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1.
Mem Inst Oswaldo Cruz ; 115: e200313, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33533870

RESUMEN

BACKGROUND: Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory. OBJECTIVES: Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan. METHODS: In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay. FINDINGS: Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltage-gated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids. CONCLUSION: The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.


Asunto(s)
Aedes/efectos de los fármacos , Insectos Vectores/genética , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Mosquitos Vectores/efectos de los fármacos , Piretrinas/farmacología , Aedes/genética , Aedes/virología , Animales , Guyana Francesa , Insectos Vectores/efectos de los fármacos , Control de Mosquitos/métodos , Mosquitos Vectores/virología , Análisis Espacio-Temporal
2.
Nat Commun ; 12(1): 215, 2021 01 11.
Artículo en Inglés | MEDLINE | ID: mdl-33431825

RESUMEN

Leishmaniasis is widely regarded as a vaccine-preventable disease, but the costs required to reach pivotal Phase 3 studies and uncertainty about which candidate vaccines should be progressed into human studies significantly limits progress in vaccine development for this neglected tropical disease. Controlled human infection models (CHIMs) provide a pathway for accelerating vaccine development and to more fully understand disease pathogenesis and correlates of protection. Here, we describe the isolation, characterization and GMP manufacture of a new clinical strain of Leishmania major. Two fresh strains of L. major from Israel were initially compared by genome sequencing, in vivo infectivity and drug sensitivity in mice, and development and transmission competence in sand flies, allowing one to be selected for GMP production. This study addresses a major roadblock in the development of vaccines for leishmaniasis, providing a key resource for CHIM studies of sand fly transmitted cutaneous leishmaniasis.


Asunto(s)
Leishmania major/fisiología , Leishmaniasis Cutánea/parasitología , Animales , Modelos Animales de Enfermedad , Humanos , Insectos Vectores/parasitología , Israel , Leishmania major/genética , Leishmania major/crecimiento & desarrollo , Leishmaniasis Cutánea/transmisión , Ratones Endogámicos BALB C , Parásitos/genética , Filogenia , Psychodidae/parasitología , Secuenciación Completa del Genoma
3.
BMC Plant Biol ; 21(1): 67, 2021 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-33514310

RESUMEN

BACKGROUND: Most plant viruses rely on vectors for their transmission and spread. One of the outstanding biological questions concerning the vector-pathogen-symbiont multi-trophic interactions is the potential involvement of vector symbionts in the virus transmission process. Here, we used a multi-factorial system containing a non-persistent plant virus, cucumber mosaic virus (CMV), its primary vector, green peach aphid, Myzus persicae, and the obligate endosymbiont, Buchnera aphidicola to explore this uncharted territory. RESULTS: Based on our preliminary research, we hypothesized that aphid endosymbiont B. aphidicola can facilitate CMV transmission by modulating plant volatile profiles. Gene expression analyses demonstrated that CMV infection reduced B. aphidicola abundance in M. persicae, in which lower abundance of B. aphidicola was associated with a preference shift in aphids from infected to healthy plants. Volatile profile analyses confirmed that feeding by aphids with lower B. aphidicola titers reduced the production of attractants, while increased the emission of deterrents. As a result, M. persicae changed their feeding preference from infected to healthy plants. CONCLUSIONS: We conclude that CMV infection reduces the B. aphidicola abundance in M. persicae. When viruliferous aphids feed on host plants, dynamic changes in obligate symbionts lead to a shift in plant volatiles from attraction to avoidance, thereby switching insect vector's feeding preference from infected to healthy plants.


