Sleeping sickness test. Technician carrying out a CATT (card agglutinated test for trypanosomiasis). This cheap quick blood test is commonly used in the field to detect the disease. Trypanosomiasis or African sleeping sickness is caused by Trypanosoma sp., a parasitic protozoan. The protozoa are passed onto humans by blood-sucking tsetse flies, Glossina sp., when they feed. The protozoa infect the blood, lymph nodes, heart and brain causing a fever. Nervous system damage leads to lethargy and tremors. Without treatment, fatal damage to the heart or brain results. Photographed in Uganda.