What is Bovine leukemia virus (BLV)?
Bovine leukemia virus (BLV) is a virus that is very commonly found in cows. About 89 percent of dairy farms and 38 percent of beef farms in the United States have cows that are infected with BLV. Cattle in other parts of the world are also frequently affected.
What is bovine leukosis in cattle?
Cattle infected with bovine leukemia virus have the disease known to veterinarians as “Enzootic Bovine Leukosis” or EBL, but it is most often referred to as “Leukosis”. How common is BLV in beef cattle? Compared with dairy cattle, much less is known about BLV and beef cattle.
Can cows get B-cell leukemia?
In general, BLV causes only a benign mononucleosis-like disease in cattle. Only some animals later develop a B-cell leukemia called enzootic bovine leukosis.
What is bovine lymphocytosis?
Proliferation of these virus-infected lymphocytes results in either a persistent lymphocytosis, a benign form of the disease, or neoplastic tumors that invade many different organ systems (referred to as enzootic bovine leucosis or lymphosarcoma). Both beef and dairy cattle are the natural hosts for this virus.
How do you get bovine leukemia virus?
How does BLV spread? Since this is a blood-borne disease, the virus spreads primarily by transferring blood or other body fluids with blood cells from infected animals to non-infected herdmates (horizontal transmission). This commonly happens as a result of the way we manage cattle.
Is bovine leukemia virus contagious?
Bovine leukemia virus is a contagious disease that is often undiagnosed and robs many herds of health and productivity.
How do humans get BLV?
There is no information on how humans become infected with BLV. Transmission from cattle through raw milk and inadequately cooked beef, and from infected humans are considered to be potential routes.
Is bovine leukemia virus infectious or noninfectious?
Enzootic bovine leukosis (EBL), also called bovine lymphosarcoma or bovine leukemia, is an infectious disease naturally occurring in cattle.
What does my cow has BLV mean?
Bovine leukemia virus (BLV) is an oncogenic retrovirus that infects lymphocytes (white blood cells).
Is there a vaccine for BLV in cattle?
The vaccine is currently used to vaccinate against BLV infection in commercial herd settings. Besides efficacy, the major challenge is safety of the vaccine: transmission from cow-to-calf, recombination with endogenous viruses, milk and meat composition.
Can you get sick from cows blood?
The most probable way people are exposed to BLV is by consuming the milk or meat of infected cows. Since BLV is a blood-borne virus that is transmitted through bodily fluids, transmission through consumption is not likely, though not impossible.
Can humans get bovine leukosis?
Background. Bovine leukemia virus (BLV) infection is widespread in cattle globally and is present in marketed beef and dairy products. Human infection with BLV has been reported in breast and lung cancer tissues and was significantly associated with breast cancer in 3 case-control studies.
Where does the word bovine come from?
Bovine comes from the Latin word for "cow", though the biological family called the Bovidae actually includes not only cows and oxen but also goats, sheep, bison, and buffalo. So bovine is often used technically, when discussing "bovine diseases", "bovine anatomy", and so on.
Which countries have eradicated bovine leukemia virus?
Similarly, New Zealand eradicated BLV from its dairy and beef herds, whereas Australia still has a low prevalence in its beef herds (Voges, 2012; Queensland Government Department of Agriculture and Fisheries, 2016).
What are the symptoms of BVD in cattle?
Respiratory infection with BVDV is characterized by signs typical of viral respiratory disease, including fever, depression, inappetance, and ocular and nasal discharge, followed by diarrhea several days after onset. Sores or ulceration in the mouth and gums may be present, along with reduced milk production in cows.
What causes lymphoma in cattle?
Leukemia and lymphosarcoma (also called lymphoma) is a form of cancer of one of the cells of the immune system called the lymphocyte. In cattle, a diagnosis of leukemia or lymphosarcoma can be rare but is most commonly caused by bovine leukemia virus (also called bovine leukosis virus or BLV).
What are the symptoms of BVD in cattle?
Respiratory infection with BVDV is characterized by signs typical of viral respiratory disease, including fever, depression, inappetance, and ocular and nasal discharge, followed by diarrhea several days after onset. Sores or ulceration in the mouth and gums may be present, along with reduced milk production in cows.
Can cows get leukemia?
In cattle, a diagnosis of leukemia or lymphosarcoma can be rare but is most commonly caused by bovine leukemia virus (also called bovine leukosis virus or BLV). Disease caused by BLV is referred to as enzootic bovine leukosis.
