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Study on the antioxidant status of rats experimentally infected with Trypanosoma evansi
Veterinary Parasitology 145 (2007) 142–145 www.elsevier.com/locate/vetpar
Short communication
Study on the antioxidant status of rats experimentally infected with Trypanosoma evansi O.H. Omer *, H.M. Mousa, N. Al-Wabel Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, P.O. Box 1482, Buraidah, Saudi Arabia Received 2 May 2006; received in revised form 6 November 2006; accepted 8 November 2006
Abstract The antioxidant status of rats experimentally infected with Trypanosoma evansi isolated from a camel was studied using established parasitological, haematological and biochemical methods. The results indicated that infections in all rats resulted in a fulminating parasitaemia. Changes in blood parameters in T. evansi-infected rats indicated leukocytosis and a macrocytic hypochromic anaemia. A degree of anisocytosis was also observed. The activities of plasma glucose-6-phosphate dehydrogenase and glutathione peroxidase in whole blood of infected rats were significantly higher ( p < 0.05 and p < 0.001, respectively) compared with control. No statistically significant difference was observed in the activity of superoxide dismutase in infected and control rats. Results obtained indicated that trypanosomosis caused oxidative stress and induced antioxidant enzymes. # 2006 Elsevier B.V. All rights reserved. Keywords: Trypanosoma evansi; Glutathione peroxidase; Superoxide dismutase; Glucose-6-phosphate dehydrogenase; Rats
1. Introduction Trypanosoma evansi is a common parasite in the tropics that causes a serious and economically important disease in domestic animals. The disease is known to occur in Northern Africa, Sudan, Eritrea, Ethiopia, Somalia, the Middle and Near East, the Indian subcontinent, Central Asia and the Far East (Mahmoud and Gray, 1980). T. evansi was reported to be the most widely distributed of the pathogenic animal trypanosomoses, affecting domesticated livestock in Asia, Africa and Central and South America. Its spread into South East Asia has occurred only relatively recently, and the serious epidemics of surra that were recorded in the early years of the present century in Indonesia and
* Corresponding author. Tel.: +966 63800050; fax: +966 63801360. E-mail address: [email protected] (O.H. Omer). 0304-4017/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2006.11.007
the Philippines, suggest that it could have spread into these regions within the last 100 years (Luckins, 1988; Lun et al., 1993). Natural infections occur in camels, horses, bovine and dogs (Al-Rawashdeh et al., 1999). More recently, a case of T. evansi trypanosomosis in humans was recorded for the first time in India (Joshi et al., 2005). The acute form of the disease is characterized by progressive anaemia, high fever, anorexia, marked depression, dullness, loss of condition and in some cases, death. The chronic form which is more common shows relapsing parasitaemia with or without pyrexia, emaciation, oedema of the abdomen and legs, abortion and death in some animals (Raisinghani et al., 1980; Haroun et al., 2000). Earlier reports have shown increased susceptibility of erythrocytes to in vitro peroxidation in acute T. brucei infection of mice (Igbokwe et al., 1994). This observation suggested that the infected mice might
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145
have a reduced ability in the prevention of free radical mediated lipid peroxidation in the erythrocyte membrane. It is concluded that peroxidative injury to the erythrocytes may contribute to the pathogenesis of anaemia in trypanosomosis. The present investigation was designed to study the antioxidant status of rats experimentally infected with T. evansi using established parasitological, haematological and biochemical methods. 