Asunto(s)
Áfidos/virología , Buchnera/fisiología , Capsicum/virología , Cucumovirus/fisiología , Enfermedades de las Plantas/virología , Simbiosis , Animales , Áfidos/efectos de los fármacos , Áfidos/microbiología , Áfidos/fisiología , Capsicum/microbiología , Capsicum/parasitología , Conducta Alimentaria , Interacciones Huésped-Parásitos , Insectos Vectores/fisiología , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Rifampin/farmacología , Compuestos Orgánicos Volátiles/metabolismo
4.
J Physiol Anthropol ; 40(1): 1, 2021 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-33413683

RESUMEN

Malaria is one of the most devastating infectious diseases of humans. It is problematic clinically and economically as it prevails in poorer countries and regions, strongly hindering socioeconomic development. The causative agents of malaria are unicellular protozoan parasites belonging to the genus Plasmodium. These parasites infect not only humans but also other vertebrates, from reptiles and birds to mammals. To date, over 200 species of Plasmodium have been formally described, and each species infects a certain range of hosts. Plasmodium species that naturally infect humans and cause malaria in large areas of the world are limited to five-P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. The first four are specific for humans, while P. knowlesi is naturally maintained in macaque monkeys and causes zoonotic malaria widely in South East Asia. Transmission of Plasmodium species between vertebrate hosts depends on an insect vector, which is usually the mosquito. The vector is not just a carrier but the definitive host, where sexual reproduction of Plasmodium species occurs, and the parasite's development in the insect is essential for transmission to the next vertebrate host. The range of insect species that can support the critical development of Plasmodium depends on the individual parasite species, but all five Plasmodium species causing malaria in humans are transmitted exclusively by anopheline mosquitoes. Plasmodium species have remarkable genetic flexibility which lets them adapt to alterations in the environment, giving them the potential to quickly develop resistance to therapeutics such as antimalarials and to change host specificity. In this article, selected topics involving the Plasmodium species that cause malaria in humans are reviewed.


Asunto(s)
Malaria , Plasmodium , Animales , Antimaláricos , Culicidae , Especificidad del Huésped , Humanos , Insectos Vectores
5.
Parasit Vectors ; 14(1): 35, 2021 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-33422133

RESUMEN

BACKGROUND: Peri-urban and urban settings have recently gained more prominence in studies on vector-borne transmission of Trypanosoma cruzi due to sustained rural-to-urban migrations and reports of urban infestations with triatomines. Prompted by the finding of Triatoma infestans across the rural-to-urban gradient in Avia Terai, an endemic municipality of the Argentine Chaco, we assessed selected components of domestic transmission risk in order to determine its variation across the gradient. METHODS: A baseline vector survey was conducted between October 2015 and March 2016, following which we used multistage random sampling to select a representative sample of T. infestans at the municipal level. We assessed T. cruzi infection and blood-feeding sources of 561 insects collected from 109 houses using kinetoplast DNA-PCR assays and direct enzyme-linked immunosorbent assays, respectively. We stratified triatomines according to their collection site (domestic or peridomestic), and we further categorized peridomestic sites in ecotopes of low- or high-risk for T. cruzi infection. RESULTS: The overall adjusted prevalence of T. cruzi-infected T. infestans was 1.8% (95% confidence interval [CI] 1.3-2.3) and did not differ between peri-urban (1.7%) and rural (2.2%) environments. No infection was detected in bugs captured in the urban setting; rather, infected triatomines were mainly collected in rural and peri-urban domiciles, occurring in 8% of T. infestans-infested houses. The main blood-feeding sources of domestic and peridomestic triatomines across the gradient were humans and chickens, respectively. The proportion of triatomines that had fed on humans did not differ between peri-urban (62.5%) and rural (65.7%) domiciles, peaking in the few domestic triatomines collected in urban houses and decreasing significantly with an increasing proportion of chicken- and dog- or cat-fed bugs. The relative odds ratio (OR) of having a T. cruzi infection was nearly threefold higher in bugs having a blood meal on humans (OR 3.15), dogs (OR 2.80) or cats (OR: 4.02) in a Firth-penalized multiple logistic model. CONCLUSIONS: Trypanosoma cruzi transmission was likely occurring both in peri-urban and rural houses of Avia Terai. Widespread infestation in a third of urban blocks combined with high levels of human-triatomine contact in the few infested domiciles implies a threat to urban inhabitants. Vector control strategies and surveillance originally conceived for rural areas should be tailored to peri-urban and urban settings in order to achieve sustainable interruption of domestic transmission in the Chaco region.


