The sterile insect technique(SIT)for tsetse involves releasing sterilized males to outcompete wild males in mating,resulting in nonviable progeny.Balancing optimum sterility and male quality is crucial.While irradiati...The sterile insect technique(SIT)for tsetse involves releasing sterilized males to outcompete wild males in mating,resulting in nonviable progeny.Balancing optimum sterility and male quality is crucial.While irradiation in hypoxia or anoxia is routine for tephritid flies,its effect on tsetse,especially postrelease,is not well understood.We conducted experiments to understand the impact of irradiation in hypoxia on the sterility of the F1 generation of Glossina morsitans morsitans(Gmm).Initially,we tested the impact of 1-h preconditioning in hypoxia before irradiation and continued hypoxia up to 24,48,and 72 h postirradiation on the emergence and flight propensity of treated males.We then assessed mating ability,survival,pupae per initial female(PPIF)and residual fertility of flies following irradiation at various doses after 1-h hypoxia conditioning.Finally,we determined the PPIF and residual fertility of the F1generation and the emergence of treated flies to the F2 generation.Results show that short-term conditioning(1 h)in hypoxia maintains or improves the qualities of the irradiated Gmm pupae.Regardless of irradiation in normoxia or hypoxia,higher residual fertility was observed in females than males in the F0 generation,and higher residual fertility in the F1 than the F0 generation for both sexes.However,the emergence rates of males decreased in the F2 generation compared with the F1 generation,a noteworthy finding for SIT programs for tsetse,implying diminishing populations of sterile flies.展开更多
Tsetse(Glossina spp.)are vectors of African trypanosomes that cause devastating human and animal African trypanosomiases.While much of the research to better understand tsetse genetics and physiology relies on colony-...Tsetse(Glossina spp.)are vectors of African trypanosomes that cause devastating human and animal African trypanosomiases.While much of the research to better understand tsetse genetics and physiology relies on colony-reared flies,these flies may not represent the genetic diversity found in natural wild populations due to their long-term captivity.To enhance the translation of colony research into field applications,we utilized Nanopore sequencing to assemble genomes for a wild-caught female Glossina fuscipes fuscipes(Gff)from northwestern Uganda and for a female Gff from a laboratory line originally sourced from the Central African Republic in 1986.The new assemblies,from the wild-caught Gff(405.98 Mb,N50:56.86 Mb)and the laboratory-derived Gff(398.22 Mb,N50:47.811 Mb),demonstrate near-chromosomal level contiguity,high BUSCO scores(>99.5%),high QV scores(>37),and over 12345 genes.Alignments between both new genomes reveal conserved synteny with only minor structural variants in the X,1L,1R,2L,and 2R tsetse chromosomes.While most orthologs(10730)were shared between both new genomes,we identified 381 unique orthologs and a small number of highly diverged shared single-copy homologs(3.84%).These gene-set differences could represent population-level variation due to the distinct geographic origin of these flies or adaptation to colony conditions.Our new high-quality genomes,with improvements in contiguity and completeness compared to the current NCBI RefSeq Gff genome,lay the foundation for advanced tsetse research,enabling robust lab-to-field translational applications to deepen our understanding of vector biology and disease transmission dynamics.展开更多
Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect t...Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect technique(SIT)stands as an environmentally friendly tool to control tsetse populations.SIT requires the mass-rearing of competent sterile males to mate with wild females.However,long-term colonization might affect the genetic structure of the reared flies.This study investigated the genetic structure of four Glossina palpalis gambiensis colonies of different ages:two originating from Senegal(SEN and ICIRSEN)and two from Burkina Faso(CIR and IBD).Samples from these colonies were genotyped at ten microsatellite loci,followed by downstream population genetic analyses.The results show that the two colonies from Burkina Faso collected from close sites(~20 km apart)over 45-year interval retained the same genetic background(FsT cIR~IBD≈0,P-value=0.47).These flies were however,genetically different from those from the Senegal colonies(FsT cIR~SEN≈0.047;FsT IBD~SEN≈0.058,P-value=10-4).Moreover,no significant difference was detected in the gene diversity of the CIR and IBD colonies,with Hs values of 0.650 and 0.665,respectively.Theinbreeding coefficient showed that all four colonies where under Hardy—Weinberg equilibrium,with FIs values of 0.026,0.012,-0.064,and 0.001,for CIR,IBD,ICIRSEN,and SEN.respectively.Furthermore,no sign of a recent bottleneck was identified in tsetse samples from any of the four colonies.The results suggest that long-term mass-rearing of tsetse flies has no significant impact on their genetic background and diversity.展开更多
Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patte...Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patterns,abundance and infection rates in relation to habitat types and age in the Maasai Steppe of northern Tanzania.In Africa,Tsetse-transmitted trypanosomiasis negatively impacted human life where about 40 million people are at risk of contracting the disease with dramatic socio-economical consequences,for instance,loss of livestock,animal productivity,and manpower.Methods:We trapped tsetse flies in dry and wet seasons between October 2014 and May 2015 in selected habitats across four villages:Emboreet,Loiborsireet,Kimotorok and Oltukai adjacent to protected areas.Data collected include number and species of tsetse flies caught in baited traps,PCR identification of trypanosome species and extraction of monitored Normalized Difference Vegetation Index(NDVI)data from Moderate Resolution Imaging Spectrometer(MODIS).Results:Our findings demonstrate the variation of tsetse fly species abundance and infection rates among habitats in surveyed villages in relation to NDVI and host abundance.Results have shown higher tsetse fly abundance in Acacia-swampy ecotone and riverine habitats for Emboreet and other villages,respectively.Tsetse abundance was inconsistent among habitats in different villages.Emboreet was highly infested with Glossina swynnertoni(68%)in ecotone and swampy habitats followed by G.morsitans(28%)and G.pallidipes(4%)in riverine habitat.In the remaining villages,the dominant tsetse fly species by 95%was G.pallidipes in all habitats.Trypanosoma vivax was the most prevalent species in all infected flies(95%)with few observations of co-infections(with T.congolense or T.brucei).Conclusions:The findings of this study provide a framework to mapping hotspots of tsetse infestation and trypanosomiasis infection and enhance the communities to plan for effective control of trypanosomiasis.展开更多
This paper summarises efforts to control Sleeping sickness [Human African Trypanosomiasis (HAT)] by Tsetse flies and Trypanosomiaisis (T & T) control for the 7 consecutive years although started a decade ago in Ta...This paper summarises efforts to control Sleeping sickness [Human African Trypanosomiasis (HAT)] by Tsetse flies and Trypanosomiaisis (T & T) control for the 7 consecutive years although started a decade ago in Tanzania National Parks (TANAPA). These efforts are critical for curbing HAT incidences and HAT epidemics. HAT cases have had profound negative impacts on human health, affecting local residents and international travel as well as tourism industry resulting into human and animal health burden and reduction in tourism income. Understanding the current efforts is essential in the proper planning and decision making on developing effective control strategy against T & T control. In this paper, we summarize the recent efforts in the control of T & T in National Parks and discuss the constraints faced. The information will enable TANAPA and other concerned authorities to make informed decision on optimal ways of controlling HAT in National Parks. The results show that much control efforts have so far concentrated in Serengeti, Ruaha, Tarangire and Katavi National Parks where tsetse fly challenges are high. A total 21,143 (average 3020) Insecticide Treated Targets (ITT) were deployed in different areas in the parks and 82,899 (average 20,725) cars entering these parks were sprayed from 2007/2008 to 2014/2015 and 2007/2008 to 2010/2011 respectively. Deployed ITTs lead to a drastic reduction of FTDs of the two dominant tsetse species to 1.3 and 1.4 of G. swynnertoni and G. pallidipes respectively, and the decline was significant at P = 0.011. The major challenges faced include tsetse re-invasion in controlled areas;resurgence of HAT cases when control efforts are relaxed, ITT maintenance and inadequate health education programs. The control strategy should be continuous and scaled up as failure to implement an effective and sustainable system for HAT control will increase the risk of new epidemic that would impede tourism development.展开更多
Sterile Insect Technique(SIT)has proven effective to reduce tsetse population density in large infected areas where animal African trypanosomosis(AAT)and human African trypanosomiasis(HAT)elimination was difficult to ...Sterile Insect Technique(SIT)has proven effective to reduce tsetse population density in large infected areas where animal African trypanosomosis(AAT)and human African trypanosomiasis(HAT)elimination was difficult to achieve.However,the decrease in mass production of insectary-reared tsetse and the limited but incomplete knowledge on symbiont–trypanosome interaction over time,impede large-scale use of SIT.We investigated the spatiotemporal changes in symbiont prevalence and symbiont–trypanosome interactions in wild tsetse of Sora-Mboum AAT focus in northern Cameroon,collected in 2019 and 2020,to provide insights into the mass production of refractory tsetse.Spiroplasma spp.,Sodalis glossinidius and trypanosomes were screened with PCR.G.tachinoides was the most abundant Glossina species found in Sora-Mboum focus.Symbiont prevalences in G.tachinoides were higher in 2019 compared to 2020,from 67.6%to 