Anaplasmosis | |
---|---|
Anaplasma centrale infecting the red blood cells of a cow: The arrow points to typical infected cell. | |
Specialty | Veterinary medicine |
Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, [1] and is caused by Anaplasma bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector processes. Anaplasmosis can also be referred to as "yellow bag" or "yellow fever" because the infected animal can develop a jaundiced look. Other signs of infection include weight loss, diarrhea, paleness of the skin, aggressive behavior, and high fever. [2]
Many different tick species can carry the bacteria that cause anaplasmosis. The two major bacterial pathogens are Anaplasma marginale and Anaplasma phagocytophilum . [3] These microorganisms are Gram-negative, [4] and infect red blood cells. [5] Once the host is infected with anaplasmosis, the immune system will try to fight off and kill the infected red blood cells, but will also kill healthy red blood cells. [2] The Anaplasma sparouinense species is responsible for a rare zoonosis, the Sparouine anaplasmosis, detected only in French Guiana, South America. [6] This disease was described from a clandestine gold miner working deep in rainforest. Infection of his red blood cells led to a severe deterioration of his health and required his hospitalization. Molecular typing showed that Anaplasma sparouinense is distinct to all known species and more genetically related to recently described Anaplasma species causing infections in rainforest wild fauna of Brazil. [6]
While there are no current live or inactivated vaccines effective for all strains of A. marginale approved by the USDA for anaplasmosis, there are other means of prevention. Tick and fly control for herds of ruminants can be effective but also labor intensive. Chemical methods can also be used, including sanitizing surgical equipment after each use. [3] Tetracycline drugs are the most common treatment for anaplasmosis, and can provide the animal with immunity for a period of time. [7] The disease is more common in the South and West parts of the United States, but is no longer considered a major problem since the use of tetracycline drugs. [8]
Mechanical and biological vector transmission work in different ways but both lead to infection of the red blood cells. Mechanical transmission happens in two ways, one when red blood cells are inoculated with the blood parasite through surgical equipment including needles, dehorners, ear taggers, castrating knives, and tattoo instruments. Another mechanical transmission mode is through the mouthparts of biting flies who carry an Anaplasma species of blood parasite. [2]
Biological vector transmission is through ticks that carry a blood parasite able to cause anaplasmosis. The most common Anaplasmosis-causing tick is Ixodes scapularis, also known as the black-legged tick or the deer tick. [9] [10] Ticks who contain species of many different Anaplasma species can transmit this disease through a bite. The blood parasite survives and can multiply in the tick, and can sit dormant for months without being transmitted to an animal. When bitten by a tick carrying a blood parasite, the blood parasite can then enter the new host and cause infection. [2]
Once infected with a species of Anaplasma, the parasite multiplies in the blood stream and attaches to red blood cells. The immune system will attempt to kill the infected blood cells but will also kill uninfected red blood cells in the process. The number of red blood cells being destroyed becomes larger than new red blood cells being made, causing the host to become anemic and leading to many other symptoms. Once infected with anaplasmosis, the cattle will always be a carrier of the infectious disease, and calves born from carriers will also carry the disease. [2]
Classic signs and symptoms of anaplasmosis will not occur until 3–6 weeks after infection. [2] The most common symptoms of anaplasmosis include fever, a decreased number of white blood cells, platelets in the bloodstream, and abnormally elevated levels of liver enzymes. The erythema chronicum migrans rash may be seen with anaplasmosis as it is co-transmitted in 10% of Lyme disease cases.[ citation needed ]
Anemia may be severe and result in cardiovascular changes such as an increase in heart rate. Blood in the urine may occur due to the lysis of red blood cells. General systemic signs include diarrhea, anorexia, and weight loss. Infected animals may develop a jaundiced look which then turns into paleness around the eyes, muzzle, lips, and teats of the cattle. [2]
All cattle are susceptible to infection by Anaplasma marginale, but the severity worsens with age increase. Older cattle tend to exhibit the most severe clinical symptoms; cattle aged 1–3 may also show severe symptoms but are able to recover easier. [11]
The two major species that cause anaplasmosis in ruminants include Anaplasma marginale and Anaplasma phagocytophilum . Anaplasma marginale is found worldwide and is transmitted by Rhipicephalus ticks. Anaplasma phagocytophilum is also found worldwide, mainly transmitted by Ixodes ticks. [12] Other species that cause anaplasmosis in specific species include:
There are many strains of Anaplasma marginale , all with differing morphology, antigenic properties, protein sequence, and ability to be transmitted by ticks. Major surface proteins (MSP) have been found to play a major role in the infection by Anaplasma marginale . Out of the six MSP found on this species, three of the major surface proteins do not seem to differ between all strains, those including MSP1a, MSP4, and MSP5. The msp1a gene, which codes for MSP1a, is used as a marker for the identification of Anaplasma marginale because it has shown to be conserved in the multiplication of rickettsia in cattle and ticks and has been shown to be involved in adhesion to bovine erythrocytes and tick cells. [3]
