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Rapid evolution of pyrethroid resistance prevalence in Anopheles gambiae populations from the cities of Douala and Yaoundé (Cameroon).

Antonio-Nkondjio C, Tene Fossog B, Kopya E, Poumachu Y, Menze Djantio B, Ndo C, Tchuinkam T, Awono-Ambene P, Wondji CS - Malar. J. (2015)

Bottom Line: The genomic region containing the upstream of intron-1 of the voltage-gated sodium channel was sequenced and compared between mosquitoes originating from different breeding habitats.A rapid decrease of mosquito mortality to permethrin and deltamethrin was recorded between 2010 and 2013 in the two cities.The present study supports rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé and calls for immediate action to fight against the increasing prevalence of pyrethroid-resistant mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. antonio_nk@yahoo.fr.

ABSTRACT

Background: The adaptation of malaria vectors to urban areas is becoming a serious challenge for malaria control. The study presents the evolution of pyrethroid resistance in mosquito populations from the cities of Douala and Yaoundé between 2010 and 2013.

Methods: Susceptibility tests to permethrin and deltamethrin were carried out with two- to four-day old unfed Anopheles gambiae sensu lato adults raised from larvae collected from the field. Mosquitoes resistant to permethrin and deltamethrin and control were screened to detect the presence of the kdr alleles using the TaqMan assays. Mosquitoes belonging to the An. gambiae complex were subjected to PCR assays designed for species and molecular forms identifications. The genomic region containing the upstream of intron-1 of the voltage-gated sodium channel was sequenced and compared between mosquitoes originating from different breeding habitats.

Results: Anopheles gambiae s.l. specimens collected from the city of Douala were all Anopheles coluzzii. In Yaoundé, both An. gambiae and An. coluzzii were recorded. A rapid decrease of mosquito mortality to permethrin and deltamethrin was recorded between 2010 and 2013 in the two cities. The mortality rate varied from 80.3 to 22.3% and 94.4 to 59.7% for permethrin and deltamethrin, respectively. Both kdr alleles L1014F and L1014S were recorded. The frequency of kdr alleles increased rapidly over the study period, varying from 44 to 88.9% in Yaoundé and from 68 to 81% in Douala. The sequencing of a 1,228 bp region of intro-1 of the voltage-gated sodium channel revealed the presence of five different haplotypes. A high number of these haplotypes were recorded in An. coluzzii samples. No evidence for a recent selective sweep on intron-1 sequence within samples originating from different breeding habitat was detected using Fu's and Tajima Fs statistics.

Conclusion: The present study supports rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé and calls for immediate action to fight against the increasing prevalence of pyrethroid-resistant mosquitoes.

No MeSH data available.


Related in: MedlinePlus

A map showing the evolution of Anopheles gambiae susceptibility to permethrin and deltamethrin between 2003 and 2012 in different parts of Cameroon.
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Fig1: A map showing the evolution of Anopheles gambiae susceptibility to permethrin and deltamethrin between 2003 and 2012 in different parts of Cameroon.

Mentions: A map describing the evolution of An. gambiae s.l. susceptibility to permethrin and deltamethrin from 2003 onwards after the first countrywide free distribution of ITNs is presented (Figure 1). Data presented here have been extracted from the present study and from different published reports [17,19,33-35]. For a better understanding of the pattern of An. gambiae s.l. susceptibility it is important to keep in mind that, the northern half of the country situated in dry savanna and humid savanna areas have as dominant malaria vector Anopheles arabiensis whereas, An. gambiae and An. coluzzii are the main vectors in the southern half of the country (highlands, coastal and equatorial forest regions).Figure 1


Rapid evolution of pyrethroid resistance prevalence in Anopheles gambiae populations from the cities of Douala and Yaoundé (Cameroon).

Antonio-Nkondjio C, Tene Fossog B, Kopya E, Poumachu Y, Menze Djantio B, Ndo C, Tchuinkam T, Awono-Ambene P, Wondji CS - Malar. J. (2015)

A map showing the evolution of Anopheles gambiae susceptibility to permethrin and deltamethrin between 2003 and 2012 in different parts of Cameroon.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4403825&req=5

Fig1: A map showing the evolution of Anopheles gambiae susceptibility to permethrin and deltamethrin between 2003 and 2012 in different parts of Cameroon.
Mentions: A map describing the evolution of An. gambiae s.l. susceptibility to permethrin and deltamethrin from 2003 onwards after the first countrywide free distribution of ITNs is presented (Figure 1). Data presented here have been extracted from the present study and from different published reports [17,19,33-35]. For a better understanding of the pattern of An. gambiae s.l. susceptibility it is important to keep in mind that, the northern half of the country situated in dry savanna and humid savanna areas have as dominant malaria vector Anopheles arabiensis whereas, An. gambiae and An. coluzzii are the main vectors in the southern half of the country (highlands, coastal and equatorial forest regions).Figure 1

Bottom Line: The genomic region containing the upstream of intron-1 of the voltage-gated sodium channel was sequenced and compared between mosquitoes originating from different breeding habitats.A rapid decrease of mosquito mortality to permethrin and deltamethrin was recorded between 2010 and 2013 in the two cities.The present study supports rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé and calls for immediate action to fight against the increasing prevalence of pyrethroid-resistant mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. antonio_nk@yahoo.fr.

ABSTRACT

Background: The adaptation of malaria vectors to urban areas is becoming a serious challenge for malaria control. The study presents the evolution of pyrethroid resistance in mosquito populations from the cities of Douala and Yaoundé between 2010 and 2013.

Methods: Susceptibility tests to permethrin and deltamethrin were carried out with two- to four-day old unfed Anopheles gambiae sensu lato adults raised from larvae collected from the field. Mosquitoes resistant to permethrin and deltamethrin and control were screened to detect the presence of the kdr alleles using the TaqMan assays. Mosquitoes belonging to the An. gambiae complex were subjected to PCR assays designed for species and molecular forms identifications. The genomic region containing the upstream of intron-1 of the voltage-gated sodium channel was sequenced and compared between mosquitoes originating from different breeding habitats.

Results: Anopheles gambiae s.l. specimens collected from the city of Douala were all Anopheles coluzzii. In Yaoundé, both An. gambiae and An. coluzzii were recorded. A rapid decrease of mosquito mortality to permethrin and deltamethrin was recorded between 2010 and 2013 in the two cities. The mortality rate varied from 80.3 to 22.3% and 94.4 to 59.7% for permethrin and deltamethrin, respectively. Both kdr alleles L1014F and L1014S were recorded. The frequency of kdr alleles increased rapidly over the study period, varying from 44 to 88.9% in Yaoundé and from 68 to 81% in Douala. The sequencing of a 1,228 bp region of intro-1 of the voltage-gated sodium channel revealed the presence of five different haplotypes. A high number of these haplotypes were recorded in An. coluzzii samples. No evidence for a recent selective sweep on intron-1 sequence within samples originating from different breeding habitat was detected using Fu's and Tajima Fs statistics.

Conclusion: The present study supports rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé and calls for immediate action to fight against the increasing prevalence of pyrethroid-resistant mosquitoes.

No MeSH data available.


Related in: MedlinePlus