This study investigated rickettsial infection in animals, humans, ticks, and fleas collected in five areas of the state of São Paulo. Eight flea species (Adoratopsylla antiquorum antiquorum, Ctenocephalides felis felis, Polygenis atopus, Polygenis rimatus, Polygenis roberti roberti, Polygenis tripus, Rhopalopsyllus lugubris, and Rhopalopsyllus lutzi lutzi), and five tick species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Ixodes loricatus, and Rhipicephalus sanguineus) were collected from dogs, cats, and opossums. Rickettsia felis was the only rickettsia found infecting fleas, whereas Rickettsia bellii was the only agent infecting ticks, but no animal or human blood was shown to contain rickettsial DNA. Testing animal and human sera by indirect immunofluorescence assay against four rickettsia antigens (R. rickettsii, R. parkeri, R. felis, and R. bellii), some opossum, dog, horse, and human sera reacted to R. rickettsii with titers at least four-fold higher than to the other three rickettsial antigens. These sera were considered to have a predominant antibody response to R. rickettsii. Using the same criteria, opossum, dog, and horse sera showed predominant antibody response to R. parkeri or a very closely related genotype. Our serological results suggest that both R. rickettsii and R. parkeri infected animals and/or humans in the studied areas.Key words: Rickettsia -spotted fever -fleas -ticks -opossum -domestic animals Rickettsiae are obligate intracellular bacteria that have been classically divided into two groups: the typhus group (TG), composed of Rickettsia prowazekii and Rickettsia typhi, which are associated with lice and fleas, respectively; and the spotted fever group (SFG), which includes more than 20 valid species, mostly associated with ticks (e.g., Rickettsia rickettsii, Rickettsia parkeri), and at least one species associated with fleas (Rickettsia felis). Other species, such as Rickettsia bellii and Rickettsia canadensis, both associated with ticks, have been considered a distinct group sharing antigenic, genetic and ecological characters with both TG and SFG rickettsiae (Parola et al. 2005b). Since all SFG Rickettsia share common outer membrane antigens, conventional serological assays employing a single Rickettsia antigen (e.g., R. rickettsii) allow detecting a SFG infection, but they do not identify the Rickettsia species responsible for the infection, even in the presence of high titers (La Scola & Raoult 1997). For a more specific serological diagnosis, it is recommended techniques such as testing serum against all known Rickettsia species present in a given area, or serum cross-absorption tests (La Scola & Raoult 1997, Parola et al. 2005b).For many years, SFG rickettsiosis in the Americas was thought to be caused only by R. rickettsii, transmitted by ticks (Weiss & Moulder 1984). This rickettsia has been reported in several countries from North, Central, and South America causing an acute, highly lethal febrile disease receiving different names according to the country...
Ctenocephalides felis felis is one of the most important ectoparasites of dogs and cats throughout the world, because of its geographical distribution, dual parasitological action as an infesting agent and a vector of diseases, the economic losses and the acquired resistance against common insecticides. In Brazil, it surpasses Ctenocephalides canis in distribution, number of host species infested, prevalence and epidemiological importance. However, in some studies the species have been misidentified on the basis of their morphological characters included in taxonomic keys. The morphological variations of chaetotaxy, especially those on the dorsal margin of the hind tibia and lateral metanotal area (LMA), found in certain specimens, have sometimes been erroneously treated as hybrids, in spite of the nonexistence of the two species of Ctenocephalides in the same municipality or region. This review focuses on the characteristics used for interspecific diagnosis and intraspecific variations found between the species. Data on distribution, hosts, prevalence and parasitological action are also presented as an auxiliary means for recognizing the species.
To explore the local transmission dynamics of Tunga penetrans in brazil, 134 soil samples from various environments were collected in three different endemic regions of the country and checked for the presence of the flea's larvae, pupae and adults. the samples, which came from an urban slum in the north-east, a village of xavante indians in the central-west and a community of yanomami indians living in traditional longhouses (malocas) in the north, were categorized as indoor, outdoor or indoor-outdoor (the latter representing samples collected in the malocas). The proportion of samples found positive for T. penetrans was lowest in the slum (9.3%) and highest in the Yanomami village (32.0%; P=0.01). Soil samples collected below bedsteads or hammocks or from the indoor resting places of dogs were significantly more likely to be positive than the indoor samples collected at other sites (65.0% v. 35.0%; P=0.02). There was no evidence indicating that the presence of T. penetrans in a soil sample was markedly affected by soil temperature, air temperature or air humidity. As no life stages of T. penetrans were found in any outdoor sample, it seems likely that, in resource-poor settings in Brazil, most transmission of T. penetrans occurs indoors. Control measures against the off-host life stages of T. penetrans should therefore be targeted at particular indoor micro-environments.
Tunga is the most specialized genus among the Siphonaptera because adult females penetrate into the skin of their hosts and, after mating and fertilization, undergo hypertrophy, forming an enlarged structure known as the neosome. In humans and other warm-blooded animals, neosomes cause tungiasis, which arises due to the action of opportunistic agents. Although its effects on humans and domestic animals are well described in the literature, little is known about the impact of tungiasis on wild animals. This review focuses on the morphology, taxonomy, geographical distribution, hosts, prevalence, sites of attachment, and impact of tungid neosomes on wild and domestic animals. Because neosomes are the most characteristic form of the genus Tunga and also the form most frequently found in hosts, they are here differentiated and illustrated to aid in the identification of the 13 currently known species. Perspectives for future studies regarding the possibility of discovering other sand flea species, adaptation to new hosts, and the transfer of tungids between hosts in natural and modified habitats are also presented.Electronic supplementary materialThe online version of this article (doi:10.1007/s00436-014-4081-8) contains supplementary material, which is available to authorized users.
We present a critical analysis of the generalized use of the "impact factor". By means of the Kruskal-Wallis test, it was shown that it is not possible to compare distinct disciplines using the "impact factor" without adjustments. After assigning the median journal the value of one (1.000), the "impact factor" value for each journal was calculated by the rule of three. The adjusted values were homogeneous, thus permitting comparison among distinct disciplines.
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