Distribution of Spotted Fever Group Rickettsiae in Hard Ticks (Ixodida: Ixodidae) from Panamanian Urban and Rural Environments (2007–2013)

Abstract

Tick-borne rickettsiosis is an important emerging disease in Panama; to date, there have been 12 confirmed cases, including eight fatalities. To evaluate the distribution of rickettsiae in Panamanian ticks, we collected questing and on-host ticks in urban and rural towns in elevations varying between 0 and 2300 m. A total of 63 sites (13 urban and 50 rural towns) were used to develop models of spatial distributions. We found the following tick species: Rhipicephalus sanguineus s.l. (present in 54 of 63 towns and cities), Amblyomma mixtum (45/63), Dermacentor nitens (40/63), A. ovale (37/63), Rhipicephalus microplus (33/63), A. oblongoguttatum (33/63), Ixodes affinis (3/63), and Ixodes boliviensis (2/63). Rhipicephalus sanguineus s.l. was present in urban and rural towns, and other species were present only in rural towns. DNA was extracted from 408 R. sanguineus s.l., 387 A. mixtum, 103 A. ovale, and 11 A. oblongoguttatum and later tested for rickettsiae genes using PCR. Rickettsia DNA was detected in ticks from 21 of 63 localities. Rickettsia rickettsii was detected in five A. mixtum (1.29%), and Candidatus "Rickettsia amblyommii" was found in 138 A. mixtum (35%), 14 R. sanguineus (3.4%), and one A. ovale (0.9%). These results suggest that much of rural Panama is suitable for the expansion of tick populations and could favor the appearance of new tick-borne rickettsiosis outbreaks.

Ticks and tick-borne pathogens of dogs along an elevational and land-use gradient in Chiriquí province, Panamá

“…Higher overall EVI values were associated with higher tick prevalence but lower tick abundance on dogs (Tables 4, 5) but we note that elevation was the single strongest predictor of tick occurrence among our sites and consistent with previous studies, we found higher tick abundance and prevalence on dogs at lower elevation sites ( Demma et al 2006;Okoli et al 2006). The relatively low infection rate with R. amblyommii in R. sanguineous (0.5%) and A. ovale (13%) is generally consistent with previously reported results in dog-derived ticks (Bermúdez et al 2009(Bermúdez et al , 2016. Similarly, our failure to detect R. rickettsia or Ehrlichia spp.…”

“…Similarly, our failure to detect R. rickettsia or Ehrlichia spp. in dog-derived ticks is consistent with previous reports (Bermúdez et al 2009(Bermúdez et al , 2016. Although elevation is an important predictor of tick parasitism in Panama, landcover and landuse change are also drivers of tick parasitism (Tables 4,5).…”

“…We expected R. sanguineus s.l. to be the most abundant and prevalent tick in low elevation and urbanized areas with other tick species more abundant as the level of urbanization decreases and elevation increases (Fairchild et al 1966;Bermudez and Miranda 2011;Bermúdez et al 2016). Beyond this, however, we aimed to weigh the relative importance of various environmental predictor variables to characterize drivers of tick parasitism on dogs.…”

Detection of rickettsiae in fleas and ticks from areas of Costa Rica with history of spotted fever group rickettsioses

“…In contrast with the low infection rate of R. rickettsii, infection rate of A. mixtum with ‗Candidatus R. amblyommii' was high, which may be expected considering that it is a common finding in other countries of the region, including Honduras and Panamá (Novakova et al, 2015;Bermúdez et al, 2016). The infection rate in A. ovale, D. nitens, and R. sanguineus s. l. was lower, but confirms previous reports of ‗Candidatus R. amblyommii' in these tick species (Bermúdez et al, 2009.…”

“…In this study, R. rickettsii was detected in ticks of the genus Amblyomma. Ticks from the A. cajennense complex or identified as A. mixtum, have been implicated as possible vectors of R. rickettsii to humans in Panama (de Rodaniche, 1953;Bermúdez et al, 2016); some of the other species of this complex are also vectors of R. rickettsii in South America (Krawczak et al, 2014;Faccini-Martínez et al, 2015). Although most of the A. mixtum ticks analyzed in the present study were collected from horses in Cahuita, some of the specimens were obtained from humans, as this species complex commonly bites humans (Guglielmone et al, 2006).…”