Trypanosoma brucei gambiense in domestic livestock of Kogo and Mbini foci (Equatorial Guinea).

OBJECTIVE: To evaluate Trypanosoma brucei gambiense infection in peri-domestic livestock from Kogo and Mbini foci (Equatorial Guinea) in order to investigate its possible implication in the sleeping sickness transmission cycle in these hypoendemic foci. METHODS: Samples from 698 domestic animals (goats, sheep and pigs) from trypanosomiasis-endemic localities of Kogo and Mbini foci were tested for animal trypanosomes and T. b. gambiense (group I) by species-specific polymerase chain reaction. RESULTS: Trypanosoma brucei s.l., the predominant trypanosome species, was detected in 182 (52.6%) samples from Mbini and in 127 (36.1%) samples from Kogo. T. b. gambiense was only identified in seven (2%) of the Mbini samples and one co-infection (with T. vivax) was observed. CONCLUSION: The occurrence of T. b. gambiense in peri-domestic livestock in Mbini and its absence in Kogo could explain the epidemiological differences between the two foci and could have significant implications for sleeping sickness control in Equatorial Guinea.

Knockdown resistance mutations (kdr) and insecticide susceptibility to DDT and pyrethroids in Anopheles gambiae from Equatorial Guinea.

OBJECTIVES: To determine the frequency of knockdown resistance (kdr) mutations in the malaria vector Anopheles gambiae s.s. from continental Equatorial Guinea; and to relate kdr genotypes with susceptibility to DDT and pyrethroid insecticides in this vector. METHODS: Female mosquitoes were collected in two villages, Miyobo and Ngonamanga, of mainland Equatorial Guinea. Insecticide susceptibility tests were performed following WHO procedures. Anopheles gambiae complex specimens were identified to species and molecular form by PCR. Genotyping of the kdr locus was performed by allele-specific PCR and direct sequencing in a subset of samples. RESULTS: Both M and S molecular forms of A. gambiae were found in Ngonamanga whereas only the S-form was identified in Miyobo. The two kdr mutations were detected in S-form samples of both villages, with a higher frequency of the kdr-e (Leu-1014-Ser) allele (Miyobo: 16%; Ngonamanga: 40%). The kdr-w (Leu-1014-Phe) mutation was also detected in 3% of the M-form. All individuals tested for pyrethroids were susceptible. A mortality rate of 86% was obtained for DDT. An overall kdr allele frequency (i.e. kdr-e + kdr-w) of 22% was detected in DDT resistant individuals, whereas susceptible individuals had a kdr frequency of 6%. CONCLUSION: The co-occurrence of both kdr mutations and reduced susceptibility to DDT found in A. gambiae highlights the importance of implementing efficient surveillance of insecticide resistance in Equatorial Guinea.

Larvae stage description of Anopheles (Cellia) carnevalei from adult individuals collected in Equatorial Guinea.

This is the first description of 3rd and 4th instars of Anopheles (Cellia) carnevalei. Adults were caught in the mainland region (Rio Muni) of Equatorial Guinea. Larvae present characteristic palmate setae different from Anopheles nili.

Anopheles (Cellia) carnevalei in Equatorial Guinea (West-Central Africa).

Anopheles (Cellia) carnevalei is described in the mainland region (Río Muni) of Equatorial Guinea. Anophelines collected were identical to An. nili with exception of some morphological characters found in wings, head, and legs.