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Kizza D, Ocaido M, Mugisha A, Azuba R, Nalule S, Onyuth H, Musinguzi SP, Okwasiimire R, Waiswa C. Prevalence and risk factors for trypanosome infection in cattle from communities surrounding the Murchison Falls National Park, Uganda. Parasit Vectors 2021; 14:513. [PMID: 34620230 PMCID: PMC8499574 DOI: 10.1186/s13071-021-04987-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/31/2021] [Indexed: 11/10/2022] Open
Abstract
Background Bovine trypanosomosis transmitted by tsetse flies is a major constraint to cattle health and productivity in all sub-Saharan countries, including Uganda. The objectives of this study were to determine the prevalence of bovine trypanosomosis and identify its associated risk factors and the species of trypanosomes associated with the disease. Methodology A cross-sectional study was conducted around Murchison Falls National Park, Uganda from January 2020 to April 2020. Trypanosomes were detected in blood samples by PCR analysis targeting the internal transcribed spacer 1 (ITS-PCR assays), and trypanosomes in positive blood samples were sequenced. Results Of 460 blood samples collected and tested, 136 (29.6%) were positive for trypanosome infections and 324 (70.4%) were negative. The overall trypanosome prevalence was 29.6% (95% confidence interval 25.4–33.8%), attributed to three trypanosome species. Of these three species, Trypanosoma vivax was the most prevalent (n = 130, 28.3%) while the others were detected as mixed infections: T. vivax + Trypanosomacongolense (n = 2, 0.4%) and T. vivax + Trypanosomaevansi (n = 1, 0.2%). There were significant differences in trypanosome prevalence according to sex (χ2 = 62, df = 1, P < 0.05), age (χ2 = 6.28, df = 2, P = 0.0043) and cattle breed (χ2 = 10.61, df = 1, P = 0.001). Conclusions Trypanosomosis remains a major limitation to cattle production around Murchison Falls National Park and interventions are urgently needed. In our study, the prevalence of trypanosome infections was high, with T. vivax identified as the most prevalent species. Age, sex and breed of cattle were risk factors for trypanosome infection. Graphical Abstract ![]()
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Affiliation(s)
- Daniel Kizza
- Department of Livestock and Industrial Resources, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda.
| | - Michael Ocaido
- Department of Wildlife, Aquatic and Animal Resources College of Veterinary Medicine Animal Resources, Biosecurity Makerere University, Kampala, Uganda
| | - Anthony Mugisha
- Department of Livestock and Industrial Resources, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Rose Azuba
- Department of Livestock and Industrial Resources, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Sarah Nalule
- Department of Wildlife, Aquatic and Animal Resources College of Veterinary Medicine Animal Resources, Biosecurity Makerere University, Kampala, Uganda
| | - Howard Onyuth
- Department of Wildlife, Aquatic and Animal Resources College of Veterinary Medicine Animal Resources, Biosecurity Makerere University, Kampala, Uganda
| | - Simon Peter Musinguzi
- Department of Agriculture, Faculty of Vocational studies, Kyambogo University, P.0 Box 1 Kyambogo, Kampala, Uganda
| | - Rodney Okwasiimire
- Central Diagnostic Laboratory, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Charles Waiswa
- Department of Veterinary Pharmacy, Clinical and Comparative Medicine, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
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MUSINGUZI SP, SUGANUMA K, ASADA M, LAOHASINNARONG D, SIVAKUMAR T, YOKOYAMA N, NAMANGALA B, SUGIMOTO C, SUZUKI Y, XUAN X, INOUE N. A PCR-based survey of animal African trypanosomosis and selected piroplasm parasites of cattle and goats in Zambia. J Vet Med Sci 2017; 78:1819-1824. [PMID: 27616437 PMCID: PMC5240760 DOI: 10.1292/jvms.16-0240] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/27/2016] [Indexed: 11/22/2022] Open
Abstract
We screened cattle and goats from the districts of Chama, Monze and Mumbwa in Zambia for animal African trypanosomes, Babesia bigemina and Theileria parva using PCRs; 38.1% of the samples tested positive for at least one of the parasite species. The most common parasite was Trypanosoma vivax (19.8%). Its incidence was significantly higher in goats than in cattle, (P<0.05). B. bigemina was found in samples from all the three areas, making it the most widespread of the parasites in Zambia. Among the tested samples, 12.0% of the positive samples were mixed infections. There were significant differences in the infection rates of T. vivax (Mumbwa had a significantly higher infection rate [39.6%, P<0.0001]), Th. parva (Monze had the only cases [P<0.0004]) and B. bigemina (Monze had a significantly higher infection rate [40.5%, P<0.0001]). According to the hematocrit values, the packed cell volume (%) among the cattle with mixed infections was significantly lower than that of the other cattle. The presence of multiple parasite species and mixed infections among the Zambian cattle and goat populations is of both clinical and economic importance to livestock farming. The absence of trypanosomosis among the samples from Monze can be attributed to tsetse eradication efforts that took place around Lake Kariba. This shows that the prevention and control of these parasitic diseases can have a significant impact on the disease status, which can translate directly into the improvement of the livestock sector in Zambia.