2. Materials and methods Thirty-five male Wistar rats (250 20 g) were obtained from the Animal House of the College of Agriculture and Veterinary Medicine, Qassim University and housed in a room at a temperature of 22 28 C and relative humidity of 50–60, with artificial light from 5.00 a.m. to 4.00 p.m. Animals had free access to tap water and standard rat chow. The rats were randomly divided into two groups, designated group I and II. Animals in groups II (20 rats) were injected intraperitonaelly with 1 105 trypanosomes isolated from a camel that was naturally infected with T. evansi, a common parasite in the Central region of Saudi Arabia. The rats in group I (15) were kept as uninfected controls. Wet blood smears were prepared daily from infected rats to assess infectivity, and Giemsa-stained thin blood smears were also prepared from the tail veins of all infected rats (OIE, 2000). Parasitaemia was estimated by examining 200 microscopic fields of wet blood film under a 22 mm 22 mm cover-slip using a 10 eyepiece and 40 objective. Five rats in group II died on days 46 and 47 post-infection. The rest of the animals were anaethetized with diethyl ether and decapitated on day 49 post-infection. Blood was collected from all rats in heparin-containing tubes. Plasma was obtained from the heparinized blood by centrifugation at 2000 g at room temperature. Glucose-6-phosphate dehydrogenase (G6P-DH) activity in plasma was determined by commercial kits (UDI, Saudi Arabia). The concentrations of plasma total protein, albumin, globulin, cholesterol and urea were also determined by commercial kits (Bio-Merieux Reagents and Products, France). The heparinized blood samples were analyzed for the activities of glutathione peroxidase (GSH-Px) by the commercial ‘‘Ransel’’ method from Randox Laboratories Ltd., UK. Superoxide dismutase (SOD) activity in whole blood was determined by the commercial ‘‘Ransod’’ method from Randox Laboratories Ltd., UK. Haemoglobin (Hb) concentration, haematocrit
143
(HCT), red blood cell (RBC), white blood cell (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), relative distribution width (RDW) and total platelets counts (PLT) were determined by the Abbott Cell Dyn 3500 (Abbott Diagnostic Division, California USA). Statistical comparisons were made using Student’s t-test followed by Mann–Whitney Rank Sum test using SigmaStat for Windows version 2.0 (Jandel Scientific, USA). 3. Results Six weeks post-infection, all infected rats had a fulminating parasitaemia (1 106 to 5 106 trypanosomes per ml). As shown in Table 1, there was a significant increase ( p < 0.01) in WBC count in group II compared with control. There were significant decreases ( p < 0.01) in RBC, Hb, PCV and MCHC values compared with controls (Table 1). These differences were highly statistically significant ( p < 0.001). There was also a significant increase ( p < 0.001) in MCV value in infected rats compared with control. There was a significant increase ( p < 0.001) in RDW in infected rats compared with controls. However, no significant difference in platelets count was observed. The Plasma total protein, albumin, globulin, cholesterol and urea concentrations were insignificantly decreased in groups II compared with control (Table 2). The activities of plasma G6P-DH and GSH-Px blood were significantly higher ( p < 0.05 and p < 0.001, respectively) in groups II compared with control. No statistically significant difference was observed in the activity of superoxide dismutase in infected and control rats.
Table 1 Haematological changes (means S.E.M.) in rats experimentally infected with Trypanosoma evansi (n = 15 rats) Units WBC RBC HGB HCT MCV MCH MCHC RDW PLT **
p < 0.001.
6
1
(10 L ) (1012 L 1) (g/dL) (L/L) (fL) (pg) (g/dL) (%) (106 L 1)
GI
GII
5.85 0.654 6.62 0.350 12.22 0.497 57.72 2.352 88.33 2.493 18.70 0.504 21.18 0.086 16.68 0.873 553.4 102.2
8.09 1.865 4.21 0.212** 8.81 0.325** 44.22 2.664** 105.12 3.94** 21.40 0.870 20.94 1.546** 22.25 0.886** 166.1 27.1
144
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145
Table 2 Biochemical changes (means S.E.M.) in rats experimentally infected with T. evansi (n = 15 rats)
Total protein Albumin Globulin A-G ratio Glutathione-S-transferase Superoxide dismutase Glucose-6-phosphatase dehydrogenase Cholesterol Urea *
p < 0.05;
Units
GI
GII
(g/L) (g/L) (g/L)
71.73 2.201 37.70 1.381 34.03 2.030 1.180 0.082 125.73 24.16 1487.24 78.56 24.21 16.26 8.947 0.553 7.199 0.560
68.90 1.786 35.01 1.29 33.31 1.474 1.100 0.076 241.12 29.15** 1310.64 178.91 33.67 14.40* 7.702 0.495 6.731 0.511
(U/g Hb) (U/g Hb) (U/L) (mmol/L) (mmol/L)
**
p < 0.001.
