Distribution and molecular characteristics of rickettsiae found in ticks across Central Mongolia.
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ABSTRACT: Little is known regarding tick-borne diseases in Mongolia, despite having 26% of the population still living nomadic pastoral lifestyles. A total of 1497 adult unfed ticks: 261 Ixodes persulcatus, 795 Dermacentor nuttalli, and 441 Hyalomma asiaticum, were collected from three ecologically distinct regions in Central Mongolia. Tick pools (n?=?299) containing ~5 ticks each, were tested for Rickettsia and Tick-borne encephalitis virus (TBEV) using nested polymerase chain reaction, reverse transcription-PCR, and quantitative real-time RT-PCR.Assays yielded pooled prevalence of 92.5% (49/53) and 1.9% (1/53) for pooled I. persulcatus testing positive for "Candidatus Rickettsia tarasevichiae" and TBEV, respectively, while Rickettsia raoultii was found in 72.8% (115/158) of pooled D. nuttalli samples. When calculating a maximum likelihood estimation, an estimated 46.6% (95% CI: 35.2-63.6%) of I. persulcatus ticks in the pooled sample were infected with "Candidatus R. tarasevichiae".Both "Candidatus R. tarasevichiae" and R. raoultii are recognized as emerging tick-borne pathogens, with this being one of the first reports of "Candidatus R. tarasevichiae" in Mongolia. Given that "Candidatus R. tarasevichiae" shares the same vector (I. persulcatus) as TBEV, and infections may present with similar symptoms, Mongolian physicians treating suspected cases of TBEV should include "Candidatus R. tarasevichiae" infection in their differential diagnosis and consider prescribing antimicrobial therapy.
<h4>Background</h4>Little is known regarding tick-borne diseases in Mongolia, despite having 26% of the population still living nomadic pastoral lifestyles. A total of 1497 adult unfed ticks: 261 Ixodes persulcatus, 795 Dermacentor nuttalli, and 441 Hyalomma asiaticum, were collected from three ecologically distinct regions in Central Mongolia. Tick pools (n = 299) containing ~5 ticks each, were tested for Rickettsia and Tick-borne encephalitis virus (TBEV) using nested polymerase chain reaction ...[more]
Project description:BackgroundThe agents of spotted fevers in Latin America are Rickettsia rickettsii, R. parkeri, Rickettsia sp. strain Atlantic rainforest, and R. massiliae. In Continental Central America, R. rickettsii remains the only known pathogenic tick-borne rickettsia. In the present study, ticks were collected from wild mammals in natural areas of Belize. Besides providing new data of ticks from Belize, we investigated rickettsial infection in some of these ticks. Our results provide ticks harboring rickettsial agents for the first time in Central America.MethodsBetween 2010 and 2015, wild mammals were lived-trapped in the tropical broadleaf moist forests of central and southern Belize. Ticks were collected from the animals and identified to species by morphological and molecular analysis (DNA sequence of the tick mitochondrial 16S RNA gene). Some of the ticks were tested for rickettsial infection by molecular methods (DNA sequences of the rickettsial gltA and ompA genes).ResultsA total of 84 ticks were collected from 8 individual hosts, as follows: Amblyomma pacae from 3 Cuniculus paca; Amblyomma ovale and Amblyomma coelebs from a Nasua narica; A. ovale from an Eira Barbara; A. ovale, Amblyomma cf. oblongoguttatum, and Ixodes affinis from a Puma concolor; and A. ovale, A. coelebs, A. cf. oblongoguttatum, and I. affinis from two Panthera onca. Three rickettsial agents were detected: Rickettsia amblyommii in A. pacae, Rickettsia sp. strain Atlantic rainforest in A. ovale, and Rickettsia sp. endosymbiont in Ixodes affinis.ConclusionsThe present study provides unprecedented records of ticks harboring rickettsial agents in the New World. An emerging rickettsial pathogen of South America, Rickettsia sp. strain Atlantic rainforest, is reported for the first time in Central America. Besides expanding the distribution of 3 rickettsial agents in Central America, our results highlight the possible occurrence of Rickettsia sp. strain Atlantic rainforest-caused spotted fever human cases in Belize, since its possible vector, A. ovale, is recognized as one of the most important human-biting ticks in the Neotropical region.
