RESUMO
Vector-borne diseases are globally prevalent and represent a major socioeconomic problem worldwide. Blood-sucking arthropods transmit most pathogenic agents that cause these human infections. The pathogens transmission to their vertebrate hosts depends on how efficiently they infect their vector, which is particularly impacted by the microbiota residing in the intestinal lumen, as well as its cells or internal organs such as ovaries. The balance between costs and benefits provided by these interactions ultimately determines the outcome of the relationship. Here, we will explore aspects concerning the nature of microbe-vector interactions, including the adaptive traits required for their establishment, the varied outcomes of symbiotic interactions, as well as the factors influencing the transition of these relationships across a continuum from parasitism to mutualism.
Assuntos
Vetores Artrópodes , Simbiose , Animais , Vetores Artrópodes/microbiologia , Vetores Artrópodes/parasitologia , Insetos Vetores/microbiologia , Insetos Vetores/fisiologia , Doenças Transmitidas por Vetores/transmissãoRESUMO
Rickettsia amblyommatis has been reported infecting various tick species throughout the western hemisphere, including Amblyomma cajennense sensu stricto (s.s.). The present study aimed to evaluate whether R. amblyommatis can be maintained by transovarial transmission and transstadial passage in A. cajennense s.s. ticks, and whether these ticks are competent vectors of this rickettsial agent. We selected engorged females that were naturally infected or uninfected by R. amblyommatis, and reared their offspring (infected and control groups, respectively). Immature ticks were allowed to feed on guinea pigs, whereas adults fed on rabbits. All stages and individuals of each generation of the infected group yielded rickettsial DNA, which was not detected in any tick from the control group. No host from the control group seroconverted to R. amblyommatis. Among 16 guinea pigs and eight rabbits infested with R. amblyommatis-infected ticks, only one guinea pig seroconverted to R. amblyommatis. Some unfed adult ticks of the infected group were dissected, and DNA was extracted from their salivary glands and from their carcasses. DNA of R. amblyommatis was detected in all carcasses, but not in the salivary glands. Results of this study indicate very low vector competence of A. cajennense s.s. for R. amblyommatis. Previous studies reported domestic animals with high titers to R. amblyommatis in areas where these animals are naturally infested chiefly by A. cajennense s.s. ticks. One may consider that the vector competence of A. cajennense s.s. for R. amblyommatis could vary among tick populations and/or rickettsial strains.
Assuntos
Vetores Artrópodes/microbiologia , Infecções por Rickettsia/veterinária , Rickettsia/isolamento & purificação , Carrapatos/microbiologia , Animais , Brasil , Feminino , Cobaias , CoelhosRESUMO
Brazilian spotted fever (BSF) is a highly lethal disease in southeastern Brazil. BSF is caused by the bacterium Rickettsia rickettsii and is transmitted by the bites of the tick of the genus Amblyomma. The spatial distribution of BSF risk areas is not well known in the country given the complexity of the transmission cycle. This study used the ecological niche modeling (ENM) approach to anticipate the potential distribution of the etiological agent (Rickettsia rickettsii), vectors (Amblyomma sculptum and A. dubitatum), and hosts (Hydrochoerus hydrochaeris, Didelphis aurita, and D. marsupialis) of BSF in Brazil. We compiled occurrence records for all vectors, hosts, and BSF from our own field surveillance, online repositories, and literature. ENM identified BSF risk areas in southeastern and southern Brazil, and anticipated other dispersed suitable areas in the western, central, and northeastern coast regions of Brazil. Tick vectors and mammalian hosts were confined to these same areas; however, host species showed broader suitability in northern Brazil. All species ENMs performed significantly better than random expectations. We also tested the BSF prediction based on 253 additional independent cases identified in our surveillance; the model anticipated 251 out of 253 of these independent cases. Background similarity tests comparing the ENMs of R. rickettsii, tick vectors, and mammalian hosts were unable to reject null hypotheses of niche similarity. Finally, we observed close coincidence between independent BSF cases, and areas suitable for combinations of vectors and hosts, reflecting the ability of these model pairs to anticipate the distribution of BSF cases across Brazil.