Asunto(s)
Enfermedad de Chagas/epidemiología , Enfermedad de Chagas/transmisión , Insectos Vectores/parasitología , Triatoma , Trypanosoma cruzi , Adulto , Animales , Argentina/epidemiología , Gatos , Pollos , Perros , Ensayo de Inmunoadsorción Enzimática , Conducta Alimentaria , Femenino , Cabras , Humanos , Masculino , Ratones , Factores de Riesgo , Población Rural
6.
Geneva; World Health Organization; 2021. (WHO/UCN/GMP/2021.01).
en Inglés | WHO IRIS | ID: who-339609
7.
Rev Soc Bras Med Trop ; 54: e00282020, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33338103

RESUMEN

INTRODUCTION: We aimed to study intraspecific variation in Triatoma costalimai, a potential vector of Chagas disease present in Brazil and Bolivia. METHODS: We analyzed phenotypic (connexivum color patterns, wing morphometrics) and genetic variation (16S mtDNA) of three Brazilian T. costalimai populations. We compared 16S sequences with those of putative Bolivian T. costalimai and its sister species, T. jatai. RESULTS: Brazilian populations had different connexivum color patterns and forewing shapes. A 16S mtDNA haplotype network showed a clear separation of Brazilian T. costalimai from both T. jatai and Bolivian T. costalimai. CONCLUSIONS: We report considerable variability in T. costalimai populations.


Asunto(s)
Enfermedad de Chagas , Triatoma , Animales , Bolivia , Brasil , Variación Genética/genética , Insectos Vectores/genética , Triatoma/genética
8.
Rev Soc Bras Med Trop ; 54: e00842020, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33338105

RESUMEN

INTRODUCTION: Panstrongylus megistus is the main triatomine involved in the human transmission of Trypanosoma cruzi in Minas Gerais, Brazil. We analyzed the occurrence of triatomines in the Itaúna micro-regions for healthcare. METHODS: Data were collected as part of routine entomological surveillance activities, including the species identity, capture site, developmental stage, and trypanosome infection. RESULTS: In total, 503 specimens from five species were captured (495 P. megistus). Adults were mainly captured by residents inside their homes, whereas nymphs were mostly captured by public health professionals outside. CONCLUSIONS: The epidemiologically important triatomine, P. megistus, continues to persist in our study region.


Asunto(s)
Enfermedad de Chagas , Panstrongylus , Trypanosoma cruzi , Animales , Brasil/epidemiología , Enfermedad de Chagas/epidemiología , Humanos , Insectos Vectores
9.
Rev Soc Bras Med Trop ; 54: e03302020, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33338112

RESUMEN

INTRODUCTION: This communication reports on the occurrence of colonization by Panstrongylus megistus in an urban park in the municipality of São Paulo, Brazil. METHODS: Entomological research includes active search for vectors based on notifications by the population and identification and examination of insects. RESULTS: A colony of triatomines was found to be associated with enclosed birds. CONCLUSIONS: The occurrence of P. megistus has already been reported in the city of São Paulo; however, reports of colonization by this species provide evidence of its potential for the occupation of artificial ecotopes, which may pose a risk to the human population.


Asunto(s)
Enfermedad de Chagas , Panstrongylus , Reduviidae , Triatominae , Animales , Brasil , Humanos , Insectos Vectores , Parques Recreativos
10.
PLoS Negl Trop Dis ; 14(12): e0009004, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33370288

