|
Marek's Disease
Marek's disease is a highly contagious viral neoplastic disease in chickens. It is named after József Marek, a Hungarian veterinarian who described it in 1907. Marek's disease is caused by an alphaherpesvirus commonly known as "Marek's disease virus" (MDV). The disease is characterized by the presence of T cell lymphoma as well as infiltration of nerves and organs by lymphocytes. Viruses related to MDV appear to be benign and can be used as vaccine strains to prevent Marek's disease. For example, the related herpesvirus found in turkeys (HVT), causes no apparent disease in the birds, and continues to be used as a vaccine strain for prevention of Marek's disease. Birds infected with MDV can be carriers and shedders of the virus for life. Newborn chicks are protected by maternal antibodies for a few weeks. After infection, microscopic lesions are present after one to two weeks, and gross lesions are present after three to four weeks. The virus is spread in dander from feat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 16,000 of the millions of List of virus species, virus species have been described in detail. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent viral particles, or ''virions'', consisting of (i) genetic material, i.e., long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crop (anatomy)
The crop (also the croup, the craw, the ingluvies, and the sublingual pouch) is a thin-walled, expanded portion of the alimentary tract, which is used for the storage of food before digestion. The crop is an anatomical structure in vertebrate animals, such as birds, and invertebrate animals, such as gastropods (snails and slugs), earthworms, leeches, and insects. Insects Cropping is used by bees to temporarily store nectar of flowers. When bees "suck" nectar, it is stored in their crops. Other Hymenoptera also use crops to store liquid food. The crop in eusocial insects, such as ants, has specialized to be distensible, and this specialization enables important communication between colonial insects through trophallaxis. The crop can be found in the foregut of insects. Birds In a bird's digestive system, the crop is an expanded, muscular pouch near the gullet or throat. It is a part of the digestive tract, essentially an enlarged part of the esophagus. As with most oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poultry Diseases
Poultry diseases occur in poultry, which are domesticated birds kept for their meat, eggs or feathers. Poultry species include the chicken, turkey, duck, goose and ostrich. Viral diseases * Avian infectious bronchitis, caused by a strain of Avian coronavirus previously known as infectious bronchitis virus * Avian infectious laryngotracheitis, caused by Gallid alphaherpesvirus 1 * Avian influenza, caused by Avian influenza virus * Duck plague, caused by Anatid alphaherpesvirus 1 * Chicken infectious anemia, caused by Chicken anaemia virus * Epidemic tremor, caused by Tremovirus * Fowlpox, caused by viruses in the genus '' Avipoxvirus'' * Infectious bursal disease (IBD), also known Gumboro disease, caused by Infectious bursal disease virus * Lymphoid leukosis caused by avian sarcoma leukosis virus * Marek's disease * Newcastle disease * Viral arthritis, caused by Avian reovirus Parasitic diseases * Scaly leg, caused by the mite '' Knemidocoptes mutans'' * Infestat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Live Science
Live Science is a science news website. The publication features stories on a wide range of topics, including space, animals, health, archaeology, human behavior, and planet Earth. It also includes a reference section with links to other websites. Its stated mission is to inform and entertain readers about science and the world around them.{{r, mission History Live Science was originally made in 2004. It was acquired by ediaNetwork, later called Purch, in 2009.{{r, purch Purch consumer brands (including Live Science) were acquired by Future The future is the time after the past and present. Its arrival is considered inevitable due to the existence of time and the laws of physics. Due to the apparent nature of reality and the unavoidability of the future, everything that currently ex ... in 2018. Reception In 2011, the '' Columbia Journalism Review''{{'s "News Startups Guide" called Live Science "a purebred Web animal, primarily featuring one-off stories and photo gall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fitness (biology)
Fitness (often denoted w or ω in population genetics models) is a quantitative representation of individual reproductive success. It is also equal to the average contribution to the gene pool of the next generation, made by the same individuals of the specified genotype or phenotype. Fitness can be defined either with respect to a genotype or to a phenotype in a given environment or time. The fitness of a genotype is manifested through its phenotype, which is also affected by the developmental environment. The fitness of a given phenotype can also be different in different selective environments. With asexual reproduction, it is sufficient to assign fitnesses to genotypes. With sexual reproduction, recombination scrambles alleles into different genotypes every generation; in this case, fitness values can be assigned to alleles by averaging over possible genetic backgrounds. Natural selection tends to make alleles with higher fitness more common over time, resulting in Darwini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Transmission
