Virus: From 3 Different Sources
The term applied to a group of infective agents which are so small that they are able to pass through the pores of collodion ?lters. They are responsible for some of the most devastating diseases affecting humans: for example, INFLUENZA, POLIOMYELITIS, SMALLPOX and YELLOW FEVER. The virus of in?uenza measures 80 nanometres, whereas the STAPHYLOCOCCUS measures 1,000 nanometres (1 nanometre = one thousand-millionth of a metre).
A single virus particle, known as a virion, comprises an inner core of NUCLEIC ACID which is surrounded by one or two protective coverings (capsid) made of protein. Sometimes the capsid is enclosed by another layer called the viral envelope (also a protein structure). The envelope often disintegrates when the virus invades a cell. Viruses enter cells and then indulge in a complex and variable process of replication using some of the cells’ own structure. Viruses may stay in a host’s nucleus, being reactivated months or years later. There are more than a score of large families of viruses, from papoviruses, which cause WARTS, through HERPES viruses (cold sores, CHICKENPOX, SHINGLES) and orthomyxoviruses (in?uenza), to corona viruses (common cold) and retroviruses (AIDS/HIV). Viral diseases are more dif?cult to treat than those caused by bacteria: ANTIBIOTICS are ine?ective but INTERFERON, a group of natural substances, shows promise. IMMUNISATION is the most e?ective way of combating viral infections; smallpox, poliomyelitis, MUMPS, MEASLES and RUBELLA are examples of viral diseases which have been successfully combated. Research is progressing to ?nd a vaccine against HIV.
An extremely small infective agent requiring living cells for replication. Are either RNA or DNA, never both.
n. a minute particle that is capable of replication but only within living cells. Viruses are too small to be visible with a light microscope and too small to be trapped by filters. They infect animals, plants, and microorganisms (see bacteriophage). Each consists of a core of nucleic acid (DNA or RNA) surrounded by a protein shell. Some bear an outer lipid capsule. Viruses cause many diseases, including the common cold, influenza, measles, mumps, chickenpox, herpes, AIDS, polio, and rabies. *Antiviral drugs are effective against some of them, and many viral diseases are controlled by means of vaccines. —viral adj.
The virus that causes glandular fever or infectious MONONUCLEOSIS. It is similar to the viruses that cause herpes and is associated with BURKITT’S LYMPHOMA. It has been suggested as precipitating some attacks of MYALGIC ENCEPHALOMYELITIS (ME), also known as CHRONIC FATIGUE SYNDROME (CFS).... epstein barr virus
A mosquito-borne viral infection that is normally harmless to healthy people who, if infected, develop a mild ?u-like illness. However, if the elderly and those in poor health, particularly immunocompromised patients, are infected, they may develop fatal in?ammation of the brain and spinal cord. In Israel in 2000, 12 people died and more than 155 survived an outbreak; and in New York in 1999, more than 60 people were infected, of whom six died. The disease was ?rst reported in Uganda in 1937 and became ENDEMIC in the Middle East and Africa, recently spreading to Europe, central Asia, Oceania and America. Mosquitoes bearing the ?aviviridae-family virus usually contract it by biting infected poultry, but the infection has been found in mammals, such as cats, dogs and horses.... west nile virus
A mosquito-borne arbovirus causing symptoms similar to Ross River virus infection in Australia. (See also Ross River virus).... barmah forest virus
A group of viruses so-called because they were ?rst isolated from two patients with a disease resembling paralytic POLIOMYELITIS, in the village of Coxsackie in New York State. Thirty distinct types have now been identi?ed. They constitute one of the three groups of viruses included in the family of ENTEROVIRUSES, and are divided into two groups: A and B. Despite the large number of types of group A virus (24) in existence, evidence of their role in causing human disease is limited. Some, however, cause aseptic MENINGITIS, non-specicifc upper respiratory infection and MYOCARDITIS, and others cause a condition known as HERPANGINA. HAND, FOOT AND MOUTH DISEASE is another disease caused by the A group. All six types of group B virus have been associated with outbreaks of aseptic meningitis, and they are also the cause of BORNHOLM DISEASE. Epidemics of type B2 infections tend to occur in alternate years. (See VIRUS.)... coxsackie viruses
Virus of Flying Foxes (Fruit Bats) in Australia. Can infect horses and humans. Also known as the Equine morbillivirus.... hendra virus
The most common causes of viral hepatitis are those caused by the Hepatitis A, B, C, D, E and G viruses. Hepatitis F virus has been described but is a doubtful entity. Other viruses which can cause hepatitis include the Epstein-Barr Virus, cytomegalovirus, and the Yellow Fever virus.... hepatitis viruses
Causative virus of genital herpes and herpes labalis or cold sores.... herpes simplex virus
One member of a group of viruses containing DNA which cause latent infections in animals and humans. Viruses from this group cause HERPES SIMPLEX, HERPES ZOSTER (shingles) and CHICKENPOX, and include CYTOMEGALOVIRUS (CCMV) and EPSTEIN-BARR VIRUS.... herpes viruses
Causative virus of chicken pox and shingles.... herpes zoster virus