Assuntos
Vetores Artrópodes/microbiologia , Didelphis/microbiologia , Rickettsia rickettsii/isolamento & purificação , Febre Maculosa das Montanhas Rochosas/etiologia , Roedores/microbiologia , Carrapatos/microbiologia , Animais , Ecossistema , Febre Maculosa das Montanhas Rochosas/transmissãoRESUMO
Rickettsiosis are emerging or re-emerging diseases, with a worldwide distribution associated to transmission by arthropod vectors. Rickettsia species belong to the spotted fever group (SFG) and are transmitted by hard ticks (Acari: Ixodidae) that may act as vectors and reservoirs. This study carried out a molecular detection of Rickettsia from 7 species of the family Ixodidae collected from domestic hosts by PCR amplification of fragments of the citrate synthase "gltA" gene and outer membrane protein "ompA" gene. Of the 204 samples analyzed, 11.3% (23) were positive for rickettsial infection. Three Rickettsia species belonging to the SFG were found, constituting the first reports of Rickettsia rickettsii in 2 departments of Colombia. Furthermore, we confirmed the first occurrence of Candidatus Rickettsia andeanae in Colombia, a species with an unknown pathogenic role in humans. These results raise awareness regarding the need to increase epidemiological control measures, as well as to consider new endemic regions in Colombia for Rocky Mountain spotted fever (RMSF).
Assuntos
Animais Domésticos/microbiologia , Doenças Endêmicas , Ixodidae/microbiologia , Infecções por Rickettsia/veterinária , Rickettsia/isolamento & purificação , Animais , Animais Domésticos/parasitologia , Vetores Artrópodes/microbiologia , Proteínas da Membrana Bacteriana Externa/genética , Bovinos/microbiologia , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/microbiologia , Colômbia/epidemiologia , Doenças do Cão/epidemiologia , Doenças do Cão/microbiologia , Cães/microbiologia , Equidae/microbiologia , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/microbiologia , Cavalos/microbiologia , Humanos , Filogenia , Reação em Cadeia da Polimerase , Rickettsia/genética , Rickettsia/patogenicidade , Infecções por Rickettsia/epidemiologia , Infecções por Rickettsia/microbiologia , Infecções por Rickettsia/transmissão , Febre Maculosa das Montanhas Rochosas , Suínos/microbiologia , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/microbiologiaRESUMO
Introduction: The species of the Amblyoma cajennense complex, potential vectors involved in the transmission of Rickettsia rickettsii in Central and South America, have a wide geographical distribution in the Neotropics. In Colombia, the knowledge about these species, their distribution, and many aspects of their ecology is still limited. Objective: To explore the ecology of A. cajennense complex in Colombia based on the study of its habitat selection, as well as the generation of potential geographic and climatic distribution models. Materials and methods: We used unique records of these ticks to study the selection patterns of the climatic habitat using the Ecological Niche Factor Analysis (ENFA), and we built distribution models using the MaxEnt and GARP algorithms. Results: The record of distributions showed that A. cajennense complex is present in all five natural regions of Colombia with 64.71% of the records found in the departments of Antioquia, Cundinamarca, and Huila. The analysis of their habitat selection showed that these ticks preferably select geographical areas (ENFA: 96.03%) according to the isothermality conditions and the precipitation of the driest quarter of the year. The potential distribution models indicated habitat suitability in 31 to 51% of the area of the country depending on the algorithm. Conclusions: The distribution of A. cajennense complex in Colombia is highly influenced by a climatebased habitat selection, a characteristic that favored the creation of distribution models. Field studies will allow the validation of the potential distribution models and further genetic studies will be required in the country to identify species within the complex and study their potential hybridization areas.