Anaplasma phagocytophilum is a gram-negative bacterium that does not have lipopolysaccharides or peptidoglycan. The outer membrane does not have a capsule, and is coarse with irregular periplasmic spaces. This species was originally included in the genus Ehrlichia (Ehrlichia phagocytophilium), but is now included in the genus Anaplasma (Anaplasma phagocytophilium). [12]
Currently, no live or inactivated vaccines have been approved by the USDA that are effective against all strains of A. marginale. Some vaccines that rely on erythrocyte-derived antigen sources provide immunity or prevent clinical disease, although these do not prevent cattle from being infected with A. marginale. Other means of prevention can include testing all ruminants in a herd and eliminating any individuals who test positive for anaplasmosis, leading to an anaplasmosis-free herd. Vector control measures can also be used. Tick control is widely used in some countries, including Africa, but rarely used in the United States due to the fact that this prevention method is labor-intensive and expensive. In contrast, the control of flies is effective and there are many ways to do this. Chemical agents can be used, sanitation methods (such as cleaning stalls/pens regularly, manure management, and protecting feed), as well as biological control by natural enemies of flies (including bees, mites, parasitoids). Ways to prevent iatrogenic transmission include avoiding re-using of needles and sanitizing medical equipment between uses. Antimicrobial treatment can also be used, although it is more commonly used in the case of active infection. This includes the drugs tetracycline and imidocarb, and is used in healthy ruminants to decrease the clinical effects of an active infection. [3]
The most common source of treatment is the use of tetracycline drugs (including tetracycline, chlortetracycline, oxytetracycline, rolitetracycline, doxycycline, and minocycline) and imidocarb. An injection of tetracycline drugs can give ruminants immunity to Anaplasma species for at least eight months. Imidocarb has been shown to be highly effective against Anaplasma marginale , but has been identified as a possible carcinogen and is not approved in the United States or Europe. Countries such as South Africa, Australia, Israel, and South America have used live vaccines containing infectious Anaplasma centrale to prevent infection of Anaplasma marginale . Live vaccines are prohibited in the United States, and there has been production of vaccines consisting of nonliving Anaplasma marginale pulled from infected bovine erythrocytes, which can provide some immunity but leaves cattle susceptible to other strains of Anaplasma marginale. [7] Supportive therapy such as blood products and fluids may be necessary. [15]
In the United States, anaplasmosis is notably present in the South and West, where the tick hosts Ixodes spp. are found. It is also a seemingly increasing antibody in humans in Europe. [4] Although vaccines have been developed, none are currently available in the United States. Early in the 20th century, this disease was considered one of major economic consequence in the Western United States. In the 1980s and 1990s, control of ticks through new acaricides and practical treatment with prolonged-action antibiotics, notably tetracycline, has led to the point where the disease is no longer considered a major problem. The disease affects immunoglobulin G, therefore G-specific antibody levels can be used to diagnose the disease. [8]
In 2005, A. ovis was found in reindeer populations in Mongolia. [16] This pathogen and its associated syndrome (characterized by lethargy, fever, and pale mucous membranes) was previously observed in only wild sheep and goats in the region, and is the first observed occurrence of A. ovis in reindeer.[ citation needed ]
In Australia, bovine anaplasmosis, caused by A. marginale, is found in only the northern and eastern parts of Australia where the cattle tick is present. It was probably introduced as early as 1829 by cattle from Indonesia infested with the cattle tick Boophilus microplus . [17]
The veterinarian George P. Broussard of New Iberia, Louisiana, conducted important research on anaplasmosis and brucellosis. [18]
Ehrlichiosis is a tick-borne disease of dogs usually caused by the rickettsial agent Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd Dogs are thought to be susceptible to a particularly severe form of the disease; other breeds generally have milder clinical signs. Cats can also be infected.
Babesiosis or piroplasmosis is a malaria-like parasitic disease caused by infection with a eukaryotic parasite in the order Piroplasmida, typically a Babesia or Theileria, in the phylum Apicomplexa. Human babesiosis transmission via tick bite is most common in the Northeastern and Midwestern United States and parts of Europe, and sporadic throughout the rest of the world. It occurs in warm weather. People can get infected with Babesia parasites by the bite of an infected tick, by getting a blood transfusion from an infected donor of blood products, or by congenital transmission . Ticks transmit the human strain of babesiosis, so it often presents with other tick-borne illnesses such as Lyme disease. After trypanosomes, Babesia is thought to be the second-most common blood parasite of mammals. They can have major adverse effects on the health of domestic animals in areas without severe winters. In cattle, the disease is known as Texas cattle fever or redwater.
