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1.
Four African buffalo (Syncerus caffer) and four Boran cattle (Bos indicus) were each exposed to the bites of 10 tsetse flies infected with Trypanosoma congolense. Although both groups of animals became infected, the buffalo showed no clinical signs of trypanosomiasis while the cattle suffered from the disease characterized by pronounced skin reactions, high parasitaemia and severe anaemia. The prepatent periods in the buffalo varied from 18 to 27 days in comparison with 11 to 14 days in the cattle. In the buffalo, skin reactions were only detectable by histological examination of skin biopsies, the peak of parasitaemia was at least a hundredfold below that in cattle and after 54 days parasites were no longer detected. In contrast, the cattle had a continuous high parasitaemia until they were treated with a trypanocidal drug 60 days after infection. Neutralizing antibody to metacyclic trypanosomes appeared in the buffalo during the prepatent period, 15-20 days after infection, whereas in cattle neutralizing antibody was not detected until 10 days after the first peak of the parasitaemia, 25-30 days after infection.  相似文献   

2.
The haematological changes, erythrokinetics and ferrokinetics of sheep were investigated after infection with Trypanosoma congolense. Following the detection of parasites in blood, the infected sheep developed macrocytic hypochromic anaemia. Studies with 51Cr-red cells, 125I-albumin and 59Fe as ferric citrate 11 weeks after infection revealed that infected sheep had significantly lower mean circulating red cell volumes but higher plasma and blood volumes than control sheep. The infected sheep also had enhanced erythropoietic activity as judged by significantly higher plasma iron turnover rates, faster disappearance of radio-labelled iron and higher iron incorporation rates than control sheep. The rate of disappearance of 51Cr-labelled red cells was greater in infected than in control sheep. It was concluded that the anaemia observed at this stage of infection was due to an increased rate of removal of red cells from the circulation coupled with haemodilution, with no evidence of dyshaemopoiesis.  相似文献   

3.
The effect of challenging cattle, chronically infected with Trypanosoma brucei brucei, with T. congolense on the development of the T. b. brucei infection was investigated. For this purpose, nine experimental animals were first infected with T. b. brucei through the bites of infected tsetse flies. Once the T. b. brucei had developed into a chronic infection, that was difficult to detect using routine parasitological diagnostic tools, seven of the experimental animals were challenged by tsetse flies infected with T. congolense. Two of the animals infected with T. b. brucei were kept as control. The infection with T. congolense resulted in a sudden increase in the parasitaemia of T. b. brucei. In the T. b. brucei control animals, on the other hand, the parasitaemia remained below the level of detection. The epidemiological repercussions of this increase in the parasitaemia of T. b. brucei after infection with T. congolense are discussed.  相似文献   

4.
Anaemia is the most prominent clinical sign of trypanosomosis in domestic animals but little is known about its pathogenesis. This work investigated erythrophagocytosis as the possible cause of anaemia. Pathogenic Trypanosoma congolense (IL3000) was intravenously inoculated into six goats at 3x10(6) trypanosomes per goat. Six other goats were maintained as controls. The infection was studied for 10 weeks and parasitaemia, packed cell volume (PCV) and serum protein levels were determined. The amount of erythrophagocytosis was determined from the amount of 51Cr-labelled red blood cells (RBCs) phagocytosed by self mononuclear cells (MNCs) in vitro and by microscopically counting phagocytosed RBCs on Giemsa stained smears of incubated mixtures of RBCs and self MNCs. The infection resulted in trypanosomosis with rapid progressive anaemia and mean peaks of parasitaemia of about 3x10(3)ml(-1). In infected goats, a significant (P<0.05) mean reduction in PCV (of 37-22%) was observed starting from about 20 days up to 56 days post-infection. Within this same phase, significant (P<0.05) differences in mean radioactivity counts of (51)Cr incorporated into MNCs were observed with infected goats' samples having counts 50% higher than the control goats' samples. Microscopically, the mean number of phagocytosed RBCs in infected goats' MNCs was noted to be 80% higher (P<0.05) than that of control goats. Appreciable increases (P<0.05) in mean serum globulin levels, from 3.5 to 4.7g/dl, were observed within 3 weeks of infection. The study showed that erythrophagocytosis is an important mechanism leading to anaemia in the pathophysiology of T. congolense infection in Zambian goats.  相似文献   

