Epidemiological aspects of the transmission of the parasites causing human African trypanosomiasis in Angola

Until the last few years, most cases of sleeping sickness or human African trypanosomiasis (HAT) occurred in Angola, the Democratic Republic of Congo and Sudan, with 17,673 cases detected in Angola alone among the 1,660,111 Angolans who were screened between 2001 and 2007 (T. Josenando, unpubl. obs.). Angola is divided into 18 provinces (see Figure). The chronic form of HAT, caused by Trypanosoma brucei gambiense, occurs in seven of the 14 provinces where tsetse flies are present (in Bengo, Cuanza Norte, Uige, Cuanza Sul, Zaire, Malange, and the periphery of Luanda). The acute form of the disease, caused by T. b. rhodesiense transmitted by Glossina morsitans centralis, could once be found in the southern province of Cuando Cubango (where 30% of new Angolan HAT cases were diagnosed between 1964 and 1974; T. Josenando, unpubl. obs.). Most of the human population of this province moved to northern Angola during the civil war that ran from 1975 to 2002, however, probably leading to the disappearance of T. b. rhodesiense from Cuando Cubango and, therefore, from Angola as a whole (T. Josenando, unpubl. obs.). Map of Angola, showing the provinces where human African trypanosomiasis (HAT) is endemic (hatched) and the location of the village of Maria Teresa, in and around which tsetse were caught in pyramidal traps. Note that HAT is only endemic on the periphery ... HAT in Angola is poorly documented, with no recent publications on the disease in the country. In 2007, the French Institut de Recherche pour le Developpement (UMR 177) and the Angolan Instituto de Combate e Controlo das Tripanossomiases (ICCT) began collaborative research on the disease at Viana Hospital, which lies in Luanda province, 20 km to the east of Luanda city. The staff at the Viana Hospital only treat HAT cases, most of whom come from Bengo province. A year later, in an attempt to reinforce the tsetse-control capacity of the ICCT, an entomological study was conducted in and around the village of Maria Teresa (a community in Bengo province with particularly high incidences of HAT). The preliminary results of the collaborative research at Viana Hospital and the entomological survey in Maria Teresa are presented below.