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At least 127 records · Page 7Linked to original sources

Use of the dot enzyme-linked immunosorbent assay with isolated Anaplasma marginale initial bodies for serodiagnosis of anaplasmosis in cattle.

Isolated Anaplasma marginale initial bodies were successfully used in a dot ELISA for rapid detection of antibodies to Anaplasma organisms. The enzyme immunoassay used only 25 ng of antigen dotted onto nitrocellulose disks. Antigen-antibody complexes were detected by use of alkaline phosphatase-conjugated protein A, and reactions were read visually after addition of a precipitable, chromogenic substrate. The test allowed the processing of multiple sera, either for screening or for titer determination, in less than 3 hours and was found to be as sensitive as the indirect fluorescent antibody test. The overall performance of the dot ELISA, using isolated A marginale initial bodies, for 580 bovine serum samples was as follows: sensitivity, 93%; specificity, 96%; and predictive value, 95%. Cross-reactivity was not observed with sera positive to Babesia bovis and B bigemina, Trypanosoma vivax, or common bacteria or viruses infecting cattle. The antigen dotted onto nitrocellulose disks was stable when stored at -20, 4, or 25 C. Compared with the indirect fluorescent antibody test, the dot ELISA allowed easier, faster, and more objective interpretation of results. Its simplicity and low cost combined with high sensitivity and specificity indicate that this assay could effectively replace serologic assays currently used for diagnosis of anaplasmosis in cattle.

Anaplasma↗

Methods currently used for the control of anaplasmosis and babesiosis: their validity and proposals for future control strategies.

Four alternative approaches to the control of anaplasmosis and babesiosis as a complex of diseases are identified: no active control, tick control, immunization, and chemoprophylaxis. These methods may be utilized in one of five strategies: tick eradication with or without concurrent immunization, tick reduction with or without concurrent immunization or no active control. Factors influencing the choice of strategy are discussed.

Anaplasma↗

Comparisons of the complement-fixation, indirect fluorescent antibody, and card agglutination tests for the diagnosis of bovine anaplasmosis.

Results of complement-fixation (CF), indirect fluorescent antibody (IFA), and card agglutination (CT) tests were statistically compared, using 380 serum samples obtained from 140 cattle which were disease-free or naturally or experimentally infected with Anaplasma marginale of Colombian origin. The IFA test was significantly the most sensitive for detection of amimals infected with anaplasmosis (97%); the CT test and the CF test were less so (84% and 79%, respectively). However, the most efficient test for identifying noninfected animals was the CF test (100%), and the CT and the IFA tests were less efficient (98% and 90%). A linear regression analysis performed on the average IFA and CF titers of 10 calves artificially infected with A marginale during a 20-week period showed significant regression coefficients for both tests. The regression line for the CF titers decreased below the sensitivity threshold at 14 weeks after calves were inoculated, whereas the regression line for the IFA titers continued above the sensitivity threshold 20 weeks after inoculation. The CT test also detected antibodies until the end of the observation period.

Agglutination Tests↗

Spherocytosis associated with anaplasmosis in two cows.

Spherocytes were detected on blood smears of 2 Angus cows. The RBC from both cows had increased fragility in hypotonic saline solution, supporting the presence of spherocytes. Other laboratory tests revealed a macrocytic, regenerative anemia with anisocytosis, polychromasia, basophilic stippling, Howell-Jolly bodies, nucleated RBC, and Anaplasma marginale organisms. A complement-fixation test was positive for anaplasmosis in cow 1 and a direct Coombs' test was positive for immunoglobulin G in both cows.

Anaplasmosis↗

Blood magnesium values in healthy cattle and in cattle affected with anaplasmosis and eperythrozoonosis.

