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.
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.
Authors: Michael R Reddy; Adrian Godoy; Kirstin Dion; Abrahan Matias; Kevin Callender; Anthony E Kiszewski; Immo Kleinschmidt; Frances C Ridl; Jeffrey R Powell; Adalgisa Caccone; Michel A Slotman Journal: Am J Trop Med Hyg Date: 2013-02-25 Impact factor: 2.345
Authors: Andrea M Rehman; Andrea G Mann; Christopher Schwabe; Michael R Reddy; Irina Roncon Gomes; Michel A Slotman; Lee Yellott; Abrahan Matias; Adalgisa Caccone; Gloria Nseng Nchama; Immo Kleinschmidt Journal: Malar J Date: 2013-05-07 Impact factor: 2.979
Authors: Ladslaus L Mnyone; Matthew J Kirby; Dickson W Lwetoijera; Monica W Mpingwa; Emmanuel T Simfukwe; Bart G J Knols; Willem Takken; Tanya L Russell Journal: Malar J Date: 2010-08-27 Impact factor: 2.979
Authors: Michael R Reddy; Hans J Overgaard; Simon Abaga; Vamsi P Reddy; Adalgisa Caccone; Anthony E Kiszewski; Michel A Slotman Journal: Malar J Date: 2011-07-07 Impact factor: 2.979