4. Discussion Changes in blood parameters (Table 1) indicated moderate anaemia and leukocystosis. The erythrocyte count, haematocrit and haemoglobin concentrations were decreased compared with those of the healthy rats. In infected rats the increase in MCV values ( p < 0.01) and the decrease in MCHC values ( p < 0.001) indicated macrocytic hypochromic anaemia. The increase in RDW values indicated a degree of anisocytosis. The significant increase in GSH-Px activity in whole blood in the present study came in line with the findings obtained by Igbokwe et al. (1996) in calves artificially infected with Trypanosoma vivax. Igbokwe et al. (1994) found that erythrocytes of Trypanosoma brucei-infected mice produced significantly greater amounts of by-products of lipid peroxidation than the erythrocytes of the control mice. This suggests that the infected mice may have reduced ability in the prevention of free radicals-mediated lipid peroxidation in the erythrocyte membrane. This may contribute to the pathogenesis in anaemia in trypanosomosis. The increase in the activity of G6P-DH can be explained by the finding that during parasitic infection, erythrocytes produce reactive oxygen species (ROS) and hydrogen peroxide (H2O2) that enhance lipid peroxidation and activate host cell hexose monophosphate shunt. Anosa and Kaneko (1983) found that when deer mice were infected with T. brucei there was a significant increase in the erythrocyte hexokinase, glutathione peroxidase and glucose-6-phosphate dehydrogenase. NADPH produced by hexose monophosphate shunt maintains glutathione in its reduced form and glutathione is a potent antioxidant. In the present study, no statistically significant difference was
observed in the activity of superoxide dismutase in infected and control rats. Similar results have been reported in other parasitic infections (Wozencraft, 1986; Grewal et al., 2005). However, Anosa and Kaneko (1983) reported that the total activity of superoxide dismutase of the enlarged spleen and liver of T. brucei-infected mice was increased, although the activity per unit weight was either decreased or not altered. References Al-Rawashdeh, O.F., Sharif, L.A., Al-Qudah, K., Al-Ani, F.K., 1999. Trypanosoma evansi infection in camels in Jordan. Rev. Elev. Med. Vet. Pays Trop. 52, 233–237. Anosa, V.O., Kaneko, J.J., 1983. Pathogenesis of Trypanosoma brucei infection in deer mice (Peromyscus maniculatus): hematologic, erythrocyte biochemical, and iron metabolic aspects. Am. J. Vet. Res. 44, 639–644. Grewal, A., Ahuja, C.S., Singha, S.P.S., Chaudhary, K.C., 2005. Status of lipid peroxidation, some antioxidant enzymes and erythrocytic fragility of crossbred cattle naturally infected with Theileria annulata. Vet. Res. Commun. 29, 387–394. Haroun, E.M., Magzoub, M., Mahmoud, O.M., Qarawi, A.A., Hawas, A., Omer, O.H., 2000. Some clinicopathological aspects of experimental Trypanosoma evansi infection in Najdi camels (Camelus dromedarius). J. Camel Pract. Res. 7, 107–108. Igbokwe, I.O., Esievo, K.A., Saror, D.I., Obagaiye, O.K., 1994. Increased susceptibility of erythrocytes to in vitro peroxidation in acute Trypanosoma brucei infection of mice. Vet. Parasitol. 55, 279–286. Igbokwe, I.O., Umar, I.A., Omage, J.J., Ibrahim, N.D., Kadima, K.B., Obagaiye, O.K., Saror, D.I., Esievo, K.A., 1996. Effect of acute Trypanosoma vivax infection on cattle erythrocyte glutathione and susceptibility to in vitro peroxidation. Vet. Parasitol. 63, 215–224. Joshi, P.P., Shegokar, V.R., Powar, R.M., Herder, S., Katti, R., Salkar, H.R., Dani, V.S., Bhargava, A., Jannin, J., Truc, P., 2005. Human trypanosomiasis caused by Trypanosoma evansi in India: the first case report. Am. J. Trop. Med. Hyg. 73, 491–549. Luckins, A.G., 1988. Separation of Trypanosoma evansi in Asia. Parasitol. Today 4, 137–142.
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145 Lun, R., Fang, Y., Wang, C.J., Brun, R., 1993. Trypanosomiasis of domestic animals in China. Parasitol. Today 9, 41–45. Mahmoud, M.M., Gray, A.R., 1980. Trypanosomiasis due to Trypanosoma evansi (Steel, 1885) Balbiani, 1888. A review of recent research. Trop. Anim. Hlth. Prod. 12, 35–47. OIE, 2000. The Office International des epizooties: Manual of Standards for Diagnostic Tests & Vaccines, 4th ed.
145
Raisinghani, P.M., Bhatia, J.S., Vjas, U.K., Arya, P.L., Lodha, K.R., 1980. Pathology of experimental surra in camels (Camelus dromedarius). Indian J. Anim. Sci. 50, 966–969. Wozencraft, A.O., 1986. Damage to malaria infected erythrocytes following exposure to oxidant generating systems. Parasitology 92, 559–567.