Magnesium (Mg) concentrations in plasma, serum, and erythrocytes (RBC) of calves subjected to splenectomy (SP), splenectomy-induced eperythrozoonosis (EP), and experimentally induced anaplasmosis (AN) were determined and compared with pre-SP, pre-EP, and pre-AN values. Mean serum and plasma Mg concentrations varied in parallel through most periods of the trial. Both were highest after SP, but neither value was significantly different from the pre-SP concentrations. Mean serum and plasma Mg values varied inversely with mean RBC values after SP and EP. Mean RBC Mg values increased significantly from previous periods during EP and AN and after AN, with the values after AN being significantly higher than those at all other periods. Mean plasma, serum, and RBC Mg concentrations were correlated to both mean percentage of parasitemia (%P) and packed-cell volume (PCV). The RBC Mg values increased significantly after mean %P reached 20 and the PCV began to decrease. There was evidence for a distinct lag variation in increasing RBC Mg concentrations with respect to both mean %P and PCV during AN. A strong correlation was observed between the RBC Mg values and the %P occurring 5 days previously and the PCV occurring 3 days previously.

Anaplasmataceae Infections↗

Evaluation of the anaplasmosis rapid card agglutination test for detecting experimentally infected elk.

Anaplasmosis was experimentally transmitted from cattle to elk to cattle. Six non-splenectomized adult elk (Cervus canadensis canadensis) that were inoculated with freshly collected heparinized blood from cattle chronically infected with Anaplasma marginale became asymptomatic carriers. Although the exposed elk did not develop clinical or hematologic evidence of infection they become seropositive by the serum and plasma rapid card agglutination (RCA) tests. Blood from the experimentally infected elk produced disease in splenectomized bovine calves and the carrier state persisted for at least one year. Infection did not occur when two elk were inoculated with 0.5 ml of frozen blood from known bovine carriers. The blood had been frozen for four weeks in liquid nitrogen with six percent dimethyl-sulfoxide.

Agglutination Tests↗

[Preparation and comparative testing of antigens for the immunodiagnosis of anaplasmosis in cattle].

Three antigen types were produced by ultra-sound treatment of the initial material (Anaplasma marginale Theiler infected blood) and its subsequent sedimentional centrifugation from 10 000 to 100 000 G. Their specificity and susceptibility to the Reaction Complement Binding (RCB) and to the capillary agglutination (CA) serological tests was comparatively checked up. Antigens A and B were very active in RCB, while antigen B--in the CA reaction. By these qualities they meet the requirements and are suitable for the practical need of discovering animals-carriers of anaplasmosis.

Anaplasma↗

Observations on the pathogenesis of anaplasmosis in cattle with particular reference to nutrition, breed and age.

Experiments are described to examine the pathogenesis of anaplasmosis in Bos indicus cattle with particular emphasis on nutrition, breed and age. The disease seemed to be less severe in animals under a poor plane of nutrition. Breed was shown to have little effect and there was an age resistance. Natural transmission in Bos indicus calves occurred with ease in endemic areas. This indicated that the introduction of Bos indicus cattle should not adversely affect enzootic stability.

Age Factors↗

Resistance to anaplasmosis after elimination of latent Anaplasma marginale infections.

Ten 30-month-old cattle (group 2) were inoculated with Anaplasma marginale 6 months after the latent A marginale infection was eliminated by oral chlortetracycline therapy. In addition, 4 cattle (group 1) with no record of infection and 4 cattle (group 3) of equivalent age previously vaccinated with a killed antigen were similarly inoculated. Moderate to severe clinical signs of acute anaplasmosis occurred in the group 1 (previously uninfected) cattle, whereas only 1 of the chlortetracycline-treated cattle (group 2) and none of the vaccinated cattle (group 3) had clinical evidence of disease.

Anaplasmosis↗

Application of various chemotherapeutic agents in experimental bovine anaplasmosis.

