Rickettsia parkeri: a Rickettsial pathogen transmitted by ticks in endemic areas for spotted fever rickettsiosis in southern Uruguay

Abstract

SUMMARYAt first Rickettsia conorii was implicated as the causative agent of spotted fever in Uruguay diagnosed by serological assays. Later Rickettsia parkeri was detected in human-biting Amblyomma triste ticks using molecular tests. The natural vector of R. conorii, Rhipicephalus sanguineus, has not been studied for the presence of rickettsial organisms in Uruguay. To address this question, 180 R. sanguineus from dogs and 245 A. triste from vegetation (flagging) collected in three endemic localities were screened for spotted fever group (SFG) rickettsiosis in southern Uruguay. Tick extracted DNA pools were subjected to PCR using primers which amplify a fragment of the rickettsial gltA gene. Positive tick DNA pools with these primers were subjected to a second PCR round with primers targeting a fragment of the ompA gene, which is only present in SFG rickettsiae. No rickettsial DNA was detected in R. sanguineus. However, DNA pools of A. triste were found to be positive for a rickettsial organism in two of the three localities, with prevalences of 11.8% to 37.5% positive pools. DNA sequences generated from these PCR-positive ticks corresponded to R. parkeri. These findings, joint with the aggressiveness shown by A. triste towards humans, support previous data on the involvement of A. triste as vector of human infections caused by R. parkeri in Uruguay.

Ticks (Acari: Ixodidae) as ectoparasites of Brazilian wild birds and their association with rickettsial diseases

“…This pathogen was also detected in A. maculatum in Peru (FLORES-MANDONZA et al, 2013), A. triste in Uruguay (VENZAL et al, 2004a(VENZAL et al, , 2012PACHECO et al, 2006;CONTI-DÍAZ et al, 2009), Argentina (NAVA et al, 2008a and Brazil (SILVEIRA et al, 2007) andin A. tigrinum in Bolivia (TOMASSONE et al, 2010b).…”

“…Larvae and nymphs of A. triste are common parasites of small rodents VENZAL et al, 2008;NAVA et al, 2011) and birds in Argentina (NAVA et al, 2011;FLORES et al, 2014) SILVEIRA et al, 2015) and Mato Grosso State . This tick is of public health relevance as its species is frequently found biting humans and involved in epidemiology of spotted fever caused by R. parkeri in Uruguay (VENZAL et al, 2004b;PACHECO et al, 2006;VENZAL et al, 2012), Argentina (NAVA et al, 2008a) and possibly in Brazil (SILVEIRA et al, 2007;MELO et al, 2015).…”

Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

“…In 2004, R. parkeri was reported to infect Amblyomma triste ticks in Uruguay (168), at the time when this rickettsia was first confirmed to be a human pathogen in the United States (see above). Several years later, R. parkeri was found to infect A. triste ticks in Brazil (169) and Argentina (170).…”

Perfil epidemiológico y molecular de Rickettsiosis en localidades de frontera peruana

“…entran en contacto con roedores peridomiciliarios y sinantrópicos, resulta necesario estudiar los probables candidatos a reservorios y vectores involucrados, a fin de establecer medidas de prevención y control. Es destacable, que estudios realizados en Argentina y Uruguay (27,28) hallan establecido la cadena epidemiológica de la fiebre manchada de las MontañasRev Peru Med Exp Salud Publica. 2017;34(1):76-84.…”