The name of the causative agent of AIDS.... hiv (human immunodeficiency virus)
See AIDS/HIV.... human immunodeficiency virus
A group of rhabdoviruses closely related to the rabies virus. The Australian Bat Lyssa virus is found in flying foxes (fruit bats) and can cause a rabies-like disease in humans. The disease should be handled as for rabies and can be prevented by using rabies vaccine.... lyssa virus
A herpes virus of monkeys that can infect humans, usually through handling monkey tissues at autopsy or in the laboratory.... monkey b virus
Virus first identified from the village of Nipah in Malaysia. Carried by flying foxes (fruit bats). Can infect pigs and humans.... nipah virus
These include the human papilloma viruses (HPV), of which nearly a hundred strains have been identi?ed. HPV cause verrucae (see WARTS) on skin and, less often, on the mucous membranes of mouth, larynx, genitalia and the cervix. Some strains may predispose to eventual cancer.... papova viruses
These are included in the paramyxoviruses (see MYXOVIRUSES) and divided into four types, all of which cause infection of the respiratory system (see RESPIRATION). Infection with type 3 begins in May, reaches a maximum in July or August and returns to base-line level in October. Types 1 and 2 are predominantly winter viruses. Children are commonly affected and the manifestations include CROUP, fever, and a rash.... parainfluenza viruses
These infectious agents derive their name from pico (small) and from RNA (because they contain ribonuleic acid). They are a group of viruses which includes the ENTEROVIRUSES and the RHINOVIRUSES.... picorna viruses
Usually known as RSV, this is one of the MYXOVIRUSES. It is among the major causes of BRONCHIOLITIS and PNEUMONIA among infants aged under 6 months; its incidence has been increasing, possibly due to atmospheric pollution.... respiratory syncytial virus (rsv)
A mosquito-borne arbovirus causing epidemic polyarthritis in Australia and certain islands of the Western Pacific to which it has spread.... ross river virus
A virus that causes infectious mononucleosis; the virus is also associated with Burkitt’s lymphoma and cancer of the nasopharynx (see nasopharynx, cancer of).... epstein–barr virus
A group of diseases of the central nervous system that occur many months or even years after infection with a virus. They cause gradual widespread destruction of nerve tissue, with progressive loss of brain function and a fatal outcome. Examples include Creutzfeldt–Jakob disease and kuru.... slow virus diseases
(echovirus) one of a group of RNA-containing viruses that are able to multiply in the gastrointestinal tract (see enterovirus). About 30 different types exist. Type A Coxsackie viruses generally cause less severe and less well-defined diseases, such as *hand, foot, and mouth disease, although some cause meningitis and severe throat infections (see herpangina). Type B Coxsackie viruses cause inflammation or degeneration of heart tissue, resulting in pericarditis or myocarditis, or brain tissue, producing meningitis or encephalitis. They can also attack the muscles of the chest wall, the bronchi, pancreas, thyroid, or conjunctiva and recent evidence suggests they may be implicated in diabetes in children and in motor neuron disease. See also Bornholm disease.... coxsackie virus
see HIV.... human immunodeficiency virus
a group of large RNA-containing viruses that cause infections of the respiratory tract producing mild influenza-like symptoms. They are included in the paramyxovirus group (see myxovirus).... parainfluenza viruses
(RSV) a paramyxovirus (see myxovirus) that causes infections of the nose and throat. It is a major cause of bronchiolitis and pneumonia in young children. In tissue cultures infected with the virus, cells merge together to form a conglomerate (syncytium). RSV is thought to have a role in *sudden infant death syndrome. Vulnerable children can be treated with *ribavirin, but most children just require supportive measures.... respiratory syncytial virus
a mosquito-borne virus that usually causes mild symptoms in humans, including fever, skin rashes, muscle and joint pain, and headache. However, infection during pregnancy can result in brain abnormalities of the fetus, notably *microcephaly. Zika virus can also trigger *Guillain–Barré syndrome. Infection is usually from a mosquito bite, although the virus may also be transmitted by sexual intercourse.... zika virus
a virus responsible for an acute infection in humans with features similar to those of *Marburg disease. Transmission is by contact with infected blood and other body fluids and the incubation period is 2–21 days (7 days on average). The mortality rate is 53–88%, but intensive treatment (including rehydration) in the early stages of the disease can halt its rapid and usually irreversible progression to haemorrhaging of internal organs. Until recently, sporadic but short-lived outbreaks have occurred in Africa since 1976, when the virus was first identified during an outbreak in the region of the Ebola river, in Zaïre (now Democratic Republic of Congo). A major epidemic of the disease broke out in West Africa at the end of 2013 and lasted until May 2016: over 11,000 people died. An unknown species of animal – possibly a fruit bat – is assumed to act as a reservoir for the virus between outbreaks of the disease in humans.... ebola virus
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