Objective:To investigate the bioecological relationship between Chagas disease peridomestic vectors and reptiles as source of feeding.Methods:In a three-story building,triatomines were captured by direct search and el...Objective:To investigate the bioecological relationship between Chagas disease peridomestic vectors and reptiles as source of feeding.Methods:In a three-story building,triatomines were captured by direct search and electric vacuum cleaner search in and outside the building.Then,age structure of the captured Triatoma maculata(T.maculata) were identified and recorded.Reptiles living in sympatric with the triatomines were also searched.Results:T.maculata were found living sympatric with geckos(Thecadactylus rapicauda) and they bit residents of the apartment building in study.A total of 1 448 individuals of T.maculata were captured within three days,of which 74.2%(1 074 eggs) were eggs,21.5%were nymphs at different stages,and 4.3%were adults.Conclusions:The association of T.maculata and T.rapicauda is an effective strategy of colonizing dwellings located in the vicinity of the habitat where both species are present;and therefore,could have implications of high importance in the intradomiciliary transmission of Chagas disease.展开更多
Background:Triatomines,also known as kissing bugs,which are found throughout the world and especially in Latin America,are well known natural vectors that transmit American trypanosomiasis,also called Chagas disease.I...Background:Triatomines,also known as kissing bugs,which are found throughout the world and especially in Latin America,are well known natural vectors that transmit American trypanosomiasis,also called Chagas disease.In China,the presence of two species of Triatoma(Triatoma rubrofasciata and T.sinica)was recorded in the past.Due to the growing population and the increasing risk of the global spread of Chagas disease,triatomines became a potential public health nuisance,and in 2016,we started monitoring triatomine activities in southern China.Methods:Triatomine specimens were collected by the National Institute of Parasitic Diseases,Chinese Center for Disease Control and Prevention,and identified by their morphological characteristics under a dissecting microscope.In addition to morphological analysis,the genomic DNA of the specimens was extracted,and the mitochondrial 16S rRNA,the cytochrome b(CytB)gene and the nuclear ribosomal 28S rRNA gene were PCRamplified to analyze and confirm the species genetically.Results:One female adult insect and one male adult insect were collected in a dwelling in the rural area of Shunde County,Foshan City,Guangdong Province,China(22°42′44.63″N,113°08′45.34″E).The results from the morphological and genetic analyses indicated that these triatomines were T.rubrofasciata.Conclusions:This is the first time that the occurrence of T.rubrofasciata has been confirmed in Foshan City,Guangdong Province in southern China.Further studies are needed to reach a clearer understanding of the ecology of this species of triatomine,since it has been found to be naturally infected by Trypanosoma cruzi and T.conorhini and there is evidence of its domiciliation capabilities.展开更多
Although having five different ways of transmission the vector-borne is the principal way of transmission of Chagas disease, which involves insects of the subfamily Triatominae (Hemiptera: Reduviidae). Nineteen of the...Although having five different ways of transmission the vector-borne is the principal way of transmission of Chagas disease, which involves insects of the subfamily Triatominae (Hemiptera: Reduviidae). Nineteen of the 31 species that occur in Mexico are associated with humans, and all are capable of transmitting the disease. Pyrethroids are the insecticides recommended for the control of these vectors in Mexico. We determined the susceptibility to the pyrethroids dcltamethrin and permethrin of peridomestic populations of Triatoma mazzottii Usinger and two populations of Triatoma longipetmis Usinger in comparison with a reference strain for each species. Bioassays were performed for the determination of the LD50 for both field populations and reference strains. A maximum of 27 fold resistance to deltamethrin was observed in T. mazzottii, meanwhile, for permethrin, T. longipennis from Jalisco show the highest value of 3.19 fold. There was significantly increased activity of esterases in field populations in comparison with their corresponding reference strain. The results of the search of kdr mutations related to the resistance to deltamethrin and permethrin in the evaluated species show the presence of mutations in the field populations, as is the case with individuals of T. mazzottii, for which the mutation was found A943V, and for the two populations of T. longipennis included in this study, we report the presence of the kdr mutation K964R. Evaluation of the various mechanisms involved in resistance to pyrethroids in triatomines from Mexico could guide us to the real justification for insecticide resistance monitoring.展开更多