A trial was conducted with several chemotherapeutic agents against clinical and carrier cases of experimental bovine anaplasmosis. Dithiosemicarbazone (in combination with oxytetracycline). Chloramphenicol and Rolitetracycline proved to be very efficacious in bringing about the clinical recovery and the elimination of the carrier status. Treatment with Imidocarb caused a clinical recovery but could not completely eliminate the organisms.

Anaplasmosis↗

Relative efficacy of two oxytetracycline formulations and doxycycline in the treatment of acute anaplasmosis in splenectomized calves.

The efficacy of 3 antibiotic formulations was measured in the treatment of artificially induced anaplasmosis in the early stages of an ascending parasitemia (1% to 4%) in 23 splenectomized calves. Group 1, consisting of 5 calves, served as nontreated controls. Four calves (group 2) were treated 1 time with 10 mg of oxytetracycline (T-50)/kg of body weight IM; 5 calves (group 3) were treated 3 times with 10 mg of T-50/kg IM; 5 calves (group 4) were treated 1 time with 20 mg of an experimental oxytetracycline (T-200)/kg IM; and 4 calves (group 5) were treated 1 time with 10 mg of a synthetically derived antibacterial agent, doxycycline (D-100)/kg IM. All control calves died and 1 of 4 calves died that was treated 1 time with T-50. Other deaths did not occur. All treatments were effective in moderating the infective process, but T-50 given 3 times and T-200 given 1 time were markedly more effective than T-50 and D-100 given 1 time. There appeared to be little or no difference in therapeutic efficacy between T-50 and D-100 given 1 time and between T-50 given 3 times and T-200 given 1 time.

Acute Disease↗

Elimination of the carrier state of bovine anaplasmosis with a long-acting oxytetracycline.

A long-acting formulation of oxytetracycline (L-200) was injected at a dose level of 20 mg/kg intramuscularly into 12 yearling cattle that had been experimentally inoculated with Anaplasma marginale 64 days previously. Four cattle were treated twice, 4 were treated 3 times, and 4 were treated 4 times. All injections were given once ever 7 days. Previous work (unpublished) with this formulation has revealed prolonged blood values following a single injection. The blood (80 ml) of each calf was inoculated into a susceptible test calf 83 days after the last treatment dose. Anaplasmosis did not occur in any of the test calves. Two infected cattle were treated with 12 daily injections of oxytetracycline (L-50) at a dose level of 11 mg/kg to establish the sensitivity of the parasite to oxytetracycline. Subsequent calf inoculation tests showed that A marginale was eliminated. Two unmedicated, infected cattle remained infected throughout the study. Complement-fixation tests with A marginale antigen at 6 months after treatment showed average sera titers of less than 5 in the treated cattle and 45 in the unmedicated cattle.

Anaplasmosis↗

Experimental bovine anaplasmosis: clinico-pathological and nutritional studies.

Groups of Brahman-cross steers maintained on two nutritional planes were infected intravenously with a stabilate of Anaplasma marginale. In general, animals on the higher plane of nutrition were more severely affected. Fever was the first clinical sign of anaplasmosis but, like anaemia, was absent in the mildest cases. When present anaemia appeared two to three weeks after infection. There was a corresponding increase in erythrocyte sedimentation rates when read after 24 h but not at 1 h. The haemolytic nature of the anaemia was indicated by a significant increase in unconjugated bilirubin during the acute phase. Some visceral damage was suggested by a significant increase of serum aspartate amino-transferase (GOT) especially in severely affected animals of the 'high' nutrition group but no significant change occurred in levels of alanine amino-transferase (GPT).

Alanine Transaminase↗

Preservation of lyophilization of anaplasmosis capillary tube-agglutination test antigen.

An antigen for anaplasmosis capillary tube agglutination test was lyophilized, using different stabilizers. The lyophilized and control (suspension) antigens were maintained at 4, 18, and 37 C and tested for reactivity with known positive and negative sera once every 7 days for a period of 28 days and then once every 2 weeks for a grand total of 154 days. Both the lyophilized and control antigens retained their antigenicities during the entire test period.

