Trypanosoma brucei.

Abstract

Disease Agent: • Trypanosoma brucei gambiense • Trypanosoma brucei rhodesiense Disease Agent Characteristics: • Protozoan, 14-33 mm • Order: Kinetoplastida • Family: Trypanosomatidae • Hemoflagellates that do not invade cells but inhabit connective tissue space • Found in humans as pleomorphic trypomastigotes present in peripheral blood, lymph nodes, spleen, and cerebrospinal fluid Disease Name: • African sleeping sickness • Human African trypanosomiasis Priority Level: • Scientific/Epidemiologic evidence regarding blood safety: Theoretical • Public perception and/or regulatory concern regarding blood safety: Absent • Public concern regarding disease agent: Very low Background: • Stable, limited to African continent Common Human Exposure Routes: • Bite of infected tsetse fly Likelihood of Secondary Transmission: • Low At-Risk Populations: • Residents of endemic areas of Africa T. b. gambiense—West and Central Africa T. b. rhodesiense—East and Southeast Africa • Over 60 million people at risk, with 150,000 new cases/year and nearly 100,000 deaths/year Vector and Reservoir Involved: • Tsetse flies of the genus Glossina • Primarily infects humans Blood Phase: • Parasitemia is present during the symptomatic phase and can be present for years. Survival/Persistence in Blood Products: • Unknown Transmission by Blood Transfusion: • Single, poorly documented case of transmission by blood transfusion Cases/Frequency in Population: • WHO estimates that nearly half a million people carry this infection, albeit underreported. Incubation Period: • Local signs present 2-3 days to weeks following bite of infected tsetse fly. • CNS signs can present a few months (T.b. rhodesiense) to several years (T.b. gambiense) after infection. Likelihood of Clinical Disease: • High Primary Disease Symptoms: • Chancre at the inoculation site, which persists for up to 2 weeks. Thereafter, generalized lymphadenopathy followed by fever, headache, pruritus, skin rash, hepatosplenomegaly, anemia, edema, cardiovascular, endocrinological, and renal disorders. • Second stage includes neurological effects (sleeping disturbances, alteration of mental state, abnormal reflexes, tone, coordination, and sensory disorders). Progressive, untreated disease leads into deterioration of consciousness and death in 100% of cases. Severity of Clinical Disease: • Severe Mortality: • Approaches 100% in untreated cases • 2-8% in treated cases Chronic Carriage: • Months to years Treatment Available/Efficacious: • Pentamidine isothionate, suramin, melarsoprol, and eflornithine are used for therapy, depending on the stage of disease (hemolymphatic or CNS) and the subspecies of T. brucei. • Treatments primarily effective during early stages of disease but less effective once central nervous system involved. Drugs can have serious side effects. Agent-Specific Screening Questions(s): • No specific question is in use. • Not indicated in the US • No sensitive or specific question is feasible. APPENDIX 2