Preliminary assessment of the potential role of urbanization in the distribution of carbamate and organophosphate resistant populations of Culex species in Ghana

Abstract

BackgroundBesides its role as a pathogen vector, Culex species also indirectly promotes the transmission of malaria if the use of bed nets or indoor residual spraying is discontinued due to a lack of insecticide efficacy against it. A recent survey revealed widespread occurrence of pyrethroid resistance among urban populations of this mosquito in Ghana. In order to plan and implement insecticide-based resistance management strategies, this study was carried out to assess resistance status of Culex species to organophosphate and carbamate in urban areas in Ghana and the possible mechanisms involved as well as environmental factors associated with its distribution.MethodsMosquito larvae were sampled from various land use and ecological settings and in different seasons. In adults, susceptibility to organophosphates (fenitrothion, malathion) and carbamates (propoxur, bendiocarb) were determined. Mixed function oxidase (MFO) and α- and β-esterase assays, as well as a PCR diagnostic assay to determine ace1 mutation were performed in individual mosquitoes.ResultsCulex quinquefasciatus as well as C. decens and other unidentified Culex species were found breeding in polluted water bodies in the study sites. Across all sites and seasons, carbamate induced mortality was 94.1% ± 15.4 whereas mortality caused by organophosphate was 99.5% ± 2.2. In addition, ace1 mutation and high levels of esterases were detected in some of the mosquito populations. There was a strong correlation between susceptibility status of the mosquitoes and the level of absorbance of β-esterase (Pearson r = − 0.841, p = 0.004).ConclusionsThe study found low prevalence of resistance to carbamate and organophosphate insecticides among Culex species from Ghana. However, there were populations with ace1 mutations and high levels of esterases, which can confer high resistance to these classes of insecticides. Thus, it is important to monitor activities or behaviour that has the potential to select for carbamate and organophosphate resistance populations.

DDT and pyrethroid resistance status and laboratory evaluation of bio-efficacy of long lasting insecticide treated nets against Culex quinquefasciatus and Culex decens in Ghana

“…quinquefasciatus were found in the most urbanized areas in Ghana (Accra and Kumasi) whereas C. decens were widely distributed in the rest of the country. The distribution of Culex species is consistent with the previous study (Kudom et al, 2015). Toxicological results from the study also showed that C. quinquefasciatus were more resistant to the pyrethroid insecticides than C. decens.…”

“…In the first reaction, the primers ACEquin (5 -CCT TCT TGA ATG GCT GTG GCA -3 ) and B1246s (5 -TGG AGC CTC CTC TTC ACG G -3 ) described by Smith and Fonseca (2004) were used for the assay. The second assay consisted of Cddir (5 -ACC TCG ACG ATA CTC CGA TTT -3 ) and Cdrev (5 -TGT GTT CTG CAG GAG GAA GA -3 ) as described by Kudom et al (2015). Each reaction contained 1 × PCR buffer containing 1.5 mM MgCl 2 , 0.2 mM of each dNTP, 0.5 M of each 'primer, one unit of Taq polymerase (HotstarTaq: Qiagen ® ), and 3 l of gDNA.…”

Seroprevalence of toxoplasma gondii infection: An umbrella review of updated systematic reviews and meta-analyses

“…Gebremedhin and Tadessein a systematic review and meta-analysis of the general population in Etiopia reported that 74.73% seroprevalence of IgG anti-Toxoplasma gondii antibodies. [ 28 ] The Significant high seroprevalence of T. gondii infection in Ethiopian humans can be due to uncontrolled cat movement, abnormal living conditions, and lifestyle and unsanitary behaviors that favor the transmission of parasites from cats or food animals. [ 28 ]…”

Pyruvate produced by Brugia spp. via glycolysis is essential for maintaining the mutualistic association between the parasite and its endosymbiont, Wolbachia

“…pahangi genome and life cycle are very similar to that of B . malayi [22], and both species can be maintained in gerbils, although B . pahangi worm recovery is more efficient in the natural host.…”