<b><span style="font-family:Verdana;">Background:</span></b></span><span><span><span style="font-family:""><span style="font-family:Verd...<b><span style="font-family:Verdana;">Background:</span></b></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> Understanding the biology of </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> malaria vector species is essential to planning effective and sustainable malaria control strategies in endemic countries. This study reported the implication of </span><i><span style="font-family:Verdana;">Anopheles leesoni </span></i><span style="font-family:Verdana;">in malaria transmission in Cameroon, Central Africa. </span><b><span style="font-family:Verdana;">Methods:</span></b><i> </i><span style="font-family:Verdana;">Mosquitoes were collected in three localities from May 2015 to March 2018 using electric aspirators and Centers for Disease Control light traps (CDC-LT). </span><i><span style="font-family:Verdana;">Anopheles funestus</span></i> <i><span style="font-family:Verdana;">sensu lato</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">.) mosquitoes were identified as species using polymerase chain reaction assay (PCR). Furthermore, </span><i><span style="font-family:Verdana;">Plasmodium falciparum</span></i><span style="font-family:Verdana;"> infection status was determined using the enzyme-linked</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">immunosorbent assay (ELISA) method. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">A total of 12,744 </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> mosquitoes were collected by electric aspirator (N = 4844) and CDC-LT (N = 7900). </span><i><span style="font-family:Verdana;">Anopheles funestus</span></i><span> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. (86.95%)</span><i> </i></span><span style="font-family:Verdana;">was the major species and the main malaria vector in rural savannah and rural forest sites followed by </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">gambiae</span></i><span> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. (13.05%)</span></span><span style="font-family:Verdana;"> whereas</span><span><span style="font-family:Verdana;"> in urban areas, </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> gambiae</span></i> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. was</span></span><span style="font-family:Verdana;"> by far the most abundant representing 91.45% of </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> mosquitoes collected. Two members of the </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus</span></i><span style="font-family:Verdana;"> group were identified among 1389 analysed by PCR: 1307 </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus sensu stricto</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.)</span><i> </i><span style="font-family:Verdana;">(94.10%) and 82 </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i><span style="font-family:Verdana;"> (5.9%). </span><i><span style="font-family:Verdana;">Plasmodium falciparum </span></i><span style="font-family:Verdana;">infection rate was 21.04% in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus </span></i></span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">. For the first time, </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i> </span><span style="font-family:Verdana;">was found positive for </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i><span style="font-family:Verdana;"> (infection rate: 10.98%)</span></span><span style="font-family:Verdana;"> in Cameroon. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">A very high </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i></span><span style="font-family:Verdana;"> infection rate was observed in this study in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i></span><span style="font-family:Verdana;">., highlighting its high implication in malaria transmission in Cameroon. Furthermore, the detection of </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i></span><span style="font-family:Verdana;"> infection in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i></span><span style="font-family:Verdana;"> calls for more attention towards this neglected vector species.展开更多
Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Cu...Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Culex quinquefasciatus and Culex pipiens were found breeding in sympatry, with some hybrid individuals identified. Larval bioassays revealed high temephos resistance (LC<sub>50</sub>s = 1.34 mg/mL and 3.01 mg/mL for Kano and Kaduna, respectively). Larvae were more sensitive to α-cypermethrin (LC<sub>50</sub>s = 0.026 mg/mL and 0.067 mg/mL for Kano and Kaduna). WHO adult tube bioassays revealed high pyrethroid and DDT resistance, with mortalities of 44.01% ± 6.79%, 35.83% ± 12.58%, 29.69% ± 9.97% and 52.47% ± 4.34% for permethrin, deltamethrin, α-cypermethrin and DDT, respectively. Highest resistance was observed with bendiocarb (mortality = 13.58% ± 3.98%). High resistance was obtained with fenitrothion and malathion (mortalities = 21% ± 4.76% and 56.47% ± 8.67%, respectively), while a full susceptibility was observed with pirimiphos-methyl. Pre-exposure to piperonylbutoxide (PBO) significantly recovered α-cypermethrin susceptibility (mortality = 82% ± 5.16%, χ<sup>2</sup> = 50.99, p < 0.0001), compared with the conventional bioassay (mortality = 32 ± 7.30). Mortalities of <20% were obtained in cone bioassays with Yorkool, DuraNet and PermaNet3.0 (side panels) nets, suggesting a loss of efficacy of conventional long-lasting insecticidal nets. However, mortalities of 99% and 86% were obtained in Kano and Kaduna populations using the roof of PermaNet3.0 (containing PBO and deltamethrin). Despite the high frequency of the 1014F VGSC knockdown resistance mutation allele (0.90), no correlation was observed between the 1014F kdr genotype and resistance phenotype. Sequencing of fragments of the acetylcholinesterase-1 gene detected no G119S mutation, in malathion-alive and malathion-dead females. These suggest a preeminent role of metabolic resistance in these Culex populations.展开更多
Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.H...Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.Here,we investigated the performance of piperonyl-butoxide(PBO)-pyrethroid[Permanet 3.0(P3.0)]and dual active ingredients(AI)nets[Interceptor G2(IG2):containing pyrethroids and chlorfenapyr and Royal Guard(RG):containing pyrethroids and pyriproxyfen]compared to pyrethroid-only net Royal Sentry(RS)against pyrethroid-resistant malaria vectors in Cameroon.Methods The efficacy of these tools was firstly evaluated onAnopheles gambiae s.l.andAnopheles funestus s.l.from Gounougou,Mibellon,Mangoum,Nkolondom,and Elende using cone/tunnel assays.In addition,experimental hut trials(EHT)were performed to evaluate the performance of unwashed and 20 times washed nets in semi-field conditions.Furthermore,pyrethroid-resistant markers were genotyped in dead vs alive,blood-fed vs unfed mosquitoes after exposure to the nets to evaluate the impact of these markers on net performance.The XLSTAT software was used to calculate the various entomological outcomes and the Chi-square test was used to compare the efficacy of various nets.The odds ratio and Fisher exact test were then used to establish the statistical significance of any association between insecticide resistance markers and bed net efficacy.Results Interceptor G2 was the most effective net against wild pyrethroid-resistantAn.funestus followed by Permanet 3.0.In EHT,this net induced up to 87.8%mortality[95%confidence interval(CI):83.5-92.1%)and 55.6%(95%CI:48.5-62.7%)after 20 washes whilst unwashed pyrethroid-only net(Royal Sentry)killed just 18.2%(95%CI:13.4-22.9%)of host-seekingAn.funestus.The unwashed Permanet 3.0 killed up to 53.8%(95%CI:44.3-63.4%)of field-resistant mosquitoes and 47.2%(95%CI:37.7-56.7%)when washed 20 times,and the Royal Guard 13.2%(95%CI:9.0-17.3%)for unwashed net and 8.5%(95%CI:5.7-11.4%)for the 20 washed net.Interceptor G2,Permanet 3.0,and Royal Guard provided better personal protection(blood-feeding inhibition 66.2%,77.8%,and 92.8%,respectively)compared to pyrethroid-only net Royal Sentry(8.4%).Interestingly,a negative association was found betweenkdrw and the chlorfenapyr-based net Interceptor G2(χ^(2)=138;P<0.0001)with homozygote-resistant mosquitoes predominantly found in the dead ones.Conclusions The high mortality recorded with Interceptor G2 against pyrethroid-resistant malaria vectors in this study provides first semi-field evidence of high efficacy against these major malaria vectors in Cameroon encouraging the implementation of this novel net for malaria control in the country.However,the performance of this net should be established in other locations and on other major malaria vectors before implementation at a large scale.展开更多
Myxosporidia constitute a major group of fish parasites which have a significant negative impact on wild and cultured fish. The used of DNA in Myxosporidia studies has progressed rapidly over the last twenty years, es...Myxosporidia constitute a major group of fish parasites which have a significant negative impact on wild and cultured fish. The used of DNA in Myxosporidia studies has progressed rapidly over the last twenty years, especially in their identification and characterization as well as determination of species diversity and investigation of their evolutionary relationships. Extraction and isolation of pure and high quality DNA are essential for any molecular study, but constitute a challenge for many laboratories especially in low and middle income countries. Myxosporidia plasmodia filled with mature myxospores were isolated from different tissues of <span style="white-space:nowrap;"><i></span>Labeo batesii<span style="white-space:nowrap;"></i></span> Boulenger, 1911. DNA from