RESUMEN

A detailed understanding of the mechanisms underlying the capacity of a virus to break the species barrier is crucial for pathogen surveillance and control. New World (NW) mammarenaviruses constitute a diverse group of rodent-borne pathogens that includes several causative agents of severe viral hemorrhagic fever in humans. The ability of the NW mammarenaviral attachment glycoprotein (GP) to utilize human transferrin receptor 1 (hTfR1) as a primary entry receptor plays a key role in dictating zoonotic potential. The recent isolation of Tacaribe and lymphocytic choriominingitis mammarenaviruses from host-seeking ticks provided evidence for the presence of mammarenaviruses in arthropods, which are established vectors for numerous other viral pathogens. Here, using next generation sequencing to search for other mammarenaviruses in ticks, we identified a novel replication-competent strain of the NW mammarenavirus Tamiami (TAMV-FL), which we found capable of utilizing hTfR1 to enter mammalian cells. During isolation through serial passaging in mammalian immunocompetent cells, the quasispecies of TAMV-FL acquired and enriched mutations leading to the amino acid changes N151K and D156N, within GP. Cell entry studies revealed that both substitutions, N151K and D156N, increased dependence of the virus on hTfR1 and binding to heparan sulfate proteoglycans. Moreover, we show that the substituted residues likely map to the sterically constrained trimeric axis of GP, and facilitate viral fusion at a lower pH, resulting in viral egress from later endosomal compartments. In summary, we identify and characterize a naturally occurring TAMV strain (TAMV-FL) within ticks that is able to utilize hTfR1. The TAMV-FL significantly diverged from previous TAMV isolates, demonstrating that TAMV quasispecies exhibit striking genetic plasticity that may facilitate zoonotic spillover and rapid adaptation to new hosts.


Asunto(s)
Antígenos CD/metabolismo , Infecciones por Arenaviridae/transmisión , Arenaviridae/genética , Receptores de Transferrina/metabolismo , Receptores Virales/metabolismo , Proteínas del Envoltorio Viral/genética , Secuencia de Aminoácidos/genética , Animales , Arenaviridae/aislamiento & purificación , Línea Celular , Chlorocebus aethiops , Células HEK293 , Humanos , Insectos Vectores/virología , Alineación de Secuencia , Garrapatas/virología , Células Vero , Zoonosis/transmisión , Zoonosis/virología
11.
PLoS Negl Trop Dis ; 14(12): e0008967, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33370303

RESUMEN

Phlebotomine sand flies employ an elaborate system of pheromone communication wherein males produce pheromones that attract other males to leks (thus acting as an aggregation pheromone) and females to the lekking males (sex pheromone). In addition, the type of pheromone produced varies among populations. Despite the numerous studies on sand fly chemical communication, little is known of their chemosensory genome. Chemoreceptors interact with chemicals in an organism's environment to elicit essential behaviors such as the identification of suitable mates and food sources. Thus, they play important roles during adaptation and speciation. Major chemoreceptor gene families, odorant receptors (ORs), gustatory receptors (GRs) and ionotropic receptors (IRs) together detect and discriminate the chemical landscape. Here, we annotated the chemoreceptor repertoire in the genomes of Lutzomyia longipalpis and Phlebotomus papatasi, major phlebotomine vectors in the New World and Old World, respectively. Comparison with other sequenced Diptera revealed a large and unique expansion where over 80% of the ~140 ORs belong to a single, taxonomically restricted clade. We next conducted a comprehensive analysis of the chemoreceptors in 63 L. longipalpis individuals from four different locations in Brazil representing allopatric and sympatric populations and three sex-aggregation pheromone types (chemotypes). Population structure based on single nucleotide polymorphisms (SNPs) and gene copy number in the chemoreceptors corresponded with their putative chemotypes, and corroborate previous studies that identified multiple populations. Our work provides genomic insights into the underlying behavioral evolution of sexual communication in the L. longipalpis species complex in Brazil, and highlights the importance of accounting for the ongoing speciation in central and South American Lutzomyia that could have important implications for vectorial capacity.