53.5%for Spiroplasma spp.and from 28.8%to 8.1%for S.glossinidius.These symbionts were also found at higher prevalence in flies from Mouhoun HAT focus in Burkina Faso.Four trypanosome taxa(Trypanosoma congolense forest type,T.congolense savannah type,T.brucei s.l.,and T.vivax)were found in Sora-Mboum focus and Mouhoun focus,though at lower prevalence in Mouhoun.The presence of Spiroplasma spp.in adult tsetse was negatively associated with that of trypanosomes.Our study highlights the potential of Spiroplasma spp.as a good paratransgenesis candidate to enhance SIT application.This symbiont is naturally found in high proportions of tsetse and could prevent factory flies from acquiring and transmitting trypanosomes during their lifespan when released for population density control.展开更多
Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target ...Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target pest colonies by maximizing the benefits provided by a genetically rich and pathogen-free mother colony, the presence of symbiotic microorganisms, and efficient domestication, mass-rearing, irradiation, and release processes. At the same time microbial (bacteria, fungi, microsporidia, and viruses) pathogen outbreaks should be minimized or eliminated, and the use of hazardous chemicals restricted. The optimization of the colony management strategies for different SIT target insects will ensure a standardized high-quality mass-rearing process and the cost-effective production of sterile males with enhanced field performance and male mating competitiveness. The aims of the Coordinated Research Project (CRP) were to develop best practices for insect colony management for the cost-effective production of high-quality sterile males for SIT applications against major insect pests and disease vectors through a multidisciplinary approach involving entomologists, geneticists, ecologists, microbiologists, pathologists, virologists, and mass-rearing experts.展开更多
Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse...Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse can harbor four genera of endosymbiotic bacteria,including Wigglesworthia,Sodalis,Wolbachia,and Spiroplasma,which are functionally crucial for the fly's physiological homeostasis and/or are potentially useful for the development of disease control strategies.Recent discoveries indicate that Spiroplasma infection negatively impacts tsetse fecundity.Conversely,housing the bacterium can benefit its fly host by making it unusually refractory to infection with parasitic African trypanosomes.In this study,we assessed the physiological impact of Spiroplasma infection on a laboratory colony of Glossina fuscipes fuscipes(Gff).For this purpose,two distinct Gff colonies were established:a Spi–colony that harbors a low Spiroplasma infection prevalence and a Spi+colony that harbors a high Spiroplasma infection prevalence.Fitness parameters for both colonies revealed no significant differences in the length of larval development,adult eclosion rate,and flight propensity.However,flies from the Spi+colony presented with lower fecundity and higher overall mortality than did individuals from the Spi–colony.Furthermore,males from the Spi–colony exhibited a competitive mating advantage over their Spi+counterparts in a field cage setting.These findings have potential implications for the improvement of mass-rearing of Gff for sterile insect technique(SIT)applications.展开更多
Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the dis...Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the disease primarily rely on controlling the tsetse populations.The discovery of Spiroplasma(class Mollicutes)in Glossina fuscipes fuscipes(Gff)(palpalis subgroup),offers promising insights into its potential use as a biological control agent to hinder trypanosomes infection in tsetse flies.Indeed,a negative correlation between Spiroplasma and trypanosome co-infection has been observed.Using a laboratory strain of Gff,we provide fundamental biological insights into the effects of Spiroplasma infection on the mating behavior of the fly.We found a sex-biased Spiroplasma infection,with males exhibiting a higher infection rate.Mass mating experiments revealed a higher mating propensity in Spiroplasma-infected flies.Additionally,the presence of Spiroplasma influenced premating isolation,leading to nonrandom mating patterns that favored the pairing of individuals with matching infection statuses.Moreover,we present evidence of Spiroplasma vertical paternal transmission.By analyzing female reproductive tissues at 2 and 24 h postmating,we confirmed that an infected male can transfer Spiroplasma to the female via the spermatophore,which can subsequently migrate to the spermathecae.This study provides foundational insights into the role of Spiroplasma in tsetse fly mating behavior and provides supporting evidence for vertical transmission from infected males.展开更多
Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This ...Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.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
基金funded by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture,IAEA(CRP No.:D4.20.17),Vienna,Austria.