Where does the word bovine come from?
Bovine comes from the Latin word for "cow", though the biological family called the Bovidae actually includes not only cows and oxen but also goats, sheep, bison, and buffalo. So bovine is often used technically, when discussing "bovine diseases", "bovine anatomy", and so on.
What is Lucosis?
Medical Definition of leukosis : leukemia especially : any of various leukemic diseases of poultry.
What type of virus causes leukemia?
Researchers have identified several viruses that can cause leukemia or lymphoma. For example, human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATLL). ATLL is a rare cancer of the lymphocytes (white blood cells that fight infection).
What is a leukemia team?
MyLeukemiaTeam is the social network for people with leukemia and their loved ones . On MyLeukemiaTeam, more than 8,000 members come together to ask questions, give advice, and share their stories with others who understand life with leukemia.
Can BLV Cause Cancer in Humans?
Over the past decade, some studies have be gun to show a link between BLV and breast cancer.
What is the most common type of leukemia?
Acute myeloid leukemia (AML), also known as acute myelogenous leukemia, is the most common type...
Can humans get BLV from cows?
Scientists aren’t exactly sure how BLV might be transmitted from cows to humans. It is possible that bovine leukemia virus particles might be present in meat or milk from cows, and that humans might become infected when they ingest these products. However, this has not yet been confirmed. Researchers are still studying the transmission of BLV.
Is BLV a type of lung cancer?
One other study found evidence of BLV in samples from a specific type of lung cancer. Researchers found that 80 percent of cases of squamous cell carcinoma of the lungs were infected with BLV. However, this study was very small, only looking at 10 samples total, and the results have not yet been repeated. More research is needed to understand how BLV and lung cancer may be connected.
Is BLV a cause of leukemia?
So far, no studies have found evidence that BLV is one of the causes of leukemia. However, it is possible that this will change in the future.
How many cattle have BLV?
Less than 5% of BLV-infected cattle develop lymphosarcoma. The remainder of BLV-infected cattle develop persistent lymphocytosis. Lymphosarcoma is most commonly observed in 4 to 8 year old animals; animals less than 2 years of age rarely show signs of disease.
What is the best test to identify BLV positive animals?
Agar gel immunodiffusion (AGID), enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) tests are all used to identify BLV-positive animals. Eliminating the transfer of blood from infected animals to naive animals is the cornerstone of preventing spread of this virus between animals.
How is BLV spread?
Transmission of BLV from an infected bovine to an uninfected one is usually a consequence of transferring BLV-infected blood between these animals during the process of performing many common farm practices such as tattooing ears, dehorning, rectal palpation, or injecting animals with a vaccine or medication.
What is BLV in medical terms?
Bovine leukemia virus (BLV) is an oncogenic retrovirus that infects lymphocytes (white blood cells). Proliferation of these virus-infected lymphocytes results in either a persistent lymphocytosis, a benign form of the disease, or neoplastic tumors that invade many different organ systems (referred to as enzootic bovine leucosis or lymphosarcoma).
Is bovine leukemia a natural host?
In the U.S., the most recent surveys indicate that 89% of dairy operations and 38% of beef operations had cattle seropositive for BLV. Currently, there are no Federal regulations specific to curbing spread of bovine leukemia virus in the U.S. cattle population.
What is the name of the bovine leukemia virus?
Name and History. The bovine leukemia virus ( BLV ), together with the human T-cell leukemia viruses ( HTLV ), belongs to the Deltaretrovirus genus. BLV causes a lymphoproliferative disease in cattle, either in the lethal enzootic bovine leucosis form, or in the benign persistent lymphocytosis form [1].
How is BLV transmitted to cattle?
Bovine leukemia virus (BLV) has been experimentally transmitted to seronegative cattle and sheep by rectal infusion of relatively large amounts of blood from viremic animals.25 BLV also has been experimentally transmitted to calves by simulated palpation with obstetric sleeves contaminated with whole blood from a seropositive donor animal. 26 Other authors, however, have reported that BLV transmission by rectal palpation in the manner typically used for reproductive tract examination of cows either does not occur or is uncommon. 27 In herds in which other measures to control transmission of BLV are practiced, it may be prudent to use a separate clean obstetric sleeve for palpation of each cow. The role of rectal palpation performed by clinicians wearing common obstetric sleeves in transmission of other infectious diseases is unknown.
What does a positive antibody titer to BLV mean?
