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anaemia in trypanosomiasis: mechanisms of erythrocyte destruction in mice infected with trypanosoma congolense or t. brucei.studies in mice infected with t. brucei or t. congolense showed that increased red cell destruction in the spleen occurred as from the third day of patent parasitaemia and this resulted in a marked reduction of the half-life of transfused syngeneic 51cr labelled cells. there was a progressive increase in the osmotic fragility of the red cells, especially in t. congolense infected mice which also showed a more severe anaemia. the antiglobulin test was only rarely positive in the late stages of t. ...197716466
non-specific induction of increased resistance in mice to trypanosoma congolense and trypanosoma brucei by immunostimulants.administration of the immunostimulants corynebacterium parvum, bacillus calmette-guérin (bcg) or bordetella pertussis prior to, or at the same time as, challenge with trypanosoma congolense significantly increased survival times in mice, both of trypano-susceptible (a/j) and trypano-resistant (c57bl) strains. the increased survival time was associated with significant alterations in parasitaemia, which included lengthening of the pre-patent period, a delay in the time taken to reach the first pe ...197944360
observations on the antigenicity and serological relationships of stocks of trypanosoma congolense from east and west africa.antigenic relationships of 4 stocks of trypanosoma congolense from different parts of africa were examined by immunofluorescence (ifat) and neutralization tests. antisera to each stock were obtained from rabbits infected with trypanosomes transmitted by glossina morsitans. trypanosomes for use as antigens were obtained from local skin reactions developing on rabbits infected with 2 of the stocks. using the ifat and antisera at end-point dilutions approximately 40% of the trypanosomes fluoresced ...197994428
immunologic analysis of host plasma proteins on bloodstream forms of african pathogenic trypanosomes. ii. identification and quantitation of surface-bound albumin, nonspecific igg, and complement on trypanosoma congolense. 197898621
conversion of dihydroorotate to orotate in parasitic protozoa.the conversion of dihydroorotate to orotate, one of the key reactions in the de novo pyrimidine biosynthetic pathway, has been studied in a number of parasitic protozoa. enzyme activities capable of carrying out this reaction were detected in six members of the kinetoplastida (trypanosoma brucei, trypanosoma congolense, trypanosoma vivax, trypanosoma lewisi, trypanosoma cruzi, leishmania enriettii) and three members of the genus plasmodium (p. knowlesi, p. berghei, p. gallinaceum). the mechanism ...1979217438
the generation of phospholipase a and hemolytic fatty acids by autolysing suspensions of trypanosoma congolense.when t. congolense undergoes autolysis there is a concomitant appearance of phospholipase a activity and hemolytic fatty acids. the generation of enzyme activity is exponential, and the appearance of hemolytic activity corresponds to a free fatty acid concentration of 0.02 to 0.03 mg. per ml. the concentration of the trypanosome suspension markedly affected the kinetics of the generation process. in contrast, the autolysis of t. lewisi did not generate hemolytic activity unless exogenous phospho ...1978347651
the pathogenesis of trypanosoma congolense infection in calves. v. quantitative histological changes.calves infected with trypanosoma congolense treu 112 had generalized microvascular dilation which was most prominent in the liver and the mesentery; there also was increase in cellularity in the lung with significant alveolar thickening and accumulation of hemosiderin-bearing cells in the alveolar septa, focal accumulations of lymphocytes primarily at the corticomedullary junction of the kidneys and a well developed glomerulonephritis, likely membranoproliferative. reticuloendothelial changes we ...1979442464
trypanosomes in the lymph nodes of cattle and sheep infected with trypanosoma congolense.the prefemoral lymph nodes of two calves and a sheep infected with a stock of trypanosoma congolense transmitted by glossina morsitans were examined histologically for the presence of trypanosomes. ten days after infection trypanosomes were found in the subcapsular sinuses of the nodes of a calf and the sheep but parasites were absent from the blood at this time. trypanosomes were also detected in the prefemeral lymph node of the other calf on examination 30 days after infection, when parasites ...1979504804
disease syndromes in sheep and goats naturally infected with trypanosoma congolense. 1979541451
maintenance of infectivity of trypanosoma congolense in vitro with explants of infected skin at 37 degrees c. 1979555067
characterisation of the surface coat of trypanosoma congolense. 1978625332
ultrastructural studies of certain aspects of the development of trypanosoma congolense in glossina morsitans morsitans.the course of trypanosoma congolense infections in glossina morsitans morsitans was followed by electron-microscopic examination of ultrathin sections of the guts and proboscises of infected flies. guts dissected from flies 7 days after infection with culture procyclic forms of t. congolense had heavy trypanosome infections in the midgut involving both the endo- and ectoperitrophic spaces. trypanosomes were also seen in the process of penetrating the fully formed peritrophic membrane in the cent ...1979544799
cyclical transmission of trypanosoma brucei rhodesiense and trypanosoma congolense by tsetse flies infected with culture-form procyclic trypanosomes.culture procyclic forms of trypanosoma brucei rhodesiense and trypanosoma congolense were fed to glossina morsitans morsitans through artificial membranes. a very high percentage of the flies so fed produced established midgut infections, a proportion of which went on to develop into mature metacyclic trypanosomes capable of infecting mammalian hosts. the method offers a safe, clean way of infecting tsetse flies with african trypanosomes which reduces the need for trypanosome-infected animals in ...1979536930
