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1.
The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodies, and Suratex for the detection of circulating antigens were compared in a cross-sectional study involving camels in eastern and central parts of Kenya. Of the 2227 camels screened, 2038 were owned by nomadic pastoralists in T. evansi endemic areas in eastern Kenya. A herd of 86 camels were from a ranch in Mugwoni. In Athi River area, 35 camels belonged to Kenya Trypanosomiasis Research Institute, and 68 were slaughter animals. Diagnostic sensitivity estimates were obtained by testing sera from 51 camels that had been found to be parasitologically positive by the haematocrit centrifugation technique, buffy-coat technique and mouse inoculation. Diagnostic specificity was estimated by testing sera from 35 camels known to be trypanosome-free. Positive and negative predictive values (NPVs) were calculated using a range of prevalence values. The sensitivity of CATT/T. evansi (68.6%) was higher than that of Suratex (58.8%), but not significantly. Both tests had equally high specificity (100%). The overall prevalence was 2.3% (51 out of 2227) by parasite detection, 32.2% (327 out of 1017) by CATT/T. evansi and 19.6% (188 out of 961) by Suratex. Overall, there was a positive association between CATT/T. evansi and Suratex though the strength of association was low (McNemar's test=46.12, P=0.001; kappa=0.26, CI: 0.20-0.33). Parasite prevalence ranged from 0% in several herds to 27.8% in a herd in Isiolo. Prevalence was highest in Isiolo with 2.5% (51 out of 2030) by parasitological detection, 38.8% (321 out of 828) by CATT/T. evansi and 21.9% (169 out of 772) by Suratex. In Mugwoni prevalence was 7 and 18% by CATT/T. evansi and Suratex, respectively, and no parasites were detected. In Athi River Suratex detected 2.9% (3 out of 103) positive while CATT/T. evansi and parasitological methods gave negative results. At prevalence values between 10 and 100%, CATT/T. evansi as well as Suratex had infinitely high positive predictive values, whereas Suratex had a lower NPV than CATT/T. evansi. In conclusion, results of this study showed that CATT/T. evansi and Suratex were able to detect aparasitaemic infections rapidly and were more sensitive than parasitological methods in revealing the true extent of trypanosomosis in a herd. The tests effectively complemented parasitological methods in the detection of T. evansi infections in camels.  相似文献   

2.
A double antibody sandwich ELISA for detection of Trypanosoma evansi variant surface glucoprotein (VSG) antigen was established by using two monoclonal antibodies against Trypanosoma evansi VSG antigen.The result of sensitivity showed when positive serum was diluted to 3200 doubles, its D450 nm value was still greater than the critical value of positive and negative,and specificity test result showed that there was no cross reaction with the antigens of Theileria,Toxoplasma gondii,Chlamydia and Fasciola gigantica.82 clinical sera were detected by this double antibody sandwich ELISA and its positive rate was 9.76%.The experiment results demonstrated that this double antibody sandwich ELISA for detection of Trypanosoma evansi VSG antigen had good detecting sensitivity and specificity,and could be used as an effective method for clinical detecting buffalo Trypanosoma evansi disease.  相似文献   

3.
Trypanosomosis due to Trypanosoma evansi (surra) is a major enzootic disease of the dromedary camel. Thus, the purpose of the present study was to assess seroprevalence and infection rates in the Canary Islands using antibody(-card agglutination test-CATT/T. evansi) and parasite detection tests (micro-Haematocrit Centrifugation technique, Giemsa stained blood smears, microscopic examination of lymph node aspirates and mouse inoculation). PCV was also determined. 745 dromedary camels (483 females and 262 males) were examined. Trypanosomes were detected in seven animals. 36 animals yielded CATT positive results while 709 animals were negative. All parasitologically positive animals were also CATT positive. Results showed a good correlation between CATT positive and low PCV and a higher seroprevalence in older animals. Trypanocidal drugs have not been registered in Spain and, consequently, if vigilance is not exercised the prevalence could be increased in the future.  相似文献   