A positive antibody titer to BLV indicates that the animal has been exposed to BLV and may be persistently and chronically infected ( Johnson and Kaneene, 1991; Miller et al., 1981 ).
What is the BLV in sheep?
The Bovine Leukemia Virus (BLV) shares structural homologies with HTLV-1. BLV transforms bovine and ovine B lymphocytes and induces monoclonal leukemia/lymphoma (malignant lymphoma) in 100% of infected sheep with an average latency of 30 months. Only a very limited fraction (±5%) of infected cattle develop tumors, but with a very long latency of about 10 years. Tumor cells always harbor BLV proviral sequences. In sheep tumors, BLV proteins are not expressed, but some degree of expression is found in bovine tumors. It was not established, however, whether expression occurred in transformed cells or in non-tumorous cells, infected by the virus and present in the tumor tissue.
What are the roles of BLV tax?
The BLV Tax, R 3 and G 4 viral products play a major role in the transformation process of sheep B cells. Tax phosphorylation occurs at serines 106 and 293 and is required for Tax to be transforming. Mutation of these aa residues into Ala abrogates the transforming potential of Tax but maintains its transactivating capacity for the proviral promoter. BLV viruses deleted for R 3 and G 4 are still infectious but propagate very weakly in sheep. Ten animals infected for more than 5 years did not show any sign of tumor development whilst an average latency of 30 months before onset of tumor was observed in wild type BLV-infected sheep.
What is the BLV in cattle?
The bovine leukemia virus (BLV), a retrovirus, is the causative agent of enzootic bovine leukosis in cattle. This is a highly fatal neoplasia of cattle characterized by the aggregation of neoplastic lymphocytes in lymph nodes.
How do you know if you have BLV?
Transmission of BLV occur s through the transfer of infected lymphocytes from one animal to another. Once acquired, viral infection is lifelong.
What is Bovine Leukosis?
Bovine leukosis is a disease of cattle caused by the bovine leukosis virus (BLV). This is a blood-borne disease; the virus survives in white blood cells, called lymphocytes. Only about 5% of the cows infected with BLV ever develop a clinical disease. When clinical disease does occur, the primary sign is the development of tumors (lymphosarcoma). These are typically found in one or more of the following sites: the uterus, abomasum, heart, spinal canal, and/or lymphoid tissue behind the eye (which makes the eyeball protrude). Sometimes most, or all, internal lymph nodes enlarge and become readily apparent under the skin.
What happens if a herd has a high prevalence of BLV?
A herd with a high prevalence of BLV infections may experience significant losses resulting from a high number of clinical BLV cases that have no salvage value .
What are the economic impacts of BLV infection?
BLV causes significant losses within the cattle industry . A large Northeast slaughter plant, processing 350,000 cattle per year, condemns about 2000 carcasses per year due to lymphosarcoma. This represents approximately half of its total condemnations.
How does BLV spread?
Since this is a blood-borne disease, the virus spreads primarily by transferring blood or other body fluids with blood cells from infected animals to non-infected herdmates (horizontal transmission). This commonly happens as a result of the way we manage cattle. For example, blood (and BLV virus) is readily spread from animal to animal with blood contaminated needles and/or syringes, obstetrical sleeves, saw or gouge dehorners, tattoo pliers, ear taggers, hoof knives, nose tongs etc. and by feeding unpasteurized mastitic waste milk .The virus also appears to spread to a limited degree through animal to animal contact. It is likely that close contact allows the lymphocytes in nasal and ocular secretions from infected cattle to gain entry into susceptible animals via their mucous membranes.
Is testing necessary to control BLV?
Although not necessary, herd testing for BLV can be very helpful for three reasons:
How is leukosis diagnosed?
When an animal is in the clinical stages of leukosis, the disease is diagnosed by the presence of the previously described tumors and/or general lymph node enlargement. If clinical disease is not present, BLV infection is diagnosed by blood tests (AGID or ELISA) that detect the presence of BLV antibodies. Since BLV infection is for life, the ...
Is BLV in cattle?
The disease is less prevalent in beef cattle. A 1997 NAHMS survey found 38.7% of participating herds were infected with BLV and 10.3% of the cows in these herds were infected. BLV infection does not occur naturally in other species.
Why should BLV infection and leukosis be of concern when it is so common in cattle?
However, like HIV in humans, now we understand the most important impact from BLV is disruption of the immune system that allows more diseases to occur, resulting in suboptimal performance and early culling. Because BLV indirectly allows other disease conditions to flourish, there has been delayed recognition of its importance to overall cattle health.