文摘The sterile insect technique(SIT)for tsetse involves releasing sterilized males to outcompete wild males in mating,resulting in nonviable progeny.Balancing optimum sterility and male quality is crucial.While irradiation in hypoxia or anoxia is routine for tephritid flies,its effect on tsetse,especially postrelease,is not well understood.We conducted experiments to understand the impact of irradiation in hypoxia on the sterility of the F1 generation of Glossina morsitans morsitans(Gmm).Initially,we tested the impact of 1-h preconditioning in hypoxia before irradiation and continued hypoxia up to 24,48,and 72 h postirradiation on the emergence and flight propensity of treated males.We then assessed mating ability,survival,pupae per initial female(PPIF)and residual fertility of flies following irradiation at various doses after 1-h hypoxia conditioning.Finally,we determined the PPIF and residual fertility of the F1generation and the emergence of treated flies to the F2 generation.Results show that short-term conditioning(1 h)in hypoxia maintains or improves the qualities of the irradiated Gmm pupae.Regardless of irradiation in normoxia or hypoxia,higher residual fertility was observed in females than males in the F0 generation,and higher residual fertility in the F1 than the F0 generation for both sexes.However,the emergence rates of males decreased in the F2 generation compared with the F1 generation,a noteworthy finding for SIT programs for tsetse,implying diminishing populations of sterile flies.
基金support provided by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture,Insect Pest Control Subprograms under the CRP D4201supported with funding from Ambrose Monell Foundation(to SA),and National Institutes of Health(R01AI068932 and R01AI139525 to SA)National Institutes of Health(R21AI163969 to SA and BW).
文摘Tsetse(Glossina spp.)are vectors of African trypanosomes that cause devastating human and animal African trypanosomiases.While much of the research to better understand tsetse genetics and physiology relies on colony-reared flies,these flies may not represent the genetic diversity found in natural wild populations due to their long-term captivity.To enhance the translation of colony research into field applications,we utilized Nanopore sequencing to assemble genomes for a wild-caught female Glossina fuscipes fuscipes(Gff)from northwestern Uganda and for a female Gff from a laboratory line originally sourced from the Central African Republic in 1986.The new assemblies,from the wild-caught Gff(405.98 Mb,N50:56.86 Mb)and the laboratory-derived Gff(398.22 Mb,N50:47.811 Mb),demonstrate near-chromosomal level contiguity,high BUSCO scores(>99.5%),high QV scores(>37),and over 12345 genes.Alignments between both new genomes reveal conserved synteny with only minor structural variants in the X,1L,1R,2L,and 2R tsetse chromosomes.While most orthologs(10730)were shared between both new genomes,we identified 381 unique orthologs and a small number of highly diverged shared single-copy homologs(3.84%).These gene-set differences could represent population-level variation due to the distinct geographic origin of these flies or adaptation to colony conditions.Our new high-quality genomes,with improvements in contiguity and completeness compared to the current NCBI RefSeq Gff genome,lay the foundation for advanced tsetse research,enabling robust lab-to-field translational applications to deepen our understanding of vector biology and disease transmission dynamics.
基金funded by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture,IAEA(CRP No.:D4.20.17),Vienna,Austria.
文摘Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect technique(SIT)stands as an environmentally friendly tool to control tsetse populations.SIT requires the mass-rearing of competent sterile males to mate with wild females.However,long-term colonization might affect the genetic structure of the reared flies.This study investigated the genetic structure of four Glossina palpalis gambiensis colonies of different ages:two originating from Senegal(SEN and ICIRSEN)and two from Burkina Faso(CIR and IBD).Samples from these colonies were genotyped at ten microsatellite loci,followed by downstream population genetic analyses.The results show that the two colonies from Burkina Faso collected from close sites(~20 km apart)over 45-year interval retained the same genetic background(FsT cIR~IBD≈0,P-value=0.47).These flies were however,genetically different from those from the Senegal colonies(FsT cIR~SEN≈0.047;FsT IBD~SEN≈0.058,P-value=10-4).Moreover,no significant difference was detected in the gene diversity of the CIR and IBD colonies,with Hs values of 0.650 and 0.665,respectively.Theinbreeding coefficient showed that all four colonies where under Hardy—Weinberg equilibrium,with FIs values of 0.026,0.012,-0.064,and 0.001,for CIR,IBD,ICIRSEN,and SEN.respectively.Furthermore,no sign of a recent bottleneck was identified in tsetse samples from any of the four colonies.The results suggest that long-term mass-rearing of tsetse flies has no significant impact on their genetic background and diversity.