4.
5.
Blood from 115 camels in Kuwait was examined for blood parasites. Two camels of a local herd (1.7%) were found to be infected with Trypanosoma (Trypanozoon) evansi and three camels (2.6%) with microfilarial nematodes. The Trypanosoma stocks isolated from these two camels were screened for isoenzyme patterns of 10 enzymes using thin-layer starch-gel electrophoresis. The results revealed that these two stocks were identical to camel stocks of T. evansi from certain countries in Africa, as well as to two stocks isolated from dogs in Kuwait. This is the first record of Trypanosoma (Trypanozoon) evansi isolates and microfilariae from camels in Kuwait.  相似文献   

6.
A direct card agglutination test for Trypanosoma evansi, CATT/T. evansi based on the predominant variable antigen-type (pVAT) RoTat 1.2 was evaluated previously in the field in Isiolo District, Kenya. Sixteen out of 51 (31.4%) parasitologically positive camels were negative by the antibody detection test. In the present study, trypanosomes isolated from the camels were analysed in an attempt to determine the cause of the false negative results of CATT/T. evansi. A total of 20 field isolates comprised 16 stocks from camels that were negative by CATT/T. evansi, and 4 from CATT/T. evansi-positive camels. In addition, 15 known T. evansi and four T. brucei were used as reference. Purified DNA samples were tested using an established RoTat 1.2-based polymerase chain reaction (PCR) that yields a 488 bp product for the specific detection of T. evansi. Antibodies to RoTat 1.2 variant surface glycoprotein (VSG) were used in Western blotting to detect RoTat 1.2 VSG linear epitopes. Results of PCR and Western blot showed that the 16 stocks isolated from CATT/T. evansi-negative camels fell into three groups. In Group 1, both the RoTat 1.2 VSG gene and the VSG were absent in three stocks. In five trypanosome stocks in Group 2, the RoTat 1.2 VSG gene was detected, but Western blot was negative indicating absence of the expressed VSG. Five other stocks containing the RoTat 1.2 VSG gene were also in this group. The RoTat 1.2 VSG gene was detected and Western blot was positive in all four trypanosome stocks in Group 3. All four stocks from CATT/T. evansi-positive camels contained the RoTat 1.2 VSG gene and the expressed VSG. The reference T. evansi KETRI 2479 lacked the RoTat 1.2 VSG gene and there was no immune reactivity detected by Western blot. The rest of the reference T. evansi stocks examined contained the RoTat 1.2 VSG gene. All the four T. brucei samples examined were negative by PCR and Western blot. In conclusion, this study showed that the RoTat 1.2 VSG gene was absent from some T. evansi trypanosomes in Kenya.  相似文献   

7.
This study was performed to investigate the presence of bovine herpesvirus-1 (BHV-1), bovine leukemia virus (BLV) and bovine viral diarrhea virus (BVDV) infections in dromedary camels (Camelus dromaderius) kept in mixed herds with sheep and goats in Algeria, since the prevalence of BHV-1, BVDV, and BLV infections among dromedary camels in Algeria is unknown. Totally, 111 camel sera were collected from two provinces (Laghouat and Ghardaia) in Algeria. The sera were analyzed for BHV-1 specific antibodies, BVDV specific antibodies and BVDV antigen using the ELISA, and BLV nucleic acid using PCR. The seropositivity rate was 9.0% for BVDV-specific antibody, although 41.4% of camels tested were positive for BVDV antigen. Moreover, there was no evidence of BHV-1 and BLV infections. The results indicated that camels might represent an important source for BVDV infection in all ruminants, including cattle, sheep, and goats bred in mixed herds in Algeria, since they had a higher BVDV prevalence rates. Therefore, the prevention and control measures for BVDV infection should put in place in camel populations to limit the spread of BVDV infection to ruminant populations in Algeria.  相似文献   