the pathogenesis of trypanosoma congolense infection in calves. iv. the kinetics of blood coagulation.blood coagulation studies showed there was a pronounced thrombocytopenia and hypofibrinogenemia in holstein calves infected with trypanosoma congolense treu 112. there was also ineffective thrombopoiesis characterized by an increased megakaryocytic mass, reduced uptake of 35s-methionine into peripheral blood platelets and a normal platelet lifespan. there was an increased uptake of isotopic label into fibrinogen and a shortened half life indicating a consumptive error with increased peripheral u ...1979442453
the pathogenesis of trypanosoma congolense infection in calves. iii. neutropenia and myeloid response.calves infected with trypanosoma congolense treu 112 had, at the onset of anemia, a very low total white cell count and neutropenia but with chronicity there was lymphocytosis. infected calves had a marked reduction in granulocyte mobilization for the first 14 weeks of infection and there was reduced ability to mount an inflammatory response during the onset of anemia. bone marrow aspiration biopsies showed marked erythroid hyperplasia in response to the anemia with a relative and likely absolut ...1979380120
immunosuppressive effect of trypanosoma congolense and trypanosoma vivax on the secondary immune response of cattle to mycoplasma mycoides subsp mycoides.trypanosoma congolense and t vivax infections in cattle were shown to have a suppressive effect on the secondary humoral immune response to m mycoides. the trypanosome infections caused an involution of the thymus. the secondary response was biphasic in nature and was unrelated to infection with trypanosomes.1978373035
fluorescent antibody analysis of host plasma components on bloodstream forms or african pathogenic trypanosomes. i. host specificity and time of accretion in trypanosoma congolense. 1977328843
bovine trypanosomiasis: effect on the immune response of the infected host.yearling cattle were inoculated with a recently isolated field strain of trypanosoma congolense. dinitrophenylated ovalbumin, a bacteriophage, or bovine parainfluenza-3 virus injected into the cattle during the first 5 weeks of infection resulted in peak serum antibody titers lower but not much lower than those produced by noninfected cattle. primary and secondary antibody responses of inoculated cattle required more time to reach peak titers. peripheral blood lymphocyte concentrations decreased ...1979224735
studies on antigenic variation of cyclically transmitted trypanosoma congolense.antigenic variants of t. congolense transmitted by g. m. morsitans through normal and x-irradiated mice were investigated by means of the neutralization test and ifat. clones of a cyclically passaged derivative strain were isolated from irradiated and normal mice. the ifat revealed cross immunofluorescent reactions between most of the stabilates, whereas only the two clones obtained from irradiated mice were totally neutralized by their homologous antisera. these two antisera showed no cross neu ...197767787
in vitro binding of trypanosoma congolense to erythrocytes.trypanosoma congolense broden, an intravascular parasite, binds to vessel walls and erythrocytes of infected hosts. in an attempt to characterize t. congolense adhesion to host cells, an in vitro assay was devised. it was shown in the in vitro experiments that t. congolense binds to bovine, sheep, and goat erythrocytes, but not always to erythrocytes of rats, mice, rabbits, horses or humans. only the anterior part of live trypanosomes adheres to erythrocytes, and the attachment site on the trypa ...197939167
trypanosoma congolense: isolation and purification. 1979446586
immunosuppression in experimental african trypanosomiasis. polyclonal b-cell activation and mitogenicity of trypanosome-derived saturated fatty acids.changes in antibody responses in adult mice infected with trypanosoma congolense and subsequently challenged with unrelated antigens (sheep red blood cells and pneumococcal polysaccharide) were studied. immune responses were significantly depressed within 1 week of infection, and complete suppression of both igm and igg responses to both types of antigen was established 15 days after immunization. coincidentally with the development of high parasitaemias, background igm plaque-forming cell respo ...1979312771
mechanisms of the anemia in trypanosomiasis: studies on the role of the hemolytic fatty acids derived from trypanosoma congolense.trypanosoma congolense releases a number of hemolytic free fatty acids on autolysis of which the most potent is linoleic acid. these fatty acids can lyse washed rat and bovine erythrocytes in vitro. autolysed t. congoleuse will cause increased fragility of erythrocytes in whole rat blood but not in whole bovine blood. the lack of effect of these fatty acids on bovine erythrocytes tends to be confirmed by the failure of this material to influence the survival of these cells in vivo. calculations ...1978644654
trypanosoma congolense: thrombocytopenia in experimentally infected cattle. 1978668836
trypanosoma congolense: mechanical removal of the surface coat in vitro. 1979510443
trypanosoma congolense: inheritance of susceptibility to infection in inbred strains of mice. 1979510441
inhibition of bovine bone marrow granulocyte/macrophage colony formation in vitro by serum collected from cattle infected with trypanosoma vivax or trypanosoma congolense.serum collected from cattle infected with trypanosoma vivax or trypanosoma congolense inhibited bovine granulocyte/macrophage colony formation in methyl cellulose cultures. maximum inhibition was caused by serum collected two and three weeks post infection. the degree of inhibition appeared to be related to the degree of parasitemia. inhibition of erythroid colony formation by serum collected from these animals was not observed.1979483385
bovine trypanosomiasis: the red cell kinetics of ndama and zebu cattle infected with trypanosoma congolense.the responses of susceptible ndama and zebu cattle to needle challenge with trypanosoma congolense were followed using parasitological, haematological and radio-isotopic methods and compared with those of corresponding uninfected animals. in both breeds, infection became patent at the same time but peak parasitaemias were significantly lower, were attained later and were of short duration in the ndama. all infected animals became anaemic, the severity of which correlated with the level and durat ...1979481905