Short communication
Study on the antioxidant status of rats experimentally infected with Trypanosoma evansi O.H. Omer *, H.M. Mousa, N. Al-Wabel Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, P.O. Box 1482, Buraidah, Saudi Arabia Received 2 May 2006; received in revised form 6 November 2006; accepted 8 November 2006
Abstract The antioxidant status of rats experimentally infected with Trypanosoma evansi isolated from a camel was studied using established parasitological, haematological and biochemical methods. The results indicated that infections in all rats resulted in a fulminating parasitaemia. Changes in blood parameters in T. evansi-infected rats indicated leukocytosis and a macrocytic hypochromic anaemia. A degree of anisocytosis was also observed. The activities of plasma glucose-6-phosphate dehydrogenase and glutathione peroxidase in whole blood of infected rats were significantly higher ( p < 0.05 and p < 0.001, respectively) compared with control. No statistically significant difference was observed in the activity of superoxide dismutase in infected and control rats. Results obtained indicated that trypanosomosis caused oxidative stress and induced antioxidant enzymes. # 2006 Elsevier B.V. All rights reserved. Keywords: Trypanosoma evansi; Glutathione peroxidase; Superoxide dismutase; Glucose-6-phosphate dehydrogenase; Rats
1. Introduction Trypanosoma evansi is a common parasite in the tropics that causes a serious and economically important disease in domestic animals. The disease is known to occur in Northern Africa, Sudan, Eritrea, Ethiopia, Somalia, the Middle and Near East, the Indian subcontinent, Central Asia and the Far East (Mahmoud and Gray, 1980). T. evansi was reported to be the most widely distributed of the pathogenic animal trypanosomoses, affecting domesticated livestock in Asia, Africa and Central and South America. Its spread into South East Asia has occurred only relatively recently, and the serious epidemics of surra that were recorded in the early years of the present century in Indonesia and
* Corresponding author. Tel.: +966 63800050; fax: +966 63801360. E-mail address: [email protected] (O.H. Omer). 0304-4017/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2006.11.007
the Philippines, suggest that it could have spread into these regions within the last 100 years (Luckins, 1988; Lun et al., 1993). Natural infections occur in camels, horses, bovine and dogs (Al-Rawashdeh et al., 1999). More recently, a case of T. evansi trypanosomosis in humans was recorded for the first time in India (Joshi et al., 2005). The acute form of the disease is characterized by progressive anaemia, high fever, anorexia, marked depression, dullness, loss of condition and in some cases, death. The chronic form which is more common shows relapsing parasitaemia with or without pyrexia, emaciation, oedema of the abdomen and legs, abortion and death in some animals (Raisinghani et al., 1980; Haroun et al., 2000). Earlier reports have shown increased susceptibility of erythrocytes to in vitro peroxidation in acute T. brucei infection of mice (Igbokwe et al., 1994). This observation suggested that the infected mice might
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145
have a reduced ability in the prevention of free radical mediated lipid peroxidation in the erythrocyte membrane. It is concluded that peroxidative injury to the erythrocytes may contribute to the pathogenesis of anaemia in trypanosomosis. The present investigation was designed to study the antioxidant status of rats experimentally infected with T. evansi using established parasitological, haematological and biochemical methods. 