5.
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 parameters (body weight change, mortality rate) were compared among the various groups. The results showed a reduced prepatent period and a markedly increased pathogenicity of H. contortus infections in animals with a concurrent T. congolense infection. The most harmful combination was a H. contortus infection 1 week after the T. congolense infection which resulted in a progressive and severe anaemia, accompanied by hypoalbuminaemia, increased weight loss and high mortality. The anaemia induced by dual infections showed a low responsiveness to chemotherapy and in several cases supportive treatment did not help recovery. The results also showed that animals with a concurrent T. congolense and H. contortus infection ran a higher risk of succumbing during the infection, and also during 10 weeks following treatment. Although infections with T. congolense alone produced no clinical signs, they were found to significantly reduce the ability of infected animals to mount a normal response to a subsequent H. contortus infection. It was concluded that the increased H. contortus egg excretion observed in animals infected with both parasites might significantly increase the risk of nematode infections and that the reduced prepatent period might necessitate more frequent anthelmintic treatments. These interactions should, therefore, be considered wherever attempts are made to control these two diseases.  相似文献   

6.
The diagnostic performance of a polymerase chain reaction assay (PCR) for monitoring the effectiveness of aceturate diminazene treatment was compared with those of an antibody-detection ELISA test and the buffy-coat technique using sheep experimentally infected with either savannah-type or forest-type Trypanosoma congolense or T. vivax. Within the period of infection, the PCR using specific savannah-type T. congolense primers showed a significant higher diagnostic sensitivity (p<0.05) than the buffy-coat technique. Both techniques gave closed results for detecting forest-type T. congolense or T. vivax infections. Following trypanocidal treatment, the PCR showed that specific product disappeared definitively 1 or 2 days later in animals in which a decrease of the antibody level and a significant improvement of the red packed cell volume were observed. The occurrence of relapse infection was detected by the PCR in one animal infected by T. vivax on day 19 post-treatment and confirmed by the persistence and increasing antibody level whereas the buffy-coat technique detected parasites 42 days later. Then, the PCR signals remained positive on several occasions while parasitaemia was detected only two times.The application of PCR combined with the antibody detection appeared to provide a useful tool as compared to the buffy-coat technique for monitoring the effectiveness of trypanocidal treatment.  相似文献   

7.
The pathogenicity of a single infection with Eperythrozoon suis and of a mixed infection of E. suis and Babesia trautmanni in experimentally-infected pigs, was described. In the pigs with a single infection, parasitaemia of E. suis was observed 4 days after blood inoculation. Although parasitaemia with this parasite was also observed on the 4th day in a mixed infection, the parasitaemia of B. trautmanni was not noted until 14 days after inoculation at a period when that of E. suis had started to fall. No parasitaemia was observed in any of the pigs in the splenectomized and unsplenectomized uninoculated control animals. The pigs carrying either single or mixed infections had pyrexia and their temperatures were consistently higher than those of the control animals. Infected pigs also showed anaemia with significant decline in Pcv, Hb and RBC values. The total WBC count rose in the infected pigs and the rise was more pronounced in pigs carrying E. suis alone. In addition, it was only in pigs infected by E. suis alone that a decline in the percentage of neutrophils and a rise in percentage lymphocytes was observed.  相似文献   

8.
The course of Trypanosoma congolense infections in African grey duiker (Sylvicapra grimmia) and sheep and goats were studied. Several parameters suggested that the grey duiker was much more resistant to trypanosomosis than sheep and goats. They showed increases in weight during infection, had a much longer pre-patent period, and their peak parasitaemia levels were about 100-fold lower than those of sheep and goats. Parasites were no longer detected in grey duiker blood 35 days after infection. Anaemia, measured as drops in packed cell volume (PCV), haemoglobin (Hb) concentration and erythrocyte (RBC) counts were not observed in the grey duiker. In contrast, sheep and goats suffered severe weight losses and had continuously high parasitaemia levels. Sheep and goats developed progressively severe normocytic normochromic anaemia and leucopenia from day 14 post-infection onwards.Serum levels of total protein, globulin and albumin of grey duiker did not change significantly throughout the course of infection, while the levels of total serum protein, globulin and gamma-globulin exhibited significant increases from day 21 post-infection onwards in sheep and goats, with peak values recorded on 28 and 35 days post-infection in sheep and goats, respectively. There were inconsistent variations in albumin levels in sheep and goats throughout the course of infection.There were no significant changes in erythrocyte activities of AST and ALT, while there were transient but significant elevations of ALP level on day 35, and GGT levels between 14 and 35 days post-infection in grey duiker. Conversely, the levels of all the enzymes were progressively depressed, especially from 14 to 49 days post-infection.In vitro erythrocyte peroxidation remained relatively unchanged throughout the period of the experiment in the grey duiker, except for slight but significant increase on day 42 post-infection. However, in vitro erythrocyte peroxidation increased significantly by between 100 and 300% of pre-infection levels from 14th to 42nd day p.i. both in sheep and goats, before returning to pre-infection levels after 14 days of treatment.Haematological values, serum and erythrocyte indices studied returned to near pre-infection levels 14 days after treatment with Berenil((R)).It is concluded that the grey duiker is inherently trypanotolerant. This is shown by its ability to control parasitaemia, suffer less severe anaemia, and to a relative degree resist pathobiochemical derangements of some serum and erythrocyte metabolites and enzymes, as well as reduction of infection-induced erythrocyte lipid peroxidase damage than sheep and goats.  相似文献   