trypanosoma congolense: calf erythrocyte survival. 1979456461
circadian rhythms of trypanosoma congolense in laboratory rodents. 1978366815
suppressor cells in trypanosoma congolense-infected mice.spleen cells from mice infected with t. congolense strongly suppressed lymphocyte stimulation induced in normal spleen cells by incubation with mitogens or allogeneic cells. cell dilution studies showed that suppressor activity was extremely strong. suppressor cell activity was markedly reduced by treatment of spleen cell populations with mitomycin-c and was unaffected by treatment with anti-thy.1 sera and complement. removal of cells which bound carbonyl iron or which bound to nylon columns, de ...1979313686
the pathogenesis of trypanosoma congolense infection in calves. ii. anemia and erythroid response.the anemia caused by trypanosoma conogolense treu 112 in holstein calves was of moderate severity and normochromic, macrocytic in the acute phase changing to normochromic, normocytic with chronicity. the anemia was hemolytic and responsive as shown by sharply decreased myeloid:erythroid ratio and increased mean corpuscular volume. 51cr red cell labelling studies showed that red cell lifespan was halved in the acute phase and there was an increase in plasma volume. surface organ counting of liver ...1978751311
experimental bovine trypanosomiasis. changes in the catabolism of serum immunoglobulins and complement components in infected cattle.the turnover of serum proteins of calves experimentally infected with trypanosoma congolense was compared to that of normal uninfected cattle. all proteins examined had much increased catabolic rates in infected animals. in normal animals the average half-lives in days for each protein were: igg1 17.4, igg2 22.4, igm 4.8, iga 3.4, ige 1.9, c1 5.6 and c3 2.9. in trypanosome infected cattle the average half-lives were igg1 1.9, igg2 1.7, igm 0.9, iga 1.2, ige 0.9, c1 1.2 and c3 1.1 days.1978721141
the response to trypanosoma congolense infection in calves. determination of immunoglobulins igg1, igg2, igm and c3 levels and the complement fixing antibody titres during the course of infection.serum immunoglobulins, igg1, igg2, igm and c3 levels and the complement fixing antibody titres were determined over a period of 15 to 18 weeks in 13 calves infected with trypanosoma congolense. the mean igm concentration increased from 2.88 mg/ml prior to infection to 23.75 mg/ml at the 3rd week after infection. this level dropped by the 5th week but elevated values of 13-19 mg/ml were maintained until the end of the experiment. the mean igg1 level increased from 10.55 mg/ml to a peak of 26.90 m ...19761006799
comparative studies on the laboratory diagnosis of experimental trypanosoma congolense infection in sheep.comparative studies on the laboratory diagnosis of sheep experimentally infected with t. congolense were carried out by parasitological and serological methods during a period of 53 weeks. trypanosomes were most numerous in the first weeks after inoculation, when they were detectable by all three parasitological tests: the wet mount preparation, the haematocrit centrifuge technique, and the mouse inoculation test. in the later stages of the infection, trypanosomes were observed intermittently by ...1976773317
immune depression in trypanosome-infected mice. ii. characterization of the spleen cell types involved.spleen cells from trypanosoma congolense-infected mice showed a drastic depression in their capacity to respond to b and t lymphocyte mitogens and to allogeneic spleen cells in mixed lymphocyte cultures. spleen cells from infected mice were also poor stimulators in mixed lymphocyte cultures. the poor responsiveness or stimulation capacity was not due simply to dilution of relevant b or t lymphocytes by the large number of null cells found in the spleens of infected animals. these null cells expr ...1979156119
suppression of antibody response to leptospira biflexa and brucella abortus and recovery from immunosuppression after berenil treatment.zebu cattle infected with either trypanosoma congolense eatro 1800 or trypanosoma vivax eatro 1721 had suppressed humoral immune responses to leptospira biflexa injected intravenously and to attenuated brucella abortus injected subcutaneously. t. congolense infections were more suppressive than t. vivax infections. in cattle infected with t. vivax, the suppression of immune responses to both bacterial immunogens was abrogated when the animals were treated with berenil at the time of antigen admi ...1979118933
experimental bovine trypanosomiasis. changes in serum immunoglobulins, complement and complement components in infected animals.in three calves experimentally infected with trypanosoma congolense the amounts of igg1 and igg2 were little changed and similar to those of normal animals. igm increased in amount early in the infection and the amount of the increase appeared related to the parasite burden. the amounts of iga and ige were both much decreased and this also appeared related to the numbers of parasites in the blood. there was a decrease in the amounts of total haemolytic complement and complement components c1, c1 ...1978721142
the nature of the teneral state in glossina and its role in the acquisition of trypanosome infection in tsetse.teneral glossina morsitans morsitans from outbred and susceptible stocks infected with trypanosoma (nannomonas) congolense developed, respectively, three and six times higher midgut infection rates than flies of the same stock which had previously taken a bloodmeal. non-teneral g. m. morsitans remained relatively refractory to infection when infected at subsequent feeds. differences in susceptibility to midgut infection between teneral flies from susceptible and outbred lines of g. m. morsitans ...19921288435
lectin analysis of trypanosoma congolense bloodstream trypomastigote and culture procyclic surface saccharides by agglutination and electron microscopic technics.living, intact bloodstream trypomastigotes and culture procyclic forms of trypanosoma congolense were tested for aggulination with the lectins concanavalin a (con a), phytohemagglutinin p (pp), wheat germ agglutinin (wga), soybean agglutinin (sba), and fucose binding protein (fbp). similar experiments were conducted with living bloodstream and culture forms treated with trypsin or dextranase. parasites were incubated for 30 min at 25 c in various concentrations of each lectin, then examined for ...1978739411