myxosporidia myxospores were extracted using a Livak optimized DNAs extraction protocol. Four particular phases of the original protocol were optimized. Yield and absorbance ratios of extracted DNA were determined using spectrophotometer. DNA samples were used as template for the amplification of the 18S rDNA region and amplicons resolved on 1.5% agarose gel for determination of fragment sizes and purity evaluation. The concentration of extracted DNA from all Myxosporidia species ranged from 4.6 to 26 ng/μl with purity indices ranging from 1.88 to 2.12. We successfully amplified the 1050 bp DNA fragment as targeted. The intensity, thickness and clarity of the bands were evidences of non-degradation of DNA. The optimized Livak protocol is simple, low-cost and manageable. Regarding the quantity, purity and quality of extracted DNA, the optimized Livak protocol is highly recommended for Myxosporidia studies.展开更多
Observed weather and projected climate change suggest an increase in the transmission of vector-borne diseases(VBDs)in the Hindu Kush Himalayan(HKH)region.In this study,we systematically explore the literature for emp...Observed weather and projected climate change suggest an increase in the transmission of vector-borne diseases(VBDs)in the Hindu Kush Himalayan(HKH)region.In this study,we systematically explore the literature for empiric associations between the climate variables and specific VBDs and their vectors in the HKH region.We conducted a systematic synthesis of the published literature on climate variables,VBDs and vectors in the HKH region until the 8th of December 2020.The majority of studies show significant positive associations of VBDs with climatic factors,such as temperature,precipitation,relative humidity,etc.This systematic review allowed us to identify the most significant variables to be considered for evidence-based trend estimates of the effects of climate change on VBDs and their vectors in the HKH region.This evidence-based trend was set into the context of climate change as well as the observed expansion of VBDs and disease vectors in the HKH region.The geographic range of VBDs expanded into previously considered non-endemic areas of highlands(mountains)in the HKH region.B ased on scarce,but clear evidence of a positive relationship of most climate variables and VBDs and the observed climatic changes,we strongly recommend an expansion of vector control and surveillance programmes in areas of the HKH region that were previously considered to be non-endemic.展开更多
Summary What is already known about this topic?Anopheles sinensis(An.sinensis)is the predominant malaria vector in China.The impact of S-methoprene on the emergence process of mosquito larvae suggests its potential as...Summary What is already known about this topic?Anopheles sinensis(An.sinensis)is the predominant malaria vector in China.The impact of S-methoprene on the emergence process of mosquito larvae suggests its potential as a control method for vector mosquitoes.However,the efficacy of S-methoprene in controlling An.sinensis has not yet been demonstrated.What is added by this report?展开更多
Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the...Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the biology of transmission between humans and tsetse,we previously developed a mechanistic transmission model,fitted to data between 2000 and 2013 which suggested that transmission was interrupted by 2015.The present study outlines refinements to the model to:(1)Assess whether elimination of transmission has already been achieved despite low-level case reporting;(2)quantify the role of intensified interventions in transmission reduction;and(3)predict the trajectory of gHAT in Mandoul for the next decade under different strategies.Method:Our previous gHAT transmission model for Mandoul was updated using human case data(2000-2019)and a series of model refinements.These include how diagnostic specificity is incorporated into the model and improvements to the fitting method(increased variance in observed case reporting and how underreporting and improvements to passive screening are captured).A side-by-side comparison of fitting to case data was performed between the models.Results:We estimated that passive detection rates have increased due to improvements in diagnostic availability in fixed health facilities since 2015,by 2.1-fold for stage 1 detection,and 1.5-fold for stage 2.We find that whilst the diagnostic algorithm for active screening is estimated to be highly specific(95%credible interval(CI):99.9-100%,Specificity=99.9%),the high screening and low infection levels mean that some recently reported cases with no parasitological confirmation might be false positives.We also find that the focus-wide tsetse reduction estimated through model fitting(95%CI:96.1-99.6%,Reduction=99.1%)is comparable to the reduction previously measured by the decline in tsetse catches from monitoring traps.In line with previous results,the model suggests that transmission was interrupted in 2015 due to intensified interventions.Conclusions:We recommend that additional confirmatory testing is performed in Mandoul to ensure the endgame can be carefully monitored.More specific measurement of cases,would better inform when it is safe to stop active screening and vector control,provided there is a strong passive surveillance system in place.展开更多