2. Materials and methods Thirty-five male Wistar rats (250 20 g) were obtained from the Animal House of the College of Agriculture and Veterinary Medicine, Qassim University and housed in a room at a temperature of 22 28 C and relative humidity of 50–60, with artificial light from 5.00 a.m. to 4.00 p.m. Animals had free access to tap water and standard rat chow. The rats were randomly divided into two groups, designated group I and II. Animals in groups II (20 rats) were injected intraperitonaelly with 1 105 trypanosomes isolated from a camel that was naturally infected with T. evansi, a common parasite in the Central region of Saudi Arabia. The rats in group I (15) were kept as uninfected controls. Wet blood smears were prepared daily from infected rats to assess infectivity, and Giemsa-stained thin blood smears were also prepared from the tail veins of all infected rats (OIE, 2000). Parasitaemia was estimated by examining 200 microscopic fields of wet blood film under a 22 mm 22 mm cover-slip using a 10 eyepiece and 40 objective. Five rats in group II died on days 46 and 47 post-infection. The rest of the animals were anaethetized with diethyl ether and decapitated on day 49 post-infection. Blood was collected from all rats in heparin-containing tubes. Plasma was obtained from the heparinized blood by centrifugation at 2000 g at room temperature. Glucose-6-phosphate dehydrogenase (G6P-DH) activity in plasma was determined by commercial kits (UDI, Saudi Arabia). The concentrations of plasma total protein, albumin, globulin, cholesterol and urea were also determined by commercial kits (Bio-Merieux Reagents and Products, France). The heparinized blood samples were analyzed for the activities of glutathione peroxidase (GSH-Px) by the commercial ‘‘Ransel’’ method from Randox Laboratories Ltd., UK. Superoxide dismutase (SOD) activity in whole blood was determined by the commercial ‘‘Ransod’’ method from Randox Laboratories Ltd., UK. Haemoglobin (Hb) concentration, haematocrit
143
(HCT), red blood cell (RBC), white blood cell (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), relative distribution width (RDW) and total platelets counts (PLT) were determined by the Abbott Cell Dyn 3500 (Abbott Diagnostic Division, California USA). Statistical comparisons were made using Student’s t-test followed by Mann–Whitney Rank Sum test using SigmaStat for Windows version 2.0 (Jandel Scientific, USA). 3. Results Six weeks post-infection, all infected rats had a fulminating parasitaemia (1 106 to 5 106 trypanosomes per ml). As shown in Table 1, there was a significant increase ( p < 0.01) in WBC count in group II compared with control. There were significant decreases ( p < 0.01) in RBC, Hb, PCV and MCHC values compared with controls (Table 1). These differences were highly statistically significant ( p < 0.001). There was also a significant increase ( p < 0.001) in MCV value in infected rats compared with control. There was a significant increase ( p < 0.001) in RDW in infected rats compared with controls. However, no significant difference in platelets count was observed. The Plasma total protein, albumin, globulin, cholesterol and urea concentrations were insignificantly decreased in groups II compared with control (Table 2). The activities of plasma G6P-DH and GSH-Px blood were significantly higher ( p < 0.05 and p < 0.001, respectively) in groups II compared with control. No statistically significant difference was observed in the activity of superoxide dismutase in infected and control rats.
Table 1 Haematological changes (means S.E.M.) in rats experimentally infected with Trypanosoma evansi (n = 15 rats) Units WBC RBC HGB HCT MCV MCH MCHC RDW PLT **
p < 0.001.
6
1
(10 L ) (1012 L 1) (g/dL) (L/L) (fL) (pg) (g/dL) (%) (106 L 1)
GI
GII
5.85 0.654 6.62 0.350 12.22 0.497 57.72 2.352 88.33 2.493 18.70 0.504 21.18 0.086 16.68 0.873 553.4 102.2
8.09 1.865 4.21 0.212** 8.81 0.325** 44.22 2.664** 105.12 3.94** 21.40 0.870 20.94 1.546** 22.25 0.886** 166.1 27.1
144
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145
Table 2 Biochemical changes (means S.E.M.) in rats experimentally infected with T. evansi (n = 15 rats)
Total protein Albumin Globulin A-G ratio Glutathione-S-transferase Superoxide dismutase Glucose-6-phosphatase dehydrogenase Cholesterol Urea *
p < 0.05;
Units
GI
GII
(g/L) (g/L) (g/L)
71.73 2.201 37.70 1.381 34.03 2.030 1.180 0.082 125.73 24.16 1487.24 78.56 24.21 16.26 8.947 0.553 7.199 0.560
68.90 1.786 35.01 1.29 33.31 1.474 1.100 0.076 241.12 29.15** 1310.64 178.91 33.67 14.40* 7.702 0.495 6.731 0.511
(U/g Hb) (U/g Hb) (U/L) (mmol/L) (mmol/L)
**
p < 0.001.