immune depression in trypanosoma congolense-infected mice. 1979157058
the susceptibility of strains of mice to infection with trypanosoma congolense.the survival times of a number of strains of mice after infection with a stabilate of trypanosoma brucei or of t congolense were examined. the mean survival times of all the strains when infected with t brucei treu 667 ranged from 27 to 63 days. greater disparity was observed after infection with t congolense gvr1 where the mean survival time ranged from seven (balb/c) to 74 days (c57 bl). it is suggested that the c57 bl mouse might provide a laboratory model for the study of trypanotolerance in ...1978749094
the absence of trypanosoma congolense from the lymph of an infected sheep.the lymph draining the prefemoral lymph node of a sheep infected with trypanosoma congolense was examined over a period of 10 days. only six trypanosomes were detected in 1500 ml of this fluid during this time, in spite of the animal having about 65,000 organisms/ml in its blood. it is concluded that the suggestion that t congolense is a strict plasma parasite is essentially proven for this specific situation.1978705045
the resistance of trypanosoma congolense, t. vivax and t. evansi to human plasma.tests were made in mice on the resistance of cattle trypanosomes to human plasma. 12 stocks of trypanosoma, congolense were tested' three were fully resistant, eight were moderately or highly resistant, and one was fully sensitive. four stocks of t. vivax were tested; two were fully resistant, one was somewhat resistant, and one was highly sensitive. two stocks of t. evansi were tested; both fully sensitive. the possibility is discussed that t. congolense and t. vivax might produce transient inf ...1978705847
modulation of the calcium pump of the kidney and testes of rats infected with trypanosoma congolense.the activity of the camgatpase (ca-pump) of the kidney and testes of wistar rats infected with trypanosoma congolense was studied during the course of infection. the activity of the enzyme in both organs was found to decrease with increase in parasitaemia. the transition temperature (tc) decreased and activation energy (ea) of the enzyme increased with increase in parasitaemia. the relevance of the ca-pump in the pathogenesis of trypanosomiasis is discussed.19921331207
diazoniobenzenesulfonate as marker for cell surface proteins: study of the surface coat of trypanosoma congolense.it is possible to label selectively the surface coat of trypanosoma congolense with radioactive sulfanilic acid diazonium salt. as demonstrated by both sodium dodecylsulfate polyacrylamide gel electrophoresis and isoelectric focusing, radioactivity is incorporated into only one protein, which has a molecular weight of 57 000 and an isoelectric point of 6.25. this indicates that the surface coat of t. congolense is a homogeneous layer, composed of molecules of one type of protein.1978711154
the aetiology and significance of the phagocytosis of erythrocytes and leucocytes in sheep infected with trypanosoma congolense (broden, 1904).the phagocytosis of erythrocytes and leucocytes in sheep infected with trypanosoma congolense is shown to be due to the coating of the blood cells with trypanosomal antigen. the occurrence of the phagocytic activity is dependent on fluctuations of the parasitaemia and is significant in maintaining the anaemic state of the subject.1978343212
mitogenicity of autolysates of trypanosoma congolense.autolysates of trypanosoma congolense, in subcytotoxic amounts, were found to be highly mitogenic in vitro for the spleen cells of normal mice. significant amounts of [3h]-thymidine were also incorporated by the responding spleen cells of nu/nu (athymic) mice. in contrast, the spleen cells of cyclophosphamide-treated mice were unresponsive. the findings suggest that a potent b-cell-mitogen is generated by the autolysing t. congolense organism.1978620724
susceptibility of inbred strains of mice to trypanosoma congolense: correlation with changes in spleen lymphocyte populations.a comparison was made of the susceptibility of eight inbred strains of mice to infection with trypanosoma congolense. marked differences in susceptibility as judged by survival were found between the different strains. the capacity of certain strains to survive longer than others appeared to be related to their ability to limit the numbers of trypanosomes in the circulation. there was no difference in the infectivity of t. congolense for mice of high and low susceptibility. furthermore, the find ...1978307464
the generation and identification of the hemolysin of trypanosoma congolense.the hemolytic activity of trypanosoma congolense appears to be due to the presence of free fatty acids generated by the action of phospholipase a on endogenous phosphatidyl choline. some lysolecithin also contributes to the lytic activity. trypanosoma lewisi, being devoid of phospholipase a, does not generate free fatty acids and is therefore non-hemolytic.1977891767
binding of trypanosoma congolense to the walls of small blood vessels.the mesenteric microvasculature was studied in rats and rabbits infected with trypanosoma congolense. by examining vessels in the living animals, trypanosomes were observed to adhere to vessel walls by their anterior ends. it was evident from stained preparations of the vessels that the microcirculation contained 4-1400 times as many trypanosomes as were free in the cardiac blood. parasites were more numerous in very small vessels than in larger vessels, and they were clustered in groups within ...1978690955
the generation of toxic activity from trypanosoma congolense.trypanosoma congolense organism, on incubation at 20 degrees c for 91/2h, were found to generate phospholipase like activity which was capable of mediating lysis of both nucleated cells and erythrocytes as well as acute inflammatory response on intradermal inoculation.19761021440
lymphocyte function in experimental african trypanosomiasis: mitogenic effects of trypanosome extracts in vitro.extracts of trypanosoma brucei and trypanosoma congolense were incubated in vitro with nonimmune lymphocytes of mice, rats, guinea pigs, and rabbits in order to test for mitogenic effects or for other characteristics of polyclonal b lymphocyte activators. trypanosome extracts (te) were not mitogenic for spleen cells of mice, rats, and guinea pigs in vitro, nor did the parasite extracts alter the mitogenic responses of lymphocytes from these animals to known b- and t-cell mitogens. te also failed ...1976992878
