Ticks infesting humans in northern Misiones, Argentina

This work presents records of ticks infesting humans in northern Misiones Province, Argentina. Also, notes on potential transmission of tick-borne pathogens are included. A total of 282 ticks attached to researchers were collected and identified by their morphological characters. Eight tick species were found: Amblyomma brasiliense, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Rhipicephalus sanguineus and Rhipicephalus microplus. Some of these species as A. dubitatum, A. ovale and R. sanguineus have been found infected with spotted fever group rickettsiae pathogenic to humans in Brazil and Argentina. The potential role as vectors of humans pathogens of the ticks found attached to humans in this study is discussed.

En este trabajo se presentan registros de garrapatas que infestan seres humanos en el norte de la provincia de Misiones, Argentina. Además, se incluyen notas sobre la posible transmisión de patógenos por garrapatas. Se colectó un total de 282 garrapatas adheridas a investigadores, las cuales fueron identificadas por sus caracteres morfológicos. Se encontraron ocho especies de garrapatas: Amblyomma brasiliense, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Rhipicephalus sanguineus y Rhipicephalus microplus. Algunas de estas especies como A. dubitatum, A. ovale y R. sanguineus han sido halladas infectadas con rickettsias del grupo de las fiebres manchadas patógenas para los seres humanos en Brasil y Argentina. Se discute el papel potencial de las garrapatas encontradas infestando humanos en este estudio como vectores de patógenos de seres humanos.

Molecular identification of Rickettsia parkeri infecting Amblyomma triste ticks in an area of Argentina where cases of rickettsiosis were diagnosed

Specimens of the hard tick Amblyomma triste were found infected with Rickettsia parkeri in an area of Argentina (General Lavalle, Buenos Aires Province) where cases of human illness attributed to this microorganism have been reported. Molecular detection of R. parkeri was based on polymerase chain reactions that amplify a ca. 400-bp fragment of the 23S-5S intergenic spacer and a ca. 500-bp fragment of the gene encoding a 190-kDa outer membrane protein. Three (6.97%) of 43 A. triste ticks were determined to be positive for R. parkeri. These results provide strong evidence that A. triste is the vector of R. parkeri in the study area. The findings of this work have epidemiological relevance because human parasitism by A. triste ticks has been frequently recorded in some riparian areas of Argentina and Uruguay and new cases of R. parkeri rickettsiosis might arise in the South American localities where humans are exposed to the bites of this tick species.

Rickettsia parkeri: a Rickettsial pathogen transmitted by ticks in endemic areas for spotted fever rickettsiosis in southern Uruguay / Rickettsia parkeri: patógeno rickettsial transmitido por garrapatas en áreas endémicas de rickettsiosis por fiebre manchada en el sur de Uruguay

At 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.

Inicialmente, Rickettsia conorii fue señalada como el agente causal de la fiebre manchada en Uruguay, diagnosticada mediante pruebas serológicas. Posteriormente, Rickettsia parkeri fue detectada mediante técnicas moleculares en garrapatas Amblyomma triste colectadas sobre humanos. El vector natural de R. conorii, Rhipicephalus sanguineus, no ha sido estudiado en cuanto a rickettsias en Uruguay. Para abordar este tema, 180 R. sanguineus fueron colectados sobre perros y 245 A. triste sobre vegetación en tres localidades consideradas endémicas para fiebres manchadas en el sur de Uruguay. El ADN de las garrapatas fue extraído en pools y sometido a una primera PCR utilizando cebadores que amplifican un fragmento del gen gltA, presente en prácticamente todas las especies de Rickettsia. Las muestras positivas fueron sometidas a una segunda PCR con cebadores que amplifican un fragmento del gen ompA, presente sólo en rickettsias del grupo de las fiebres manchadas (GFM). No se detectó ADN rickettsial en R. sanguineus. Sin embargo, muestras de A. triste fueron positivas a rickettsiales en dos de las tres localidades estudiadas, con prevalencias de pools positivos del 11.8 y 37.5% respectivamente. La secuenciación del ADN evidenció la presencia de R. parkeri. Basados en estos resultados junto a los anteriores y la agresividad de A. triste hacia los humanos, se concluye que esta garrapata es vector de rickettsiosis humana por R. parkeri en Uruguay.