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Affiliation(s)
- Simon Peter MUSINGUZI
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
| | - Keisuke SUGANUMA
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
| | - Masahito ASADA
- Department of Protozoology, Institute of Tropical Medicine
(NEKKEN), Nagasaki University, 1–12–4 Sakamoto, Nagasaki 852–8523, Japan
| | - Dusit LAOHASINNARONG
- Faculty of Veterinary Science, Mahidol University, 999
Phuttamonthon Sai 4, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand
| | - Thillaiampalam SIVAKUMAR
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
- Veterinary Research Institute, Peradeniya, Sri Lanka
| | - Naoaki YOKOYAMA
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
| | - Boniface NAMANGALA
- Department of Paraclinical Studies, School of Veterinary
Medicine, University of Zambia, P.O. Box 32379, Lusaka, Zambia
| | - Chihiro SUGIMOTO
- Research Center for Zoonosis Control, Hokkaido University,
Sapporo, Hokkaido 060–0818, Japan
| | - Yasuhiko SUZUKI
- Research Center for Zoonosis Control, Hokkaido University,
Sapporo, Hokkaido 060–0818, Japan
| | - Xuenan XUAN
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
| | - Noboru INOUE
- OIE Reference Laboratory on Surra, National Research Center
for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine,
Inada-cho, Obihiro, Hokkaido 080–8555, Japan
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Angwech H, Nyeko JHP, Opiyo EA, Okello-Onen J, Opiro R, Echodu R, Malinga GM, Njahira MN, Skilton RA. Heterogeneity in the prevalence and intensity of bovine trypanosomiasis in the districts of Amuru and Nwoya, Northern Uganda. BMC Vet Res 2015; 11:255. [PMID: 26449544 PMCID: PMC4599665 DOI: 10.1186/s12917-015-0567-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 09/30/2015] [Indexed: 11/11/2022] Open
Abstract
Background Livestock trypanosomiasis, transmitted mainly by tsetse flies of the genus Glossina is a major constraint to livestock health and productivity in the sub-Saharan Africa. Knowledge of the prevalence and intensity of trypanosomiasis is important in understanding the epidemiology of the disease. The objectives of this study were to (a) assess the prevalence and intensity of trypanosome infections in cattle, and (b) to investigate the reasons for the heterogeneity of the disease in the tsetse infested districts of Amuru and Nwoya, northern Uganda. Methods A cross-sectional study was conducted from September, 2011 to January, 2012. Blood samples were collected from 816 cattle following jugular vein puncture, and screened for trypanosomes by HCT and ITS-PCR. A Pearson chi-squared test and logistic regression analyses were performed to determine the association between location, age, sex, and prevalence of trypanosome infections. Results Out of the 816 blood samples examined, 178 (22 %) and 338 (41 %) tested positive for trypanosomiasis by HCT and ITS-PCR, respectively. Trypanosoma vivax infection accounted for 77 % of infections detected by ITS-PCR, T. congolense (16 %), T. brucei s.l (4 %) and mixed (T. vivax/ T. congolense/T.brucei) infections (3 %). The risk of trypanosome infection was significantly associated with cattle age (χ2
= 220.4, df = 3, P < 0.001). The highest proportions of infected animals were adult males (26.7 %) and the least infected were the less than one year old calves (2.0 %). In addition, the risk of trypanosome infection was significantly associated with sex (χ2 = 16.64, df = 1, P < 0.001), and males had a significantly higher prevalence of infections (26.8 %) than females (14.6 %). Conclusion Our results indicate that the prevalence and intensity of trypanosome infections are highly heterogeneous being associated with cattle age, location and sex.
