Avian adenovirus
Encyclopedia
Also known as: Haemorrhagic Enteritis — HE — Egg Drop Syndrome — EDS — Quail Bronchitis — QB — Pheasant Marble Spleen Disease — MSD — Inclusion Body Hepatitis — IBH
es that affect birds - particularly chickens
, ducks
, geese
, turkeys
and pheasants
- representing one of four genera of the family Adenoviridae
, the others being Mastadenovirus, Atadenovirus and Siadenovirus. They are class I, non-enveloped, icosahedral viruses that are 74–80 nm in diameter, having a double stranded DNA
genome
of approximately 26–45 kilo–base pair
s (kbp) and a guanine
/cytosine
content of 53–59%. The viruses causes specific disease syndromes such as Quail Bronchitis (QB), Egg Drop Syndrome (EDS), Haemorrhagic Enteritis (HE), Pheasant Marble Spleen Disease (MSD) and Inclusion Body Hepatitis (IBH).
Avian adenovirus has a worldwide distribution and it is common to find multiple species on a single farm. The most common serogroups
are serogroup 1, 2 and 3. It is not a zoonoses.
The virus is mainly spread horizontally
by the oro-fecal route
, but vertical transmission
can occur in serogroup 1. Once it has infected the bird the virus may remain latent until a period of stress, when it may then cause clinical disease.
, however clinical disease can occur - especially in young birds as maternal antibody
levels begin to wane.
Clinical signs are related to the organ effected:
Signs of gastrointestinal disease (Haemorrhagic Enteritis) include diarrhea
, anorexia
, melena
and hematochezia
. Anaemia and dehydration
may develop secondary to this haemorrhagic enteritis. Signs of reproductive disease (Egg Drop Syndrome) include low egg production/hatching and the laying of abnormal eggs (size, shape, colour, texture). Adenovirus infection may infect other organs, causing a splenitis, inclusion body hepatitis
, bronchitis
, pulmonary congestion ventriculitis
, pancreatitis
, or oedema, depending on the species of bird infected.
Diagnosis of aviadenovirus is by histopathology
, electron microscopy
, viral isolation and ELISA
. In addition, virus antigen can be detected double immunodiffusion. Postmortem examination
may reveal a variety of clinical signs relating directly to the organ affected. Specifically, Egg Drop Syndrome can be diagnosed by hemagglutinin inhibition
and the virus causes haemagglutination in chickens and ducks.
Introduction
Aviadenoviridae are virusVirus
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...
es that affect birds - particularly chickens
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
, ducks
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
, geese
Goose
The word goose is the English name for a group of waterfowl, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....
, turkeys
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
and pheasants
Pheasant
Pheasants refer to some members of the Phasianinae subfamily of Phasianidae in the order Galliformes.Pheasants are characterised by strong sexual dimorphism, males being highly ornate with bright colours and adornments such as wattles and long tails. Males are usually larger than females and have...
- representing one of four genera of the family Adenoviridae
Adenoviridae
Adenoviruses are medium-sized , nonenveloped icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA genome...
, the others being Mastadenovirus, Atadenovirus and Siadenovirus. They are class I, non-enveloped, icosahedral viruses that are 74–80 nm in diameter, having a double stranded DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
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....
of approximately 26–45 kilo–base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s (kbp) and a guanine
Guanine
Guanine is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine . In DNA, guanine is paired with cytosine. With the formula C5H5N5O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with...
/cytosine
Cytosine
Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine . It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached . The nucleoside of cytosine is cytidine...
content of 53–59%. The viruses causes specific disease syndromes such as Quail Bronchitis (QB), Egg Drop Syndrome (EDS), Haemorrhagic Enteritis (HE), Pheasant Marble Spleen Disease (MSD) and Inclusion Body Hepatitis (IBH).
