Ehrlichia ruminantium
Heartwater Disease
Ehrlichia
Ehrlichia chaffeensis
Ehrlichia canis
Selenomonas
Ehrlichiosis
Potential value of major antigenic protein 2 for serological diagnosis of heartwater and related ehrlichial infections. (1/49)
Cowdria ruminantium is the etiologic agent of heartwater, a disease causing major economic loss in ruminants in sub-Saharan Africa and the Caribbean. Development of a serodiagnostic test is essential for determining the carrier status of animals from regions where heartwater is endemic, but most available tests give false-positive reactions with sera against related Erhlichia species. Current approaches rely on molecular methods to define proteins and epitopes that may allow specific diagnosis. Two major antigenic proteins (MAPs), MAP1 and MAP2, have been examined for their use as antigens in the serodiagnosis of heartwater. The objectives of this study were (i) to determine if MAP2 is conserved among five geographically divergent strains of C. ruminantium and (ii) to determine if MAP2 homologs are present in Ehrlichia canis, the causative agent of canine ehrlichiosis, and Ehrlichia chaffeensis, the organism responsible for human monocytic ehrlichiosis. These two agents are closely related to C. ruminantium. The map2 gene from four strains of C. ruminantium was cloned, sequenced, and compared with the previously reported map2 gene from the Crystal Springs strain. Only 10 nucleic acid differences between the strains were identified, and they translate to only 3 amino acid changes, indicating that MAP2 is highly conserved. Genes encoding MAP2 homologs from E. canis and E. chaffeensis also were cloned and sequenced. Amino acid analysis of MAP2 homologs of E. chaffeensis and E. canis with MAP2 of C. ruminantium revealed 83.4 and 84.4% identities, respectively. Further analysis of MAP2 and its homologs revealed that the whole protein lacks specificity for heartwater diagnosis. The development of epitope-specific assays using this sequence information may produce diagnostic tests suitable for C. ruminantium and also other related rickettsiae. (+info)Evaluation of 16S, map1 and pCS20 probes for detection of Cowdria and Ehrlichia species. (2/49)
A panel of 16S ribosomal RNA gene probes has been developed for the study of the epidemiology of heartwater; five of these detect different cowdria genotypes, one detects five distinct genotypes; one detects any Group III Ehrlichia species other than Cowdria and one detects any Group II Ehrlichia species. These probes have been used on PCR-amplified rickettsial 16S rRNA genes from over 200 Amblyomma hebraeum ticks. Control ticks were laboratory-reared and either uninfected or fed on sheep experimentally infected with different cowdria isolates, field ticks were collected from animals in heartwater-endemic areas. All tick-derived DNA samples were also examined by PCR amplification and probing for two other cowdria genes (map1 and pCS20) which have previously been used for heartwater epidemiology. This paper describes the first direct comparison of all currently available DNA probes for heartwater-associated organisms. (+info)Prevalence of Cowdria ruminantium infection in Amblyomma hebraeum ticks from heartwater-endemic areas of Zimbabwe. (3/49)
Analysis of the transmission dynamics of Cowdria ruminantium, the tick-borne rickettsial agent of heartwater in ruminants, requires accurate measures of infection in vector populations. To obtain these, Amblomnia hebraeum ticks were collected at two heartwater-endemic locations in the lowveld and highveld regions of Zimbabwe and assessed for C. ruminantium infection with specific polymerase chain reaction (PCR) and DNA probe detection assays. At the lowveld site, 11.2% (50/446) of adult ticks and 8.5% (23/271) of nymphs carried C. ruminantium, as detected by PCR. At the highveld site, the prevalence of infection in adult ticks was 10.2% (40/392). DNA probe analysis revealed that most infections at both sites were of low intensity; only 9% and 23% of all nymph and adult tick infections, respectively, were greater than 70000 organisms, the detection limit of the DNA probe. However, the majority (70%) of probe-detectable adult tick infections were high, between 10(7) and 10(9) organisms/tick, while those within nymphs were lower, between 10(5) and 10(6) organisms/tick. (+info)Identification of Cowdria ruminantium antigens that stimulate proliferation of lymphocytes from cattle immunized by infection and treatment or with inactivated organisms. (4/49)
Cowdria ruminantium is an obligate intracellular pathogen that causes heartwater in ruminants. Several findings suggest that T cells play an important role in protection against the disease. In order to identify which proteins are involved in T-cell immunity, C. ruminantium proteins were fractionated by continuous-flow electrophoresis and tested for their ability to stimulate lymphocyte proliferation in vitro. C. ruminantium-infected endothelial cell lysates were fractionated at between 11 and 38 kDa and 50 and 168 kDa on 15 and 7% acrylamide gels, respectively. In an attempt to stimulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with fractionated proteins. In a parallel study, four cattle were immunized with inactivated C. ruminantium to determine whether their lymphocytes also responded to fractionated proteins. Proliferation assays after immunization by infection and treatment detected no C. ruminantium-specific proliferation in vitro after one vaccination. Proliferation was observed, however, between 1 and 4 weeks after challenge. This was followed by a period of no detectable response, after which the response reappeared. PBMC from animals immunized with inactivated organisms proliferated specifically in response to antigen soon after the first immunization. Only C. ruminantium proteins with low molecular masses of 11, 12, 14 to 17, and 19 to 23 kDa induced proliferative responses by lymphocytes from all six animals. These protein fractions may have potential as vaccine antigens. (+info)Growth of Cowdria ruminantium, the causative agent of heartwater, in a tick cell line. (5/49)