9.
The non-steroidal anti-inflammatory drug (NSAID) flurbiprofen caused a rise in parasitaemia in goats infected with Trypanosoma vivax, Trypanosoma congolense and Trypanosoma brucei. All trypanosome-infected goats treated with flurbiprofen showed many dividing trypanosomes. This also included the short-stumpy forms of T. brucei. In T. vivax-infected goats flurbiprofen treatment resulted in 100% mortality in the acute and chronic stages of the infection. The increase in parasitaemia of T. brucei infected goats, treated with flurbiprofen, was not associated with an increase in mortality. The increase in parasitaemia of T. congolense-infected goats, treated with flurbiprofen, tended to be associated with a somewhat higher mortality but this was statistically not significant. The significant rise in parasitaemia could be reproduced in T. brucei-infected sheep without, however, killing the animals. Two other NSAIDs were also studied. Suprofen caused a rise in parasitaemia and 100% mortality when given to goats in the acute stage of T. vivax infection. Results with flunixin meglumine, when tested in T. brucei infected goats, were not conclusive.  相似文献   

10.
The effects of intravenous administration of vasopressor drugs on parasite concentration was studied in cows and sheep infected with Trypanosoma congolense. Ephedrine (USP), adrenaline (BP) and insulin increased jugular concentration of the parasite. Maximum effects were reached between 1 1/2 and 2 h with ephedrine and at 2 1/2-3 h with adrenaline. Increases in parasitaemia resulting from epinephrine were sustained only in sheep and adrenaline gave similar effects in both ruminants. Only epinephrine significantly increased parasitaemia within 45 min of administration. Ephedrine, hydralazine and guanethidine had no significant effects on parasitaemia. It is suggested that one of the mechanisms by which trypanocides increase jugular concentration of T. congolense may be by vasoconstriction of the capillary endothelium.  相似文献   

11.
Following tsetse-transmitted infection with Trypanosoma congolense, major differences in development of localised skin reactions, the ability to control parasitaemia, the degree of anaemia and in antibody response to trypanosomes were found between the reputedly trypanotolerant breeds of cattle (N'Dama, N'Dama/Baoule crosses, Baoule) and the trypanosusceptible West African Zebu. The local skin reactions that developed in the Zebu were large and severe while those that occurred in the other breeds were smaller and less severe or mild. The timing of appearance of parasitaemia and the height of the first peaks were similar in all the animals, but the Zebu were less able to control subsequent waves of parasitaemia. Possibly reflecting these events, it was only in the Zebu that significant anaemia developed. Neutralizing antibody against homologous metacyclic trypanosomes developed between 14 to 18 days after infection in all breeds of cattle; however, marked differences were found when antibody to trypanosomes derived from first peak parasitaemias were tested in the Zebu and Baoule. Neutralizing antibody against these parasites appeared in the Baoule on day 24 but were not detected in Zebu until day 51. Furthermore, the antibody titres were 3 log2 higher in the Baoule. It was concluded that the trypanotolerance exhibited by the West African taurine cattle might be related to a) their ability to control trypanosome numbers in the skin and in the bloodstream, an outcome that was possibly brought about by the earlier and superior immune response and b) failure to develop anaemia which might be associated with their capacity to control parasitaemia.  相似文献   