BackgroundTriatomines in Latin America are natural Chagas disease (ChD) vectors. Triatomine domiciliation is one of the main factors increasing the occurrence risk of this disease in humans. There are 66 triatomine sp...BackgroundTriatomines in Latin America are natural Chagas disease (ChD) vectors. Triatomine domiciliation is one of the main factors increasing the occurrence risk of this disease in humans. There are 66 triatomine species in Brazil, with three genera of significant epidemiological importance—Panstrongylus, Rhodnius, and Triatoma. Among the Triatoma species, Triatoma williami, a wild species, has been reported in Goiás, Mato Grosso, and Mato Grosso do Sul. In the Barra do Garças, Mato Grosso, the invasion by triatomines has been reported, with T. williami being the most common species. This study aimed to survey triatomine fauna and determine the Trypanosoma cruzi natural infection rates in triatomines in the urban area of Barra do Garças, Mato Grosso, Brazil.MethodsTriatomine specimens were sampled by passive surveillance or active search by agents combating endemic diseases from 2019 to 2020. A parasitological feces diagnosis was performed to detect the presence of T. cruzi after the specimens were identified. Concerning T. cruzi identification, molecular diagnosis and genetic sequencing were performed to determine the strain, also called discrete typing units (DTUs).ResultsThe 211 triatomines were collected, distributed in specimens of T. williami (84.4%), P. geniculatus (3.3%), P. diasi (1.4%), and R. neglectus (10.9%). Two colonies of T. williami were found through morphological analyses. These insects were sampled inside domiciles in an urban area neighboring Jardim Pitaluga (15° 51′57.7″ N, 052° 16′ 04.5 E). The records were sampled in September 2019 and January 2021. The rate of natural infection by T. cruzi was 39.4%. Two T. williami specimens from the sampled colonies were positive for the T. cruzi strain DTU IV.ConclusionsThis is the first time that T. williami has been confirmed in an urban area of Barra do Garças, Mato Grosso, Brazil. Further studies are needed for a clearer understanding of the ecology of this species for prevention and control mechanisms since its sampled specimens had a high rate of natural infection by T. cruzi.展开更多
Background:Two health concerns primarily related to triatomine bugs are transmission of Trypanosoma cruzi through infective feces,and allergic reactions induced by triatomine bites.In the Southwestern United States,re...Background:Two health concerns primarily related to triatomine bugs are transmission of Trypanosoma cruzi through infective feces,and allergic reactions induced by triatomine bites.In the Southwestern United States,reduviid bugs bites commonly cause insect allergy.In South China,four cases of anaphylactic shock have been reported after this bite exposure.To further classify the species of these bugs and confirm the sensitization of the triatomine saliva,we caught triatomine bugs from the region where the bites occurred and performed phylogenetic and immunohistochemical(IHC)analysis.Methods:Triatomine bugs were collected in Donghai Island of Zhanjiang City in South China.The genomic DNA was extracted from three legs of the bugs.The fragments of mitochondrial 16S rRNA,cytochrome c oxidase subunit I(COI)gene and nuclear ribosomal 18S and 28S rRNA genes were obtained by PCR and sequenced.A phylogenetic tree was constructed based on the sequence of 16S rRNA gene using a maximum likelihood method with MEGA 7.0 software.Trypanosomal specific fragments and vertebrate COI genes were amplified from the fecal DNA to detect the infection of trypanosomes and analyze the blood feeding patterns,respectively.Paraffin-embedded sections were then prepared from adult triatomines and sent for IHC staining.Results:We collected two adult triatomine bugs in Donghai Island.Morphological and molecular analyses indicated that the triatomines were Triatoma rubrofasciata.No fragments of T.cruzi or other trypanosomes were detected from the fecal DNA.Mitochondrial gene segments of Homo sapiens and Mus musculus were successfully amplified.The allergens which induced specific IgE antibodies in human serum were localized in the triatomine saliva by IHC assay.Conclusions:The two triatomine bugs from Donghai Island were T.rubrofasciata.They had bitten humans and mice.Their saliva should contain the allergens related to the allergic symptoms and even anaphylactic shock of exposed residents.Great consideration should be given to this triatomine bugs due to their considerable distribution and potential threat to public health in South China.展开更多