Bovine alphaherpesvirus 1 (BoHV-1) is a virus of the family Herpesviridae and the subfamily Alphaherpesvirinae, known to cause several diseases worldwide in cattle, including rhinotracheitis, vaginitis, balanoposthitis, abortion, conjunctivitis, and enteritis. BoHV-1 is also a contributing factor in shipping fever, also known as bovine respiratory disease (BRD). It is spread horizontally through sexual contact, artificial insemination, and aerosol transmission and it may also be transmitted vertically across the placenta. BoHV-1 can cause both clinical and subclinical infections, depending on the virulence of the strain. Although these symptoms are mainly non-life-threatening it is an economically important disease as infection may cause a drop in production and affect trade restrictions. Like other herpesviruses, BoHV-1 causes a lifelong latent infection and sporadic shedding of the virus. The sciatic nerve and trigeminal nerve are the sites of latency. A reactivated latent carrier is normally the source of infection in a herd. The clinical signs displayed are dependent on the virulence of the strain. There is a vaccine available which reduces the severity and incidence of disease. Some countries in Europe have successfully eradicated the disease by applying a strict culling policy.
Bovine malignant catarrhal fever (BMCF) is a fatal lymphoproliferative disease caused by a group of ruminant gamma herpes viruses including Alcelaphine gammaherpesvirus 1 (AlHV-1) and Ovine gammaherpesvirus 2 (OvHV-2) These viruses cause unapparent infection in their reservoir hosts, but are usually fatal in cattle and other ungulates such as deer, antelope, and buffalo. In Southern Africa the disease is known as snotsiekte, from the Afrikaans.
Babesia, also called Nuttallia, is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș in 1888, over 100 species of Babesia have since been identified.
Anaplasma phagocytophilum is a Gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis.
Ehrlichiosis is a tick-borne bacterial infection, caused by bacteria of the family Anaplasmataceae, genera Ehrlichia and Anaplasma. These obligate intracellular bacteria infect and kill white blood cells.
Anaplasma is a genus of gram-negative bacteria of the alphaproteobacterial order Rickettsiales, family Anaplasmataceae.
Heartwater is a tick-borne rickettsial disease. The name is derived from the fact that fluid can collect around the heart or in the lungs of infected animals. It is caused by Ehrlichia ruminantium —an intracellular Gram-negative coccal bacterium. The disease is spread by various Amblyomma ticks, and has a large economic impact on cattle production in affected areas. There are four documented manifestations of the disease, these are acute, peracute, subacute, and a mild form known as heartwater fever. There are reports of zoonotic infections of humans by E. ruminantium, similar to other Ehrlichia species, such as those that cause human ehrlichiosis.
Ehrlichia chaffeensis is an obligate intracellular, Gram-negative species of Rickettsiales bacteria. It is a zoonotic pathogen transmitted to humans by the lone star tick. It is the causative agent of human monocytic ehrlichiosis.
Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium that is typically transmitted to humans by ticks of the Ixodes ricinus species complex, including Ixodes scapularis and Ixodes pacificus in North America. These ticks also transmit Lyme disease and other tick-borne diseases.
Ehrlichiosis ewingii infection is an infectious disease caused by an intracellular bacteria, Ehrlichia ewingii. The infection is transmitted to humans by the tick, Amblyomma americanum. This tick can also transmit Ehrlichia chaffeensis, the bacteria that causes human monocytic ehrlichiosis (HME).
Babesia bovis is an Apicomplexan single-celled parasite of cattle which occasionally infects humans. The disease it and other members of the genus Babesia cause is a hemolytic anemia known as babesiosis and colloquially called Texas cattle fever, redwater or piroplasmosis. It is transmitted by bites from infected larval ticks of the order Ixodida. It was eradicated from the United States by 1943, but is still present in Mexico and much of the world's tropics. The chief vector of Babesia species is the southern cattle fever tick Rhipicephalus microplus.
Theileria parva is a species of parasites, named in honour of Arnold Theiler, that causes East Coast fever (theileriosis) in cattle, a costly disease in Africa. The main vector for T. parva is the tick Rhipicephalus appendiculatus. Theiler found that East Coast fever was not the same as redwater, but caused by a different protozoan.
