causes epidemic

tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, fa ...

chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...

s. Tremovirus is of economic importance to chicken farmers because it causes a drop in egg production in laying hens, and neurological diseases in chicks less than three weeks old. The domestic host is the

, but it can also infect

partridge A partridge is a medium-sized Galliformes, galliform bird in any of several genera, with a wide Indigenous (ecology), native distribution throughout parts of Europe, Asia and Africa. Several species have been introduced to the Americas. They a ...

turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

quail Quail is a collective name for several genera of mid-sized birds generally placed in the order Galliformes. The collective noun for a group of quail is a flock, covey, or bevy. Old World quail are placed in the family Phasianidae, and New Wor ...

guineafowl Guineafowl (; sometimes called "pet speckled hens" or "original fowl") are birds of the family Numididae in the order Galliformes. They are endemic to Africa and rank among the oldest of the gallinaceous birds. Phylogenetically, they branched o ...

, and

pheasant Pheasants ( ) are birds of several genera within the family (biology), family Phasianidae in the order (biology), order Galliformes. Although they can be found all over the world in introduced (and captive) populations, the pheasant genera na ...

s. It has a worldwide distribution. The virus can be spread by both

vertical Vertical is a geometric term of location which may refer to: * Vertical direction, the direction aligned with the direction of the force of gravity, up or down * Vertical (angles), a pair of angles opposite each other, formed by two intersecting s ...

and

horizontal transmission Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. This concept has been generalized to include transmissions of infectious agents, symbiont ...

. It is not a

zoonosis A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...

, meaning that it cannot be transmitted to humans.

Symptoms and diagnosis

Neurological signs such as

ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...

of the head and neck, drooping wings,

weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

paralysis Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 ...

exercise intolerance Exercise intolerance is a condition of inability or decreased ability to perform physical exercise at the normally expected level or duration for people of that age, size, sex, and muscle mass. It also includes experiences of unusually severe post ...

and

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

are seen in chicks less than 3 weeks old. In laying hens the disease causes a temporary reduction in egg production. Antibodies can be detected using an

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 ...

or virus neutralisation. Definitive diagnosis of the disease is by

histopathology Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία '' -logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spe ...

or virus isolation.Avian Encephalomyelitis
expert reviewed and published by

WikiVet WikiVet is a wiki of veterinary content based on the MediaWiki platform. The website is a collaborative initiative between various veterinary schools, and its content covers the entire veterinary curriculum. WikiVet is part of the WikiVet Educatio ...

, accessed 10 October 2011.

Treatment and control

Currently, no treatment is available, but chicks that survive infection are immune. Control is achieved by

vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...

of the flock. The vaccine can be administered via inoculation of the wing web, by drinking water or eyedrops, though eyedrop administration is much more effective. Mortality ranges from 25–60% and surviving animals are considered nonprofitable.

Taxonomy

The genus ''Tremovirus'' contains two species: *'' Tremovirus A'' *'' Tremovirus B''

References

{{Taxonbar, from=Q22112089, from2=Q18814771, from3=Q4112122 Poultry diseases Bird diseases Picornaviridae Animal viral diseases Virus genera Animal vaccines