Background:Chagas disease is one of the neglected tropical diseases(NTDs).International goals for its control involve elimination of vector-borne transmission.Central American countries face challenges in establishing...Background:Chagas disease is one of the neglected tropical diseases(NTDs).International goals for its control involve elimination of vector-borne transmission.Central American countries face challenges in establishing sustainable vector control programmes,since the main vector,Triatoma dimidiata,cannot be eliminated.In 2012,the Ministry of Health in Nicaragua started a field test of a vector surveillance-response system to control domestic vector infestation.This paper reports the main findings from this pilot study.Methods:This study was carried out from 2012 to 2015 in the Municipality of Totogalpa.The Japan International Cooperation Agency provided technical cooperation in designing and monitoring the surveillance-response system until 2014.This system involved 1)vector reports by householders to health facilities,2)data analysis and planning of responses at the municipal health centre and 3)house visits or insecticide spraying by health personnel as a response.We registered all vector reports and responses in a digital database.The collected data were used to describe and analyse the system performance in terms of amount of vector reports as well as rates and timeliness of responses.Results:During the study period,T.dimidiata was reported 396 times.Spatiotemporal analysis identified some high-risk clusters.All houses reported to be infested were visited by health personnel in 2013 and this response rate dropped to 39%in 2015.Rates of insecticide spraying rose above 80%in 2013 but no spraying was carried out in the following 2 years.The timeliness of house visits improved significantly after the responsibility was transferred from a vector control technician to primary health care staff.Conclusions:We argue that the proposed vector surveillance-response system is workable within the resourceconstrained health system in Nicaragua.Integration to the primary health care services was a key to improve the system performance.Continual efforts are necessary to keep adapting the surveillance-response system to the dynamic health systems.We also discuss that the goal of eliminating vector-borne transmission remains unachievable.This paper provides lessons not only for Chagas disease control in Central America,but also for control efforts for other NTDs that need a sustainable surveillance-response system to support elimination.展开更多
Background:Since the late twentieth century,Chagas disease gained global attention to suppress the vector burden as a main control strategy in endemic countries.In Central America,multi-national initiative successfull...Background:Since the late twentieth century,Chagas disease gained global attention to suppress the vector burden as a main control strategy in endemic countries.In Central America,multi-national initiative successfully achieved significant reduction in the estimated disease prevalence as well as elimination of the region's principal vector species at the time in 2012.While the last decade has witnessed significant changes in ecosystem-such as urbanization and replacement of the main vector species-that can possibly affect the vector's habitation and residual transmission,the up-to-date vector burden in the region has not been evaluated thoroughly due to the cessation of active vector surveillance.The aim of this study was to update the risk of vector-borne Trypanosoma cruzi infection in El Salvador,the top Chagas disease-endemic country in Central America.Methods:A nationwide vector survey was conducted in the domestic environment of El Salvador from September 2018 to November 2020.The selection of the houses for inspection was based on expert purposeful sampling.Infection for T.cruzi was examined by microscopic observation of the insects'feces,followed by a species confrmation using PCR.The data were analyzed using R software version 4.1.3.Proportion estimates with 95%confidence intervals were inferred using the Jeffrey's method provided under the epiR package.Results:A total of 1529 Triatoma dimidiata was captured from 107 houses(infestation rate,34.4%;107/311)in all the fourteen departments of the country visited within the period;prevalence of T.cruzi infection was as high as 10%(153/1529).In the country,domestic T.dimidiata infestation was distributed ubiquitously,while T.cruzi infection rates varied across the departments.Five out of fourteen departments showed higher infection rates than the average,suggesting sporadic high-risk areas in the country.Conclusions:Our comprehensive study revealed substantial T.cruzi infection of T.dimidiata across the country,indicating potential active transmission of the disease.Therefore,strengthened surveillance for both vector and human infection is required to truly eliminate the risk of T.cruzi transmission in Central America.展开更多