Agglutination Tests↗

Bovine anaplasmosis: clinical, hematologic, and serologic manifestations in cows given a long-acting oxytetracycline formulation in the prepatent period.

The prophylactic efficacy of a long-acting oxytetracycline formulation was determined in 36 susceptible cows experimentally inoculated with Anaplasma marginale. Each of 10 cows in 3 treatment groups (T2, T3, T4) were given IM injections of 20 mg of oxytetracycline/kg of body weight once, twice, or three times during the prepatent period. The T2 group was treated once at 1 week after experimental inoculation, the T3 group was treated 2 times (at 1 and 2 weeks) after exposure, and the T4 group was treated 3 times (at 1, 2, and 3 weeks) after exposure. Six cows comprising group T1 served as nonmedicated controls. Treatment of cattle in the prepatent period with the long-acting oxytetracycline formulation produced significantly fewer clinical anaplasmosis cases. This reduction in frequency was proportional to the number of weekly treatments given. In cattle which developed clinical disease, only 1 IM injection of 20 mg of oxytetracycline/kg was necessary to induce recovery. The prepatent period in the treated cattle was extended approximately 30 days beyond the prepatent period of the control cattle after their final treatment. Humoral rapid card agglutinating and complement fixing antibodies regularly were present in the cows 10 days after they were inoculated; however, neither the presence of antibody nor that of the antibiotic was sufficient to prevent establishment of the carrier state in the principals.

Anaplasmosis↗

[Humoral immune response of cattle with anaplasmosis].

A study was carried out tracing the humoral and immune response of cows who have suffered from anaplasmosis (A. marginale). Selected antigens were utilized according to the method of McHardy and Gillson in a series of CF and RA serological tests. We studied 75 blood serums from 6 cows, taken periodically in the course of a year. The complement fixation antibodies reached their highest titre between the first and the second month after the infection (1:640) and their lowest titre towards the eleventh/twelfth month (1:40), whereas the agglutinative antibodies reached their highest titre between the second and the third month (1:64) and their lowest titre towards the twelfth month (1:4).

Agglutination Tests↗

Chemoprophylaxis of vector-borne anaplasmosis with sustained-release boluses.

Sustained-release oxytetracycline boluses (20%) delivering 145 to 150 mg/bolus/day were administered to complement-fixation test-negative cattle at dosages of 2.0, 2.5, and 3.0 mg/kg of body weight. Subsequent challenge exposure of cattle with Dermacentor andersoni Stiles infected with Anaplasma marginale Theiler indicated that treatment with the dosage of 2.5 mg/kg prevented clinical anaplasmosis and that treatment with the dosage of 3.0 mg/kg prevented disease infection.

Anaplasmosis↗

Molecular epidemiology of bovine anaplasmosis.

Bovine anaplasmosis presents a worldwide distribution. However, specific models for studying the epidemiology of the disease are not available. Epidemiological modeling encounters some difficulties due to a lack of culturing techniques for Anaplasma marginale, the causative agent, as well as for the lack of typing techniques to characterize strains. The chronic carrier state and the population dynamics of mechanical and biological vectors also create difficulties. In addition, conventional serology and blood smear diagnostic techniques fail to detect all chronic carriers. Fortunately the needs for the accurate typing of isolates and for detecting chronic carriers made it possible to encourage the development of new tools based on molecular epidemiology principles. A. marginale isolates can now be typed by using panels of monoclonal antibodies, and the genes coding for some major surface proteins can be expressed or analyzed by looking at the nucleotide arrangement level. In the same manner, the latest techniques for detecting A. marginale chronic infections use DNA and RNA probes, and PCR-based methods to detect A. marginale DNA from bovine blood samples with extremely low rickettsaemias. Currently all these new epidemiological tools are being incorporated to experimental models to analyze their applicability for epidemiological studies in the near future.

Anaplasma↗