[Control of Trypanosoma gambiense trypanosomiasis. Evaluation of a strategy based on the treatment of serologically suspected cases with a single dose of diminazene].

A novel method for the control of T.b. gambiense trypanosomiasis was evaluated in an endemic focus of Zaïre where a high incidence had persisted despite massive participation in active case-finding surveys based on lymph node puncture. All inhabitants of 3 villages were examined with a card agglutination serological test (CATT), and parasitological examinations were performed on those who were CATT+. Individuals in whom we detected trypanosomes were treated as usual. A lumbar puncture was carried out on CATT+/parasitology- subjects; those whose cerebrospinal fluid showed more than 3 white blood cell (WBC) per mm3 were treated with a full course of melarsoprol while those with a CSF WBC count between 1 and 3 per mm3 were given a single injection of diminazene (7 mg/kg). Three such surveys were performed, with a 6-month interval, during which 282 "serological suspects" received diminazene, 39 "clinical cases" were given melarsoprol and 82 "parasitological cases" were treated according to standard protocols. The annual incidence of trypanosomiasis decreased rapidly from 10.4-41.1/1.000 inhabitants (mean: 17.6/1.000) during the 10 years before the intervention to 1.1-2.6/1.000 (mean: 1.7/1.000) in the 3 years following the intervention. No major adverse effect was seen with diminazene. Among the 282 serological suspects, an elevated CSF WBC count was later documented in 12 individuals, who were all cured with melarsoprol. The incidence increased 5 years after the intervention (7.1/1.000 in 1992), which may have been avoided had we carried out similar interventions in adjacent foci.