an extravascular site of development of trypanosoma congolense. 1978643055
[adherence phenomena in trypanosoma congolense (author's transl)].two adherence phenomena in trypanosoma congolense as a possible cause of trypanosome aggregation in the capillaries of certain organs are described: 1. adherence of trypanosomes to blood cells of nonimmune mice, 2. dovetailing of trypanosome membranes into one another and into the vessel wall.1976982553
vector competence of glossina pallidipes and g. morsitans centralis for trypanosoma vivax, t. congolense and t. b. brucei.vector competence of glossina pallidipes for pathogenic trypanosoma species was compared to that of g. morsitans centralis. cattle or goats were the hosts used to infect teneral tsetse, rabbits were used to maintain tsetse which were dissected on day 30. mean infection rates of g. pallidipes and g. m. centralis by t. vivax isolated from a cow in kenya were respectively 39.5 +/- 8.9% and 32.1 +/- 10.3% whilst for t. vivax isolated from a cow in nigeria, they were 30.0 +/- 7.5% and 19.8 +/- 4.3%. ...19921359753
suppression of t-cell responsiveness during tsetse-transmitted trypanosomiasis in cattle.in the present study, we demonstrate that lymph node cells from cattle infected with t. congolense through tsetse fly challenge were unable to proliferate in vitro following activation with the t-cell mitogen concanavalin a. this was associated with a simultaneous suppression of interleukin 2 (il-2) production and interleukin 2 receptor (il-2r) expression. however, the capacity of the cells to secrete interferon gamma following the mitogenic activation was not affected by the infection.19921355308
sequential infection of tsetse flies with trypanosoma congolense and trypanosoma brucei.the question whether tsetse flies can be experimentally infected with more than one trypanosome species or strain by sequential feeding was investigated using dna probe technology to identify directly the small numbers of trypanosomes in the fly gut. bloodstream form trypanosomes of trypanosoma congolense or t. brucei ssp. were used for initial infection, followed by sequential feeds using either t. congolense or t. brucei ssp. midgut trypanosome populations were subsequently analysed by hybridi ...19921356306
isolation of drug-resistant strains of trypanosoma congolense from the lower shabelle region of southern somalia.drug resistance by pathogenic trypanosomes in somali livestock has been suspected for some time but there have been few attempts to examine this problem in detail. field isolations from two areas in the lower shabelle region were obtained by injecting blood from trypanosome infected cattle into a recipient calf. once the calf became parasitaemic it was treated with a standard dose of isometamidium chloride (samorin, rmb) at 0.5 mg/kg. when a subsequent relapse infection developed, indicative of ...19921305337
trypanosomiasis:goats as a possible reservoir of trypanosoma congolense in the republic of the sudan.experimental trypanosoma congolense infections of goats and calves were compared. goats developed a chronic form of trypanosomiasis, often recovering spontaneously from a strain which caused an acute fatal disease in calves. goats may be important in the maintenace of t. congolense in nature in the sudan.1977910302
trypanosoma congolense: partial cyclic development in a glossina cell system and oxygen consumption. 1977915617
attempted protection of zebu cattle against trypanosomiasis using a multi-stabilate vaccine.the protective value of double vaccination with 11 recently isolated stabilates of trypanosoma congolense given either as live or dead organisms, followed by trypanocidal therapy, was assessed in zebu cattle subsequently challenged by nine of the original stabilates. both vaccination regimens failed to prevent the animals becoming parasitaemic and eventually succumbing to the infection, although the mean survival times and prepatent periods of the calves which received the live vaccine were long ...1978705039
studies on the anemia in experimental african trypanosomiasis. ii. the pathogenesis of the anemia in calves infected with trypanosoma congolense.it was postulated that the anemia commonly seen in mammalian trypanosomiasis, and specifically in trypanosoma congolense-infected calves, was of immunological origin. specifically, we postulated that trypanosome antigen-antibody-complement complexes, deposited on the surface of erythrocytes of infected calves, resulted in their immune elimination leading to clinical anemia. this hypothesis was tested experimentally. immunoglobulins bound to the erythrocytes of 13 infected calves were detected by ...1976937631
the immune response of zebu cattle infection with trypanosoma congolense and t. vivax.zebu cattle were infected with trypanosoma congolense and t. vivax and changes in the levels of serum immunoglobulins were measured during infection and after treatment. increases in the levels of igm occurred within 14 days of infection coincidentally with the first appearance of trypanosomes in the peripheral blood. igm levels rose to 2-10 times preinfection levels and remained high until the animals were treated with diminazene aceturate. levels then declined to approximately pre-infection le ...1976938121
trypanosomiasis control in boran cattle in kenya: a comparison between chemoprophylaxis and a parasite detection and intravenous treatment method using isometamidium chloride.two methods of trypanosome control in boran cattle kept under very high trypanosomiasis risk were compared: the traditional intramuscular isometamidium chloride prophylaxis with a parasite detection and intravenous isometamidium chloride treatment method. the results were related to a control group under diminazene aceturate treatment. isometamidium chloride at 0.25 mg/kg as routinely used by the ranch was of little benefit by either method, with breakthrough infections occurring as early as one ...19921306914