基金Supported by Proyecto Control de Vectores IMT-UCV
文摘Objective:To investigate the bioecological relationship between Chagas disease peridomestic vectors and reptiles as source of feeding.Methods:In a three-story building,triatomines were captured by direct search and electric vacuum cleaner search in and outside the building.Then,age structure of the captured Triatoma maculata(T.maculata) were identified and recorded.Reptiles living in sympatric with the triatomines were also searched.Results:T.maculata were found living sympatric with geckos(Thecadactylus rapicauda) and they bit residents of the apartment building in study.A total of 1 448 individuals of T.maculata were captured within three days,of which 74.2%(1 074 eggs) were eggs,21.5%were nymphs at different stages,and 4.3%were adults.Conclusions:The association of T.maculata and T.rapicauda is an effective strategy of colonizing dwellings located in the vicinity of the habitat where both species are present;and therefore,could have implications of high importance in the intradomiciliary transmission of Chagas disease.
基金This work was supported by the National Key Research and Development Program of China(grant No.2016YFC1202000,No.2016YFC1202002).
文摘Background:Triatomines,also known as kissing bugs,which are found throughout the world and especially in Latin America,are well known natural vectors that transmit American trypanosomiasis,also called Chagas disease.In China,the presence of two species of Triatoma(Triatoma rubrofasciata and T.sinica)was recorded in the past.Due to the growing population and the increasing risk of the global spread of Chagas disease,triatomines became a potential public health nuisance,and in 2016,we started monitoring triatomine activities in southern China.Methods:Triatomine specimens were collected by the National Institute of Parasitic Diseases,Chinese Center for Disease Control and Prevention,and identified by their morphological characteristics under a dissecting microscope.In addition to morphological analysis,the genomic DNA of the specimens was extracted,and the mitochondrial 16S rRNA,the cytochrome b(CytB)gene and the nuclear ribosomal 28S rRNA gene were PCRamplified to analyze and confirm the species genetically.Results:One female adult insect and one male adult insect were collected in a dwelling in the rural area of Shunde County,Foshan City,Guangdong Province,China(22°42′44.63″N,113°08′45.34″E).The results from the morphological and genetic analyses indicated that these triatomines were T.rubrofasciata.Conclusions:This is the first time that the occurrence of T.rubrofasciata has been confirmed in Foshan City,Guangdong Province in southern China.Further studies are needed to reach a clearer understanding of the ecology of this species of triatomine,since it has been found to be naturally infected by Trypanosoma cruzi and T.conorhini and there is evidence of its domiciliation capabilities.
文摘Although having five different ways of transmission the vector-borne is the principal way of transmission of Chagas disease, which involves insects of the subfamily Triatominae (Hemiptera: Reduviidae). Nineteen of the 31 species that occur in Mexico are associated with humans, and all are capable of transmitting the disease. Pyrethroids are the insecticides recommended for the control of these vectors in Mexico. We determined the susceptibility to the pyrethroids dcltamethrin and permethrin of peridomestic populations of Triatoma mazzottii Usinger and two populations of Triatoma longipetmis Usinger in comparison with a reference strain for each species. Bioassays were performed for the determination of the LD50 for both field populations and reference strains. A maximum of 27 fold resistance to deltamethrin was observed in T. mazzottii, meanwhile, for permethrin, T. longipennis from Jalisco show the highest value of 3.19 fold. There was significantly increased activity of esterases in field populations in comparison with their corresponding reference strain. The results of the search of kdr mutations related to the resistance to deltamethrin and permethrin in the evaluated species show the presence of mutations in the field populations, as is the case with individuals of T. mazzottii, for which the mutation was found A943V, and for the two populations of T. longipennis included in this study, we report the presence of the kdr mutation K964R. Evaluation of the various mechanisms involved in resistance to pyrethroids in triatomines from Mexico could guide us to the real justification for insecticide resistance monitoring.