8.
An epidemiological survey of camel trypanosomosis was conducted for the first time in Morocco in 1997 and 1998. Five provinces located in the south and southeast of the High Atlas mountain chain were included in this study. A total number of 1460 serum samples were collected and tested by a card agglutination test for trypanosomosis (CATT) and enzyme-linked immunosorbant assay (Ab-ELISA) to detect anti-Trypanosoma evansi antibodies. The overall seroprevalence was 14.1% by CATT and 18.2% by Ab-ELISA. Two very active foci were identified in Zagora and Merzouga with high Ab-ELISA prevalences of 43.3 and 35.4%, respectively, for each area. The concordance between the CATT and Ab-ELISA was 94.1%. The age-related distribution of seroprevalence showed a tendency for the infection rate to increase with age up to a maximum in the 7-10 year-old group. Clinical examination revealed that enlargement of lymph nodes was the most frequent sign in seropositive animals (79.7%). The comparison of haematocrit values of seropositive and seronegative animals showed a significant difference that indicated severe anaemia in infected animals. Isolation of the parasite by inoculation of mice allowed us to collect 15 T. evansi isolates from Zagora and three from Merzouga. The study showed that the Saharan provinces of Morocco were slightly affected by camel trypanosomosis but two hyperendemic foci, Zagora and Merzouga, were found to be sources of contamination for the surrounding regions.  相似文献   

9.
A five year investigation of Brucella antibody prevalence in camel sera was conducted in 1502 one-humped camels of both sexes and different ages. The average (mean +/- SD) incidence rate of positive results was 6.95 +/- 1.55%. Among adult one-humped camels, the rate was 4.94 +/- 2.51% in males and 13.76 +/- 4.41% in females. Juvenile one-humped camel calves showed a 0% incidence rate in males and a 1.82 +/- 3.64% in females. Antibodies against Brucella abortus were prevalent in one-humped camel sera throughout the five years of the survey with incidence rates of 6.54, 5.79, 9.32, 5.03 and 8.06%, respectively from 1985 to 1989.  相似文献   

10.
Serological prevalence of IgG antibodies against Rift Valley fever (RVFV) virus was investigated in 22 major localities in five different regions of Saudi Arabia where vaccination against RVF virus (RVFV) is not practiced. The study excludes the southwestern region where a major outbreak of RVF occurred in 2000 and where annual vaccination of ruminants is practiced. Sheep and goat IgG-sandwich ELISA were used to test serum samples from sheep and goats, and bovine IgG-sandwich ELISA was used to test cattle sera. A nonspecies-specific, nonantibody isotype-specific ELISA was used to test camel sera. A total of 3,480 sheep, goats, cattle and camels with no previous history of vaccination against RVFV were randomly tested. All tested animals were negative for IgG class antibodies against the virus except four out of 1,508 sheep and three out of 913 goats, which tested positive. All animals were clinically normal and no evidence was found of virus activity in the studied areas. It is, therefore, most likely that those rare positive cases, which constituted 0.002% of the total animals tested, were either false positives or vaccinates smuggled from the outbreak zone. The need for regular monitoring of animals both within the outbreak zone of 2000 and other parts of the kingdom is strongly emphasized.  相似文献   

11.
An outbreak of trypanosomoasis caused by Trypanosoma evansi involving horses, camels and donkeys occurred in a farm in Israel. A longitudinal study of two outbreak phases was conducted which included clinical monitoring, blood smears, packed cell volume (PCV), serology and polymerase chain reaction (PCR) followed by reverse dot blot (RDB) for the molecular detection of infection. This was the first reported T. evansi outbreak in domestic animals in Israel. Most of the camels on the farm (8/10; 80%) were diagnosed with T. evansi infection whereas infection was less prevalent in the horses (3/7; 43%) and donkeys (6/13; 46%). Clinical disease was evident in 4 camels and 1 horse exhibiting characteristic clinical signs, anemia and parasitemia detected on blood smears and by positive RDB. Six other animals were diagnosed as asymptomatic latent carriers by positive RDB and 6 additional animals were only seropositive and were considered suspected carriers. A significant difference was found in the mean PCV between symptomatic and latent carriers with severe anemia observed only in the symptomatic animals. An anaphylactic-like reaction, fatal in one case, was observed in 2 camels diagnosed with severe trypanosome parasitemia immediately following treatment with melarsenoxide cysteamine. Furthermore, recurrence of infection was documented in one camel 4 months post treatment.  相似文献   

