Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks

Abstract Background Brazilian spotted fever is a tick-borne disease caused by the bacterium Rickettsia rickettsii, whose main vector in Brazil is the tick Amblyomma sculptum. Amplifying hosts are essential for the perpetuation of this bacterium in the tick population as they can be sources of infect...

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Main Authors: Lucianne Cardoso Neves, Lina de Campos Binder, Warley Vieira de Freitas Paula, Nicolas Jalowitzki de Lima, Ennya Rafaella Neves Cardoso, Rayane Almeida Santos, Raphaela Bueno Mendes Bittencourt, Gracielle Teles Pádua, Gabriel Cândido dos Santos, Mariana Avelar Tavares, Maria Carolina de Azevedo Serpa, Adriano Pinter, Artur Luiz de Almeida Felicio, Marcelo B. Labruna, Felipe da Silva Krawczak
Format: Article
Language:English
Published: BMC 2025-01-01
Series:Parasites & Vectors
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Online Access:https://doi.org/10.1186/s13071-024-06612-y
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author Lucianne Cardoso Neves
Lina de Campos Binder
Warley Vieira de Freitas Paula
Nicolas Jalowitzki de Lima
Ennya Rafaella Neves Cardoso
Rayane Almeida Santos
Raphaela Bueno Mendes Bittencourt
Gracielle Teles Pádua
Gabriel Cândido dos Santos
Mariana Avelar Tavares
Maria Carolina de Azevedo Serpa
Adriano Pinter
Artur Luiz de Almeida Felicio
Marcelo B. Labruna
Felipe da Silva Krawczak
author_facet Lucianne Cardoso Neves
Lina de Campos Binder
Warley Vieira de Freitas Paula
Nicolas Jalowitzki de Lima
Ennya Rafaella Neves Cardoso
Rayane Almeida Santos
Raphaela Bueno Mendes Bittencourt
Gracielle Teles Pádua
Gabriel Cândido dos Santos
Mariana Avelar Tavares
Maria Carolina de Azevedo Serpa
Adriano Pinter
Artur Luiz de Almeida Felicio
Marcelo B. Labruna
Felipe da Silva Krawczak
author_sort Lucianne Cardoso Neves
collection DOAJ
description Abstract Background Brazilian spotted fever is a tick-borne disease caused by the bacterium Rickettsia rickettsii, whose main vector in Brazil is the tick Amblyomma sculptum. Amplifying hosts are essential for the perpetuation of this bacterium in the tick population as they can be sources of infection during bacteremic periods. Recent studies demonstrated the ability of suids (Sus scrofa) to sustain populations of A. sculptum, one of the main tick species found parasitizing wild boars in the midwestern and southeastern regions of Brazil. In this study, wild boars were experimentally infected with R. rickettsii by tick infestation and were evaluated for their ability to transmit the infection to A. sculptum ticks, under laboratory conditions. Methods Four wild boars were infected with R. rickettsii through infestation with R. rickettsii-infected A. sculptum adults (infected group); a fifth wild boar was infested with uninfected A. sculptum adults (control group). Simultaneously, the animals were infested with uninfected larvae and nymphs of A. sculptum. The wild boars were monitored for 28 days by clinical examination and hematological tests, real-time quantitative PCR (qPCR) of blood for the detection of Rickettsia and inoculation of blood in guinea pigs. IgG antibody titers were followed until the end of the experiment. Unfed nymphs and adults, molted from engorged larvae and nymphs that fed on wild boars, were used to infest susceptible guinea pigs and rabbits; some of these unfed ticks were tested by qPCR for rickettsial detection. Results The wild boars showed no clinical or hematological alterations, and bacteremia was not detected by qPCR or inoculation of wild boar blood into guinea pigs. Furthermore, wild boars showed a moderate humoral response, with anti-R. rickettsii endpoint titers up to 256 or 512. Rickettsial DNA was not detected in molted ticks after acquisition feeding on wild boars. Moreover, no disease or seroconversion was observed in guinea pigs and rabbits that were infested with ticks originated from wild boar acquisition feeding. Conclusions Wild boars seroconverted to Rickettsia spp. after being infested with R. rickettsii-infected A. sculptum; however, they did not develop bacteremia and did not act as competent amplifying hosts of R. rickettsii for A. sculptum ticks. Graphical Abstract
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series Parasites & Vectors