文摘BackgroundTriatomines in Latin America are natural Chagas disease (ChD) vectors. Triatomine domiciliation is one of the main factors increasing the occurrence risk of this disease in humans. There are 66 triatomine species in Brazil, with three genera of significant epidemiological importance—Panstrongylus, Rhodnius, and Triatoma. Among the Triatoma species, Triatoma williami, a wild species, has been reported in Goiás, Mato Grosso, and Mato Grosso do Sul. In the Barra do Garças, Mato Grosso, the invasion by triatomines has been reported, with T. williami being the most common species. This study aimed to survey triatomine fauna and determine the Trypanosoma cruzi natural infection rates in triatomines in the urban area of Barra do Garças, Mato Grosso, Brazil.MethodsTriatomine specimens were sampled by passive surveillance or active search by agents combating endemic diseases from 2019 to 2020. A parasitological feces diagnosis was performed to detect the presence of T. cruzi after the specimens were identified. Concerning T. cruzi identification, molecular diagnosis and genetic sequencing were performed to determine the strain, also called discrete typing units (DTUs).ResultsThe 211 triatomines were collected, distributed in specimens of T. williami (84.4%), P. geniculatus (3.3%), P. diasi (1.4%), and R. neglectus (10.9%). Two colonies of T. williami were found through morphological analyses. These insects were sampled inside domiciles in an urban area neighboring Jardim Pitaluga (15° 51′57.7″ N, 052° 16′ 04.5 E). The records were sampled in September 2019 and January 2021. The rate of natural infection by T. cruzi was 39.4%. Two T. williami specimens from the sampled colonies were positive for the T. cruzi strain DTU IV.ConclusionsThis is the first time that T. williami has been confirmed in an urban area of Barra do Garças, Mato Grosso, Brazil. Further studies are needed for a clearer understanding of the ecology of this species for prevention and control mechanisms since its sampled specimens had a high rate of natural infection by T. cruzi.
基金This work was supported by National Key Research and Development Program of China(No.2016YFC1202000,2016YFC1202001,and 2016YFC1200500)Shenzhen San-Ming Project for prevention and research on vector-borne diseases(SZSM201611064).
文摘Background:Two health concerns primarily related to triatomine bugs are transmission of Trypanosoma cruzi through infective feces,and allergic reactions induced by triatomine bites.In the Southwestern United States,reduviid bugs bites commonly cause insect allergy.In South China,four cases of anaphylactic shock have been reported after this bite exposure.To further classify the species of these bugs and confirm the sensitization of the triatomine saliva,we caught triatomine bugs from the region where the bites occurred and performed phylogenetic and immunohistochemical(IHC)analysis.Methods:Triatomine bugs were collected in Donghai Island of Zhanjiang City in South China.The genomic DNA was extracted from three legs of the bugs.The fragments of mitochondrial 16S rRNA,cytochrome c oxidase subunit I(COI)gene and nuclear ribosomal 18S and 28S rRNA genes were obtained by PCR and sequenced.A phylogenetic tree was constructed based on the sequence of 16S rRNA gene using a maximum likelihood method with MEGA 7.0 software.Trypanosomal specific fragments and vertebrate COI genes were amplified from the fecal DNA to detect the infection of trypanosomes and analyze the blood feeding patterns,respectively.Paraffin-embedded sections were then prepared from adult triatomines and sent for IHC staining.Results:We collected two adult triatomine bugs in Donghai Island.Morphological and molecular analyses indicated that the triatomines were Triatoma rubrofasciata.No fragments of T.cruzi or other trypanosomes were detected from the fecal DNA.Mitochondrial gene segments of Homo sapiens and Mus musculus were successfully amplified.The allergens which induced specific IgE antibodies in human serum were localized in the triatomine saliva by IHC assay.Conclusions:The two triatomine bugs from Donghai Island were T.rubrofasciata.They had bitten humans and mice.Their saliva should contain the allergens related to the allergic symptoms and even anaphylactic shock of exposed residents.Great consideration should be given to this triatomine bugs due to their considerable distribution and potential threat to public health in South China.