12.
The first outbreak of trypanosomosis caused by Trypanosoma evansi in camels in France was reported on a farm in the Aveyron Department. Five camels were imported from the Canary Islands to the farm in early July 2006, and trypanosomes were observed on a stained blood smear from one of them, which died in October. On further investigations, trypanosomes were observed in the blood of five camels, three of them indigenous to the farm and two that had been imported. On the basis of microscopical examination (morphological criteria and measurements) and serological results based on the card agglutination T evansi test and PCR typing, the parasites were identified as T evansi. After treatment with melarsomine, the infected camels rapidly became negative by parasitological tests and were negative two to four months later by serological tests. The parasite was probably transmitted by tabanids and Stomoxys calcitrans, which were abundant in July to September 2006. No parasites were observed in other animals on the farm or on neighbouring farms, but some of the sheep on these farms were positive by PCR or serology.  相似文献   

13.
In order to define whether the variable antigenic type RoTat 1.2 is restricted to Trypansoma evansi and could be used as antigen in serological tests to differentiate T. evansi from Trypansoma equiperdum, the appearance of RoTat 1.2-specific antibodies in rabbits, experimentally infected with T. evansi and T. equiperdum, respectively, was analyzed. Ten strains of T. evansi and 11 strains of T. equiperdum originating from Asia, Europe, Africa and Latin America were tested. Rabbit pre-infection sera and sera of days 7, 14, 25, 35 post-infection (p.i.) were analyzed for the presence of antibodies reactive with RoTat 1.2 in immune trypanolysis, ELISA/T. evansi and CATT/T. evansi. Within the duration of the infection (maximum 35 days), all T. evansi as well as 9 out of 11 T. equiperdum infected rabbits became positive in all these tests. The rabbits infected with T. equiperdum OVI (South Africa) and BoTat 1.1 (Morocco) remained negative in the immune trypanolysis test although the latter rabbit became positive in the CATT/T. evansi and ELISA/T. evansi. On the contrary, both rabbits were positive in immune trypanolysis when tested against their respective infecting population. From these data, we conclude that most T. equiperdum strains express isoVATs of RoTat 1.2. This explains, in part, why antibody tests based on T. evansi RoTat 1.2 cannot reliably distinguish between infections caused by T. evansi and those caused by T. equiperdum unless it can be proven that most described T. equiperdum are actually misclassified T. evansi.  相似文献   

14.
Point prevalences and animal-level risk factors for Trypanosoma evansi infection were investigated in a cross-sectional study that involved 2227 camels from eastern and central parts of Kenya. The screening tests used were haematocrit centrifugation technique (HCT), mouse inoculation and latex agglutination (Suratex). All camels were screened with HCT, while 396 and 961 of them were, in addition, screened with mouse inoculation and Suratex tests, respectively. Parasitological and Suratex test results were used in parallel to determine the number of camels exposed to T. evansi infections. Statistical analyses were conducted using Statistical Analysis Systems. Parasitological and Suratex test results in parallel were dependent variables in multivariable logistic regression models that determined risk factors for T. evansi infection. Herd-level clustering was corrected with general estimation equations. The prevalences were 2.3% and 19.6%, using parasitological and Suratex tests, respectively, and 21.7% when both tests were used in parallel. There was a positive association between the screening tests (McNemar's test = 104.8, P = 0.001) although the strength of association was low (Kappa = 0.2; 95% CI: 0.1-0.3). Before accounting for herd-level clustering, dry season (OR = 1.5; 95% CI: 1.0, 2.1) and nomadic pastoralism (OR = 1.8; 95% CI: 1.1, 3.2) were associated with increased odds of a camel being exposed to T. evansi infection compared to wet season and ranching, respectively. Following this correction, only nomadic pastoralism was significantly associated (OR = 3.1; 95% CI = 1.0, 14.4) with T. evansi infection compared to ranching. It is concluded that camels managed under nomadic pastoralism had higher risk of being exposed to T. evansi infections than camels from ranching systems of management.  相似文献   

