African animal trypanosomiasis [trypanosomosis] (AAT) is a disease complex caused by tsetse-fly-transmitted Trypanosoma congolense Broden, T. vivax Ziemann, or T. brucei brucei Plimmer and Bradford, or simultaneous infection with one or more of these trypanosomes. African animal trypanosomiasis is most important in cattle, but can cause serious losses in pigs, camels, goats, and sheep. Infection of cattle by one or more of the three African animal trypanosomes results in subacute, acute, or chronic disease characterized by intermittent fever, anemia, occasional diarrhea, and rapid loss of condition, and often terminates in death. In southern Africa the disease is widely known as nagana (USAHA 1998). Tsetse-transmitted [Glossina] trypanosomiasis is an infectious disease unique to Africa and caused by various species of blood parasites. The disease affects both people [Human African Trypanosomiasis (HAT) or sleeping sickness] (Pentreath and Kennedy 2004) and animals [Animal African Trypanosomiasis (AAT) or nagana], and occurs in 37 sub-Saharan countries covering more than 9 million km2, an area which corresponds approximately to one-third of the Africa's total land area. The infection threatens an estimated about 50 million head of cattle. Every year, AAT causes about 3 million deaths in cattle while approximately 35 million doses of trypanocidal drugs are administered. Nagana has a severe impact on agriculture in sub-Saharan Africa (PAAT 2008a; Shaw 2004; Taylor and Authié 2004; Feldmann et al., this volume). There now exists a reasonable collection of methods and reagents from which scientists in well-equipped laboratories may choose the one most appropriate for diagnosis of trypanosomiasis in an given situation (Eisler et al. 2004). See ‘trypanosomosis’.