Asunto(s)
Células Quimiorreceptoras/metabolismo , Proteínas de Insectos/genética , Leishmaniasis/prevención & control , Leishmaniasis/transmisión , Phlebotomus/parasitología , Atractivos Sexuales/química , Animales , Brasil , Femenino , Insectos Vectores/parasitología , Leishmania , Masculino , Phlebotomus/genética , Phlebotomus/fisiología , Polimorfismo de Nucleótido Simple/genética
12.
PLoS Negl Trop Dis ; 14(12): e0009015, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33370305

RESUMEN

Trypanosoma rangeli is a non-pathogenic protozoan parasite that infects mammals, including humans, in Chagas disease-endemic areas of South and Central America. The parasite is transmitted to a mammalian host when an infected triatomine injects metacyclic trypomastigotes into the host's skin during a bloodmeal. Infected mammals behave as parasite reservoirs for several months and despite intensive research, some major aspects of T. rangeli-vertebrate interactions are still poorly understood. In particular, many questions still remain unanswered, e.g. parasite survival and development inside vertebrates, as no parasite multiplication sites have yet been identified. The present study used an insect bite transmission strategy to investigate whether the vector inoculation spot in the skin behave as a parasite-replication site. Histological data from the skin identified extracellular parasites in the dermis and hypodermis of infected mice in the first 24 hours post-infection, as well as the presence of inflammatory infiltrates in a period of up to 7 days. However, qPCR analyses demonstrated that T. rangeli is eliminated from the skin after 7 days of infection despite being still consistently found on circulating blood and secondary lymphoid tissues for up to 30 days post-infection. Interestingly, significant numbers of parasites were found in the spleen and mesenteric lymph nodes of infected mice during different periods of infection and steady basal numbers of flagellates are maintained in the host's bloodstream, which might behave as a transmission source to insect vectors. The presence of parasites in the spleen was confirmed by fluorescent photomicrography of free and cell-associated T. rangeli forms. Altogether our results suggest that this organ could possibly behave as a T. rangeli maintenance hotspot in vertebrates.


Asunto(s)
Enfermedad de Chagas/transmisión , Ganglios Linfáticos/parasitología , Piel/parasitología , Bazo/parasitología , Trypanosoma rangeli/aislamiento & purificación , Animales , América Central/epidemiología , Enfermedad de Chagas/epidemiología , Modelos Animales de Enfermedad , Interacciones Huésped-Parásitos , Humanos , Mordeduras y Picaduras de Insectos/parasitología , Insectos Vectores/parasitología , Ratones , Rhodnius/parasitología , Sepsis/parasitología , América del Sur/epidemiología
13.
Nat Commun ; 11(1): 5801, 2020 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-33199712

RESUMEN

Historically endemic to Sub-Saharan Africa and South America, yellow fever is absent from the Asia-Pacific region. Yellow fever virus (YFV) is mainly transmitted by the anthropophilic Aedes mosquitoes whose distribution encompasses a large belt of tropical and sub tropical regions. Increasing exchanges between Africa and Asia have caused imported YFV incidents in non-endemic areas, which are threatening Asia with a new viral emergence. Here, using experimental infections of field-collected mosquitoes, we show that Asian-Pacific Aedes mosquitoes are competent vectors for YFV. We observe that Aedes aegypti populations from Singapore, Taiwan, Thailand, and New Caledonia are capable of transmitting YFV 14 days after oral infections, with a number of viral particles excreted from saliva reaching up to 23,000 viral particles. These findings represent the most comprehensive assessment of vector competence and show that Ae. aegypti mosquitoes from the Asia-Pacific region are highly competent to YFV, corroborating that vector populations are seemingly not a brake to the emergence of yellow fever in the region.


Asunto(s)
Fiebre Amarilla/transmisión , Fiebre Amarilla/virología , Virus de la Fiebre Amarilla/fisiología , Aedes/virología , Animales , Asia/epidemiología , Geografía , Insectos Vectores/virología , Modelos Lineales , Probabilidad , Factores de Riesgo , Saliva/virología , Carga Viral
14.
Mem Inst Oswaldo Cruz ; 115: e200157, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33206821