Introducción. Las especies del complejo Amblyomma cajennense, potenciales vectores implicados en la transmisión de Rickettsia rickettsii en Centroamérica y Suramérica, presentan una amplia distribución geográfica en el neotrópico. En Colombia, todavía es incipiente el conocimiento sobre las especies de este complejo, su distribución y su ecología.Objetivo. Explorar la ecología del complejo A. cajennense en Colombia a partir del estudio de su selección de hábitat y la generación de modelos potenciales de distribución geográfica y climática.Materiales y métodos. Se utilizaron registros únicos de la presencia de estas garrapatas en el estudio de sus patrones de selección del hábitat, mediante el análisis factorial del nicho ecológico (Ecological Niche Factor Analysis, ENFA), y se construyeron modelos de distribución potencial con las metodologías MaxEnt y GARP.Resultados. El complejo A. cajennense se encontró en las cinco regiones naturales de Colombia, con 64,71 % de los registros procedentes de los departamentos de Antioquia, Cundinamarca y Huila. La selección del hábitat evidenció que estas garrapatas escogen preferentemente las áreas geográficas (ENFA: 96,03 %) según sus condiciones de índice de estabilidad térmica y de precipitación en el trimestre más seco del año. Los modelos de distribución potencial indicaron la idoneidad del hábitat en 31 a 51 % del área del país dependiendo del algoritmo empleado.Conclusiones. En Colombia, el complejo A. cajennense presenta una distribución muy influenciada por el comportamiento en la selección del hábitat climático, característica que facilitó la creación de modelos de distribución. En futuros estudios de campo, se podrían validar los modelos presentados; se requieren, además, otros estudios genéticos para la identificación de especies del complejo y el manejo de sus potenciales zonas de hibridación en el país.
Assuntos
Vetores Artrópodes/microbiologia , Ixodidae/microbiologia , Modelos Teóricos , Rickettsia rickettsii/isolamento & purificação , Distribuição Animal , Animais , Clima , ColômbiaRESUMO
Little is known about tick-borne rickettsial pathogens in Belize, Central America. We tested ixodid ticks for the presence of Rickettsia species in three of the six northern and western Belizean districts. Ticks were collected from domestic animals and tick drags over vegetation in 23 different villages in November 2014, February 2015, and May 2015. A total of 2,506 collected ticks were identified to the following species: Dermacentor nitens Neumann (46.69%), Rhipicephalus sanguineus (Latreille) (19.55%), Rhipicephalus microplus (Canestrini) (19.47%), Amblyomma cajennense complex (9.74%), Amblyomma maculatum Koch (3.47%), Amblyomma ovale Koch (0.68%), Ixodes nr affinis (0.16%), Amblyomma nr maculatum (0.12%), and Amblyomma nr oblongoguttatum (0.12%). Ticks were pooled according to species, life stage (larva, nymph, or adult), and location (n = 509) for DNA extraction and screened for genus Rickettsia by quantitative real-time polymerase chain reaction (qPCR). All 42 positive pools were found to be positive for spotted fever group (SFG) Rickettsia in pools of A. cajennense complex (n = 33), A. maculatum (n = 4), A. nr maculatum (n = 1), A. ovale (n = 1), R. sanguineus (n = 1), and I. nr affinis (n = 2). Rickettsia amblyommatis was identified from A. cajennense complex and A. nr maculatum. Rickettsia parkeri was found in A. maculatum, and Rickettsia sp. endosymbiont was detected in I. nr affinis. The presence of infected ticks suggests a risk of tick-borne rickettsioses to humans and animals in Belize. This knowledge can contribute to an effective tick management and disease control program benefiting residents and travelers.
Assuntos
Vetores Artrópodes/microbiologia , Ixodidae/microbiologia , Rickettsia/classificação , Rickettsia/isolamento & purificação , Animais , Belize , Feminino , Masculino , Rickettsia/genéticaRESUMO
Vertebrate blood composition is heavily biased towards proteins, and hemoglobin, which is a hemeprotein, is by far the most abundant protein. Typically, hematophagous insects ingest blood volumes several times their weight before the blood meal. This barbarian feast offers an abundance of nutrients, but the degradation of blood proteins generates toxic concentrations of amino acids and heme, along with unparalleled microbiota growth. Despite this challenge, hematophagous arthropods have successfully developed mechanisms that bypass the toxicity of these molecules. While these adaptations allow hematophagous arthropods to tolerate their diet, they also constitute a unique mode of operation for cell signaling, immunity, and metabolism, the study of which may offer insights into the biology of disease vectors and may lead to novel vector-specific control methods.
