NAVLE Hemic and Lymphatic

Bovine Trypanosomiasis Study Guide

African Animal Trypanosomiasis (AAT), also known as nagana, is a devastating protozoan disease of cattle caused by several species of Trypanosoma transmitted primarily by tsetse flies (Glossina spp.).

Overview and Clinical Importance

African Animal Trypanosomiasis (AAT), also known as nagana, is a devastating protozoan disease of cattle caused by several species of Trypanosoma transmitted primarily by tsetse flies (Glossina spp.). This disease represents one of the most significant constraints on livestock production in sub-Saharan Africa, causing annual economic losses estimated at over 1 billion USD.

The disease is characterized by intermittent fever, progressive anemia, weight loss, and lymphadenopathy. Trypanosomiasis affects the hemic and lymphatic systems through complex mechanisms involving immune-mediated hemolysis, erythrophagocytosis, and lymphoid hyperplasia followed by depletion.

High-YieldAnemia is the KEY clinical indicator in bovine trypanosomiasis and is better correlated with productivity loss than parasitemia. Treatment decisions in the field are often based on packed cell volume (PCV) rather than parasite detection.
Species Subgenus Location in Host Severity in Cattle
T. congolense Nannomonas Intravascular (microvasculature) Severe - Most important in East Africa
T. vivax Duttonella Intravascular (bloodstream) Moderate to Severe - Most important in West Africa
T. brucei brucei Trypanozoon Extravascular (tissues) Mild to Moderate in cattle

Etiology and Classification

Bovine trypanosomiasis is caused by flagellated protozoan parasites of the genus Trypanosoma. The three most important species affecting cattle in Africa are:

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