Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?

<h4>Background</h4>Rickettsia conorii conorii is the etiological agent of Mediterranean spotted fever, which is transmitted by the brown dog tick, Rhipicephalus sanguineus. The relationship between the Rickettsia and its tick vector are still poorly understood one century after the first...

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Autores principales:	Cristina Socolovschi, Jean Gaudart, Idir Bitam, Thi Phong Huynh, Didier Raoult, Philippe Parola
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270
Acceso en línea:	https://doaj.org/article/bb89036469394a37a75377dfbaa3a03c
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spelling	oai:doaj.org-article:bb89036469394a37a75377dfbaa3a03c2021-11-18T09:14:05ZWhy are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?1935-27271935-273510.1371/journal.pntd.0001697https://doaj.org/article/bb89036469394a37a75377dfbaa3a03c2012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22724035/?tool=EBIhttps://doaj.org/toc/1935-2727https://doaj.org/toc/1935-2735<h4>Background</h4>Rickettsia conorii conorii is the etiological agent of Mediterranean spotted fever, which is transmitted by the brown dog tick, Rhipicephalus sanguineus. The relationship between the Rickettsia and its tick vector are still poorly understood one century after the first description of this disease.<h4>Methodology/principal findings</h4>An entomological survey was organized in Algeria to collect ticks from the houses of patients with spotted fever signs. Colonies of R. conorii conorii-infected and non-infected ticks were established under laboratory conditions. Gimenez staining and electron microscopy on the ovaries of infected ticks indicated heavy rickettsial infection. The transovarial transmission of R. conorii conorii in naturally infected Rh. sanguineus ticks was 100% at eleven generations, and the filial infection rate was up to 99% according to molecular analyses. No differences in life cycle duration were observed between infected and non-infected ticks held at 25°C, but the average weight of engorged females and eggs was significantly lower in infected ticks than in non-infected ticks. The eggs, larvae and unfed nymphs of infected and non-infected ticks could not tolerate low (4°C) or high (37°C) temperatures or long starvation periods. R. conorii conorii-infected engorged nymphs that were exposed to a low or high temperature for one month experienced higher mortality when they were transferred to 25°C than non-infected ticks after similar exposure. High mortality was observed in infected adults that were maintained for one month at a low or high temperature after tick-feeding on rabbits.<h4>Conclusion/significance</h4>These preliminary results suggest that infected quiescent ticks may not survive the winter and may help explain the low prevalence of infected Rh. sanguineus in nature. Further investigations on the influence of extrinsic factors on diapaused R. conorii-infected and non-infected ticks are required.Cristina SocolovschiJean GaudartIdir BitamThi Phong HuynhDidier RaoultPhilippe ParolaPublic Library of Science (PLoS)articleArctic medicine. Tropical medicineRC955-962Public aspects of medicineRA1-1270ENPLoS Neglected Tropical Diseases, Vol 6, Iss 6, p e1697 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270
spellingShingle	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Cristina Socolovschi Jean Gaudart Idir Bitam Thi Phong Huynh Didier Raoult Philippe Parola Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
description	<h4>Background</h4>Rickettsia conorii conorii is the etiological agent of Mediterranean spotted fever, which is transmitted by the brown dog tick, Rhipicephalus sanguineus. The relationship between the Rickettsia and its tick vector are still poorly understood one century after the first description of this disease.<h4>Methodology/principal findings</h4>An entomological survey was organized in Algeria to collect ticks from the houses of patients with spotted fever signs. Colonies of R. conorii conorii-infected and non-infected ticks were established under laboratory conditions. Gimenez staining and electron microscopy on the ovaries of infected ticks indicated heavy rickettsial infection. The transovarial transmission of R. conorii conorii in naturally infected Rh. sanguineus ticks was 100% at eleven generations, and the filial infection rate was up to 99% according to molecular analyses. No differences in life cycle duration were observed between infected and non-infected ticks held at 25°C, but the average weight of engorged females and eggs was significantly lower in infected ticks than in non-infected ticks. The eggs, larvae and unfed nymphs of infected and non-infected ticks could not tolerate low (4°C) or high (37°C) temperatures or long starvation periods. R. conorii conorii-infected engorged nymphs that were exposed to a low or high temperature for one month experienced higher mortality when they were transferred to 25°C than non-infected ticks after similar exposure. High mortality was observed in infected adults that were maintained for one month at a low or high temperature after tick-feeding on rabbits.<h4>Conclusion/significance</h4>These preliminary results suggest that infected quiescent ticks may not survive the winter and may help explain the low prevalence of infected Rh. sanguineus in nature. Further investigations on the influence of extrinsic factors on diapaused R. conorii-infected and non-infected ticks are required.
format	article
author	Cristina Socolovschi Jean Gaudart Idir Bitam Thi Phong Huynh Didier Raoult Philippe Parola
author_facet	Cristina Socolovschi Jean Gaudart Idir Bitam Thi Phong Huynh Didier Raoult Philippe Parola
author_sort	Cristina Socolovschi
title	Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
title_short	Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
title_full	Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
title_fullStr	Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
title_full_unstemmed	Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?
title_sort	why are there so few rickettsia conorii conorii-infected rhipicephalus sanguineus ticks in the wild?
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/bb89036469394a37a75377dfbaa3a03c
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Why are there so few Rickettsia conorii conorii-infected Rhipicephalus sanguineus ticks in the wild?

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