12.
A standard radioactive chromium (51Cr) release assay was used to assess the in vitro phagocytosis and lysis of bovine erythrocytes by cultured splenic, bone marrow and peripheral blood monocyte-derived (PBM) macrophages isolated from healthy and Trypanosoma congolense and T. vivax-infected cattle of the Boran and N'Dama breeds. Recombinant cytokines (rHuTNF-alpha and rBolFN-gamma) and non-acid-dialysed peripheral blood mononuclear cell (PBMNC) culture supernatants stimulated these PBM for enhanced activities. The stimulants caused increases in the rate of erythrocyte phagocytosis and lysis by cultured PBM in a concentration-dependent manner. But very high stimulant concentrations caused deceased in vitro erythrophagocytosis. However, bacterial lipopolysaccharide (LPS) and acid-dialysed PBMNC culture supernatants did not cause any increase in cultured PBM erythrophagocytosis. In vitro erythrocyte phagocytosis and lysis by splenic, bone marrow and peripheral blood monocyte (PBM)-derived macrophages of Boran breed of cattle infected with Trypanosoma congolense increased from 14 days post-infection (DPI) onwards and thereafter maintained at various levels above pre-infection. Cultured splenic macrophages showed the greatest erythrocyte destruction capability while PBM-derived macrophages was the least. The rates of in vitro erythrocyte phagocytosis and lysis were higher with the cultured PBM of the Boran than those of the N'Dama cattle during T. congolense infection. The rate of in vitro erythrocyte destruction was however, similar in both groups of cattle during T. vivax infection. These results correlated positively with the dynamics and degree of anaemia developed by these groups of animals during both T. congolense and T. vivax infections. Cattle infected with T. congolense and T. vivax developed varying degrees of normocytic normochromic anaemia during infection. Boran cattle developed a more severe anaemia, and had to be treated with diminazine aceturate, than N'Dama cattle during T. congolense infection. Both breeds of cattle developed a milder but similar degree of anaemia during T. vivax infection. None of the animals were treated. The results of this study indicated a role of in vivo macrophage stimulatory factors, notably cytokines such as TNF-alpha and IFN-gamma in host's serum, as well as parasite antigens, which may act singly or in concert, in the process of enhanced erythrocyte destruction, hence anaemia by the mononuclear phagocytic system (MPS) during bovine trypanosomosis.  相似文献   

13.
The pathogenicity of Theileria recondita infection in both splenectomised and non-splenectomised sheep was investigated. Following transmission of T. recondita to splenectomised animals both by adult ticks and blood transfusion a fever and severe macrocytic hypochromic anaemia developed which lasted the 9 days or more of patent infection. The prepatent period following tick attachment was about 8 days, but was variable following blood transfusion. Infection of normal animals caused a transient macrocytic hypochromic anaemia and slight fever which lasted throughout the period of low parasitaemia (7 days). The increase in mean cell volume was due to an increase in numbers of juvenile red cells in the peripheral blood. There was a transient neutrophilia and lymphocytopenia but no significant changes in thrombocyte or leucocyte numbers.  相似文献   

14.
Relationships were evaluated between trypanosome infection as measured by antigen detection enzyme immunoassays (antigen ELISA), anaemia as determined by average packed red cell volume (PCV), and animal performance as assessed by daily weight gain in 99 N'Dama cattle in Gabon exposed to natural tsetse challenge at 11.5 months of age and recorded 14 times over a 13 week period. Approximately half the animals were found to be infected for an average of five of the 14 times that they were examined: 38% with Trypanosoma congolense, 13% with Trypanosoma vivax and 49% with a mixed infection. Trypanosoma congolense infections had significant deleterious effects on animal growth, while T. vivax infections did not. Animals found on several occasions to be infected with T. congolense had significantly lower PCV values than those demonstrated to be infected on fewer occasions. No relationship was found between mean optical density (OD) values in antigen ELISA and PCV values. Animals capable of maintaining PCV values, even when antigen ELISA positive on a high number of occasions, grew at the same rate as uninfected animals. Animals that could not maintain PCV values when infected had poorer growth. Antigen ELISA has the potential to increase the efficiency of selection of trypanotolerant N'Dama cattle under tsetse challenge in the field, in three main ways. (1) Accurate identification of trypanosome species, especially in mixed species infections, clarifies relations between infection, anaemia and animal performance. (2) Detection of animals antigenaemic without patent parasitaemia could allow individuals with superior ability to control trypanosome infection to be identified. (3) More accurate measurement of the proportion of time an animal is infected allows more accurate evaluation of its anaemia control capability.  相似文献   

