Isolation of Ehrlichia risticii from the aborted fetus of an infected mare.
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Biomedical subjects
Publications and source records attributed to I Kakoma.
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The suitability of blood collected on filter papers in comparison with corresponding conventional serum samples in the diagnosis of bovine anaplasmosis was studied using the complement fixation test, DOT-ELISA, Western immunoblot and rapid card agglutination test. Dried blood on Whatman filter paper no. 1 was eluted in PBS 0.05% Tween 20 giving an initial dilution of 1:10. The reactivity of the eluted samples in both DOT-ELISA and Western immunoblotting were similar to those obtained with the corresponding straight serum sample dilutions. Filter paper samples gave lower reactivity in the remaining tests when compared with corresponding serum samples. There was no significant difference in the reactivity between the eluates from filter papers stored at temperatures ranging between 15.5 and 24 degrees C and those kept refrigerated. Storage at 15.5 to 24 degrees C did not significantly affect reactivity for up to six months. Eluates from filter papers stored for six months at 15.5 to 24 degrees C continued to give similar reactivity as those from freshly prepared filter papers in both DOT-ELISA and Western blot, and in the rapid card agglutination test. It is concluded that collecting blood on filter papers is a suitable technique for large scale seroepidemiological studies on anaplasmosis and offers many advantages in developing countries where transport and cold chain facilities are a major constraint.
Various combinations of human serum (from blood of groups A and Rhesus positive) with bovine serum, i.e. 20% + 20% (Medium I), 30% + 10% (II), 40% + 0% (III) and 0% + 40% (IV) and Medium-199 (60%) were used in the propagation of Babesia bovis. Babesia bovis stabilate revived by inoculation in a bovine calf was used at a level of 6% parasitized erythrocytes (PPE). The medium was replenished every 24 h. The medium changed from bright red to dark-coffee color every 24 h. The increase in PPE was maximal between 24 and 48 h. It was also observed that the increase in PPE was significantly higher in a 1:2 dilution compared with a 1:1 dilution. The increase in PPE was highest in Medium I with a 50% replacement of bovine with human serum. However, the parasites could not be subcultured and maintained continuously. Fifty percent replacement was thus optimal for the human-bovine serum combination in a microaerophilous stationary phase (MASP) system. The results indicate that B. bovis can also multiply in a human/bovine serum MASP culture system at least for a period of 48 h, and this is consistent with the zoonotic nature of Babesia species.
The suitability of blood collected on filter papers in comparison with corresponding conventional serum samples in the diagnosis of bovine anaplasmosis was studied using the Complement Fixation Test (CFT), DOT-ELISA, Western immunoblot and Rapid Card Agglutination Test (RCAT). Dried blood on Whatman filter paper no. 1 was eluted in 1.8 ml of PBS 0.05% Tween 20 given an initial dilution of 1:100. The reactivity in both DOT-ELISA and Western immunoblotting was similar to that obtained with the sera diluted 1:100. Filter paper samples gave lower reactivity in all the tests as compared with corresponding serum samples. There was no significant difference in the reactivity between the eluates from filter papers stored at room temperature and those stored at 4 degrees C. Storage at room temperature did not significantly affect reactivity for up to 6 months. Eluates from filter papers stored for 6 months at room temperature continued to give similar reactivity to those from freshly prepared filter papers in both DOT-ELISA and Western blot, and in the Rapid Card Agglutination Test. It is concluded that collecting blood on filter papers is a suitable technique for large-scale screening and for seroepidemiological studies on anaplasmosis, and offers many advantages especially in developing countries where transport and cold chain facilities are a major constraint.
The prevalence of bovine anaplasmosis was studied in 320 Zebu cattle randomly selected from three regions of Uganda (central, south-western and north-western) using DOT-ELISA, Western immunoblotting, Rapid Card Agglutination Test (RCAT), Capillary Tube Agglutination Test (CAT), Complement Fixation Test (CFT), and parasitological techniques. Dried blood on Whatman filter paper no. 1 was eluated in PBS 0.05% Tween 20 prior to testing at an initial dilution of 1:25. The incidence of parasitaemia ranged from 25% in the central region to 35% in the north-western region and the serological prevalence was lower in the central region and highest in the north-west. Prevalence rates assayed by DOT-ELISA and Western immunoblotting were 1.5-fold greater than those tested with RCAT and 3-fold greater than in CAT. The overall prevalence rates by DOT-ELISA and Western immunoblotting compared favourably with CFT data. The present data utilizing dried blood on filter papers indicate that there is a high prevalence of anaplasmosis in those regions of Uganda surveyed and it confirms our observations and those of others that collecting blood on filter papers is a suitable technique for large-scale screening and for seroepidemiological studies.