Avian adenovirus has a worldwide distribution and it is common to find multiple species on a single farm. The most common serogroups
Serotype
Serotype or serovar refers to distinct variations within a subspecies of bacteria or viruses. These microorganisms, viruses, or cells are classified together based on their cell surface antigens...
are serogroup 1, 2 and 3. It is not a zoonoses.
The virus is mainly spread horizontally
Horizontal transmission
Horizontal transmission is the transmission of a bacterial, fungal, or viral infection between members of the same species that are not in a parent-child relationship....
by the oro-fecal route
Fecal-oral route
The fecal-oral route, or alternatively, the oral-fecal route or orofecal route is a route of transmission of diseases, in which they are passed when pathogens in fecal particles from one host are introduced into the oral cavity of another potential host.There are usually intermediate steps,...
, but vertical transmission
Vertical transmission
Vertical transmission, also known as mother-to-child transmission, is the transmission of an infection or other disease from mother to child immediately before and after birth during the perinatal period. A pathogen's transmissibility refers to its capacity for vertical transmission...
can occur in serogroup 1. Once it has infected the bird the virus may remain latent until a period of stress, when it may then cause clinical disease.
Clinical Signs & Diagnosis
Infections are normally subclinicalSubclinical infection
A subclinical infection is the asymptomatic carrying of an by an individual of an agent that usually is a pathogen causing illness, at least in some individuals. Many pathogens spread by being silently carried in this way by some of their host population...
, however clinical disease can occur - especially in young birds as maternal antibody
Passive immunity
Passive immunity is the transfer of active humoral immunity in the form of readymade antibodies, from one individual to another. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and can also be induced artificially, when high levels...
levels begin to wane.
Clinical signs are related to the organ effected:
Signs of gastrointestinal disease (Haemorrhagic Enteritis) include diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, anorexia
Anorexia (symptom)
Anorexia is the decreased sensation of appetite...
, melena
Melena
In medicine, melena or melaena refers to the black, "tarry" feces that are associated with gastrointestinal hemorrhage. The black color is caused by oxidation of the iron in hemoglobin during its passage through the ileum and colon.-Melena vs...
and hematochezia
Hematochezia
Hematochezia is the passage of fresh blood per anus, usually in or with stools . Hematochezia is commonly associated with lower gastrointestinal bleeding, but may also occur from a brisk upper GI bleed...
. Anaemia and dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
may develop secondary to this haemorrhagic enteritis. Signs of reproductive disease (Egg Drop Syndrome) include low egg production/hatching and the laying of abnormal eggs (size, shape, colour, texture). Adenovirus infection may infect other organs, causing a splenitis, inclusion body hepatitis
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...
, bronchitis
Bronchitis
Acute bronchitis is an inflammation of the large bronchi in the lungs that is usually caused by viruses or bacteria and may last several days or weeks. Characteristic symptoms include cough, sputum production, and shortness of breath and wheezing related to the obstruction of the inflamed airways...
, pulmonary congestion ventriculitis
Ventriculitis
Ventriculitis is the inflammation of the ventricles in the brain. The ventricles are responsible for containing and circulating cerebrospinal fluid throughout the brain. Ventriculitits is caused by and infection in the ventricles, leading to an immune response in the cells lining them, followed by...
, pancreatitis
Pancreatitis
Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
, or oedema, depending on the species of bird infected.
Diagnosis of aviadenovirus is by histopathology
Histopathology
Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...
, electron microscopy
Electron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...
, viral isolation and 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...
. In addition, virus antigen can be detected double immunodiffusion. Postmortem examination
Autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...
may reveal a variety of clinical signs relating directly to the organ affected. Specifically, Egg Drop Syndrome can be diagnosed by hemagglutinin inhibition
Hemagglutinin
Influenza hemagglutinin or haemagglutinin is a type of hemagglutinin found on the surface of the influenza viruses. It is an antigenic glycoprotein. It is responsible for binding the virus to the cell that is being infected...
and the virus causes haemagglutination in chickens and ducks.