RESUMEN

BACKGROUND: In Acre state, Brazil, the dissemination of cutaneous leishmaniasis has increased in recent years, with limited knowledge of the potential Leishmania spp. vectors involved. OBJECTIVES: Here, data concerning the sandfly fauna of Brasiléia municipality, Leishmania DNA-detection rates and the identification of blood meal sources of insects captured in 2013-2015 are presented. METHODS: Parasite detection in female sandflies was performed individually by multiplex polymerase chain reaction (PCR) (Leishmania kDNA/sandfly cacophony-gene), with the identification of Leishmania spp. by hsp70-PCR and sequencing. The identification of blood gut-content from fed females was performed by cyt b-PCR and sequencing. FINDINGS: A total of 4,473 sandflies were captured. A subgroup of 864 non-blood-fed females evaluated for the presence of Leishmania DNA showed 2.9% positivity for Leishmania (Viannia) braziliensis and L. (V.) guyanensis. The identification of blood meal sources was performed in 96 blood-fed females, allowing the identification of 13 vertebrate species. In nine/96 fed females, DNA from L. (V.) shawi, L. (V.) guyanensis, L. (V.) braziliensis and Endotrypanum sp. was detected. MAIN CONCLUSIONS: In Brumptomyia sp. and Evandromyia termitophila, the first report of Leishmania DNA-detection is provided in Acre; Nyssomyia shawi is implicated as potential vector of L. (V.) braziliensis and L. (V.) guyanensis for the first time in Brazil.


Asunto(s)
ADN/análisis , Insectos Vectores/genética , Leishmania/genética , Psychodidae/parasitología , Animales , Brasil , ADN Protozoario/análisis , Femenino , Insectos Vectores/clasificación , Insectos Vectores/parasitología , Leishmania/aislamiento & purificación , Leishmaniasis Cutánea/transmisión , Reacción en Cadena de la Polimerasa , Psychodidae/clasificación
15.
Artículo en Inglés | MEDLINE | ID: mdl-33206861

RESUMEN

The etiological agent of American trypanosomiasis is the protozoan Trypanosoma cruzi , typically transmitted by triatomines. The aim of this study was to investigate the triatomine fauna and trypanosomiasis infections in Acre State , Western Brazilian Amazon. Insect collection was performed by dissecting palm trees and installing traps. We found that T. cruzi infection rate was 24.5% and Rhodnius pictipes (57.1%) was the most abundant triatomine species. Health education as well as epidemiological and entomological surveillance are necessary to diagnose and prevent new cases of Chagas disease in the region.


Asunto(s)
Enfermedad de Chagas , Insectos Vectores/parasitología , Rhodnius/parasitología , Trypanosoma cruzi , Animales , Brasil/epidemiología , Enfermedad de Chagas/epidemiología , Enfermedad de Chagas/transmisión
16.
Mem Inst Oswaldo Cruz ; 115: e200203, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33146245

RESUMEN

BACKGROUND: Deforestation, driven by anthropogenic change in land use, influences the behaviour and abundance of vector-borne diseases. For various species of Chagas disease vectors, there is evidence that change in land use affects population density and abundance. Triatoma dimidiata is the most important Chagas vector in Guatemala, and at least one million people live in T. dimidiata endemic areas; however, infestation dynamics vary among regions, from high infestation with all life stages to low seasonal infestation by sylvatic adults. OBJECTIVES: The aim of this study was to evaluate how land-use, combined with domiciliary risk factors, influences the infestation dynamics of T. dimidiata for four villages in a dry forest region with a strong deforestation history. METHODS: Land use, measured with drone and satellite images, was classified into four categories (houses, monocultures and pastures, woodland and shrubland, and bare soil). Domiciliary risk factors and infestation were assessed through entomological surveys. Statistical analyses compared infestation indices and the ability of land use and domiciliary risk factors to explain infestation. FINDINGS: Two villages had significantly higher infestation (26 and 30% vs. 5 and 6%), yet all villages had high colonisation (71-100% of infested houses had immature insects), with no significant difference among them. Because of the high level of deforestation across the study area, land use was not related to infestation; however, domiciliary risk factors were. A model based on four weighted domiciliary risk factors (adobe or bajareque walls, intradomicile animals, intradomicile clutter, and dirt floors) explains the infestation risk. MAIN CONCLUSIONS: Because almost all infested houses have reproducing populations in this deforested dry forest region and statistical analysis identified the domiciliary risk factors for infestation, intermediate and long-term control of Chagas disease vectors in this region requires management of these risk factors.