Project description:Tick-borne rickettsioses are world-spreading infectious zoonoses. Ticks serve as reservoirs and vectors for Rickettsia and play a key role in transmission of rickettsioses. Most of the Chinese rickettsiosis patients are reported from Northeastern China but the distribution of tick and tick-borne Rickettsia species in Northeastern China remain poorly studied. In this study, a total of 1,286 ticks were captured from the seven counties of Harbin, an area in Northeastern China, and the tick-borne Rickettsia species were identified by PCR and sequencing of rrs, gltA, groEL, ompA and 17-kDa antigen-encoding genes. Of the 5 identified tick species, Haemaphysalis longicornis and Ixodes persulcatus were the predominant tick species in the livestock and vegetation, respectively. Rickettsia raoultii and "Candidatus Rickettsia tarasevichiae" were the two detectable Rickettsia species in the ticks with a 28.8% positive rate but no rickettsiae were found in ticks of Haemaphysalis concinna. R. raoultii detected in 37.6% of the Dermacentor nuttalli, Dermacentor silvarum and H. longicornis ticks while "Ca. R. tarasevichiae" was only present in 22.8% of the I. persulcatus ticks. In particular, the positive rate of both R. raoultii and "Ca. R. tarasevichiae" in ticks from the livestock (40.7%) was significantly higher than that from the vegetation (19.5%). The results indicate that the tick and tick-borne Rickettsia species are diverse in different regions of Harbin due to geographic difference and the ticks from livestock may play a more important role in transmission of rickettsioses to human.
Project description:Tick-borne infections are a significant threat to public health, particularly in regions where individuals frequently enter tick habitats. Roughly 26% of the population in Mongolia practice nomadic pastoralism and are considered at high risk of exposure to ticks and the diseases they carry. This study tested ticks from Mongolia's southern border for Rickettsia spp. to better understand the epidemiology of tick-borne diseases in the region. Dermacentor nuttalli and Hyalomma asiaticum ticks (n = 4022) were pooled and tested for Rickettsia spp. by real-time PCR. Melt-curve analyses and Sanger sequencing were used to identify Rickettsia species. Approximately 64% of the 786 tick pools tested positive for Rickettsia bacteria. Melt curve analyses identified four different Rickettsia species circulating in these tick pools. Amplicon sequencing of the ompA gene identified Rickettsia spp. that closely resembled R. raoultii and R. sibirica. Dermacentor nuttalli ticks from Govi-Altai had the highest maximum likelihood estimation infection rate 48.4% (95% CI: 41.7-56.5%), while Hyalommaasiaticum collected in Omnogovi had a rate of 7.6% (95% CI: 6.2-9.2%). The high detection of Rickettsia suggests a substantial risk of infection in southern Mongolia. Further studies are necessary to investigate the clinical burden of tick-borne diseases in Mongolia.
Project description:To describe the presence and distribution of tickborne bacteria and their vectors in Texas, USA, we screened ticks collected from humans during 2008-2014 for Rickettsia, Borrelia, and Ehrlichia spp. Thirteen tick species were identified, and 23% of ticks carried bacterial DNA from at least 1 of the 3 genera tested.
Project description:To explore increased risk for human Rickettsia spp. infection in Germany, we investigated recreational areas and renatured brown coal surface-mining sites (also used for recreation) for the presence of spotted fever group rickettsiae in ticks. R. raoultii (56.7%), R. slovaca (13.3%), and R. helvetica (>13.4%) were detected in the respective tick species.
Project description:To determine the cause of spotted fever cases in the southern United States, we screened Gulf Coast ticks (Amblyomma maculatum) collected in Arkansas for rickettsiae. Of the screened ticks, 30% had PCR amplicons consistent with Rickettsia parkeri or Candidatus Rickettsia amblyommii.
Project description:A total of 370 ticks, encompassing 7 species from 4 genera, were collected during 2002-2006 from domestic animals and vegetation in the Taza region of northeastern Morocco. Rickettsial DNA was identified in 101 ticks (27%) by sequencing PCR products of fragments of the citrate synthase and outer membrane protein genes of Rickettsia spp. Seven rickettsiae of the spotted fever group were identified, including 4 pathogens: R. aeschlimannii in Hyalomma marginatum marginatum, R. massiliae in Rhipicephalus sanguineus, R. slovaca in Dermacentor marginatus, and R. monacensis in Ixodes ricinus. Two suspected pathogens were also detected (R. raoultii in D. marginatus and R. helvetica in I. ricinus). An incompletely described Rickettsia sp. was detected in Haemaphysalis spp. ticks.