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Affiliation(s)
- Harriet Angwech
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
| | - Jack H P Nyeko
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
| | - Elizabeth A Opiyo
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
| | - Joseph Okello-Onen
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda
| | - Robert Opiro
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
| | - Geoffrey M Malinga
- Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. .,Department of Biology, University of Eastern Finland, P. O. Box 111, 80101, Joensuu, Finland.
| | - Moses N Njahira
- Biosciences Eastern and Central Africa (BecA), International Livestock Research Institute (ILRI) - Hub, Old Naivasha Road, P.O. Box 30709- 00100, Nairobi, Kenya.
| | - Robert A Skilton
- Biosciences Eastern and Central Africa (BecA), International Livestock Research Institute (ILRI) - Hub, Old Naivasha Road, P.O. Box 30709- 00100, Nairobi, Kenya.
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Duguma R, Tasew S, Olani A, Damena D, Alemu D, Mulatu T, Alemayehu Y, Yohannes M, Bekana M, Hoppenheit A, Abatih E, Habtewold T, Delespaux V, Duchateau L. Spatial distribution of Glossina sp. and Trypanosoma sp. in south-western Ethiopia. Parasit Vectors 2015; 8:430. [PMID: 26286484 PMCID: PMC4544814 DOI: 10.1186/s13071-015-1041-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 08/10/2015] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Accurate information on the distribution of the tsetse fly is of paramount importance to better control animal trypanosomosis. Entomological and parasitological surveys were conducted in the tsetse belt of south-western Ethiopia to describe the prevalence of trypanosomosis (PoT), the abundance of tsetse flies (AT) and to evaluate the association with potential risk factors. METHODS The study was conducted between 2009 and 2012. The parasitological survey data were analysed by a random effects logistic regression model, whereas the entomological survey data were analysed by a Poisson regression model. The percentage of animals with trypanosomosis was regressed on the tsetse fly count using a random effects logistic regression model. RESULTS The following six risk factors were evaluated for PoT (i) altitude: significant and inverse correlation with trypanosomosis, (ii) annual variation of PoT: no significant difference between years, (iii) regional state: compared to Benishangul-Gumuz (18.0%), the three remaining regional states showed significantly lower PoT, (iv) river system: the PoT differed significantly between the river systems, (iv) sex: male animals (11.0%) were more affected than females (9.0%), and finally (vi) age at sampling: no difference between the considered classes. Observed trypanosome species were T. congolense (76.0%), T. vivax (18.1%), T. b. brucei (3.6%), and mixed T. congolense/vivax (2.4%). The first four risk factors listed above were also evaluated for AT, and all have a significant effect on AT. In the multivariable model only altitude was retained with AT decreasing with increasing altitude. Four different Glossina species were identified i.e. G. tachinoides (52.0%), G. pallidipes (26.0%), G.morsitans submorsitans (15.0%) and G. fuscipes fuscipes (7.0 %). Significant differences in catches/trap/day between districts were observed for each species. No association could be found between the tsetse fly counts and trypanosomosis prevalence. CONCLUSIONS Trypanosomosis remains a constraint to livestock production in south-western Ethiopia. Four Glossina and three Trypanosoma species were observed. Altitude had a significant impact on AT and PoT. PoT is not associated with AT, which could be explained by the importance of mechanical transmission. This needs to be investigated further as it might jeopardize control strategies that target the tsetse fly population.
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Affiliation(s)
- Reta Duguma
- Department of Clinical studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O.Box 34, Bishoftu, Oromia, Ethiopia.
- Department of Comparative Physiology and Biometrics, Faculty of Veterinary Sciences, Universiteit Gent, Salisburylaan 133, B-9820, Merelbeke, Belgium.
| | - Senbeta Tasew
- National Tsetse and Trypanosome Investigation and Control Centre, P.O.Box 13, Illu-Aba-Bora, Bedelle, Ethiopia.
| | - Abebe Olani
- National Animal Health Diagnostic and Investigation Centre, P.O. Box 04, Sebeta, Oromia, Ethiopia.
| | - Delesa Damena
- National Animal Health Diagnostic and Investigation Centre, P.O. Box 04, Sebeta, Oromia, Ethiopia.
| | - Dereje Alemu
- National Tsetse and Trypanosome Investigation and Control Centre, P.O.Box 13, Illu-Aba-Bora, Bedelle, Ethiopia.
| | - Tesfaye Mulatu
- National Animal Health Diagnostic and Investigation Centre, P.O. Box 04, Sebeta, Oromia, Ethiopia.
| | - Yoseph Alemayehu
- International Maize & Wheat Improvement Centre (CIMMYT), Socio-economics Program, Global Cereal Rust Monitoring system, P.O. Box 5689, Addis Ababa, Ethiopia.
| | - Moti Yohannes
- Department of Microbiology and Veterinary Public Health, School of Veterinary Medicine, Jimma University, P.O. Box 307, Jimma, Ethiopia.
