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EVIDENCE OF SPOTTED FEVER GROUP RICKETTSIAE IN STATE OF RIO DE JANEIRO, BRAZIL - page 2 / 4

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Cacaria

122/33

121 (99.2 %)

Serra do Matoso

456/96

353 (77.4%)

TOTAL

578/129

474 (81.8%)

Cacaria

A. cajennense R. sanguineus Amblyomma sp

- 5 -

Serra do Matoso A. cajennense A. ovale Amblyomma sp R. sanguineus

- - 12 1

Total

18

ROZENTAL, T.; BUSTAMANTE, M.C.; AMORIM, M.; SERRA-FREIRE, N.M. & LEMOS, E.R.S. - Evidence of spotted fever group rickettsiae in state of Rio de Janeiro, Brazil. Rev. Inst. Med. trop. S. Paulo, 44(3):155-158, 2002.

Larvae Nymph Adult

Total

-

12

12

7

90

102

7

-

7

45

46

91

-

7

7

136

-

148

5

101

107

200

256

474

Table 1 Number of ticks collected and identified

Localities

Table 2 Number of ticks taxonomically identified collected from dogs

Localities

Tick species

No. identified

Total no. of ticks/ Total no. of dogs

Total no. of ticks identified (%)

sanguineus specie. This positive exemplar was also collected from Serra do Matoso.

DISCUSSION

Fonte: Atlas do Estado do Rio de Janeiro, 1992 - FAPERJ; Anuário Estatístico do Estado do Rio de Janeiro, 1990/91 - CIDE

The Giemsa staining technique showed microorganisms with shape and size compatible with rickettsia.Although this technique is unspecific, unable to distinguish from other bacterias, the presence of infection in the nucleus of some hemocytes suggest, almost certainly, spotted fever group rickettsiae10. Another exemplar tested, only one tick presented rickettsia-like organisms, with rounding shape bacillus-like organisms that differed from the short, ovoid forms compatible with R. rickettsii. Although significant differences in the prevalence of the infection can be observed during the year, the results showed here are similar from other investigators, that perform studies in different regions in the World25,26,27,37,38.

Fig. 1 - County of Piraí (Monumento District), Rio de Janeiro, Brazil.

cytoplasm of the hemocyte and one adult R. sanguineus only in the cytoplasm. The prevalence of infection found was 1.3%.

The low prevalence (0.6%) observed in the direct immuno- fluorescence assay may have been due to the small number of exemplars studied. In spite of this, a similar finding was observed by MAGNARELLI et al. (1981)26 in Connecticut. Beside this, various studies on infection in ticks display wide variation, with prevalences ranging from 0.14% to 13.5%4,6,11,13,18,24,41,44.

All positive exemplars were collected from Serra do Matoso.

Hemolymph test and direct immunofluorescence: One hundred and sixty three ticks (34.3%) were submitted to hemolymph test associated to direct immunofluorescence. The prevalence of infection to Spotted fever group rickettsiae was 0.6%, detected in one nimph R.

As this study was performed in a population of dogs, R. sanguineus (known as a vector for spotted fever caused by R. conorii in Europe) was the most abundant specie in the ixodid fauna studied that was positive by hemolymph test. They are also important because this tick may be implicated in maintaining spotted fever group rickettsiae in nature7,8,36.

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