15.
水牛伊氏锥虫病免疫胶体金试纸条的研制及初步应用   总被引:1,自引:0,他引:1  
为建立一种快速、简便、适应现场应用的水牛伊氏锥虫病诊断方法,采用柠檬酸三钠还原法制备胶体金颗粒,标记纯化的抗伊氏锥虫VSG抗原的OB6单克隆抗体,在硝酸纤维素膜上包被纯化的抗伊氏锥虫VSG抗原的TB7单克隆抗体和兔抗小鼠IgG,作为检测带和质控带,然后优化条件,研制成检测伊氏锥虫病的免疫胶体金试纸条.通过交叉试验表明该试纸条与衣原体、弓形虫、旋毛虫、巴贝斯焦虫和大片吸虫无交叉反应.该试纸条最低可以检出1∶3 200倍稀释的伊氏锥虫VSG抗原(浓度为3.11 mg·mL-1).应用该试纸条对230份水牛血清样本进行初步检测,同时用ELISA做平行试验,阳性符合率为88.2%.结果证明该试纸条是一种快速、灵敏、特异的水牛伊氏锥虫病的检测方法,为水牛伊氏锥虫病的现场检测诊断和预控提供了有效的方法.  相似文献   

16.
ELISAs using recombinant parasite polypeptides as antigens were developed to measure Toxoplasma gondii-specific antibodies in the sera of sheep and cats. Compared with an ELISA based on traditional parasite antigen, the ELISA for sheep sera had a sensitivity of 79% and a negative predictive value of 80%, and the ELISA for cat sera had a sensitivity of 100% and a negative predictive value of 100%. Both ELISAs had specificities of 100% and positive predictive values of 100%. These ELISAs appear to be a useful cost-effective alternative to ELISAs based on traditional parasite antigen for the measurement of T. gondii-specific antibodies in the sera of sheep and cats.  相似文献   

17.
OBJECTIVE: To confirm serological evidence that Trypanosoma evansi is present in Papua New Guinea. DESIGN: Three surveys were undertaken in PNG during 1997/1998. Animals were selected for sampling on the basis of convenience. Samples of blood were examined for the presence of T evansi by the haematocrit centrifugation technique (HCT) and mouse inoculation test (MI). Sera were tested in the field using the card agglutination test for trypanosomiasis/T evansi (CATT). Bovine sera were tested at James Cook University using an antibody-detection ELISA (Ab-ELISA). Results from testing bovine sera with the Ab-ELISA and sera from wallabies with the CATT were analysed using FreeCalc to determine the probability that animals in these populations were infected with T evansi. RESULTS: A total of 545 serum samples were collected, during the three surveys of which 39 cattle, two pig and three agile wallaby samples were positive with the CATT. All bovine sera collected were negative when tested with an Ab-ELISA. T evansi was not isolated using the HCT or the MI from any of these animals. CONCLUSION: Based on the Ab-ELISA results it was concluded that T evansi infection was not present in cattle in villages around Balimo at a minimum expected prevalence of 10% (P < 0.05) and, based on the CATT results, that infection was not present in wallabies on the Bula plain at a minimum expected prevalence of 10% (P < 0.1). These results indicate that it is unlikely that T evansi is endemic in PNG.  相似文献   

18.
Seven surra negative horses were intravenously inoculated with 3 x 10(6)Trypanosoma evansi parasites derived from a camel. One horse was maintained as an uninfected negative control. Three antigen and three antibody detection tests were evaluated for diagnosis of infection in horses. The microhaematocrit centrifugation test (MHCT) was the most sensitive, first detecting parasites between one and three days (x 2.4) post infection (p.i.). The antigen (ag)-ELISA detected antigen between three and ten days (x 6.6) p.i. The latex agglutination test (LAT) first gave positive results on day 3 (x 3.0) p.i. Following the treatment of horses with trypanocidal drugs, the MCHT and the mouse inoculation test (MIT) became negative. Antigen levels using LAT declined and reached pre-infection levels in five out of six horses during the period of observation (92-279 days). Antigen levels using the ag-ELISA declined as well but did not reach pre-infection levels in any of the six horses.Three antibody detection techniques, ab-ELISA, card agglutination test (CATT), and immunofluorescent antibody test (IFAT) detected antibodies in the blood of all seven infected horses but not in the uninfected control. However, the ab-ELISA did not discriminate clearly between sera from infected and uninfected horses because unacceptably high ELISA background readings were detected in 15% of the surra negative horses shipped to the UAE from the UK. The ELISA antibody increased above pre-infection levels in the six horses experimentally infected, but not in one horse. In this horse the ELISA antibody level exceeded the cut-off level only after the reoccurrence of the T. evansi infection. The IFAT detected antibodies 15.7 days p.i. in all infected horses.  相似文献   