| | - Merga Bekana
- Department of Clinical studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O.Box 34, Bishoftu, Oromia, Ethiopia.
| | - Antje Hoppenheit
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universitaet Berlin, Robert-von-Ostertagstr. 7-13, 14163, Berlin, Germany.
| | - Emmanuel Abatih
- Department of Biomedical Sciences, Institute of Tropical Medicine, Nationalestraat 155, Antwerp, Belgium.
| | - Tibebu Habtewold
- Department of Comparative Physiology and Biometrics, Faculty of Veterinary Sciences, Universiteit Gent, Salisburylaan 133, B-9820, Merelbeke, Belgium.
| | - Vincent Delespaux
- Department of Biomedical Sciences, Institute of Tropical Medicine, Nationalestraat 155, Antwerp, Belgium.
| | - Luc Duchateau
- Department of Comparative Physiology and Biometrics, Faculty of Veterinary Sciences, Universiteit Gent, Salisburylaan 133, B-9820, Merelbeke, Belgium.
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Van den Bossche P, Delespaux V. Options for the control of tsetse-transmitted livestock trypanosomosis. An epidemiological perspective. Vet Parasitol 2011; 181:37-42. [DOI: 10.1016/j.vetpar.2011.04.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Analysis of host genetic factors influencing African trypanosome species infection in a cohort of Tanzanian Bos indicus cattle. Vet Parasitol 2011; 179:35-42. [PMID: 21377802 DOI: 10.1016/j.vetpar.2011.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/31/2011] [Accepted: 02/07/2011] [Indexed: 11/21/2022]
Abstract
Trypanosomosis caused by infection with protozoan parasites of the genus Trypanosoma is a major health constraint to cattle production in many African countries. One hundred and seventy one Bos indicus cattle from traditional pastoral Maasai (87) and more intensively managed Boran (84) animals in Tanzania were screened by PCR for the presence of African animal trypanosomes (Trypanosoma congolense, Trypanosoma vivax and Trypanosoma brucei), using blood samples archived on FTA cards. All cattle screened for trypanosomes were also genotyped at the highly polymorphic major histocompatibility complex (MHC) class II DRB3 locus to investigate possible associations between host MHC and trypanosome infection. Overall, 23.4% of the 171 cattle tested positive for at least one of the three trypanosome species. The prevalence of individual trypanosome species was 8.8% (T. congolense), 4.7% (T. vivax) and 15.8% (T. brucei). The high prevalence of T. brucei compared with T. congolense and T. vivax was unexpected as this species has previously been considered to be of lesser importance in terms of African bovine trypanosomosis. Significantly higher numbers of Maasai cattle were infected with T. brucei (23.0%, p=0.009) and T. congolense (13.8%, p=0.019) compared with Boran cattle (8.3% and 3.6%, respectively). Analysis of BoLA-DRB3 diversity in this cohort identified extensive allelic diversity. Thirty-three BoLA-DRB3 PCR-RFLP defined alleles were identified. One allele (DRB3*15) was significantly associated with an increased risk (odds ratio, OR=2.71, p=0.034) of T. brucei infection and three alleles (DRB3*35, *16 and *23) were associated with increased risk of T. congolense infection. While further work is required to dissect the role of these alleles in susceptibility to T. brucei and T. congolense infections, this study demonstrates the utility of FTA archived blood samples in combined molecular analyses of both host and pathogen.
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Prevalence and incidence of bovine trypanosomosis in an agro-pastoral area of southwestern Burkina Faso. Res Vet Sci 2009; 88:470-7. [PMID: 20044115 DOI: 10.1016/j.rvsc.2009.10.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 09/02/2009] [Accepted: 10/06/2009] [Indexed: 11/21/2022]
Abstract
The present study was conducted to determine the prevalence and incidence of trypanosomosis and to investigate some factors influencing them in an agro-pastoral area of southwestern Burkina Faso. A total of 363 crossbred cattle (Baoule-zebu peul), which were bred under natural trypanosomosis challenge, were monitored monthly for parasitaemia, packed cell volume (PCV) and serological analyses over 2years. The parasitological prevalence estimated at the beginning of the survey using the buffy coat technique (BCT) was 7.54%. As much as 66.7% of all trypanosome infections were due to Trypanosoma vivax, 23.8% due to Trypanosoma congolense and 9.5% due to T. vivax/T. congolense mixed infections. The monthly serological incidence varied from 0.29% to 19.29%. The season was the most important factor influencing the serological prevalence and incidence and the animal PCV. The dry hot season is associated with increasing seroprevalences and incidences and consequently a decreasing average of PCV. In addition, an important spatial heterogeneity was observed.