文摘<b><span style="font-family:Verdana;">Background:</span></b></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> Understanding the biology of </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> malaria vector species is essential to planning effective and sustainable malaria control strategies in endemic countries. This study reported the implication of </span><i><span style="font-family:Verdana;">Anopheles leesoni </span></i><span style="font-family:Verdana;">in malaria transmission in Cameroon, Central Africa. </span><b><span style="font-family:Verdana;">Methods:</span></b><i> </i><span style="font-family:Verdana;">Mosquitoes were collected in three localities from May 2015 to March 2018 using electric aspirators and Centers for Disease Control light traps (CDC-LT). </span><i><span style="font-family:Verdana;">Anopheles funestus</span></i> <i><span style="font-family:Verdana;">sensu lato</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">.) mosquitoes were identified as species using polymerase chain reaction assay (PCR). Furthermore, </span><i><span style="font-family:Verdana;">Plasmodium falciparum</span></i><span style="font-family:Verdana;"> infection status was determined using the enzyme-linked</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">immunosorbent assay (ELISA) method. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">A total of 12,744 </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> mosquitoes were collected by electric aspirator (N = 4844) and CDC-LT (N = 7900). </span><i><span style="font-family:Verdana;">Anopheles funestus</span></i><span> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. (86.95%)</span><i> </i></span><span style="font-family:Verdana;">was the major species and the main malaria vector in rural savannah and rural forest sites followed by </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">gambiae</span></i><span> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. (13.05%)</span></span><span style="font-family:Verdana;"> whereas</span><span><span style="font-family:Verdana;"> in urban areas, </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> gambiae</span></i> <i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">l</span></i><span style="font-family:Verdana;">. was</span></span><span style="font-family:Verdana;"> by far the most abundant representing 91.45% of </span><i><span style="font-family:Verdana;">Anopheles</span></i><span style="font-family:Verdana;"> mosquitoes collected. Two members of the </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus</span></i><span style="font-family:Verdana;"> group were identified among 1389 analysed by PCR: 1307 </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus sensu stricto</span></i><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.)</span><i> </i><span style="font-family:Verdana;">(94.10%) and 82 </span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i><span style="font-family:Verdana;"> (5.9%). </span><i><span style="font-family:Verdana;">Plasmodium falciparum </span></i><span style="font-family:Verdana;">infection rate was 21.04% in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus </span></i></span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i><span style="font-family:Verdana;">. For the first time, </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i> </span><span style="font-family:Verdana;">was found positive for </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i><span style="font-family:Verdana;"> (infection rate: 10.98%)</span></span><span style="font-family:Verdana;"> in Cameroon. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">A very high </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i></span><span style="font-family:Verdana;"> infection rate was observed in this study in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> funestus s</span></i><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;">s</span></i></span><span style="font-family:Verdana;">., highlighting its high implication in malaria transmission in Cameroon. Furthermore, the detection of </span><i><span style="font-family:Verdana;">P</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> falciparum</span></i></span><span style="font-family:Verdana;"> infection in </span><i><span style="font-family:Verdana;">A</span></i><span><span style="font-family:Verdana;">.</span><i><span style="font-family:Verdana;"> leesoni</span></i></span><span style="font-family:Verdana;"> calls for more attention towards this neglected vector species.
