Rickettsial pathogens circulating in urban districts of Rio de Janeiro, without report of human Brazilian Spotted Fever

Abstract

Spotted fever group rickettsioses are emerging diseases. In some of these diseases, domestic dogs act as sentinels. Canine serological studies have demonstrated that rickettsial dispersion is concentrated in rural areas, seroprevalence being higher where human rickettsioses are endemic. In Rio de Janeiro, the Atlantic forest vegetation has been devastated by urbanization. In this context, we aimed to detect Rickettsia spp. in urban areas of the West Zone of Rio de Janeiro. Sera from 130 dogs were tested by Indirect Immunofluorescence Assay, and ticks collected from these dogs were tested by polymerase chain reaction. We found the rate of serological reactions against R. rickettsii and R. parkeri in our study area to exceed those of rural and non-endemic areas, highlighting the importance of dogs as urban sentinels. The possibility of contact with opossums and capybaras increased the chances of exposure to Rickettsia spp., reinforcing the hypothetical link between the landscape and the rickettsial wild cycle. Rhipicephalus sanguineus sensu lato was the tick most frequently observed. PCR-positive samples showed similarity with R. rickettsii and R. felis, an emerging pathogen rarely reported from ticks. We observed that rickettsiae circulate in urban places and ticks from indoor environments, which may be involved in bacterial epidemiology.

Culture Isolate of Rickettsia felis from a Tick

“…By molecular techniques, R. felis has been detected in different flea species, mosquitoes, mites, and ticks (both Ixodid and Argasid). These tick species include Rhipicephalus sanguineus in Brazil, Spain, Chile, China, and the Philippines [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]; Rhipicephalus bursa in Turkey [ 22 ]; Rhipicephalus turanicus in Italy [ 23 ]; Haemaphysalis flava, Haemaphysalis kitasatoe, and Ixodes ovatus in Japan [ 24 ]; Haemaphysalis sulcata in Croatia [ 25 ]; Haemaphysalis leporispalustris in the United States [ 26 ]; Haemaphysalis sp. and Rhipicephalus microplus in Malaysia [ 27 ]; Heamaphysalis bancrofti in Australia [ 28 ]; Amblyomma maculatum in the United States [ 29 ]; Amblyomma cajennense , Amblyomma humerale, Amblyomma ovale , and Amblyomma sculptum in Brazil [ 14 , 30 , 31 , 32 ]; Ixodes granulatus in Taiwan [ 33 ]; Ixodes hexagonus in Italy [ 34 ]; Ixodes ricinus in Germany, France, Spain, Romania, and Serbia [ 35 , 36 , 37 , 38 , 39 , 40 ]; Dermacentor nitens in Brazil and Cuba [ 21 , 41 ]; and Dermacentor variabilis and Carios capensis in the United States [ 42 , 43 ] ( Table S1 ).…”

Mapping potential risks for the transmission of spotted fever rickettsiosis: The case study from the Rio de Janeiro state, Brazil

“…It is recognized that the bacterium Rickettsia rickettsii has a very high lethality profile and, in Rio de Janeiro state, it is responsible for cases with hospitalization and death in patients affected by the disease called Brazilian Spotted Fever [ 24 , 25 ]. The other rickettsiosis, with a milder clinical course, sometimes oligosymptomatic, are called Spotted Fever [ 26 , 27 ].…”

Aspectos Etioepidemiológicos Da Febre Maculosa Brasileira: Revisão Sistemática

“…Entretanto, a doença canina é raramente relatada (7). Em estudo realizado por Campos et al (30), objetivou-se avaliar a infecção natural por Rickettsia spp. do GFM em cães e carrapatos com domicílios próximos a fragmentos de matas.…”

“…e o gene ompA das espécies do GFM. Um cão (0,87%) foi positivo para R. rickettsii, apresentando sintomatologia da doença e alterações laboratoriais inespecíficas, reforçando a importância dos cães como suscetíveis e hospedeiros amplificadores da doença (30).…”