The tick-borne rickettsia Cowdria ruminantium has been propagated continuously for over 500 days in the Ixodes scapularis tick cell line IDE8 by using the Gardel isolate from bovine endothelial cells as an inoculum. Infection of the tick cells was confirmed by PCR, karyotyping, electron microscopy, and reinfection of bovine cells. (+info)Detection of the agent of heartwater, Cowdria ruminantium, in Amblyomma ticks by PCR: validation and application of the assay to field ticks. (6/49)
We have previously reported that the pCS20 PCR detection assay for Cowdria ruminantium, the causative agent of heartwater disease of ruminants, is more sensitive than xenodiagnosis and the pCS20 DNA probe for the detection of infection in the vector Amblyomma ticks. Here, we further assessed the reliability of the PCR assay and applied it to field ticks. The assay detected DNA of 37 isolates of C. ruminantium originating from sites throughout the distribution of heartwater and had a specificity of 98% when infected ticks were processed concurrently with uninfected ticks. The assay did not detect DNA of Ehrlichia chaffeensis, which is closely related to C. ruminantium. PCR sensitivity varied with tick infection intensity and was high (97 to 88%) with ticks bearing 10(7) to 10(4) organisms but dropped to 61 and 28%, respectively, with ticks bearing 10(3) and 10(2) organisms. The assay also detected C. ruminantium in collections of Amblyomma hebraeum and Amblyomma variegatum field ticks from 17 heartwater-endemic sites in four southern African countries. Attempts at tick transmission of infection to small ruminants failed with four of these collections. The pCS20 PCR assay is presently the most characterized and reliable test for C. ruminantium in ticks and thus is highly useful for field and laboratory epidemiological investigations of heartwater. (+info)Macrorestriction fragment profiles reveal genetic variation of Cowdria ruminantium isolates. (7/49)
Macrorestriction profile analysis by pulsed-field gel electrophoresis (PFGE) was used to distinguish between seven isolates of Cowdria ruminantium from geographically different areas. Characteristic profiles were generated for each isolate by using the restriction endonucleases KspI, SalI, and SmaI with chromosomal sizes ranging between 1,546 and 1,692 kb. Statistical analysis of the macrorestriction profiles indicated that all the isolates were distinct from each other; these data contribute to a better understanding of the epidemiology of this pathogen and may be exploited for the identification of genotype-specific DNA probes. (+info)Genome size and genetic map of Cowdria ruminantium. (8/49)
Cowdria ruminantium is the cause of a serious tick-borne disease of domestic ruminants, known as heartwater or cowdriosis. The organism belongs to the tribe Ehrlichieae:, which contains obligate intracellular pathogens, causing several important animal and human diseases. Although a few C. ruminantium genes have been cloned and sequenced, very little is known about the size, gross structure and organization of the genome. This paper presents a complete physical map and a preliminary genetic map for C. ruminantium. Chromosomal C. ruminantium DNA was examined by PFGE and Southern hybridization. PFGE analysis revealed that C. ruminantium has a circular chromosome approximately 1576 kb in size. A physical map was derived by combining the results of PFGE analysis of DNA fragments resulting from digestion of the whole genome with KSP:I, RSR:II and SMA:I and Southern hybridization analysis with a series of gene probes and isolated macrorestriction fragments. A genetic map for C. ruminantium with a mean resolution of 290 kb was established, the first for a member of the Ehrlichieae: A total of nine genes or cloned C. ruminantium DNA fragments were mapped to specific KSP:I, RSR:II and SMA:I fragments, including the major antigenic protein gene, map-1. (+info)'Ehrlichia ruminantium' is a gram-negative, intracellular bacterium that belongs to the family Anaplasmataceae. It is the etiological agent of heartwater, a tick-borne disease that affects mainly ruminants such as cattle, sheep, and goats. The bacteria infect endothelial cells in various organs, including the brain and heart, causing vasculitis, edema, and hemorrhage, which can lead to severe clinical signs and death in infected animals.
The bacterium is transmitted through the bite of infected ticks, mainly from the genus Amblyomma. The disease is endemic in many tropical and subtropical regions of the world, including Africa, the Caribbean, and South America. Heartwater is a major constraint to livestock production in affected areas, causing significant economic losses to farmers and pastoralists.
Prevention and control measures for heartwater include the use of acaricides to control tick infestations, vaccination of susceptible animals, and quarantine measures to prevent the introduction of infected animals into disease-free areas.
Heartwater disease is not a human condition, but rather a tick-borne illness that affects ruminants, particularly cattle, sheep, and goats. It's primarily found in sub-Saharan Africa and the Caribbean. Here is a veterinary medical definition:
Heartwater disease, also known as Cowdria disease, is a rickettsial infection caused by the intracellular bacterium Ehrlichia ruminantium. The disease is transmitted through the bite of infected ticks, primarily of the genus Amblyomma.