基金This research received financial support from the project“Predicting vulnerability and improving resilience of the Maasai communities to vector borne infections:An Eco-health approach in Maasai steppe ecosystem,based at Nelson Mandela African Institute of Science and Technology(NM-AIST)”.
文摘Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patterns,abundance and infection rates in relation to habitat types and age in the Maasai Steppe of northern Tanzania.In Africa,Tsetse-transmitted trypanosomiasis negatively impacted human life where about 40 million people are at risk of contracting the disease with dramatic socio-economical consequences,for instance,loss of livestock,animal productivity,and manpower.Methods:We trapped tsetse flies in dry and wet seasons between October 2014 and May 2015 in selected habitats across four villages:Emboreet,Loiborsireet,Kimotorok and Oltukai adjacent to protected areas.Data collected include number and species of tsetse flies caught in baited traps,PCR identification of trypanosome species and extraction of monitored Normalized Difference Vegetation Index(NDVI)data from Moderate Resolution Imaging Spectrometer(MODIS).Results:Our findings demonstrate the variation of tsetse fly species abundance and infection rates among habitats in surveyed villages in relation to NDVI and host abundance.Results have shown higher tsetse fly abundance in Acacia-swampy ecotone and riverine habitats for Emboreet and other villages,respectively.Tsetse abundance was inconsistent among habitats in different villages.Emboreet was highly infested with Glossina swynnertoni(68%)in ecotone and swampy habitats followed by G.morsitans(28%)and G.pallidipes(4%)in riverine habitat.In the remaining villages,the dominant tsetse fly species by 95%was G.pallidipes in all habitats.Trypanosoma vivax was the most prevalent species in all infected flies(95%)with few observations of co-infections(with T.congolense or T.brucei).Conclusions:The findings of this study provide a framework to mapping hotspots of tsetse infestation and trypanosomiasis infection and enhance the communities to plan for effective control of trypanosomiasis.
文摘This paper summarises efforts to control Sleeping sickness [Human African Trypanosomiasis (HAT)] by Tsetse flies and Trypanosomiaisis (T & T) control for the 7 consecutive years although started a decade ago in Tanzania National Parks (TANAPA). These efforts are critical for curbing HAT incidences and HAT epidemics. HAT cases have had profound negative impacts on human health, affecting local residents and international travel as well as tourism industry resulting into human and animal health burden and reduction in tourism income. Understanding the current efforts is essential in the proper planning and decision making on developing effective control strategy against T & T control. In this paper, we summarize the recent efforts in the control of T & T in National Parks and discuss the constraints faced. The information will enable TANAPA and other concerned authorities to make informed decision on optimal ways of controlling HAT in National Parks. The results show that much control efforts have so far concentrated in Serengeti, Ruaha, Tarangire and Katavi National Parks where tsetse fly challenges are high. A total 21,143 (average 3020) Insecticide Treated Targets (ITT) were deployed in different areas in the parks and 82,899 (average 20,725) cars entering these parks were sprayed from 2007/2008 to 2014/2015 and 2007/2008 to 2010/2011 respectively. Deployed ITTs lead to a drastic reduction of FTDs of the two dominant tsetse species to 1.3 and 1.4 of G. swynnertoni and G. pallidipes respectively, and the decline was significant at P = 0.011. The major challenges faced include tsetse re-invasion in controlled areas;resurgence of HAT cases when control efforts are relaxed, ITT maintenance and inadequate health education programs. The control strategy should be continuous and scaled up as failure to implement an effective and sustainable system for HAT control will increase the risk of new epidemic that would impede tourism development.
基金financial support from IAEA CRP D42017(Improvement of Colony Management in insect Mass-Rearing for SIT Applications)Contract Number:22636,from the Medical Research Council of the UK through the Global Challenges Research Fund(grant number MR/P027873/1)Laboratory facilities from the Centre for Research in Infectious Diseases(CRID),Yaoundé,Cameroon.