Vertical transmission of symbionts is the transfer of a microbial symbiont from the parent directly to the offspring. Many metazoan species carry symbiotic bacteria which play a mutualistic, commensal, or parasitic role. A symbiont is acquired by a host via horizontal, vertical, or mixed transmission. Fitness benefits Vertical transmission, passage of symbiotic microflora from parents to offspring, is common in species of animals which have parental care. There are fitness benefits in providing youths with established microorganism community early on. # Immune system development: parents microbes prime young immune system. # Disease resistance: because skin is already colonized by parental microbes, pathogen flora has a harder time to establish itself. # Digestive help: parental microbes might help with digestion, as a result, the young ones can survive on a diet which would not meet their nutritious needs otherwise. # Environmental adaptation: microflora might help t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Because the evolutionary fate of the agent is not tied to reproductive success of the host, horizontal transmission tends to evolve virulence. It is therefore a critical concept for evolutionary medicine. Biological Pathogen transmission In biological, but not cultural, transmissions the carriers (also known as vectors) may include other species. The two main biological modes of transmission are ''anterior station'' and ''posterior station''. In anterior station, transmission occurs via the bite of an infected organism (the vector), like in malaria, dengue fever, and bubonic plague. Posterior station is transmission via contact with infected feces. Examples are rickettsiae driven diseases (like typhus), which are contracted by a body louse's fecal material being scratched into the bloodstream. The vector is not nec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, which may be called a tumour or tumor.'' ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior. Malignant neoplasms are also simply known as cancers and are the focus of oncology. Prior to the abnormal growth of tissue, such as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia does not always progress to neoplasia and can occur in other conditions as well. The word neoplasm is from Ancient Greek 'new' and 'formation, creation'. Types A neopla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 the body's Adaptive immune system, adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them. The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the Eradication of infectious diseases, worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. According to the World Health Organization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Organisation For Animal Health
The World Organisation for Animal Health (WOAH), formerly the (OIE), is an intergovernmental organisation founded in 1924, coordinating, supporting and promoting animal disease control. The primary objective of WOAH is to control epizootic diseases and prevent their spread. Further objectives include the sharing of transparent, scientific information; international solidarity; sanitary safety; and the promotion of veterinary services‚ food safety and animal welfare. WOAH is recognised by the World Trade Organization, World Trade Organisation (WTO) as an international reference for the safe trade of animals and animal products regarding risks due to animal diseases and zoonoses. WOAH is not a part of the United Nations (UN) system. Its autonomy is institutional and financial, and its own constitutional texts govern its activities. Since its first General Session held in Paris, the Organisation has carried out its work under the authority of a committee consisting of delegates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bursa Of Fabricius
In birds, the bursa of Fabricius (Latin: ''bursa cloacalis'' or ''bursa Fabricii'') is the site of hematopoiesis. It is a specialized organ that, as first demonstrated by Bruce Glick and later by Max Dale Cooper and Robert Good, is necessary for B cell (part of the immune system) development in birds. Mammals generally do not have an equivalent organ; the bone marrow is often the site of both hematopoiesis and B cell development. The bursa is present in the cloaca of birds and is named after Hieronymus Fabricius, who described it in 1621. Description The bursa is an epithelial and lymphoid organ that is found only in birds. The bursa develops as a dorsal diverticulum of the proctodeal region of the cloaca. The luminal (interior) surface of the bursa is plicated with as many as 15 primary and 7 secondary plicae or folds. These plicae have hundreds of bursal follicles containing follicle-associated epithelial cells, lymphocytes, macrophages, and plasma cells. Lymphoid stem ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisocoria
Anisocoria is a condition characterized by an unequal size of the eyes' pupils. Affecting up to 20% of the population, anisocoria is often entirely harmless, but can be a sign of more serious medical problems. Causes Anisocoria is a common condition, defined by a diameter difference of 0.4 mm or more between the sizes of the pupils of the eyes. Anisocoria has various causes: * Physiological anisocoria: About 20% of the population has a slight difference in pupil size, which is known as physiological anisocoria. In this condition, the difference between pupils is usually less than 1 mm. * Horner's syndrome * Mechanical anisocoria: Occasionally, previous trauma, eye surgery, or inflammation ( uveitis, angle closure glaucoma) can lead to adhesions between the iris and the lens. * Adie tonic pupil: Tonic pupil is usually an isolated benign entity, presenting in young women. It may be associated with loss of deep tendon reflex (Adie's syndrome). Tonic pupil is charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