Asunto(s)
Enfermedad de Chagas/transmisión , Insectos Vectores , Triatoma , Adulto , Animales , Bosques , Guatemala , Vivienda , Humanos
17.
Korean J Parasitol ; 58(5): 551-558, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33202507

RESUMEN

The flaviviruses are small single-stranded RNA viruses that are typically transmitted by mosquitoes or tick vectors and are etiological agents of acute zoonotic infections. The viruses are found around the world and account for significant cases of human diseases. We investigated population of culicine mosquitoes in central region of Korean Peninsula, Incheon Metropolitan City and Hwaseong-si. Aedes vexans nipponii was the most frequently collected mosquitoes (56.5%), followed by Ochlerotatus dorsalis (23.6%), Anopheles spp. (10.9%), and Culex pipiens complex (5.9%). In rural regions of Hwaseong, Aedes vexans nipponii was the highest population (62.9%), followed by Ochlerotatus dorsalis (23.9%) and Anopheles spp. (12.0%). In another rural region of Incheon (habitat of migratory birds), Culex pipiens complex was the highest population (31.4%), followed by Ochlerotatus dorsalis (30.5%), and Aedes vexans vexans (27.5%). Culex pipiens complex was the predominant species in the urban region (84.7%). Culicine mosquitoes were identified at the species level, pooled up to 30 mosquitoes each, and tested for flaviviral RNA using the SYBR Green-based RT-PCR and confirmed by cDNA sequencing. Three of the assayed 2,683 pools (989 pools without Anopheles spp.) were positive for Culex flaviviruses, an insect-specific virus, from Culex pipiens pallens collected at the habitats for migratory birds in Incheon. The maximum likelihood estimation (the estimated number) for Culex pipiens pallens positive for Culex flavivirus was 25. Although viruses responsible for mosquito-borne diseases were not identified, we encourage intensified monitoring and long-term surveillance of both vector and viruses in the interest of global public health.


Asunto(s)
Culicidae/virología , Flavivirus , Insectos Vectores/virología , Animales , Monitoreo del Ambiente , Flavivirus/genética , Flavivirus/aislamiento & purificación , Humanos , ARN Viral/análisis , República de Corea , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Tiempo
18.
Korean J Parasitol ; 58(5): 583-587, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33202512

RESUMEN

Blastocystis sp. is a kind of protozoa living in the intestinal tract of human and animals, which will cause intestinal diseases such as diarrhea, abdominal distension and vomiting. This paper was aimed to understand the infection of Blastocystis sp. In golden monkeys and the transmission path in North China. Thirty-seven feces samples from golden monkeys and 116 cockroach samples from Shijiazhuang Zoo were collected from July to October 2019 for PCR analysis of Blastocystis sp. Genetic diversity analysis was further conducted on the samples with positive PCR results. The results showed that the infection rate was 48.7% (18/37) in golden monkeys and 82.8% (96/116) in cockroaches, respectively. The genetic evolution analysis based on small subunit ribosomal RNA demonstrated that three subtypes (ST) of Blastocystis sp. including ST1, ST2, and ST3 existed in the intestinal tract of golden monkeys, while only ST2 was detected in the intestinal tract of cockroaches. This paper may provide supports for the quarantine and control of Blastocystis sp. for the zoo in Northern China.


Asunto(s)
Animales de Zoológico , Infecciones por Blastocystis/transmisión , Infecciones por Blastocystis/veterinaria , Blastocystis/aislamiento & purificación , Cucarachas/parasitología , Vectores de Enfermedades , Insectos Vectores , Enfermedades de los Monos/parasitología , Enfermedades de los Monos/transmisión , Enfermedades Parasitarias en Animales/parasitología , Enfermedades Parasitarias en Animales/transmisión , Animales , Blastocystis/clasificación , Blastocystis/genética , Infecciones por Blastocystis/epidemiología , Infecciones por Blastocystis/parasitología , Cercopithecus , China/epidemiología , Heces/parasitología , Femenino , Masculino , Enfermedades de los Monos/epidemiología , Enfermedades Parasitarias en Animales/epidemiología , Reacción en Cadena de la Polimerasa
19.
PLoS Comput Biol ; 16(10): e1008292, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33075052

