Echovirus
Encyclopedia
An ECHO virus, is a type of RNA virus
that belongs to the genus
Enterovirus
of the Picornaviridae family. Echoviruses are found in the gastrointestinal tract (hence it being part of the enterovirus genus) and exposure to the virus causes other opportunistic infections and diseases.
of asymptomatic
children early in the 1950s, just after cell culturing
had been developed. The echo– part of the name was originally an acronym for "enteric
cytopathic human orphan" virus: Orphan virus means a virus that is not associated with any known disease. Even though Echoviruses have since been identified with various diseases, the original name is still used.
, and its primary target is children. The echovirus is among the leading causes of acute febrile
illness in infants and young children, and is the most common cause of aseptic meningitis
.
Infection of an infant with this virus following birth
may cause severe systemic disease
s, and is associated with high infant mortality
rates. The echovirus can mimic symptom
s caused by other common bacteria
l and viral
infection
s.
capsid
, which makes up 75% of the virus particle that encloses a dense central core of single-stranded RNA
. This RNA has a length of approximately 7.5 kilobase (kb), contains an RNA replicase, viral-coded proteins, and a single polyprotein that is responsible for the formation of structural proteins and other proteins necessary for cellular replication. The structural proteins determine host range and play a very important role in delivering the RNA genome
into the cytoplasm
of new host cells
.
Some viral replication of an echovirus occurs in the nasopharynx
after infection and then spreads to regional lymph node
s. However, most viral particles are swallowed and they reach the lower gut tract, where the virus is presumed to bind to specific receptors
. The virus then spreads to the lower intestinal tract, replicating but not causing any major cellular effects along the way. Next, the virus spreads to many secondary sites in the body such as the central nervous system
, liver
, spleen
, bone marrow
, heart
and finally the lung
s. Additional replication of the virus will occur, causing symptoms 4 to 6 days after infection. The most deadly part however is delayed when symptoms of a central nervous system disease start to appear. Enteroviruses are capable of infecting any cell in the body. These viruses are highly infectious. They can spread through the air to other hosts 1–3 weeks after infection and can spread through feces to other hosts eight weeks after infection.
or myocarditis
, rather than infection of the central nervous system. Older children and adults have a better prognosis. Myocarditis is the most frequent complication in adults.
ECHO virus, like the other Enteroviruses Coxsackievirus A and B, typically causes a mild, nonspecific illness with a low fever. Echovirus may also produce a rash that spreads from the face down to the neck, upper extremities, and chest. Laboratory diagnosis is made with acute and convalescent titers of serum antibodies to Echovirus.
. Echoviruses are transmitted person-to-person; the fecal-oral route is the predominant mode, although transmission sometimes occurs via respiration of oral secretions such as saliva
. Indirect transmission occurs through numerous routes, including via contaminated water, food, and fomite
s (inanimate objects). Contaminated swimming and wading pools can also transmit the virus. Also, there are well-documented reports of transmission via the contaminated hands of hospital personnel.
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...
that belongs to the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Enterovirus
Enterovirus
Enteroviruses are a genus of ssRNA viruses associated with several human and mammalian diseases. Serologic studies have distinguished 66 human enterovirus serotypes on the basis of antibody neutralization tests. Additional antigenic variants have been defined within several of the serotypes on the...
of the Picornaviridae family. Echoviruses are found in the gastrointestinal tract (hence it being part of the enterovirus genus) and exposure to the virus causes other opportunistic infections and diseases.
History
The first isolation of echoviruses occurred from the fecesFeces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
of asymptomatic
Asymptomatic
In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...
children early in the 1950s, just after cell culturing
Cell culture
Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...
had been developed. The echo– part of the name was originally an acronym for "enteric
Enteric
Enteric can refer to:* A general term describing something related to or associated with the intestines** Microorganisms that inhabit the intestines are commonly known as enteric bacteria* Enteric nervous system...
cytopathic human orphan" virus: Orphan virus means a virus that is not associated with any known disease. Even though Echoviruses have since been identified with various diseases, the original name is still used.
Description
Echovirus is highly infectiousInfectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
, and its primary target is children. The echovirus is among the leading causes of acute febrile
Fever
Fever 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...
illness in infants and young children, and is the most common cause of aseptic meningitis
Aseptic meningitis
Aseptic meningitis, or sterile meningitis, is a condition in which the layers lining the brain, meninges, become inflamed and a pyogenic bacterial source is not to blame. Meningitis is diagnosed on a history of characteristic symptoms and certain examination findings...