19.
Camel trypanosomosis (Surra) causes high morbidity and is an impediment to the camel husbandry in Kenya. The lack of a sensitive diagnostic test has hindered the collection of accurate epidemiological data and institution of control programmes. A cross-sectional study was conducted in three districts of Kenya to estimate the prevalence of Trypanosoma evansi (T. evansi) and to compare four diagnostic tests: polymerase chain reaction (PCR), card agglutination test (CATT/T. evansi), microhaematocrit centrifugation technique (MHCT) and mouse inoculation (MI). A total of 549 camels were randomly sampled. The overall prevalence of Surra was 5.3% using MHCT, 26.6% using PCR and 45.9% using CATT/T.evansi. There was a significant difference (P < 0.001) between PCR and CATT/T.evansi test, MHCT and MI in detection of T. evansi. The prevalence of T. evansi was 39.8% in Samburu, 24.7% in Nanyuki and 14.4% in Isiolo districts using PCR. A male camel was 2.6 times more likely to be infected with T. evansi compared to a female camel (OR = 3.0% CI: 1.6, 4.1), while an adult camel was 2.2 times more likely to be infected compared to non-adults (OR = 2.2; 95% CI: 1.2, 5.0). There was a poor association between the presence of the published clinical signs and seropositivity (kappa = 0.12), PCR (kappa = 0.11) and MHCT (kappa = 0.05). However, there was a higher agreement between farmers' classification of disease with the PCR test (kappa = 0.5, n = 61). The mean PCV varied with age, presence of infection, locality and gender, with the lowest mean PCV being recorded in MHCT-positive animals (20.97 +/- 0.5) and from infected calves (19.5 +/- 1.2). This study shows that PCR was more sensitive in detecting T. evansi than other tests used. Further, the prevalence of T. evansi in the camel herds sampled is higher than that previously reported in Kenya, and that the judgment by camel keepers may be a reliable "pen-side" diagnostic test for Surra. Considering the low sensitivity of parasitological techniques in detection of chronic T. evansi infection and high cost of PCR, development of a sensitive pen side diagnostic test, with a low cost is still a priority.  相似文献   

20.
The existence of peste des petits ruminants (PPR) in domestic ruminants and camels in Sudan during 2008–2012 was investigated. Lung tissues and serum samples were randomly collected from sheep, goats, cattle, and camels at different areas of Sudan. A total of 12,384 serum samples were collected from clinically healthy 7413 sheep, 1988 camels, 1501 cattle, 1459 goats, and 23 gazelles at different areas in the Sudan. They were examined for PPR antibodies using competitive ELISA (cELISA). The overall detected seroprevalence of PPR in tested sera was 49.4%; seroprevalence values within species were 67.1, 48.2, 25.8, 2.1, and 21.7% in sheep, goat, cattle, camels, and gazelles, respectively. The highest seroprevalence (68.1%) was observed in sera collected from Darfur states, then the central states (54.3%). A total of 1276 lung tissue samples (623 sheep, 324 cattle, 220 camels, and 109 goats) were collected. The majority of lung samples were collected from clinically healthy animals that showed lesions on PM in slaughterhouses (95%) and during PPR outbreaks; samples were tested for PPR antigen using immunocapture ELISA (IcELISA). PPR antigen was detected in 233 out of the 1276 tested samples (18.3%). Positive results were observed in samples collected from clinically healthy and diseased animals. The observed prevalence values in each species were 33.6, 21.1, 15.4, and 12.3% in camel, goat, sheep, and cattle, respectively. PPR antigen was detected in samples from different areas; however, the highest prevalence (63.9%) was found in samples collected from the eastern states, then Khartoum state (28%). Trials for virus isolation were done in different cell cultures. Out of 30 IcELISA-positive samples inoculated in primary bovine and ovine kidney cells, Vero cells, the PPR virus was successfully isolated from 15 (eight sheep, five camels, and two goats) samples in the three cell culture types. Using RT-PCR, PPRV nucleic acid was detected in all 25 IcELISA-positive tested samples.  相似文献   

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