文摘Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Culex quinquefasciatus and Culex pipiens were found breeding in sympatry, with some hybrid individuals identified. Larval bioassays revealed high temephos resistance (LC<sub>50</sub>s = 1.34 mg/mL and 3.01 mg/mL for Kano and Kaduna, respectively). Larvae were more sensitive to α-cypermethrin (LC<sub>50</sub>s = 0.026 mg/mL and 0.067 mg/mL for Kano and Kaduna). WHO adult tube bioassays revealed high pyrethroid and DDT resistance, with mortalities of 44.01% ± 6.79%, 35.83% ± 12.58%, 29.69% ± 9.97% and 52.47% ± 4.34% for permethrin, deltamethrin, α-cypermethrin and DDT, respectively. Highest resistance was observed with bendiocarb (mortality = 13.58% ± 3.98%). High resistance was obtained with fenitrothion and malathion (mortalities = 21% ± 4.76% and 56.47% ± 8.67%, respectively), while a full susceptibility was observed with pirimiphos-methyl. Pre-exposure to piperonylbutoxide (PBO) significantly recovered α-cypermethrin susceptibility (mortality = 82% ± 5.16%, χ<sup>2</sup> = 50.99, p < 0.0001), compared with the conventional bioassay (mortality = 32 ± 7.30). Mortalities of <20% were obtained in cone bioassays with Yorkool, DuraNet and PermaNet3.0 (side panels) nets, suggesting a loss of efficacy of conventional long-lasting insecticidal nets. However, mortalities of 99% and 86% were obtained in Kano and Kaduna populations using the roof of PermaNet3.0 (containing PBO and deltamethrin). Despite the high frequency of the 1014F VGSC knockdown resistance mutation allele (0.90), no correlation was observed between the 1014F kdr genotype and resistance phenotype. Sequencing of fragments of the acetylcholinesterase-1 gene detected no G119S mutation, in malathion-alive and malathion-dead females. These suggest a preeminent role of metabolic resistance in these Culex populations.
基金This work was supported by the PIIVEC operational research project(PV/OP2-03/TW to MT under the MRC grant MR/PO27873/1),the Renewal Wellcome Trust Senior Research Fellowship in Biomedical Sciences(217188/Z/19/Z),and the BMGF Grant(INV-006003)awarded to CSW.