Assuntos
Vetores Artrópodes/metabolismo , Artrópodes/metabolismo , Hemeproteínas/metabolismo , Fenômenos Fisiológicos da Nutrição/fisiologia , Adaptação Fisiológica , Animais , Vetores Artrópodes/imunologia , Vetores Artrópodes/microbiologia , Artrópodes/imunologia , Artrópodes/microbiologia , Comportamento Alimentar/fisiologia , Transdução de Sinais/fisiologiaRESUMO
Arthropods harbor a diverse array of microbes that profoundly influence many aspects of host biology, including vector competence. Additionally, symbionts can be engineered to produce molecules that inhibit pathogens. Due to their intimate association with the host, microbes have developed strategies that facilitate their transmission, either horizontally or vertically, to conspecifics. These attributes make microbes attractive agents for applied strategies to control arthropod-borne disease. Here we discuss the recent advances in microbial control approaches to reduce the burden of pathogens such as Zika, Dengue and Chikungunya viruses, and Trypanosome and Plasmodium parasites. We also highlight where further investigation is warranted.
Assuntos
Vetores Artrópodes/microbiologia , Interações Hospedeiro-Patógeno , Microbiota/fisiologia , Controle Biológico de Vetores/métodos , AnimaisRESUMO
Synanthropic wild mammals can be important hosts for many vector-borne zoonotic pathogens. The aim of this study was determine the exposure of synanthropic mammals to two types of tick-borne pathogens in Panama, spotted fever group Rickettsia (SFGR) and Borrelia relapsing fever (RF) spirochetes. One hundred and thirty-one wild mammals were evaluated, including two gray foxes, two crab-eating foxes (from zoos), four coyotes, 62 opossum and 63 spiny rats captured close to rural towns. To evaluate exposure to SFGR, serum samples from the animals were tested by indirect immunofluorescence assay (IFA) using Rickettsia rickettsii and Candidatus Rickettsia amblyommii antigen. Immunoblotting was performed using Borrelia turicatae protein lysates and rGlpQ, to assess infection caused by RF spirochetes. One coyote (25%) and 27 (43%) opossums showed seroreactivity to SFGR. Of these opossums, 11 were seroreactive to C. R. amblyommii. Serological reactivity was not detected to B. turicatae in mammal samples. These findings may reflect a potential role of both mammals in the ecology of tick-borne pathogens in Panama.
Assuntos
Vetores Artrópodes/microbiologia , Reservatórios de Doenças , Mamíferos , Carrapatos/microbiologia , Animais , Animais Selvagens , Geografia , Humanos , Panamá/epidemiologia , Infecções por Rickettsia/epidemiologia , Infecções por Rickettsia/transmissãoRESUMO
Mayaro, Oropouche, and O'Nyong-Nyong share many traits with more prominent arboviruses, like dengue and yellow fever, chikungunya, and Zika. These include severe clinical symptoms, multiple animal hosts, and widespread vector species living in close proximity to human habitats, all of which constitute significant risk factors for more frequent outbreaks in the future, greatly increasing the potential of these hidden enemies to follow Zika and become the next wave of global arboviral threats. Critically, the current dearth of knowledge on these arboviruses might impede the success of future control efforts, including the potential application of Wolbachia pipientis. This bacterium inherently possesses broad anti-pathogen properties and a means of genetic drive that allows it to eliminate or replace target vector populations. We conclude that control of obscure arboviruses with Wolbachia might be possible, but successful implementation will be critically dependent on the ability to transinfect key vector species.