Acta Parasitologica Globalis 8 (1): 39-49, 2017 ISSN 2079-2018 © IDOSI Publications, 2017 DOI: 10.5829/idosi.apg.2017.39.49 Corresponding Authore: Abrham Ayele, P.O. Box; 196; University of Gondar, Gondar, Ethiopia. Cell: +251946236928, E-mail: abrhamts21@gmail.com. 39 Review on Characterization of Trypanosoma congolense; A Major Parasite of Cattle in Africa Ayele Abrham, Dagnachew Shemeles, Adugna Takele and Dessie Berhanu 1 1 2 3 Department of Paraclinicalstudies, Faculty of Veterinary Medicine, University of Gondar, Ethiopia 1 Department Veterinary Clinical Medicine, Faculty of Veterinary Medicine, University of Gondar, Ethiopia 2 Faculty of Veterinary Medicine, University of Gondar, Ethiopia 3 Abstract: Trypanosomosis is a protozoan disease caused by the genus Trypanosoma affecting animals and human mainly in sub-Saharan Africa and also in Latin America. Trypanosoma congolense (T. congolense) is one of the important pathogen of livestock in Africa transmitted cyclically by tsetse flies. The disease results in clinical syndromes such as anemia, emaciation and mortality. T. congolense is a complex species comprising three distinct genotypic types: (1) the savannah-type, (2) the West African riverine/forest-type and (3) the kilifi- type. Each genotype of T. congolense contains different strains of Trypanosoma. The ability of trypanosomes to change their surface-coat-antigen continuously leads to the exhaustion of the antibody production by the host leading to immune suppression. T. congolense infection can be diagnosed by clinical, parasitological, immunological and molecular methods. Control of the disease should combine treatment of infected animals and vector control. Even though, trypanocidal drugs will continue to play an important role in the integrated control of trypanosomosis, the development of trypanosome resistance to trypanocides is a continuous threat to their sustainable use. The available information on the molecular characteristics of different strains and genetic composition of T. congolense in relation to its pathology in different species of hosts is not yet elucidated in Ethiopia and hence requires thorough investigations. Key words: Molecular Characteristics Trypanosoma congolense Pathogen Africa Ethiopia INTRODUCTION AAT is a collection of symptomatically similar Trypanosomosis is a worldwide disease caused by species. In cattle, the most widespread and virulent of the species of the genus Trypanosoma, which affects these species is T. congolense [2]. T. congolense is an humans, as well as domestic and wild animals. This animal pathogenic trypanosome species which discovered wasting disease is spread by the bite of the infamous in 1904 by Broden, next to T. brucei (in 1895 by Bruce) tsetse (Glossina). Tsetse flies inhabit 8.7 million km of but before T. vivax (in 1905 by Ziemann) [3]. Although 2 sub-Saharan Africa known as the “tsetse belt” [1]. This this species of trypanosome is the smallest of the area represents approximately a third of Africa, or to trypanosome, it remains the most pathogenic to animals put it into perspective, an area greater than that of the [4]. A wide range of domestic animals such as cattle, entire Australian continent. In the areas where tsetse is horses, camels, donkeys, mules, water buffalo, pigs, goats prevalent, agricultural output is suboptimal because of the and dogs are victim to trypanosome infection [5]. The risk of African animal trypanosomosis (AAT). Every year main pathological symptoms of animal trypanosomosis approximately 40 million cattle are threatened and 3 million are weight loss, anaemia and immunosuppression; but the are killed by trypanosomosis. The economic loss resulting mechanisms involved are poorly understood [6]. directly from animal death is in the range of US$ 1.0–1.2 Parasitemia in all strains of T. congolense infection is billion annually. When secondary losses such as reduced developed between 7 and 11 days post-infection (dpi). manure and draft power and thus decreased crop yields The savannah-type causes consistently higher levels are included, the total gross domestic product lost can be of parasitaemia and lower packed red cell volume as much as $4.5 billion per annum [1]. percentages and leukocyte counts than the other two diseases caused by a number of different trypanosome