Seroprevalence of <I>Rickettsia</I> spp. in Equids and Molecular Detection of ‘<I>Candidatus</I> Rickettsia amblyommii’ in <I>Amblyomma cajennense</I> Sensu Lato Ticks From the Pantanal Region of Mato Grosso, Brazil

Abstract

The aim of the study was to evaluate exposure of equids to rickettsial agents (Rickettsia rickettsii, Rickettsia parkeri, 'Candidatus Rickettsia amblyommii', Rickettsia rhipicephali, and Rickettsia bellii) and rickettsial infection in ticks of a Pantanal region of Brazil. Sera of 547 equids (500 horses and 47 donkeys) were evaluated by indirect immunofluorescence assay. In total, 665 adults and 106 nymphal pools of Amblyomma cajennense F. sensu lato, 10 Dermacentor nitens Neumann ticks, and 88 larval pools of Amblyomma sp. were tested by polymerase chain reaction (PCR). Overall, 337 (61.6%) equids were reactive (titer ≥64) to at least one antigen of Rickettsia spp. The prevalence values for Rickettsia were 66%, and the highest endpoint titers were observed for 'Ca. R. amblyommii'. By PCR 3 (0.45%) A. cajennense s.l. females were positive for 'Ca. R. amblyommii'. Minimum infection rates of 0.75% for nymphs and 0.34% for larvae were calculated. Positive samples of ticks have had a fragment of the 16S mitochondrial rRNA gene sequenced and sequences showed 99% identity to Amblyomma sculptum Berlese. This study reports a wide exposure of equids to Rickettsia agents, and PCR evidence of infection with 'Ca. R. amblyommii', for the first time, in A. sculptum.

Amblyomma sculptum: genetic diversity and rickettsias in the Brazilian Cerrado biome

“…3). In Brazil, R. amblyommatis has been detected in A. sculptum from the Pantanal (MT) (Alves et al, 2014), and in the Atlantic rainforest (Minas Gerais-MG) (Nunes et al, 2015). Ca.…”

A survey of tick‐borne pathogens in dogs and their ticks in the Pantanal biome, Brazil

“…sculptum populations; the only exception refers to that in a recent study conducted in Poconé (in the same area as the present study), in which < 1% of Am. sculptum were found to be infected by R. amblyommii (Alves et al ., ). The much lower rates of R. amblyommii infection among Am.…”

“…ticks positive for R. amblyommii and H. canis in the present study was 99.74% (381/382 bp) identical to the corresponding sequence for Amblyomma sculptum (KJ557134), a member of the Am. cajennense species complex (Alves et al, 2014). Therefore, the Am.…”

“…cajennense sensu stricto, which is restricted to the Amazonian region, and Am. sculptum, which is present in other Brazilian biomes, including the Pantanal (Alves et al, 2014;Nava et al, 2014). Whereas infection by R. amblyommii appears to be common in Am.…”

Rickettsia infection in Amblyomma tonelliae, a tick species from the Amblyomma cajennense complex

“…This rickettsia is widely distributed in America where it was reported in Argentina, Brazil, Costa Rica, French Guiana, Panama and USA associated to several tick species of the genera Amblyomma, Dermacentor and Rhipicephalus Parola et al, 2013;Saraiva et al, 2013), also including species of the A. cajennense complex. In fact, Candidatus "R. amblyommii" was detected in A. mixtum 1 , A. sculptum 1 , A. cajennense s.s 1 and now, in A. tonelliae (Labruna et al, 2004b;Bermúdez et al, 2011;Hun et al, 2011;Alves et al, 2014;this work). The ubiquity of Candidatus "R. amblyommii" implicates a health risk because it is found in different potential vectors along a wide geographic range which increase the probability of its transmission to humans.…”