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Acute haemorrhagic syndrome of bovine trypanosomosis in Uganda. Acta Trop 2008; 107:186-91. [PMID: 18599006 DOI: 10.1016/j.actatropica.2008.05.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 11/21/2022]
Abstract
A study was undertaken in July 2005 to investigate an acute haemorrhagic syndrome that caused cattle mortality starting March 2005 in Mifumi, Senda, Kainja and Nyagoke villages of Tororo district in Uganda; areas dominantly infested with Glossina fuscipes fuscipes with scanty G. pallidipes. Four hundred and one (401) cattle belonging to 158 farmers were randomly sampled from a population of 549 and screened using a combination of Haematocrit Centrifugation Technique (HCT) and Buffy Coat Technique (BCT) for trypanosomosis. Of which 49 (12.2%) had trypanosome infection. Clinical cases manifested bleeding through the ears, severe weight loss, anaemia, weakness and enlarged lymph nodes prior to death. Out of an original population of 844 cattle 295 (35%) had died. The prevalence of bovine trypanosomosis in herds experiencing mortality (21.5%) was significantly higher than in those without mortality (2.6%) (chi(2)=33.4, P<0.001). Herd size, number of draught oxen and lactating cows in a given herd significantly influenced the risk of mortality (P<0.001). Males had a significantly higher prevalence of trypanosomosis (17.8%) than females (9.5%) (chi(2)=5.58, P<0.05) and significantly lower mean packed cell volume (PCV) (23.7%) than females (25.4%) (P<0.05). Older calves (7-12 months), yearlings (13-24 months) and adults (>24 months) with prevalences of 11.1%, 15.4% and 11.8%, respectively, were the most affected age categories. Trypanosome-infected cattle had a significantly lower mean PCV (17.9%) than non-infected ones (25.8%) (P<0.001), and a significantly higher proportion of anaemic animals (81.6%) than non-infected ones (37.2%) (chi(2)=34.6, P<0.001). Trypanosoma vivax was the dominant trypanosome species, constituting 82% of trypanosome infections. This work has provided further evidence on the importance of T. vivax-induced acute haemorrhagic syndrome in livestock trypanosomosis.
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Marcotty T, Simukoko H, Berkvens D, Vercruysse J, Praet N, Van den Bossche P. Evaluating the use of packed cell volume as an indicator of trypanosomal infections in cattle in eastern Zambia. Prev Vet Med 2008; 87:288-300. [PMID: 18586340 DOI: 10.1016/j.prevetmed.2008.05.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 04/23/2008] [Accepted: 05/09/2008] [Indexed: 11/29/2022]
Abstract
In this study, packed cell volume-values (PCV) are evaluated as indicator of trypanosomiasis infections in cattle. A total of 734 blood samples were collected in 11 different sampling sites in eastern Zambia: 84 calves (< 1 year), 52 young females and 40 young males (between 1 and 3 years), 228 cows, 317 oxen and 13 bulls (> 3 years). All samples were subjected to three diagnostic tests: parasitological examination using the buffy coat method, PCR/RFLP and PCV determination. The results were compared and analysed in a Bayesian model, which allowed the estimation of the infection prevalence and the respective test sensitivities and specificities. The presence of a trypanosomal infection significantly reduced the PCV, independently of the age and sex of the infected animal. The estimated prevalence of trypanosomal infections in the study area was 34% (95% credibility interval: 30-38%). While the specificity of both the parasitological and the PCR/RFLP tests were set to 1, the parasitological diagnosis had a low sensitivity (37%) compared to the PCR/RFLP (96%). When using a cut-off value of 24, the PCV had a high specificity (98%) but a rather low sensitivity (53%) for identifying trypanosomiasis infections. Using 26% as a cut-off increased the sensitivity to 76% without much affecting the specificity (94%). A parallel combination of the parasitological diagnosis and the PCV improved the diagnostic sensitivity (74% and 89% for PCV cut-off values of 24% or 26%, respectively) while specificity remained high (98% and 94% for PCV cut-off values of 24% or 26%, respectively). These results suggest that such a combination could advantageously be used for the diagnosis of cattle trypanosomiasis in the field: it is much more sensitive than parasitological examination alone and it is much cheaper than molecular tests. However, the value of this approach depends largely on the determination of an appropriate cut-off value to consider a sample positive, depending on the required test sensitivities and specificities.
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Affiliation(s)
- T Marcotty
- Institute of Tropical Medicine Antwerp, Animal Health Department, Nationalestraat 155, B-2000 Antwerp, Belgium.
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