Ubiquitous bacteria Borrelia crocidurae in Western African ticks Ornithodoros sonrai

Ticks are considered the second vector of human and animal diseases after mosquitoes. Therefore, identification of ticks and associated pathogens is an important step in the management of these vectors. In recent years, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a promising method for the identification of arthropods including ticks. The objective of this study was to improve the conditions for the preparation of tick samples for their identification by MALDI-TOF MS from field-collected ethanol-stored Malian samples and to evaluate the capacity of this technology to distinguish infected and uninfected ticks. A total of 1,333 ticks were collected from mammals in three distinct sites from Mali. Morphological identification allowed classification of ticks into 6 species including Amblyomma variegatum, Hyalomma truncatum, Hyalomma marginatum rufipes, Rhipicephalus (Boophilus) microplus, Rhipicephalus evertsi evertsi and Rhipicephalus sanguineus sl. Among those, 471 ticks were randomly selected for molecular and proteomic analyses. Tick legs submitted to MALDI-TOF MS revealed a concordant morpho/molecular identification of 99.6%. The inclusion in our MALDI-TOF MS arthropod database of MS reference spectra from ethanol-preserved tick leg specimens was required to obtain reliable identification. When tested by molecular tools, 76.6%, 37.6%, 20.8% and 1.1% of the specimens tested were positive for Rickettsia spp., Coxiella burnetii, Anaplasmataceae and Borrelia spp., respectively. These results support the fact that MALDI-TOF is a reliable tool for the identification of ticks conserved in alcohol and enhances knowledge about the diversity of tick species and pathogens transmitted by ticks circulating in Mali.

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“…theileri in the hard tick ( Rh . geigyi ) [ 12 , 13 ]. Our results show the presence of Borrelia spp.…”

Section: Discussionmentioning

confidence: 99%

“…crocidurae , agents of relapsing fever in humans, have been detected in Rh . geigyi and Ornithodoros sonrai , respectively [ 12 – 14 ].…”

Section: Introductionmentioning

confidence: 99%

Molecular and MALDI-TOF identification of ticks and tick-associated bacteria in Mali

et al. 2017

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“…sequencing platform in Senegal. To our knowledge, only B. crocidurae and its many strains have been reported in O. sonrai ticks, Senegal and even in endemic West African countries [1,19,32,37]. In addition, for most work on Borrelia infection circulating in O. sonrai ticks and rodents in this part of West Africa, the TBRF endemic area only reports the presence of B. crocidurae associated with the O. sonrai tick vectors and hosted by rodents and insectivores [1,8,38,39,40].…”

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 98%

Tick-borne relapsing fever Borreliosis, a major public health problem overlooked in Senegal

et al. 2021

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Background Tick-borne relapsing fever (TBRF) is the most common vector-borne bacterial disease in humans in West Africa. It is frequently clinically confused with malaria. Our study aims to determine, on a micro-geographic scale, the conditions for the maintenance and spread of TBRF in the Niakhar district of Senegal. Methodology/Principal findings We conducted clinical, entomological and animal reservoir investigations. Field surveys were carried out in order to investigate the presence of Ornithodoros sonrai vector ticks and to detect Borrelia spp. by qPCR using the 16S rRNA and glpQ genes, respectively. Micromammal trapping series were carried out inside homes and Borrelia infection was detected using brain tissue qPCR. Capillary blood samples from febrile patients were also tested for Borrelia using qPCR. More than 97% (40/41) of the villages surveyed were infested with O. sonrai ticks. The prevalence of Borrelia spp. infections in ticks was 13% (116/910), and over 73% (85/116) were positively confirmed as being Borrelia crocidurae. Borreliosis cases accounted for 12% (94/800) of episodes of fever and all age groups were infected, with children and young people between the ages of 8–14 and 22–28 being the most infected by the disease (16% and 18.4%). TBRF cases occurred in all seasons, with a peak in August. In two species of small rodents that were found to be infected (Arvicanthis niloticus, Mus musculus), the proportion of Borrelia infection was 17.5% (10/57), and the highest prevalence of infection (40.9%, 9/22) was observed in A. niloticus. Conclusion/Significance Our study indicates that TBRF is an endemic disease in the Niakhar district, where children and young people are the most infected. Arvicanthis niloticus and O. sonrai ticks are massively present and appear to be the main epidemiological reservoirs causing its extensive spread to humans.

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“…2 Since this seminal discovery, numerous species of small mammals have been found to be naturally infected with B. crocidurae when captured during field investigations, including the multimammate rat Mastomys natalensis. [3][4][5][6][7][8][9][10][11][12] These rats often live in peridomestic settings in close association with humans and comprise the most widespread species of rodents in sub-Saharan Africa. 13 This behavior and wide geographic distribution make them ideally suited as potential sources of zoonotic pathogens.…”

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confidence: 99%

Host Competency of the Multimammate Rat Mastomys natalensis Demonstrated by Prolonged Spirochetemias with the African Relapsing Fever Spirochete Borrelia crocidurae

Boardman

Rosenke

Safronetz

et al. 2019

The American Journal of Tropical Medicine and Hygiene

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African multimammate rats, Mastomys natalensis, are widely distributed in sub-Saharan Africa and live in close association with humans. In West Africa, numerous field studies have shown these animals may be naturally infected with the relapsing fever spirochete Borrelia crocidurae, the primary cause of tick-borne relapsing fever in this region of the continent. However, naturally infected individual rats have never been examined over time; therefore, the true host competency of these rats for this spirochete is unknown. Therefore, using animals from an established laboratory colony of M. natalensis, rats were experimentally infected with B. crocidurae and their blood examined to 28 days postinoculation. These animals were highly susceptible to infection and displayed prolonged and cyclic spirochetemias. Our results demonstrate these peridomestic rodents are likely competent hosts for infecting argasid tick vectors and play a primary role in the enzootic cycle for B. crocidurae in West Africa.

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Ubiquitous bacteria Borrelia crocidurae in Western African ticks Ornithodoros sonrai

Cited by 11 publications

References 12 publications

Molecular and MALDI-TOF identification of ticks and tick-associated bacteria in Mali

Molecular and MALDI-TOF identification of ticks and tick-associated bacteria in Mali

Tick-borne relapsing fever Borreliosis, a major public health problem overlooked in Senegal

Host Competency of the Multimammate Rat Mastomys natalensis Demonstrated by Prolonged Spirochetemias with the African Relapsing Fever Spirochete Borrelia crocidurae

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