The development of additional methods for detecting and identifying Babesia and Plasmodium infections may be useful in disease monitoring, management and control efforts. The preliminary evaluate synthetic peptide-based serodiagnosis, a hydrophilic sequence (DDESEFDKEK) was selected from the published BabR gene of B. bovis. Immunization of rabbits and cattle with the hemocyanin-conjugated peptide elicited antibody responses that specifically detected both P. falciparum and B. bovis antigens by immunofluorescence and Western blots. Using a dot-ELISA with this peptide, antisera from immunized and naturally-infected cattle, and immunized rodents, were specifically detected. Reactivity was weak and correlated with peptide immunization or infection. DNA-based detection using repetitive DNA was species-specific in dot-blot formats for B. bovis DNA, and in both dot-blot and in situ formats for P. falciparum; a streamlined enzyme-linked synthetic DNA assay for P. falciparum detected 30 parasites/mm3 from patient blood using either colorimetric (2-15 h color development) or chemiluminescent detection (0.5-6-min exposures). Serodiagnostic and DNA hybridization methods may be complementary in the respective detection of both chronic and acute infections. However, recent improvements in the polymerase chain reaction (PCR) make feasible a more sensitive and uniform approach to the diagnosis of these and other infectious disease complexes, with appropriate primers and processing methods. An analysis of ribosomal DNA genes of Plasmodium and Toxoplasma identified Apicomplexa-conserved sequence regions. Specific and distinctive PCR profiles were obtained for primers spanning the internal transcribed spacer locus for each of several Plasmodium and Babesia species.
Theileria sergenti were isolated from infected erythrocytes by hypotonic lysis, and soluble merozoite antigens were purified by sonication and differential centrifugation. The preparation contained 29, 34, 35 and 105 kD immuno-dominant poly-peptides. The soluble antigens (0.5 mg/ml) were prepared and fortified with Freund's adjuvant. Five month old naive Korean calves were subcutaneously inoculated with the preparation and a booster dose was administered 4 weeks later. Nine weeks after the booster dose, vaccinates and controls were challenged with a homologous stabilate (5.6 x 10(6) RBC/dose, 40% Parasitemia). All animals were monitored for hematocrit, total erythrocyte count, parasitemia and for the specific antibody by Western immunoblot (WB) and indirect immuno-fluorescent antibody (IFA) test. By 18 weeks after vaccination (6 weeks after the challenge), vaccinated cattle had an average IFA titer of 1:10,240 compared with 1:1,280 of the controls. The vaccinates showed negligible change in hematocrit and total RBC count whereas control animals showed significant (p less than 0.05) hematological changes and associated anemia. After vaccination and challenge, the antibody responses demonstrated that vaccination had induced significant production of antibody to the 29 and 35 kD polypeptides. The latter polypeptide was much more strongly recognized by the vaccinated animals, and thus it may be a potential candidate for the vaccine.
Levels of platelets and other hematological values were monitored in 21 Saimiri and 12 Aotus monkeys over a period of three weeks post-infection with monkey-adapted Indochina CDC-1 strain of Plasmodium falciparum. In both Saimiri sciureus boliviensis and Aotus nancymai karyotype-1 monkeys the severest thrombocytopenia was observed at 14 days post-infection coinciding with peak parasitemia, neutropenia, lymphocytosis, and anemia associated with severe hemoglobinemia and elevated fibrinogen degeneration products(FDP's). MCH and MCV profiles in Aotus monkeys decreased with ascending parasitemia. In contrast, these parameters in Saimiri were characterized by a significant compensatory increase correlating with parasitemia. In general, thrombocytopenia was one of the earliest clinical manifestations of the infection with the platelets returning to normal levels shortly after peak parasitemia at 14 days. Platelet kinetics had a strong correlation with hematologic and parasitologic values in the Aotus model. No consistent associations were observed between platelet kinetics and other parameters in the Saimiri model. These data indicate that the Aotus model for malaria is more predictable than the Saimiri. Further, platelet turnover rates and recovery provide a useful prognostic parameter during malaria infection. The results are discussed in relation to the value of the two species of monkeys as models for the pathogenesis of human malaria.