文摘Sterile Insect Technique(SIT)has proven effective to reduce tsetse population density in large infected areas where animal African trypanosomosis(AAT)and human African trypanosomiasis(HAT)elimination was difficult to achieve.However,the decrease in mass production of insectary-reared tsetse and the limited but incomplete knowledge on symbiont–trypanosome interaction over time,impede large-scale use of SIT.We investigated the spatiotemporal changes in symbiont prevalence and symbiont–trypanosome interactions in wild tsetse of Sora-Mboum AAT focus in northern Cameroon,collected in 2019 and 2020,to provide insights into the mass production of refractory tsetse.Spiroplasma spp.,Sodalis glossinidius and trypanosomes were screened with PCR.G.tachinoides was the most abundant Glossina species found in Sora-Mboum focus.Symbiont prevalences in G.tachinoides were higher in 2019 compared to 2020,from 67.6%to 53.5%for Spiroplasma spp.and from 28.8%to 8.1%for S.glossinidius.These symbionts were also found at higher prevalence in flies from Mouhoun HAT focus in Burkina Faso.Four trypanosome taxa(Trypanosoma congolense forest type,T.congolense savannah type,T.brucei s.l.,and T.vivax)were found in Sora-Mboum focus and Mouhoun focus,though at lower prevalence in Mouhoun.The presence of Spiroplasma spp.in adult tsetse was negatively associated with that of trypanosomes.Our study highlights the potential of Spiroplasma spp.as a good paratransgenesis candidate to enhance SIT application.This symbiont is naturally found in high proportions of tsetse and could prevent factory flies from acquiring and transmitting trypanosomes during their lifespan when released for population density control.
文摘Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target pest colonies by maximizing the benefits provided by a genetically rich and pathogen-free mother colony, the presence of symbiotic microorganisms, and efficient domestication, mass-rearing, irradiation, and release processes. At the same time microbial (bacteria, fungi, microsporidia, and viruses) pathogen outbreaks should be minimized or eliminated, and the use of hazardous chemicals restricted. The optimization of the colony management strategies for different SIT target insects will ensure a standardized high-quality mass-rearing process and the cost-effective production of sterile males with enhanced field performance and male mating competitiveness. The aims of the Coordinated Research Project (CRP) were to develop best practices for insect colony management for the cost-effective production of high-quality sterile males for SIT applications against major insect pests and disease vectors through a multidisciplinary approach involving entomologists, geneticists, ecologists, microbiologists, pathologists, virologists, and mass-rearing experts.
文摘Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse can harbor four genera of endosymbiotic bacteria,including Wigglesworthia,Sodalis,Wolbachia,and Spiroplasma,which are functionally crucial for the fly's physiological homeostasis and/or are potentially useful for the development of disease control strategies.Recent discoveries indicate that Spiroplasma infection negatively impacts tsetse fecundity.Conversely,housing the bacterium can benefit its fly host by making it unusually refractory to infection with parasitic African trypanosomes.In this study,we assessed the physiological impact of Spiroplasma infection on a laboratory colony of Glossina fuscipes fuscipes(Gff).For this purpose,two distinct Gff colonies were established:a Spi–colony that harbors a low Spiroplasma infection prevalence and a Spi+colony that harbors a high Spiroplasma infection prevalence.Fitness parameters for both colonies revealed no significant differences in the length of larval development,adult eclosion rate,and flight propensity.However,flies from the Spi+colony presented with lower fecundity and higher overall mortality than did individuals from the Spi–colony.Furthermore,males from the Spi–colony exhibited a competitive mating advantage over their Spi+counterparts in a field cage setting.These findings have potential implications for the improvement of mass-rearing of Gff for sterile insect technique(SIT)applications.
文摘Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the disease primarily rely on controlling the tsetse populations.The discovery of Spiroplasma(class Mollicutes)in Glossina fuscipes fuscipes(Gff)(palpalis subgroup),offers promising insights into its potential use as a biological control agent to hinder trypanosomes infection in tsetse flies.Indeed,a negative correlation between Spiroplasma and trypanosome co-infection has been observed.Using a laboratory strain of Gff,we provide fundamental biological insights into the effects of Spiroplasma infection on the mating behavior of the fly.We found a sex-biased Spiroplasma infection,with males exhibiting a higher infection rate.Mass mating experiments revealed a higher mating propensity in Spiroplasma-infected flies.Additionally,the presence of Spiroplasma influenced premating isolation,leading to nonrandom mating patterns that favored the pairing of individuals with matching infection statuses.Moreover,we present evidence of Spiroplasma vertical paternal transmission.By analyzing female reproductive tissues at 2 and 24 h postmating,we confirmed that an infected male can transfer Spiroplasma to the female via the spermatophore,which can subsequently migrate to the spermathecae.This study provides foundational insights into the role of Spiroplasma in tsetse fly mating behavior and provides supporting evidence for vertical transmission from infected males.
文摘Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.
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.