.
Infection of an infant with this virus following birth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
may cause severe systemic disease
Systemic disease
Life-threatening disease redirects here.A systemic disease is one that affects a number of organs and tissues, or affects the body as a whole. Although most medical conditions will eventually involve multiple organs in advanced stage Life-threatening disease redirects here.A systemic disease is one...
s, and is associated with high infant mortality
Infant mortality
Infant mortality is defined as the number of infant deaths per 1000 live births. Traditionally, the most common cause worldwide was dehydration from diarrhea. However, the spreading information about Oral Re-hydration Solution to mothers around the world has decreased the rate of children dying...
rates. The echovirus can mimic symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s caused by other common bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l and viral
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
s.
Viral structure and infection
An echovirus measures 24-30 nanometres (nm), and is similar to other viruses, since it has a naked proteinProtein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
capsid
Capsid
A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...
, which makes up 75% of the virus particle that encloses a dense central core of single-stranded RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
. This RNA has a length of approximately 7.5 kilobase (kb), contains an RNA replicase, viral-coded proteins, and a single polyprotein that is responsible for the formation of structural proteins and other proteins necessary for cellular replication. The structural proteins determine host range and play a very important role in delivering the RNA genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
into the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
of new host cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.
Some viral replication of an echovirus occurs in the nasopharynx
Nasopharynx
The nasopharynx is the uppermost part of the pharynx. It extends from the base of the skull to the upper surface of the soft palate; it differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent .-Lateral:On its lateral wall is the pharyngeal ostium of the...
after infection and then spreads to regional lymph node
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
s. However, most viral particles are swallowed and they reach the lower gut tract, where the virus is presumed to bind to specific receptors
Receptor (biochemistry)
In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
. The virus then spreads to the lower intestinal tract, replicating but not causing any major cellular effects along the way. Next, the virus spreads to many secondary sites in the body such as the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
, spleen
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
, bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
, heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
and finally the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s. Additional replication of the virus will occur, causing symptoms 4 to 6 days after infection. The most deadly part however is delayed when symptoms of a central nervous system disease start to appear. Enteroviruses are capable of infecting any cell in the body. These viruses are highly infectious. They can spread through the air to other hosts 1–3 weeks after infection and can spread through feces to other hosts eight weeks after infection.
Symptoms and diagnosis
Echovirus disease occurs disproportionately in males and children. Infection within the first two weeks of birth can cause devastating and potentially fatal disease. In this population, death usually results from overwhelming liver failureLiver failure
Acute liver failure is the appearance of severe complications rapidly after the first signs of liver disease , and indicates that the liver has sustained severe damage . The complications are hepatic encephalopathy and impaired protein synthesis...
or myocarditis
Myocarditis
Myocarditis is inflammation of heart muscle . It resembles a heart attack but coronary arteries are not blocked.Myocarditis is most often due to infection by common viruses, such as parvovirus B19, less commonly non-viral pathogens such as Borrelia burgdorferi or Trypanosoma cruzi, or as a...
, rather than infection of the central nervous system. Older children and adults have a better prognosis. Myocarditis is the most frequent complication in adults.
ECHO virus, like the other Enteroviruses Coxsackievirus A and B, typically causes a mild, nonspecific illness with a low fever. Echovirus may also produce a rash that spreads from the face down to the neck, upper extremities, and chest. Laboratory diagnosis is made with acute and convalescent titers of serum antibodies to Echovirus.
Cause of infection
Causes of echovirus infections (Acute meningitis) can be placed in several categories. Main causes of infection are from overcrowded conditions such as the poor districts of a city and poor hygieneHygiene
Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
. Echoviruses are transmitted person-to-person; the fecal-oral route is the predominant mode, although transmission sometimes occurs via respiration of oral secretions such as saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
. Indirect transmission occurs through numerous routes, including via contaminated water, food, and fomite
Fomite
A fomite is any inanimate object or substance capable of carrying infectious organisms and hence transferring them from one individual to another. A fomite can be anything...
s (inanimate objects). Contaminated swimming and wading pools can also transmit the virus. Also, there are well-documented reports of transmission via the contaminated hands of hospital personnel.