A Theileria sergenti soluble merozoite preparation containing the 29, 34, 35 and 105 KD as the immunodominant polypeptides, was evaluated for efficacy, safety and protectivity in Holstein calves against virulent field tick challenge. The soluble antigens (100 mg/dose) were fortified with either complete or incomplete Freund's adjuvant. Twenty naive calves, aged one month, were subcutaneously inoculated with the preparation and a booster dose was administered 4 weeks later. Twenty additional calves served as controls. Five weeks after the booster dose, vaccinates and uninoculated controls were moved to a pasture, a heavily tick infested area in Cheju-do, Korea. The vaccinates showed negligible change in hematocrit and total RBC count whereas control animals showed significant (p < 0.05) hematological changes and associated anemia. Only 30% of vaccinates required chemotherapy after the experiment was terminated. All control animals required chemotherapy and 25% received blood transfusion. The highest percent parasitized erythrocytes in vaccinated cattle was 0.4% as compared with 3.6% among controls during the month of July. A significant difference (p < 0.05) was observed in the rate of body weight increase. Significant differences were also noted in serum albumin, aspartate aminotransferase, total protein and bilirubin. Significantly more vaccinated cattle maintained normal ranges of hematological and biochemical values as compared with the control group. It is suggested that soluble merozoite T. sergenti antigens may be potential vaccine candidates for developing a genetic vaccine in Korea.
Randomly selected goat sera from north-western, central, and south-western regions of Uganda were analyzed parasitologically and serologically for evidence of anaplasmosis. Prevalence rates of 3.2% by parasitemia, 4.8% by card-agglutination test, and 12.9% by DOT-ELISA combined with western blotting were established. Parasitologically positive samples were consistently serologically positive. Positive samples were all from either the north-western or south-western regions of the country. Goats in these regions graze with cattle and are presumable exposed to the same tick species. There was no evidence of clinical caprine anaplasmosis, whereas bovine anaplasmosis cases are very common. Rhipicephalus evertsi was frequently observed on goats which cograze with cattle.
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The prevalence of bovine anaplasmosis was studied in 320 Zebu cattle randomly selected from three regions of Uganda: (Central, Southwestern and Northwestern) using dot-ELISA, Western immunoblotting, rapid card agglutination test (RCAT), capillary tube agglutination test (CAT), complement fixation test (CFT), and parasitological techniques. Dried blood on Whatman filter paper No. 1 was eluted in PBS 0.05% Tween 20 prior to testing at an initial dilution of 1:25. The prevalences of parasitaemia were 25% in the central region, 28% in the southwestern region, and 35% in the northwestern region, and the serological prevalence was lowest in the central region and highest in the northwest. Overall, prevalence rates obtained by dot-ELISA (61.9%) and Western immunoblotting (62.5%) were 1.5 times those obtained by RCAT (41%) and three times those obtained by CAT (22.5%). The overall prevalence rates obtained by dot-ELISA and Western immunoblotting compared favourably with the CFT data. The present data utilizing dried blood on filter papers indicate that there is a high prevalence of anaplasmosis in those regions of Uganda surveyed, and confirm our observations and those of others that collecting blood on filter papers is a suitable technique for large scale screening and for seroepidemiological studies.
Babesia bovis (a Mexican isolate) was cultivated in MASP culture system using goat serum in various concentrations as substitute of bovine serum. It was observed that 20% goat serum + 20% bovine serum + 60% Parker's medium 199 supported the growth of the parasite, which was maintained in this medium through 8 subcultures. The soluble exoantigen (vaccine) present in the culture supernatant is to be quantified and tested in vitro. Goat serum from slaughterhouses may be utilized for in vitro cultivation of the parasite and, expectedly, production of vaccine. This study may prove to be useful in reducing the cost of vaccine at least in tropical countries.