文摘Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.Here,we investigated the performance of piperonyl-butoxide(PBO)-pyrethroid[Permanet 3.0(P3.0)]and dual active ingredients(AI)nets[Interceptor G2(IG2):containing pyrethroids and chlorfenapyr and Royal Guard(RG):containing pyrethroids and pyriproxyfen]compared to pyrethroid-only net Royal Sentry(RS)against pyrethroid-resistant malaria vectors in Cameroon.Methods The efficacy of these tools was firstly evaluated onAnopheles gambiae s.l.andAnopheles funestus s.l.from Gounougou,Mibellon,Mangoum,Nkolondom,and Elende using cone/tunnel assays.In addition,experimental hut trials(EHT)were performed to evaluate the performance of unwashed and 20 times washed nets in semi-field conditions.Furthermore,pyrethroid-resistant markers were genotyped in dead vs alive,blood-fed vs unfed mosquitoes after exposure to the nets to evaluate the impact of these markers on net performance.The XLSTAT software was used to calculate the various entomological outcomes and the Chi-square test was used to compare the efficacy of various nets.The odds ratio and Fisher exact test were then used to establish the statistical significance of any association between insecticide resistance markers and bed net efficacy.Results Interceptor G2 was the most effective net against wild pyrethroid-resistantAn.funestus followed by Permanet 3.0.In EHT,this net induced up to 87.8%mortality[95%confidence interval(CI):83.5-92.1%)and 55.6%(95%CI:48.5-62.7%)after 20 washes whilst unwashed pyrethroid-only net(Royal Sentry)killed just 18.2%(95%CI:13.4-22.9%)of host-seekingAn.funestus.The unwashed Permanet 3.0 killed up to 53.8%(95%CI:44.3-63.4%)of field-resistant mosquitoes and 47.2%(95%CI:37.7-56.7%)when washed 20 times,and the Royal Guard 13.2%(95%CI:9.0-17.3%)for unwashed net and 8.5%(95%CI:5.7-11.4%)for the 20 washed net.Interceptor G2,Permanet 3.0,and Royal Guard provided better personal protection(blood-feeding inhibition 66.2%,77.8%,and 92.8%,respectively)compared to pyrethroid-only net Royal Sentry(8.4%).Interestingly,a negative association was found betweenkdrw and the chlorfenapyr-based net Interceptor G2(χ^(2)=138;P<0.0001)with homozygote-resistant mosquitoes predominantly found in the dead ones.Conclusions The high mortality recorded with Interceptor G2 against pyrethroid-resistant malaria vectors in this study provides first semi-field evidence of high efficacy against these major malaria vectors in Cameroon encouraging the implementation of this novel net for malaria control in the country.However,the performance of this net should be established in other locations and on other major malaria vectors before implementation at a large scale.
文摘Myxosporidia constitute a major group of fish parasites which have a significant negative impact on wild and cultured fish. The used of DNA in Myxosporidia studies has progressed rapidly over the last twenty years, especially in their identification and characterization as well as determination of species diversity and investigation of their evolutionary relationships. Extraction and isolation of pure and high quality DNA are essential for any molecular study, but constitute a challenge for many laboratories especially in low and middle income countries. Myxosporidia plasmodia filled with mature myxospores were isolated from different tissues of <span style="white-space:nowrap;"><i></span>Labeo batesii<span style="white-space:nowrap;"></i></span> Boulenger, 1911. DNA from myxosporidia myxospores were extracted using a Livak optimized DNAs extraction protocol. Four particular phases of the original protocol were optimized. Yield and absorbance ratios of extracted DNA were determined using spectrophotometer. DNA samples were used as template for the amplification of the 18S rDNA region and amplicons resolved on 1.5% agarose gel for determination of fragment sizes and purity evaluation. The concentration of extracted DNA from all Myxosporidia species ranged from 4.6 to 26 ng/μl with purity indices ranging from 1.88 to 2.12. We successfully amplified the 1050 bp DNA fragment as targeted. The intensity, thickness and clarity of the bands were evidences of non-degradation of DNA. The optimized Livak protocol is simple, low-cost and manageable. Regarding the quantity, purity and quality of extracted DNA, the optimized Livak protocol is highly recommended for Myxosporidia studies.
基金funded by the Federal Ministry of Education and Research of Germany(BMBF)under the project AECO(01K11717)as part of the National Research Network on Zoonotic Infectious Diseases of Germanysupported by core funds of ICIMOD(contributed by the governments of Afghanistan,Australia,Austria,Bangladesh,Bhutan,China,India,Myanmar,Nepal,Norway,Pakistan,Sweden and Switzerland)funded by the Bill and Melinda Gates Foundation under the project EntoCAP(OPP1210801).