effect of puparia incubation temperature: increased infection rates of trypanosoma congolense in glossina morsitans centralis, g. fuscipes fuscipes and g. brevipalpis.puparia of glossina morsitans centralis (machado), g.fuscipes fuscipes (newstead) and g.brevipalpis (newstead) were incubated at 25 +/- 1 degrees c, 28 +/- 1:25 +/- 1 degrees c, day:night or 29 +/- 1 degrees c throughout the puparial period, and maintained at 70-80% relative humidity. puparial mortality was higher at 29 than at 25 degrees c (optimum temperature) in all three species, particularly in g.f.fuscipes and g.brevipalpis. adults of g.m.centralis from puparia incubated at 29 degrees c, a ...19921421481
hypothalamic-pituitary-adrenal axis responsiveness to insulin-induced hypoglycaemia is modified by trypanosome infection in boran (bos indicus) cattle.ten boran (bos indicus) cattle were used to study the stress responsiveness of the hypothalamic-pituitary-adrenal (hpa) axis during trypanosome infection. five cattle were infected with trypanosoma congolense il 1180 by tsetse challenge and five cattle served as controls. all infected animals developed acute trypanosomiasis. insulin-induced hypoglycaemia (50 per cent of pre-insulin glucose concentration) was used as a stress factor. acute hypoglycaemia was observed in three infected and three co ...19921329164
brain na+ k+ atpase and cholesterol in acute experimental trypanosomiasis.brain na+ k+ atpase activity has been found to decrease in experimental trypanosomiasis in rats infected with trypanosoma congolense. some physical features that affect membrane fluidity were also observed to be altered. the levels of cholesterol in the brain and free fatty acids in the serum were found to increase in the infected animals. these findings might be relevant to the development of brain lesions.19921335378
changes in levels of transaminases in goats experimentally infected with trypanosoma congolense.goats were experimentally infected with trypanosoma congolense and then treated with berenil after 9 days of infection. the infection produced increases in glutamate oxalacetate transaminase (got) and glutamate pyruvic transaminase (gpt) values. mean got values in infected west african dwarf goats were generally lower than in infected red sokoto goats. treatment with berenil did not produce any significant effect on their levels probably because of the relapse infection recorded in this study.19921339996
letter: circadian rhythms in trypanosoma congolense. 1976960209
maternal antibodies in n'dama calves kept under natural trypanosomiasis risk in the gambia. 19921352635
molecular studies on trypanothione reductase: an antiparasitic target enzyme. 19921354149
development of multiple drug resistance of trypanosoma congolense in zebu cattle under high natural tsetse fly challenge in the pastoral zone of samorogouan, burkina faso.preliminary data from an ongoing epidemiological survey in the pastoral zone of samorogouan (kénédougou) indicate the occurrence of multiple-drug-resistant trypanosoma congolense. despite frequent trypanocidal drug treatments with diminazene aceturate (berenil, hoechst) at 7 mg/kg body weight (bw) at intervals of 2 to 4 weeks, no significant drop in the prevalence of african animal trypanosomosis (aat) was observed. to examine a suspected drug resistance, 20 zebu cattle, naturally infected with ...19921359750
experimental infection with a haemorrhage-causing trypanosoma vivax in n'dama and boran cattle.n'dama cattle control experimental infections with clones of trypanosoma congolense of varying degrees of virulence, but nothing is known about their capacity to control infections caused by highly virulent, east african stocks of t. vivax. thus four n'damas and four trypanosusceptible borans were infected with a tsetse-transmitted stock of t. vivax il2337. in ayrshire cattle this stock is known to cause severe haemorrhagic disease. no differences were observed in the parasitaemia between the tw ...19921355307
the influence of the size of the initial inoculum on the efficacy of isometamidium (samorin) on a stock of trypanosoma congolense.the effect of the number of trypanosomes in the initial inoculum on the minimum curative dose, was determined for an experimental infection of trypanosoma congolense in mice treated with isometamidium. mice were infected by the intravenous route and were then treated three hours later by intraperitoneal injection. the minimum curative dose was shown to be dependent on the size of the initial inoculum, with a difference of a factor of 7.5 as the initial inoculum was increased from 10(3) to 10(6) ...19921359748
the erythrokinetics of zebu cattle chronically infected with trypanosoma congolense.the erythrokinetics of ethiopian zebu cattle infected with t congolense were studied at 12-16 weeks after infection using 59fe and 51cr-labelled red cells. the severe anaemia which developed as a result of the infectionw as found to be due principally to a massive loss of red cells from the circulation.19751118657
letter: effect of dexamethasone upon trypanosoma congolense infection in calves. 19751166500
[course of trypanosoma musculi infections in nmri mice (author's transl)].the trypanosomes multiply during prepatency after minimal infection by a factor of 2.2-3.6 per day. during patency, increase of trypanosome number in the peripheral blood is basically non-logarithmic as the actual proliferating forms remain hidden in special vascular areas (kidney, placenta). the mean increase during patency is approximately linear, typically by 1-10 trypanosomes per 10(4) erythrocytes per day, and depends on the number of infective organisms introduced. - length of parasitemia ...19751236679
genital lesions and histopathology of male guinea-pigs infected with trypanosomes.sixty adult male guinea-pigs were used to study the effect of trypanosoma brucei brucei and trypanosoma congolense infections on genitalia, testicles and reproductive capacity. both infections showed acute to chronic courses. t. b. brucei appeared more virulent than t. congolense. in both cases the infection periods significantly (p < 0.01) influenced resultant decrease in body and gonadal weight, testicular mass index and extent of lesion formation. histopathological lesions included mononuclea ...19921298022