spelling doaj-art-fe5d4ebce4834437ac2d938c19265ff02025-01-19T12:12:09ZengBMCParasites & Vectors1756-33052025-01-0118111310.1186/s13071-024-06612-yExperimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticksLucianne Cardoso Neves0Lina de Campos Binder1Warley Vieira de Freitas Paula2Nicolas Jalowitzki de Lima3Ennya Rafaella Neves Cardoso4Rayane Almeida Santos5Raphaela Bueno Mendes Bittencourt6Gracielle Teles Pádua7Gabriel Cândido dos Santos8Mariana Avelar Tavares9Maria Carolina de Azevedo Serpa10Adriano Pinter11Artur Luiz de Almeida Felicio12Marcelo B. Labruna13Felipe da Silva Krawczak14Veterinary and Animal Science School, Federal University of GoiásDepartment of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São PauloVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásVeterinary and Animal Science School, Federal University of GoiásDepartment of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São PauloDepartment of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São PauloCoordination of Agricultural Defense, Secretary of Agriculture and Supply, Government of the State of São PauloDepartment of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São PauloVeterinary and Animal Science School, Federal University of GoiásAbstract Background Brazilian spotted fever is a tick-borne disease caused by the bacterium Rickettsia rickettsii, whose main vector in Brazil is the tick Amblyomma sculptum. Amplifying hosts are essential for the perpetuation of this bacterium in the tick population as they can be sources of infection during bacteremic periods. Recent studies demonstrated the ability of suids (Sus scrofa) to sustain populations of A. sculptum, one of the main tick species found parasitizing wild boars in the midwestern and southeastern regions of Brazil. In this study, wild boars were experimentally infected with R. rickettsii by tick infestation and were evaluated for their ability to transmit the infection to A. sculptum ticks, under laboratory conditions. Methods Four wild boars were infected with R. rickettsii through infestation with R. rickettsii-infected A. sculptum adults (infected group); a fifth wild boar was infested with uninfected A. sculptum adults (control group). Simultaneously, the animals were infested with uninfected larvae and nymphs of A. sculptum. The wild boars were monitored for 28 days by clinical examination and hematological tests, real-time quantitative PCR (qPCR) of blood for the detection of Rickettsia and inoculation of blood in guinea pigs. IgG antibody titers were followed until the end of the experiment. Unfed nymphs and adults, molted from engorged larvae and nymphs that fed on wild boars, were used to infest susceptible guinea pigs and rabbits; some of these unfed ticks were tested by qPCR for rickettsial detection. Results The wild boars showed no clinical or hematological alterations, and bacteremia was not detected by qPCR or inoculation of wild boar blood into guinea pigs. Furthermore, wild boars showed a moderate humoral response, with anti-R. rickettsii endpoint titers up to 256 or 512. Rickettsial DNA was not detected in molted ticks after acquisition feeding on wild boars. Moreover, no disease or seroconversion was observed in guinea pigs and rabbits that were infested with ticks originated from wild boar acquisition feeding. Conclusions Wild boars seroconverted to Rickettsia spp. after being infested with R. rickettsii-infected A. sculptum; however, they did not develop bacteremia and did not act as competent amplifying hosts of R. rickettsii for A. sculptum ticks. Graphical Abstracthttps://doi.org/10.1186/s13071-024-06612-yTick-borne diseasesBrazilian spotted feverSuidaeAmblyomma sculptum
spellingShingle Lucianne Cardoso Neves
Lina de Campos Binder
Warley Vieira de Freitas Paula
Nicolas Jalowitzki de Lima
Ennya Rafaella Neves Cardoso
Rayane Almeida Santos
Raphaela Bueno Mendes Bittencourt
Gracielle Teles Pádua
Gabriel Cândido dos Santos
Mariana Avelar Tavares
Maria Carolina de Azevedo Serpa
Adriano Pinter
Artur Luiz de Almeida Felicio
Marcelo B. Labruna
Felipe da Silva Krawczak
Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
Parasites & Vectors
Tick-borne diseases
Brazilian spotted fever
Suidae
Amblyomma sculptum
title Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
title_full Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
title_fullStr Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
title_full_unstemmed Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
title_short Experimental infection of wild boars (Sus scrofa) with Rickettsia rickettsii and evaluation of the transmission potential to Amblyomma sculptum ticks
title_sort experimental infection of wild boars sus scrofa with rickettsia rickettsii and evaluation of the transmission potential to amblyomma sculptum ticks
topic Tick-borne diseases
Brazilian spotted fever
Suidae
Amblyomma sculptum
url https://doi.org/10.1186/s13071-024-06612-y
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