The name "heartwater" refers to the accumulation of fluid in the lungs and around the heart that can occur as a result of the infection. Initial symptoms may include fever, depression, loss of appetite, and swelling of the legs and brisket. As the disease progresses, it can lead to neurological signs such as aimless wandering, muscle twitching, and difficulty swallowing. If left untreated, heartwater disease is often fatal.
Prevention strategies include tick control measures, such as the use of acaricides (chemicals that kill ticks), and vaccination.
Ehrlichia is a genus of gram-negative, obligate intracellular bacteria that infect and replicate within the vacuoles of host cells. These bacteria are transmitted to humans and animals through the bite of infected arthropods, such as ticks. Infection with Ehrlichia can cause a variety of symptoms, including fever, headache, muscle aches, and gastrointestinal symptoms. Some species of Ehrlichia, such as Ehrlichia chaffeensis and Ehrlichia ewingii, are known to cause human disease, including ehrlichiosis.
Ehrlichiosis is a tick-borne disease that can range in severity from mild to severe and can be fatal if not promptly diagnosed and treated. Symptoms of ehrlichiosis may include fever, headache, muscle aches, fatigue, and gastrointestinal symptoms such as nausea, vomiting, and diarrhea. In some cases, the infection can lead to more serious complications, such as neurological problems, respiratory failure, or kidney failure.
Ehrlichiosis is typically treated with antibiotics, such as doxycycline, which are effective against the bacteria. It is important to seek medical attention promptly if you suspect that you may have been infected with Ehrlichia, as early treatment can help prevent serious complications. Prevention measures, such as using insect repellent and avoiding tick-infested areas, can also help reduce the risk of infection.
'Ehrlichia chaffeensis' is a gram-negative, intracellular bacterium that causes human ehrlichiosis, a tick-borne disease. It is transmitted to humans through the bite of infected ticks, primarily the lone star tick (Amblyomma americanum). The bacteria infect and replicate within white blood cells, causing symptoms such as fever, headache, muscle aches, and fatigue. In severe cases, ehrlichiosis can cause damage to organs and may be fatal if not promptly diagnosed and treated with appropriate antibiotics.
Ehrlichia chaffeensis is named after Dr. William A. Ehrlich, who first described the bacterium in 1937, and Fort Chaffee in Arkansas, where the tick vector was first identified.
'Ehrlichia canis' is a gram-negative, intracellular bacterium that belongs to the family Anaplasmataceae. It is the etiological agent of canine monocytic ehrlichiosis (CME), which is a tick-borne disease in dogs. The bacteria are transmitted to dogs through the bite of infected brown dog ticks (Rhipicephalus sanguineus).
The infection can cause a variety of clinical signs, including fever, lethargy, anorexia, lymphadenopathy, thrombocytopenia, and hemorrhages. In severe cases, the infection may lead to serious complications such as disseminated intravascular coagulation (DIC), neurological disorders, and even death.
Diagnosis of CME is typically made through detection of Ehrlichia canis antibodies in the dog's serum or by PCR-based methods to detect the bacterial DNA. Treatment usually involves the use of antibiotics such as doxycycline, which has been shown to be effective against Ehrlichia canis.
It is important to note that 'Ehrlichia canis' can also infect humans, causing a similar disease known as human monocytic ehrlichiosis (HME). However, this is rare and usually occurs in individuals who are immunocompromised or have been exposed to infected dogs or ticks.
Selenomonas is a genus of gram-negative, anaerobic bacteria that are commonly found in the oral cavity and gastrointestinal tract of humans and animals. These bacteria have a unique characteristic of having curved or spiral-shaped morphology and a polar flagellum for motility. They are named after their ability to reduce selenite to elemental selenium, which gives them a characteristic red color.
Selenomonas species are often associated with dental caries and periodontal disease due to their production of acid and other virulence factors that can contribute to tissue destruction. However, they also play important roles in the breakdown of complex carbohydrates and the production of volatile sulfur compounds in the gut.
It's worth noting that while Selenomonas species are generally considered to be commensal organisms, they have been implicated in various opportunistic infections, particularly in immunocompromised individuals or those with underlying medical conditions.
Ehrlichiosis is a tick-borne disease caused by infection with Ehrlichia bacteria. It is typically transmitted to humans through the bite of an infected tick. The symptoms of ehrlichiosis can include fever, headache, muscle aches, fatigue, and gastrointestinal symptoms such as nausea, vomiting, and diarrhea. If left untreated, ehrlichiosis can cause serious complications, including damage to the central nervous system and other organs. It is important to seek medical attention if you think you may have been exposed to ehrlichiosis and are experiencing symptoms of the disease. A healthcare provider can diagnose ehrlichiosis through laboratory tests and can recommend appropriate treatment, which typically involves antibiotics. Prevention measures, such as using insect repellent and avoiding tick-infested areas, can help reduce the risk of ehrlichiosis and other tick-borne diseases.
Ehrlichia ruminantium - Wikipedia
Ehrlichia ruminantium | NAL Agricultural Thesaurus
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