4. Discussion Changes in blood parameters (Table 1) indicated moderate anaemia and leukocystosis. The erythrocyte count, haematocrit and haemoglobin concentrations were decreased compared with those of the healthy rats. In infected rats the increase in MCV values ( p < 0.01) and the decrease in MCHC values ( p < 0.001) indicated macrocytic hypochromic anaemia. The increase in RDW values indicated a degree of anisocytosis. The significant increase in GSH-Px activity in whole blood in the present study came in line with the findings obtained by Igbokwe et al. (1996) in calves artificially infected with Trypanosoma vivax. Igbokwe et al. (1994) found that erythrocytes of Trypanosoma brucei-infected mice produced significantly greater amounts of by-products of lipid peroxidation than the erythrocytes of the control mice. This suggests that the infected mice may have reduced ability in the prevention of free radicals-mediated lipid peroxidation in the erythrocyte membrane. This may contribute to the pathogenesis in anaemia in trypanosomosis. The increase in the activity of G6P-DH can be explained by the finding that during parasitic infection, erythrocytes produce reactive oxygen species (ROS) and hydrogen peroxide (H2O2) that enhance lipid peroxidation and activate host cell hexose monophosphate shunt. Anosa and Kaneko (1983) found that when deer mice were infected with T. brucei there was a significant increase in the erythrocyte hexokinase, glutathione peroxidase and glucose-6-phosphate dehydrogenase. NADPH produced by hexose monophosphate shunt maintains glutathione in its reduced form and glutathione is a potent antioxidant. In the present study, no statistically significant difference was
observed in the activity of superoxide dismutase in infected and control rats. Similar results have been reported in other parasitic infections (Wozencraft, 1986; Grewal et al., 2005). However, Anosa and Kaneko (1983) reported that the total activity of superoxide dismutase of the enlarged spleen and liver of T. brucei-infected mice was increased, although the activity per unit weight was either decreased or not altered. References Al-Rawashdeh, O.F., Sharif, L.A., Al-Qudah, K., Al-Ani, F.K., 1999. Trypanosoma evansi infection in camels in Jordan. Rev. Elev. Med. Vet. Pays Trop. 52, 233–237. Anosa, V.O., Kaneko, J.J., 1983. Pathogenesis of Trypanosoma brucei infection in deer mice (Peromyscus maniculatus): hematologic, erythrocyte biochemical, and iron metabolic aspects. Am. J. Vet. Res. 44, 639–644. Grewal, A., Ahuja, C.S., Singha, S.P.S., Chaudhary, K.C., 2005. Status of lipid peroxidation, some antioxidant enzymes and erythrocytic fragility of crossbred cattle naturally infected with Theileria annulata. Vet. Res. Commun. 29, 387–394. Haroun, E.M., Magzoub, M., Mahmoud, O.M., Qarawi, A.A., Hawas, A., Omer, O.H., 2000. Some clinicopathological aspects of experimental Trypanosoma evansi infection in Najdi camels (Camelus dromedarius). J. Camel Pract. Res. 7, 107–108. Igbokwe, I.O., Esievo, K.A., Saror, D.I., Obagaiye, O.K., 1994. Increased susceptibility of erythrocytes to in vitro peroxidation in acute Trypanosoma brucei infection of mice. Vet. Parasitol. 55, 279–286. Igbokwe, I.O., Umar, I.A., Omage, J.J., Ibrahim, N.D., Kadima, K.B., Obagaiye, O.K., Saror, D.I., Esievo, K.A., 1996. Effect of acute Trypanosoma vivax infection on cattle erythrocyte glutathione and susceptibility to in vitro peroxidation. Vet. Parasitol. 63, 215–224. Joshi, P.P., Shegokar, V.R., Powar, R.M., Herder, S., Katti, R., Salkar, H.R., Dani, V.S., Bhargava, A., Jannin, J., Truc, P., 2005. Human trypanosomiasis caused by Trypanosoma evansi in India: the first case report. Am. J. Trop. Med. Hyg. 73, 491–549. Luckins, A.G., 1988. Separation of Trypanosoma evansi in Asia. Parasitol. Today 4, 137–142.
O.H. Omer et al. / Veterinary Parasitology 145 (2007) 142–145 Lun, R., Fang, Y., Wang, C.J., Brun, R., 1993. Trypanosomiasis of domestic animals in China. Parasitol. Today 9, 41–45. Mahmoud, M.M., Gray, A.R., 1980. Trypanosomiasis due to Trypanosoma evansi (Steel, 1885) Balbiani, 1888. A review of recent research. Trop. Anim. Hlth. Prod. 12, 35–47. OIE, 2000. The Office International des epizooties: Manual of Standards for Diagnostic Tests & Vaccines, 4th ed.
145
Raisinghani, P.M., Bhatia, J.S., Vjas, U.K., Arya, P.L., Lodha, K.R., 1980. Pathology of experimental surra in camels (Camelus dromedarius). Indian J. Anim. Sci. 50, 966–969. Wozencraft, A.O., 1986. Damage to malaria infected erythrocytes following exposure to oxidant generating systems. Parasitology 92, 559–567.