therapeutic activity of isometamidium chloride in boran cattle against a tsetse-transmitted clone of trypanosoma congolense with a low level of drug resistance.experiments were conducted with a clone of trypanosoma congolense, il 3580, which exhibited a low level of resistance to isometamidium chloride. five cattle were treated intramuscularly with isometamidium chloride at a dose rate of 0.5 mg kg-1 body weight (bw) and challenged 28 days later with 5 glossina morsitans centralis infected with t. congolense il 3580. all 5 cattle and 15 untreated steers challenged on the same day became parasitaemic by day 15 post-infection. thus, at a dose of 0.5 mg k ...19921304663
a comparative study of gastrointestinal nematode egg output in n'dama, zebu and n'dama x zebu crossbred cattle.strongyle faecal egg output was estimated in n'dama, zebu and n'dama x zebu crossbred (f1) cattle. n'dama cattle showed a significantly lower prevalence of strongyle infection, as measured by faecal egg output, than f1 (p < 0.01) and zebu (p < 0.001) cattle. in strongyle-infected animals, mean egg output was also significantly lower in n'damas (p < 0.03) than in zebus. a previous trypanosomiasis infection did not affect the results. the presence of a natural resistance trait to strongyle infecti ...19921364087
identification and characterization of two repetitive non-variable antigens from african trypanosomes which are recognized early during infection.the present paper describes two repetitive proteins representing common antigens of african trypanosomes which are non-variant and which are recognized early in infection by the host immune system. these antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. screening of a cdna library from t. b. gambiense with such early infection serum identified a protein which contains a repetitive motif consisting of 68 ami ...19921614728
parasite-specific t-cell responses of trypanotolerant and trypanosusceptible cattle during infection with trypanosoma congolense.during primary tsetse-transmitted challenge of boran (bos indicus) cattle with trypanosoma congolense ilnat 3.1, a transient parasite antigen-specific t-cell proliferative response was observed in peripheral blood mononuclear cells and splenic mononuclear cells stimulated in vitro. a response was also observed with cells of n'dama (bos taurus) cattle, but in this case higher stimulation indices were observed and the response was maintained until the termination of the experiment at 40 days post- ...19921375583
characterization and measurement of cd5+ b cells in normal and trypanosoma congolense-infected cattle.cd5+ b cells in cattle are present in peripheral blood and spleen, but not in lymph nodes, tonsils or peyer's patches. compared to classical b cells, they express similar levels of b cell surface markers, but have higher levels of surface igm. we failed to find evidence for igd on bovine b lymphocytes. the cd5+ b cells expressed cd11b (mac-1). another small subpopulation of b cells carried cd11b but not cd5. in cattle infected with trypanosoma congolense, a dramatic increase in the percentage of ...19921378013
the interaction of trypanosoma congolense and haemonchus contortus infections in trypanotolerant n'dama cattle.the interactions between trypanosoma congolense and haemonchus contortus infections were studied in n'dama calves. a total of 38 n'dama bulls was divided into four groups and each group infected either with h. contortus 1 week after infection with t. congolense or with t. congolense 4 weeks after infection with h. contortus, or with either infection singly. parasitological (faecal egg counts, parasitaemia), haematological (packed cell volume, white blood cell counts, albumin) and clinical parame ...19921413448
application of a monoclonal antibody-based antigen detection enzyme-linked immunosorbent assay (antigen elisa) for field diagnosis of bovine trypanosomiasis at nguruman, kenya.a monoclonal antibody-based, enzyme immunoassay (antigen elisa) for the detection of species-specific invariant antigens of trypanosoma congolense, t. vivax or t. brucei in the serum of infected animals was evaluated as a means of diagnosis using bovine field sera from a trypanosomiasis endemic area, nguruman, kenya. circulating trypanosome antigens were detected in 126 (96.2%) of 131 serum samples from animals with parasitologically confirmed diagnosis: 74.8% were positive for antigens of two o ...19921360196
[infection of glossina palpalis palpalis (diptera, glossinidae) by trypanosomes in the forest zone of gagnoa in the ivory coast].2,153 glossina palpalis palpalis caught in biconical traps from different biotopes in relation with human activities in the forest areas of côte d'ivoire were used to calculate the trypanosome infection rates. the results showed that there was no preferential biotope for glossina infected by trypanosomes. the most widespread species of trypanosomes infecting glossina p. palpalis is t. congolense (10.13%) followed by t. vivax (8.22%) and seldomly by t. brucei (0.70%). female glossina are infected ...19911665576
trypanosoma congolense: the use of 4,6-diamidino-2-phenylindole (dapi) in the akinetoplastic induction sensitivity test. 19921382626
identification of a 33-kilodalton immunodominant antigen of trypanosoma congolense as a cysteine protease.a 33-kda protein of trypanosoma congolense is a major antigen in infected cattle and the production of antibody to this antigen appeared to correlate with enhanced resistance to trypanosomiasis [4]. immunoelectron microscopy using a monoclonal antibody (mab 4c5) raised against the 33-kda antigen showed a lysosomal localisation, similar to that of a previously described 32-kda cysteine protease of t. congolense. both mab 4c5 and anti-33 kda antibody from infected cattle bound on western blots to ...19921474989
suppression of interleukin 2 secretion and interleukin 2 receptor expression during tsetse-transmitted trypanosomiasis in cattle.infection with trypanosoma congolense in cattle was found to be associated with a profound suppression of the host's immune system. lymph node cells from infected cattle were unable to secrete interleukin 2 (il 2) in vitro following mitogenic stimulation and the exogenous supply of il 2 did not restore t cell proliferative responses. this was associated with an impaired expression of the alpha chain of the il 2 receptor (il 2r alpha). co-culture experiments, where cells from an infected animal w ...19921547821