基金This study used funding from the Ministry of Health in Nicaragua(MoH)and Japan International Cooperation Agency(JICA)The MoH played an important role in the design of the study and data collection as described in the paper.Neither organization were not involved in analysing and interpreting data or in writing the manuscript.
文摘Background:Chagas disease is one of the neglected tropical diseases(NTDs).International goals for its control involve elimination of vector-borne transmission.Central American countries face challenges in establishing sustainable vector control programmes,since the main vector,Triatoma dimidiata,cannot be eliminated.In 2012,the Ministry of Health in Nicaragua started a field test of a vector surveillance-response system to control domestic vector infestation.This paper reports the main findings from this pilot study.Methods:This study was carried out from 2012 to 2015 in the Municipality of Totogalpa.The Japan International Cooperation Agency provided technical cooperation in designing and monitoring the surveillance-response system until 2014.This system involved 1)vector reports by householders to health facilities,2)data analysis and planning of responses at the municipal health centre and 3)house visits or insecticide spraying by health personnel as a response.We registered all vector reports and responses in a digital database.The collected data were used to describe and analyse the system performance in terms of amount of vector reports as well as rates and timeliness of responses.Results:During the study period,T.dimidiata was reported 396 times.Spatiotemporal analysis identified some high-risk clusters.All houses reported to be infested were visited by health personnel in 2013 and this response rate dropped to 39%in 2015.Rates of insecticide spraying rose above 80%in 2013 but no spraying was carried out in the following 2 years.The timeliness of house visits improved significantly after the responsibility was transferred from a vector control technician to primary health care staff.Conclusions:We argue that the proposed vector surveillance-response system is workable within the resourceconstrained health system in Nicaragua.Integration to the primary health care services was a key to improve the system performance.Continual efforts are necessary to keep adapting the surveillance-response system to the dynamic health systems.We also discuss that the goal of eliminating vector-borne transmission remains unachievable.This paper provides lessons not only for Chagas disease control in Central America,but also for control efforts for other NTDs that need a sustainable surveillance-response system to support elimination.
文摘Background:Since the late twentieth century,Chagas disease gained global attention to suppress the vector burden as a main control strategy in endemic countries.In Central America,multi-national initiative successfully achieved significant reduction in the estimated disease prevalence as well as elimination of the region's principal vector species at the time in 2012.While the last decade has witnessed significant changes in ecosystem-such as urbanization and replacement of the main vector species-that can possibly affect the vector's habitation and residual transmission,the up-to-date vector burden in the region has not been evaluated thoroughly due to the cessation of active vector surveillance.The aim of this study was to update the risk of vector-borne Trypanosoma cruzi infection in El Salvador,the top Chagas disease-endemic country in Central America.Methods:A nationwide vector survey was conducted in the domestic environment of El Salvador from September 2018 to November 2020.The selection of the houses for inspection was based on expert purposeful sampling.Infection for T.cruzi was examined by microscopic observation of the insects'feces,followed by a species confrmation using PCR.The data were analyzed using R software version 4.1.3.Proportion estimates with 95%confidence intervals were inferred using the Jeffrey's method provided under the epiR package.Results:A total of 1529 Triatoma dimidiata was captured from 107 houses(infestation rate,34.4%;107/311)in all the fourteen departments of the country visited within the period;prevalence of T.cruzi infection was as high as 10%(153/1529).In the country,domestic T.dimidiata infestation was distributed ubiquitously,while T.cruzi infection rates varied across the departments.Five out of fourteen departments showed higher infection rates than the average,suggesting sporadic high-risk areas in the country.Conclusions:Our comprehensive study revealed substantial T.cruzi infection of T.dimidiata across the country,indicating potential active transmission of the disease.Therefore,strengthened surveillance for both vector and human infection is required to truly eliminate the risk of T.cruzi transmission in Central America.