The antigenic profile of Ehrlichia canis, E risticii, E sennetsu, and E equi was investigated by the use of protein (western) immunoblot technique. Results of analysis of serum from acutely and chronically infected animals indicated that the 4 Ehrlichia species share a unique 25-kD polypeptide in addition to other peptides. Immune sera from dogs inoculated with E canis recognized a wide range of E canis polypeptide antigens, as determined by western blot analysis. A larger number of E sennetsu polypeptides were detected when homologous antiserum and antiserum to E equi were used. The latter antiserum did not recognize antigens of E canis or E risticii. Antisera to E canis, E risticii, and E sennetsu detected E equi antigens. Data indicate that a 25-kD protein is a common antigen among the species of the genus Ehrlichia and that the ascending order of abundance of immunodominant determinants in the 4 species of Ehrlichia studied would be: E risticii----E equi----E sennetsu----E canis. Implications of these findings for diagnosis of ehrlichial infections and prophylaxis are evident.
Soluble Plasmodium falciparum polypeptides, affinity-purified from culture supernatant fluids using sequential immunoadsorptions employing both monoclonal and polyclonal antibodies, induced protective immunity against experimental falciparum malaria in Peruvian Aotus nancymai monkeys. Susceptible monkeys were vaccinated with polypeptides affinity-purified from supernatant fluids of P. falciparum Indochina I/CDC cultures. Eighteen animals (6 immunized with purified antigens plus adjuvants, 6 injected with only the adjuvant preparation, and 6 untreated) were challenged with whole blood containing monkey-adapted virulent organisms of the Indochina I/CDC strain. Selected hematologic, serologic and parasitologic profiles served as potential indicators of protection. This immunogen, when fortified with an aluminum hydroxide/Quil-A saponin adjuvant combination, elicited good antibody responses to major P. falciparum antigens. Protection in vaccinated animals was evidenced by a significantly limited reduction in hematocrit and hemoglobin levels and a relatively moderate course of infection after homologous needle-challenge with Aotus monkey-adapted P. falciparum parasites.
Knowledge of the microbiology of the canine and feline eye in normal and pathologic states is an important aspect of the clinician's assessment of external ocular disease. Gram-positive bacteria predominate in surveys of microbial flora in normal and diseased eyes. These same organisms are routinely isolated from skin and the upper respiratory tract. Injury to the eye may result in proliferation and potential pathogenicity of normal ocular flora. A variety of bacterial, fungal, viral, and other microbial isolates affect the diagnosis and treatment of external ocular disease.
This review suggests that we are on the threshold of a new epoch in the control of ticks and the diseases transmitted by them. Ecological studies of parasitic and non-parasitic stages of the tick life cycle have shown how strategic dipping can lead to effective control of Boophilus ticks. However, this approach can lead to drastic reduction in tick populations which may favour the development of enzootic instability. On the other hand, mathematical models and field studies indicate that we can eradicate babesiosis without eradicating the tick vector. As no well-established vaccine exists for babesiosis or its vectors, it is important to anticipate the possible effects of low or fluctuating populations of ticks caused by strategic control programmes. Under these conditions, it is probable that babesiosis will disappear before the tick vector does. Prudent use of tick bionomic data from several centres of field research, as well as models to analyse these data, should accelerate the latter process. Epidemiological models should be included in the analysis of babesiosis in areas that run the risk of converting from stable zones to unstable zones due to strategic dipping. These observations and projections underscore the value of integration of traditional and modern techniques in the control of babesiosis and other vector-borne diseases.
Heterophile antibodies to sheep red blood cells (SRBC), rabbit red blood cells (RRBC), horse red blood cells (HRBC), murine (rat) red blood cells (MRBC) were investigated in a total of 416 serum samples from two rural areas of Zambia where major parasitic diseases are endemic. Distribution of antibody titers to RRBC were significantly different between the two study areas, whereas titers to SRBC were not significantly different. Sheep RBC's did not reveal a uniform consistent difference between the two communities with respect to schistosomiasis and malaria. Rabbit erythrocytes showed significant differences (P less than 0.05) between parasitologically positive and negative samples for schistosomiasis and malaria, respectively. No significant difference was observed between sexes, although females generally have a slightly higher titer for both SRBC and RRBC than males. No significant agglutinins were detected to HRBC and BRBC. Agglutinins to MRBC were generally too high to be of any differential value. It is suggested that sheep and rabbit erythrocytes might be useful probes for evidence of exposure to parasites and assessment of humoral immunologic status, albeit nonspecific. Further, it is inferred that the incidence of infectious mononucleosis in this region is rather low. A controlled investigation into the distribution of E-B viruses is suggested to explain absence of I-M-like agglutinins in a region climatically conductive to existence of arborviruses in general, and the E-B virus group in particular.