15.
West African Dwarf goats (WADs) and their Saanen crosses were experimentally infected with Trypanosoma congolense. No significant differences were found between trypanosome parasitaemia and antibody response of the crossbred and WAD goats. Neither the WAD goats nor the Saanen crosses were able to control the drop in PCV following trypanosome infection. The level of anaemia caused by the trypanosome infection was similar in the two breeds during the trial. Based on these findings, no difference in tolerance or susceptibility to T. congolense could be demonstrated between the WAD goats and their Saanen crosses. Although the weight of all goats increased during the trial, the crosses gained significantly more weight than the WAD goats. The trypanosome infection reduced the growth rate of both breeds, but this reduction was not statistically significant. Crossbreeding trypanotolerant WADs with trypanosusceptible Saanen goats might, therefore, be an effective means of increasing productivity.  相似文献   

16.
Four groups of non-pregnant, first second and third trimester pregnant Zebu heifers were used to study and compare the clinical manifestations of Trypanosoma vivax infection. All the infected heifers developed clinical trypanosomiasis manifested by massive parasitaemia, fluctuating pyrexia, anaemia, dull hair coat, emaciation, jugular pulse and enlarged superficial lymph nodes. There were group variations in the severity of signs shown. Infected non-pregnant heifers and heifers in the third trimester of pregnancy developed a more severe form of the disease than pregnant heifers in the first and second trimesters of pregnancy.  相似文献   

17.
The nature and usefulness of trypanoresistance in West African Baoule cattle was studied by exposing animals in areas of high Glossina density. Under such conditions, Zebu and some Baoule died soon with high parasitaemia while resistant Baoule showed little patent parasitemia, almost no anaemia and thrived. Subsequently the role that specific antibody may play in such trypanoresistance was analyzed. In the first instance we examined protective antibody titres during T. congolense infection of inbred mice strains, comparing results obtained in trypanosome-mouse combinations where the host controls parasitemia and survives with those obtained when the host fails to control parasitemia and dies. We then attempted to extend these observations to cattle by following the disease course and appearance of neutralizing antibodies in animals of known sensitivity to natural Glossina challenges, following artificial challenge with T. congolense infected Glossina.  相似文献   

18.
Trypanosoma brucei infection produced an acute and fatal disease in Nigerian mongrel dogs due to a rapidly developing anaemia. Infected dogs responded with increased reticulocytosis, which was not sustained with chronicity. In comparison the response to artificially-induced haemolytic anaemia was progressive, marked and sustained. The anaemia of T. brucei infection of dogs was either normocytic normochromic in acute infection or microcytic normochromic in chronic infection. Artificially-induced haemolytic anaemia was either macrocytic normochromic or normocytic normochromic. The erythropoietic potential of plasma in vivo in mice increased in T. brucei-infected dogs except at the terminal parasitaemia. The anaemia in Trypanosoma brucei-infected dogs is therefore initially responsive but becomes poorly involved with chronicity.  相似文献   

19.
Humoral immune response of sheep to infection with Eperythrozoon ovis   总被引：3，自引：0，他引：3  
Circulating antibody was detected by an indirect fluorescent antibody test (IFAT) in the serum of sheep infected experimentally with Eperythrozoon ovis. Antibodies were first detected 15 to 32 days after infection with E ovis and titres peaked at 41 days. This antibody may be associated, at least in part, with protection against infection with E ovis since the initial increase in antibody titre coincided with a fall in the primary parasitaemia. A role for antibody is suggested further by the fact that the prepatent period of infection was prolonged by one day and the parasitaemia initially remained at low levels in infected sheep protected by passively transferred hyperimmune serum. Moreover, following primary infection, acquired immunity was manifest by a lack of parasitaemia following challenge infections while increased IFA titres were observed. No evidence of opsonic activity was observed in an in vitro erythrophagocytosis test in that neither mouse macrophages nor sheep monocytes phagocytosed E ovis infected or uninfected erythrocytes sensitised with hyperimmune serum.  相似文献   

20.
The effects of Eperythrozoon ovis in sheep   总被引：2，自引：0，他引：2  
Infection of adult sheep with a single strain of Eperythrozoon ovis led to three different situations. First, the animal resisted the organism and no haematological changes occurred. Second, the host developed a controllable parasitaemia in which erythrocyte values fell shortly after peak parasitaemia and then returned to normal. Third, the host failed to control the parasitaemia and chronic low grade anaemia developed. Dexamethasone sometimes caused a resurgence of parasitaemia in sheep.  相似文献   

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