[serological evidence of the existence of a wild reservoir of trypanosoma brucei gambiense in the pendjari biosphere reservation in the republic of benin].in the national park of pendjari, situated in the north-west of benin, 91 wild animals, belonging to seven species, were darted. thick and thin blood smears were examined for trypanosomes and plasma for trypanolytic antibodies against 6 antigenic variants of trypanosoma brucei gambiense. parasites were found in 13.92% and trypanolytic antibodies in 20.88% of the samples. a total of 28.57% of animals were positive by at least one of the two test systems used. morphologically trypanosoma congolens ...19921417158
adrenal and thyroid dysfunctions in experimental trypanosoma congolense infection in cattle.severe pathological changes were observed in the adrenal and thyroid glands of zebu (bos indicus) heifers infected with trypanosoma congolense. in the adrenal glands, severe inflammatory changes characterised by mononuclear cellular infiltration in the subcapsular areas, zona glomerulosa, zona fasciculata and zona reticularis were observed. in addition, there were hyperaemia, haemorrhage and hyperplasia resulting in increased adrenal weight in the two heifers slaughtered on days 50 and 70 post-i ...19921615626
trypanosoma congolense: re-expression of a deleted metacyclic variable antigen type in vivo and in vitro.the expression of variable antigen types (vats) was determined among dividing populations of t. congolense growing in vivo in rabbit chancres and in vitro on bovine aorta endothelial cell monolayers. experiments were performed in which a single metacyclic vat (m-vat) was deleted from a cultured metacyclic population by neutralisation with a monoclonal antibody and complement. subsequent expression of the deleted m-vat and two unrelated m-vats was determined by an indirect immunofluorescent antib ...19911685300
the effect of diminazene aceturate and isometamidium chloride on cultured procyclic forms of susceptible and drug-resistant trypanosoma congolense.cultures of insect forms of trypanosoma congolense stocks and clones with different susceptibilities to trypanocidal drugs in vivo were initiated from bloodstream trypomastigotes harvested from mammalian hosts and maintained axenically in vitro at 27 degrees c. growth inhibition of procyclic forms of susceptible and drug-resistant t. congolense occurred after incubation for 48 h with 0.1 ng isometamidium chloride ml or 500 ng diminazene aceturate/ml. procyclic forms were propagated in vitro in t ...19911685301
the pathogenesis of trypanosoma congolense infection in calves. i. clinical observations and gross pathological changes.holstein calves infected with trypanosoma congolense treu 112 had intermittent fever, debility and a poor hair coat. at postmortem examination the most significant findings were enlargement of the liver, kidneys and spleen and increased volume of hematopoietic marrow. a group of 13 calves infected for 18 weeks had marked enlargement of lymph nodes throughout the body and hemal nodes were prominent in the sublumbar area caudal to the kidneys. another group infected for 7 weeks had no increase in ...1978716157
the release of soluble vasoactive material from trypanosoma congolense in intraperitoneal diffusion chambers.millipore diffusion chambers containing living or lysed trypanosoma congolense cause a local inflammatory reaction when implanted intraperitoneally into rats. empty chambers do not do this. the active material is of low molecular weight and is possibly peptide in nature. it appears to act by increasing local vascular permeability. it was found to be neither chemotactic nor cytotoxic in several assay systems. it is considered that this material may contribute to the pathogenesis of t. congolense ...1977860314
a comparative study of the responses of the thymus, spleen, lymph nodes and bone marrow of the albino rat to infection with trypanosoma congolense and trypanosoma brucei.using 90 albino rats, a comparison was made between the response to experimental infections of trypanosoma brucei and t congolense of approximately three weeks duration by observation of parasitaemia, packed cell volume values, post mortem spleen and lymph weights, and histology of thymus, spleen, lymph nodes and bone marrow. in t congolense infection, phagocytosis of trypanosomes in the spleen appeared to be the main response of the host's haemopoietic tissues to the parasites, which were obser ...1977928984
variability of in vitro culture characteristics, including metacyclic trypomastigote production, in different stocks of trypanosoma congolense.six cloned stocks of trypanosoma congolense, isolated from the same area of eastern zambia, were maintained in vitro as insect form cultures producing infective metacyclic trypanosomes. although the same general culture conditions were applied, different handling regimes were required for optimum growth of each stock. during primary isolation, many differences were found in the culture characteristics of the stocks. the time taken for cytoadherence to occur varied from 14 to 62 days, while the i ...19911685869
in vivo assessment of drug sensitivity of african trypanosomes using the akinetoplastic induction test.following treatment of mice infected with trypanosoma congolense or t brucei brucei with various doses of isometamidium chloride or diminazene aceturate, the induction of akinetoplastic (ak) forms was observed in the trypomastigotes of both species within 10 hours of drug administration. the levels of ak-induction were closely correlated with the levels of resistance to each compound found using a standard in vivo drug assay in mice. in general, ineffective doses of either compound conferred ak- ...19921374928
comparative studies on n'dama and zebu cattle following repeated infections with trypanosoma congolense.twenty n'dama and eight zebu cattle were inoculated intradermally with bloodstream forms of a cloned strain of trypanosoma congolense originating from east africa. all inoculated cattle became parasitaemic. zebus showed consistently higher levels of parasitaemia and lower packed red cell volume (pcv) percentages than did n'damas. three of the eight zebus required treatment when high numbers of trypanosomes were present in the blood and pcv values dropped below 15 per cent. none of the n'dama cat ...19921620961
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