African Trypanosomes: Virulence Factors, Pathogenicity and Host Responses

Trypanosomosis is a vector-born protozoan disease of animals and man caused by several Trypanosoma species or subspecies. Many virulence factors of the parasite such as the variant surface glycoproteins, trypanosome enzymes, B-cell mitogens and T lymphocyte triggering factors act in concert to cause the disease. During infection, complex interactions occur between the hosts’ immune responses and trypanosomes resulting in anemia, leukopenia, thrombocytopenia, tissue inflammation and damage, meningoencephalitis, splenomegaly and cachexia. The severity of the disease varies among hosts in which some are susceptible and others are resistant. The unlimited capacity of the parasite to change the targeted surface antigens is the major limiting factor in the development of effective vaccines. However, vaccination and treatment strategies targeting the virulence factors are promising approaches. The use of host resistance is one potentially cost effective solution in the control of Trypanosomosis. In addition to the existing methods of control, a deeper understanding of the parasite genomics and proteomics may provide insights to develop means to interfere the associated pathologies and control the disease.