Ticks of domestic animals directly cause poor health and loss of production to their hosts. Ticks also transmit numerous kinds of viruses, bacteria, and protozoa between domestic animals. These microbes cause diseases which can be severely debilitating or fatal to domestic animals, and may also affect humans. Ticks are especially important to domestic animals in tropical and subtropical countries, where the warm climate enables many species to flourish. Also, the large populations of wild animals in warm countries provide a reservoir of ticks and infective microbes that spread to domestic animals. Farmers of livestock animals use many methods to control ticks, and related treatments are used to reduce infestation of companion animals.
Anaplasma bovis is gram negative, obligate intracellular organism, which can be found in wild and domestic ruminants, and potentially a wide variety of other species. It is one of the last species of the Family Anaplasmaceae to be formally described. It preferentially infects host monocytes, and is often diagnosed via blood smears, PCR, and ELISA. A. bovis is not currently considered zoonotic, and does not frequently cause serious clinical disease in its host. This organism is transmitted by tick vectors, so tick bite prevention is the mainstay of A. bovis control, although clinical infections can be treated with tetracyclines. This organism has a global distribution, with infections noted in many areas, including Korea, Japan, Europe, Brazil, Africa, and North America.
Histophilus somni is a non-motile, gram-negative, rod or coccobacillus shaped, facultative anaerobe bacterial species belonging to the family Pasteurellaceae. Prior to 2003, it was thought Haemophilus somnus, Histophilus ovis, and Histophilus agni were three different species, but now are all classified as Histophilus somni. Histophilus somni is a commensal bacteria of mucous membranes of the upper respiratory tract and reproductive tract with a global prevalence and is found in cattle and other small ruminants. Histophilus somni is also a known causative agent that is a part of the Bovine Respiratory Disease (BRD) complex, which typically involves multiple pathogens residing together in biofilm environments. Histophilus somni may also cause Histophilosus symptoms and clinical presentation will depend on the tissue affected. When disease does occur, it can be difficult to catch in time and is often diagnosed post mortem. This means that treatment often involves metaphylactic mass treatment or no treatment at all. This organism is more fastidious than others and requires knowledge for sample collection, storage and culture. Genomic studies related to this bacteria have enabled scientists to pinpoint antibiotic resistance genes.
Vaccinations for cattle involves the process of applying subcutaneous injections of biological microorganisms in a weakened state to help the immune system develop protection by providing active acquirement of immunity to a particular disease. Cattle are bovine livestock and are thus very susceptible to diseases. Vaccinations for cattle are widely used in the livestock industries of the Australian agriculture sector by farmers to prevent harmful and deadly diseases from infecting their livestock, avoiding any economical or biological harm. Farmed livestock industries account for 45% of the gross value of Australian agricultural output, beef cattle being the largest farmed livestock nationally with around 26.2 million head of cattle nationwide. The beef industry within Australia generates a gross value of approximately $8 billion AUD in beef exports and a total gross value of $11.4 billion in farm production (2017–18). Thus, vaccinations play a vital role in protecting, sustaining and growing the beef cattle industry in the Australian agriculture sector.
Border disease (BD) is a viral disease of sheep and goats, primarily causing congenital diseases, but can also cause acute and persistent infections. It first appeared in the border regions of England and Wales in 1959, and has since spread world-wide. Lambs that are born with BD are commonly known as 'hairy shakers' due to the primary presentation of the disease. The disease was recognized before the virus, therefore the common name of the disease predates the understanding of the viral pathology. The virus can cause a significant reduction in the percentage of surviving lambs, thus it has a large economic impact on farmers.
Corynebacterium pseudotuberculosis is a Gram-positive bacterium known to infect ruminants, horses, and rarely people. It is a facultative anaerobic organism that is catalase-positive and capable of beta-hemolysis. In small ruminants, C. pseudotuberculosis causes a disease called caseous lymphadenitis, which is characterized by pyogranulomatous abscess formation. In general, the bacterium causes lesions of the skin, lymph nodes, and internal organs. A disease known as ulcerative lymphagenitis can also result from infection with C. pseudotuberculosis in the distal limbs of horses. This bacterium uses the virulence factors phospholipase D and mycolic acid to damage eukaryotic cell walls and resist phagocytic lysosomal degradation, respectively. Infection with this bacterium is often confirmed by bacterial culture of the purulent exudate. Once the diagnosis has been made, treatment of the infection can begin, but this is difficult due to the nature of the organism and the lesions it forms. Specifically, C. pseudotuberculosis is intrinsically resistant to streptomycin, with varying resistance to penicillin and neomycin depending on the strain. It has been shown to be susceptible to ampicillin, gentamicin, tetracycline, lincomycin, and chloramphenicol. Vaccines have also been produced to develop acquired immunity to this infection.