Raimundo Diogo Machado

Primary isolation of spotted fever group rickettsiae from Amblyomma cooperi collected from Hydrochaeris hydrochaeris in Brazil

This paper reports the first isolation of a spotted fever group rickettsia from an Amblyomma cooperi ixodid collected from a capybara (Hydrochaeris hydrochaeris) in an endemic area of spotted fever in the County of Pedreira, State of São Paulo, Brazil. Isolation was performed in Vero cell culture and submitted to immunofluorescence, using antibody from Rickettsia rickettsii-positive human serum.

Epidemiological aspects of the Brazilian spotted fever: seasonal activity of ticks collected in an endemic area in São Paulo, Brazil

Ticks were collected from vegetation and animals at monthly intervals during one year (1993-1994) in an endemic area of Brazilian spotted fever in the Country of Pedreira, State of São Paulo. Six species of ticks were identified Amblyomma cajennense, Amblyomma cooperi, Amblyomma triste, Anocentor nitens, Rhipicephalus sanguineus and Boophilus microplus. Only the first species was sufficiently numerous to permit a quantitative study with seasonal activity, although the distribution and source of capture of other species were observed and are reported. This information is correlated with the epidemiology of tick-borne rickettsiosis.

Epidemiological aspects of the Brazilian spotted fever: serological survey of dogs and horses in an endemic area in the State of São Paulo, Brazil

In order to obtain information on Brazilian spotted fever, a study in domestic animals was performed in the County of Pedreira, State of São Paulo, Brazil, where 17 human cases had been notified. Serum samples obtained from animals were tested by indirect immunofluorescence for detectable antibodies to spotted fever-group rickettsiae. Seropositivity was revealed in 12 (36.4%) of 33 dogs and seven (77.8%) of nine horses from the endemic area. For comparison, blood samples from dogs and horses from non endemic area were tested and four (12.9%) of 31 dogs and three (27.3%) of 11 horses were positive. The highest titers of antibodies by IFA (IgG > or = 1:1024) were found only in three dogs and six horses from endemic area. The results suggest that dogs as horses may serve as environmental sentinels for establishing the prevalence of foci of spotted fever in Brazil.

Rickettsiae-infected ticks in an endemic area of spotted fever in the State of Minas Gerais, Brazil.

A study on tick-borne rickettsiosis was developed in the county of Santa Cruz do Escalvado, State of Minas Gerais, Brazil, where a clinical case of the disease, confirmed by necropsy, had been reported. Of the 1,254 ticks collected, 1,061 belonged to the Amblyomma genus, 57 to the Rhipicephalus sanguineus species, 81 to Boophilus microplus, and 46 to Anocentor nitens. The hemolymph test associated with Giménez staining showed that 18 of the 221 A. cajennense specimens, 1 of the 16 R. sanguineus, 1 of the 22 B. microplus, 3 of the A. nitens, and 1 of the A. ovale contained rickettsia-like microorganisms. Only 3 A. cajennense ticks were positive under direct immunofluorescence. A. cajennense was the only species found on humans.

Rocky Mountain spotted fever in an endemic area in Minas Gerais, Brazil

Only one species of spotted fever-group rickettsiae that is pathogenic for humans has been isolated in Brazil, where few physicians are familiar with this disease. In order to obtain information on tick-borne rickettsiosis, a study was performed in the County of Santa Cruz do Escalvado, State of Minas Gerais, Brazil, where a fatal clinical case confirmed by specific immunofluorescence had been reported. Serum samples obtained from 679 humans and 96 dogs were tested by indirect immunofluorescence for detectable antibodies to spotted fever-group rickettsiae, the criterion for a positive result being a titer > or = 1:64. Seropositivity was detected in 7.14% of the humans sera examined and 13.68% of the dogs. We discuss the significance of these findings and formulate some questions, emphasizing the need for further investigation.

Molluscum contagiosum: serology and electron microscopy findings in twenty one patients

Twenty one cases of molluscum contagiosum virus disease were collected for electron microscopical and serological tests. Molluscum virus was detected in the crust, inside the vacuoles formed in the keratinocytes cells. The patients developed specific antibodies to the virus detected by complement fixation test.

Infestation by ticks and detection of antibodies to spotted fever group rickettsiae in wild animals captured in the state of São Paulo, Brazil: A preliminary report

Since 1985 several human cases of Brazilian spotted fever, an acute infectious disease of variable severity, has been reported in the county of Pedreira, State of São Paulo. Since humans are accidental victims, the epidemiology of this tickborne rickettsiosis depends primarily on the species and ecology of the tick vector involved and its mammal hosts. Several species of ticks have been recognized as natural carries of Rickettsia rickettsii, but Amblyomma cajennense is the most important vector in Brazil. Considering the scarced available information on this rickettsiosis in Brazil, we designed a multidisciplinary project in an endemic area in Pedreira. As part of this project we attempted to determine the significance of wild animals caught near human settlements, where rickettsiosis transmission foci for active transmission had been detected (ERS Lemos et al. 1996 Mem Inst Oswaldo Cruz 91: 273-275). A total of 605 ticks were collected from 14 animals belonging to four different species (Hydrochaeris hidrochaeris, Myocastor coypus bonariensis, Rattus norvergicus and Didelphis marsupialis) (Table). These animals were caught alive in special traps and were bled from the brachium vein (capibara) or from the heart (small animals). After collecting ticks and bleeding all animals were freed in same place where they were captured. After taxonomic identification, ticks were inoculated onto fresh monolayers of Vero cells for isolation. In an effort to analyse the presence of antibodies from sera of animals, a blocking imunofluorescence test was done with antigens R. rickettsii obtained from Vero cell cultures prepared at the Center for Disease Control, Atlanta, Georgia. This modified test was used to detect blocked antibodies because FITC-labeled of some anti-wild animals immunoglobulins were difficult to produce in hyper-immunized rabbits. Serial dilutions of animal sera ranging from 1:4 to 1:64 were placed on the antigen, incubated at 37°C for 30 min, and washed in phosphate buffered saline (PBS). Next, slides were incubated with a positive human sera in a 1:20 dilution for 30 min. After this step, a goat conjugate of anti-human immunoglobulin (Ig) was used. A positive sera of horse was used as positive control. Slides were examined with a Zeiss fluorescence microscope and sera title without fluorescence was considered positive. In spite of the small number of animals, it is worth of note that ectoparasites were abundant. Furthermore, a spotted fever group rickettsia was isolated from three A. cooperi ixodids collected from one of the two seroreactive (1:16) H. hydrochaeris (capibara) (Lemos et al. 1oc. cit.). All isolation attempts from blood of wild animals were negative. To further clarify serologic results and other informations mentioned in this preliminary report, studies will continue and specific anti-wild animals reagent will be prepared, mainly anti-capibara reagent.