What are the most common diseases in cattle?
Cancers , including leukemia, lymphoma and malignant lymphosarcoma, are the most common neoplastic (cancerous) diseases identified in cattle slaughtered in the United States and the largest single reason cattle are condemned during postmortem inspection. However, less than 5% of BLV- infected cattle go on to develop cancer.
How to diagnose BLV in animals?
How is BLV diagnosed? Blood testing is the first step to identify BLV-positive (infected) animals. An inexpensive serum ELISA test is available at the UK Veterinary Diagnostic Laboratory to detect antibodies to the virus. Once an animal is infected and tests positive for antibodies, she will remain test positive for her lifetime. Testing can be done in animals over six months of age. Peripheral lymphocytosis can be diagnosed by a complete blood count (CBC) on a blood sample submitted to a veterinary practice or vet diagnostic lab. Tumors such as lymphosarcoma are usually diagnosed after death at necropsy but some are identified ante-mortem through a biopsy of an affected lymph node.
What does PVL mean in a cow?
PVL is a good indicator of infectivity; for example, a cow that is highly infectious may have a PVL = 0.5 or more, which a 0.5 means there is one BLV-infected lymphocyte out of every 2 in the sample. For more information, visit https://mycentralstar.com/diagnostic-services#1556487494253-1f97cd0c-b360 and click on BLV.
How did BLV spread?
Traditionally, BLV was thought to spread primarily through biting flies and poor management procedures such as injections with used needles, surgical castration/dehorning/tattooing with bloody equipment, and rectal palpation with dirty sleeves.
How common is BLV in beef cattle?
How common is BLV in beef cattle? Compared with dairy cattle, much less is known about BLV and beef cattle. A survey completed in 2019 of 28 cow-calf herds in the Midwest found at least one BLV-infected animal in 21 of those 28 herds and more than a third of the individual cows tested were positive. A similar study of bulls on 39 Midwest farms found nearly 50% of these operations had at least one positive bull and 45% of the 121 bulls tested were positive.
What are the symptoms of a cow's heart tumor?
Abomasal (stomach) tumors cause digestive problems resulting in loss of appetite and weight, constipation, or diarrhea, abomasal tympany (bloat), and slow gut motility.
What are the most common diseases in cattle?
Cancers , including leukemia, lymphoma and malignant lymphosarcoma, are the most common neoplastic (cancerous) diseases identified in cattle slaughtered in the United States and the largest single reason cattle are condemned during postmortem inspection. However, less than 5% of BLV- infected cattle go on to develop cancer.
What is the BLV in cattle?
Bovine Leukemia Virus (BLV) is an “oncogenic retrovirus” common in cattle throughout the United States. “Oncogenic” means the virus can cause the infected animal to develop cancer. A “Retrovirus” is a unique type of virus that uses an enzyme to reverse its genetic code from RNA into DNA which then gets inserted into the host cell’s DNA ...
How to reduce BLV?
The good news is that you can progressively reduce BLV transmission by removing the most infectious cattle first. A majority of antibody + cows (ELISA +) pose a low risk of transmitting BLV to their herdmates so by identifying and culling only the most infectious cattle first will greatly reduce new cases of the disease.
What are the symptoms of a cow's heart tumor?
Abomasal (stomach) tumors cause digestive problems resulting in loss of appetite and weight, constipation, or diarrhea, abomasal tympany (bloat), and slow gut motility.
How long does it take for a cow to develop cancer?
Only a small fraction of BLV-infected cattle, < 5%, develop cancer after an average incubation period of 7 years after infection with the virus. The sites most affected by tumors are the heart, abomasum (true stomach), uterus, kidney (see Figure 1), spinal cord, and the area behind the eyeball.
What is the name of the virus that causes AIDS?
A well-known retrovirus in humans is the human immunodeficiency virus or “HIV” that causes the disease “Acquired Immune Deficiency Syndrome” or “AIDS”. Cattle infected with bovine leukemia virus have the disease known to veterinarians as “Enzootic Bovine Leukosis” or EBL, but it is most often referred to as “Leukosis”.
How many cows in the Midwest have BLV?
A survey completed in 2019 of 28 cow-calf herds in the Midwest found at least one BLV-infected animal in 21 of those 28 herds and more than a third of the individual cows tested were positive. A similar study of bulls on 39 Midwest farms found nearly 50% of these operations had at least one positive bull and 45% of the 121 bulls tested were ...