RESUMEN

The lack of effective vaccines for many endemic diseases often forces policymakers to rely on non-immunizing control measures, such as vector control, to reduce the massive burden of these diseases. Controls can have well-known counterintuitive effects on endemic infections, including the honeymoon effect, in which partially effective controls cause not only a greater initial reduction in infection than expected, but also large outbreaks during control resulting from accumulation of susceptibles. Unfortunately, many control measures cannot be maintained indefinitely, and the results of cessation are poorly understood. Here, we examine the results of stopped or failed non-immunizing control measures in endemic settings. By using a mathematical model to compare the cumulative number of cases expected with and without control, we show that deployment of control can lead to a larger total number of infections, counting from the time that control started, than without any control-the divorce effect. This result is directly related to the population-level loss of immunity resulting from non-immunizing controls and is seen in a variety of models when non-immunizing controls are used against an infection that confers immunity. Finally, we examine three control plans for minimizing the magnitude of the divorce effect in seasonal infections and show that they are incapable of eliminating the divorce effect. While we do not suggest stopping control programs that rely on non-immunizing controls, our results strongly argue that the accumulation of susceptibility should be considered before deploying such controls against endemic infections when indefinite use of the control is unlikely. We highlight that our results are particularly germane to endemic mosquito-borne infections, such as dengue virus, both for routine management involving vector control and for field trials of novel control approaches, and in the context of non-pharmaceutical interventions aimed at COVID-19.


Asunto(s)
Control de Enfermedades Transmisibles/métodos , Enfermedades Endémicas/prevención & control , Programas de Inmunización , Animales , Número Básico de Reproducción , Infecciones por Coronavirus/prevención & control , Culicidae , Vacunas contra el Dengue/uso terapéutico , Política de Salud , Humanos , Insectos Vectores , Modelos Teóricos , Pandemias/prevención & control , Neumonía Viral/prevención & control , Salud Pública , Rubéola (Sarampión Alemán)/prevención & control , Vacuna contra la Rubéola/uso terapéutico , Estaciones del Año , Dengue Grave/prevención & control , Vacunas Virales/uso terapéutico
20.
PLoS One ; 15(10): e0234454, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33075073

RESUMEN

Corn Stunt is an important disease in the Americas due to it high prevalence and the yield reductions that can cause when present. However, changes in the presence of this disease across years hampers the effective identification of resistant genotypes to this disease. To avoid the limitations of phenotypic selection under natural pressure, this research aimed to devise an effective strategy to screen disease-resistant genotypes in the absence of high and constant natural pressures. To do so, we investigated the presence of antixenosis and antibiosis as components of resistance to the vector Dalbulus maidis as well as resistance to the pathogen Spiroplasma kunkelii under artificial inoculation conditions in four maize hybrids. The hybrids shown differences in their levels of resistance and target organisms, either the insect vector or the pathogen. Antixenosis and antibiosis to D. maidis were observed in DK72-10. Resistance to S. kunkelii by DK79-10 was seen as a delayed onset of symptoms, and DKB390 showed antixenosis to D. maidis and resistance to S. kunkelii. An association between symptom severity and yield reduction was found, but not between accumulation of pathogen S. kunkelii and symptom severity nor yield. In conclusion, the proposed methodology was efficacious and can aid in the screening of resistant genotypes in breeding programs to reduce the impact of Corn Stunt disease, ensuring that hybrids with good resistance level will be planted by farmers whenever disease occurs.


Asunto(s)
Resistencia a la Enfermedad , Hemípteros/microbiología , Zea mays/crecimiento & desarrollo , Animales , Antibiosis , Femenino , Insectos Vectores/microbiología , Fitomejoramiento , Spiroplasma , Zea mays/genética , Zea mays/parasitología
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