Detección de Rickettsia spp. en ectoparásitos de animales domésticos y silvestres de la Reserva Natural Privada Cerro Chucantí y comunidades aledañas, Panamá, 2007-2010 / Detection of Rickettsia in ectoparasites of wild and domestic mammals from the Cerro Chucanti private reserve and from neighboring towns, Panamá, 2007-2010

Introducción. Los ectoparásitos son los principales vectores de rickettsiosis. En Panamá se tienen escasos datos sobre los artrópodos que pudieran considerarse vectores o reservorios. Objetivos. Presentar datos sobre la presencia de Rickettsia spp. en ectoparásitos de fauna silvestre y animales domésticos en la Reserva Natural Privada Cerro Chucantí y poblados vecinos. Materiales y métodos. Se revisaron 9 personas, 95 mamíferos domésticos y 48 silvestres. Los animales domésticos se examinaron con anuencia del propietario, mientras que la fauna silvestre se capturó con trampas Sherman y Tomahawk. Se extrajeron 21 especies de ectoparásitos: pulgas, piojos, garrapatas y otros ácaros, los cuales se preservaron en etanol al 95 %. Se extrajo material genético de garrapatas y pulgas para ser analizado por técnicas moleculares en la detección de Rickettsia spp. Resultados. Se practicaron 425 reacciones de PCR, de las cuales, 270 resultaron negativas y 155 positivas. De las positivas, 86 amplificaron para el gen gltA (55 % de las positivas); de estos también amplificaron 41 (26 %) para ompA. Se encontró material genético de Rickettsia amblyommii, en garrapatas de caballos (Amblyomma cajennense, Dermacentor nitens), de perros (Rhipicephalus sanguineus) y ninfas de Amblyomma recolectadas en el bosque. Además, se detectó ADN de R. felis en pulgas Ctenocephalides felis de perros. Conclusiones. Se pudo detectar la presencia de R. amblyommii y R. felis en garrapatas y pulgas de animales domésticos de los poblados cercanos a Cerro Chucantí, aun cuando no se pudo encontrar material genético de Rickettsia en ectoparásitos de la fauna silvestre.

Introduction. Ectoparasites are the main vectors of rickettsiosis. In Panama, however, limited data are available concerning the arthropod species that serve as vectors or reservoirs. Objectives. Data are presented concerning the presence of Rickettsia in ectoparasites of wildlife and domestic animals in the Cerro Chucantí private nature reserve and in neighboring villages. Materials and methods. Nine humans, 95 domestic mammals and 48 wild mammals were examined. Twenty-one species of ectoparasites were obtained, including fleas, lice, ticks and mites. These were preserved in 95% ethanol. Later, the DNA was extracted from the ticks and fleas and analyzed by molecular techniques to detect presence of Rickettsia. Results. Of a total of 425 PCR reactions, 270 were positive for Rickettsia and 155 negative. Among the positive samples, 86 PCR amplified for the gltA gene (55% of positives) and 41 of these also amplified the ompA gene. DNA of Rickettsiaamblyommii was found in horses ticks (Amblyomma cajennense, Dermacentor nitens), dogs ticks (Rhipicephalus sanguineus) and free living nymphs in the forest. Additionally, DNA of R. felis was found in fleas from dogs Ctenocephalides felis. Conclusions. The presence of R. amblyommii and R. felis was detected in ticks and fleas of domestic animals in villages near Cerro Chucanti; however no Rickettsia DNA was found in ectoparasites of non-domestic wildlife.

A study of'febrile illnesses on the Thai-Myanmar border: predictive factors of rickettsioses.

We have performed a case-control analysis to determine the significance of clinical, laboratory and epidemiological features as predictive factors of rickettsioses among patients in Sangkhla Buri, Thailand (Thai-Myanmar border). Fifteen serologically-confirmed rickettsiosis patients including Spotted Fever Group (SFG) rickettsioses, scrub typhus, and murine typhus were classified as 'cases'; one hundred and sixty-three acutely febrile patients presenting to the same hospital during the same time period, who had no serological evidence of acute rickettsiosis, were classified as 'controls'. Patients' report of rash/arthropod bite [Odds ratio (OR) 22.90, 95% CI (confidence interval) 6.23, 84.13] and history of jungle trips (OR 5.30, 95% CI 1.69-16.62) were significant risk factors. Elevated ALT (OR 3.04, 95% CI 1.04, 8.88) and depressed platelet count (OR 3.38, 95% CI 1.13, 10.10) were also useful differentiating markers of rickettsioses in this population. Definitive diagnosis of rickettsioses is difficult without specialized diagnostic capabilities that are rarely available in remote areas such as Sangkhla Buri, where other acute febrile illnesses with similar presentation are commonly found. The relative importance of predictive factors presented here may provide clinicians with some useful guidance in distinguishing rickettsioses from other acute febrile illnesses. Timely administration of empiric treatment in highly suspicious cases can deter potential morbidity from these arthropod-borne infections.