文摘Observed weather and projected climate change suggest an increase in the transmission of vector-borne diseases(VBDs)in the Hindu Kush Himalayan(HKH)region.In this study,we systematically explore the literature for empiric associations between the climate variables and specific VBDs and their vectors in the HKH region.We conducted a systematic synthesis of the published literature on climate variables,VBDs and vectors in the HKH region until the 8th of December 2020.The majority of studies show significant positive associations of VBDs with climatic factors,such as temperature,precipitation,relative humidity,etc.This systematic review allowed us to identify the most significant variables to be considered for evidence-based trend estimates of the effects of climate change on VBDs and their vectors in the HKH region.This evidence-based trend was set into the context of climate change as well as the observed expansion of VBDs and disease vectors in the HKH region.The geographic range of VBDs expanded into previously considered non-endemic areas of highlands(mountains)in the HKH region.B ased on scarce,but clear evidence of a positive relationship of most climate variables and VBDs and the observed climatic changes,we strongly recommend an expansion of vector control and surveillance programmes in areas of the HKH region that were previously considered to be non-endemic.
基金Project on the Establishment of China-ASEAN Science and Technology Cooperation Center for Public Health(KY202101004)funded by The National Key Research and Development Program of China.
文摘Summary What is already known about this topic?Anopheles sinensis(An.sinensis)is the predominant malaria vector in China.The impact of S-methoprene on the emergence process of mosquito larvae suggests its potential as a control method for vector mosquitoes.However,the efficacy of S-methoprene in controlling An.sinensis has not yet been demonstrated.What is added by this report?
基金This work was supported by the Bill and Melinda Gates Foundation(www.gatesfoundation.org)through the Human African Trypanosomiasis Modelling and Economic Predictions for Policy(HAT MEPP)project[OPP1177824 and INV-005121](CH,REC,PEB,MA,EHC,KSR)through the NTD Modelling Consortium[OPP1184344](KSR),and the Trypa-NO!project[INV-008412 and INV-001785](PRB,AP,SJT,PS and IT)+1 种基金SJT received funding from the Biotechnology and Biological Sciences Research Council(www.bbsrc.ukri.orgGrants BB/S01375X/1,BB/S00243X/1,BB/P005888/1).The funders had no role in study design,data collection and analysis,decision to publish,or preparation of the manuscript.
文摘Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the biology of transmission between humans and tsetse,we previously developed a mechanistic transmission model,fitted to data between 2000 and 2013 which suggested that transmission was interrupted by 2015.The present study outlines refinements to the model to:(1)Assess whether elimination of transmission has already been achieved despite low-level case reporting;(2)quantify the role of intensified interventions in transmission reduction;and(3)predict the trajectory of gHAT in Mandoul for the next decade under different strategies.Method:Our previous gHAT transmission model for Mandoul was updated using human case data(2000-2019)and a series of model refinements.These include how diagnostic specificity is incorporated into the model and improvements to the fitting method(increased variance in observed case reporting and how underreporting and improvements to passive screening are captured).A side-by-side comparison of fitting to case data was performed between the models.Results:We estimated that passive detection rates have increased due to improvements in diagnostic availability in fixed health facilities since 2015,by 2.1-fold for stage 1 detection,and 1.5-fold for stage 2.We find that whilst the diagnostic algorithm for active screening is estimated to be highly specific(95%credible interval(CI):99.9-100%,Specificity=99.9%),the high screening and low infection levels mean that some recently reported cases with no parasitological confirmation might be false positives.We also find that the focus-wide tsetse reduction estimated through model fitting(95%CI:96.1-99.6%,Reduction=99.1%)is comparable to the reduction previously measured by the decline in tsetse catches from monitoring traps.In line with previous results,the model suggests that transmission was interrupted in 2015 due to intensified interventions.Conclusions:We recommend that additional confirmatory testing is performed in Mandoul to ensure the endgame can be carefully monitored.More specific measurement of cases,would better inform when it is safe to stop active screening and vector control,provided there is a strong passive surveillance system in place.