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This study aims to report the presence of Neorickettsia risticii DNA in blood samples from naturally infected horses in Rio de Janeiro, provide clinicopathological findings related to the infection, and report the phylogenetic diversity of the 16S rDNA of N. risticii in order to evaluate its heterogeneity. Real-time quantitative polymerase chain reaction (qPCR) was performed to investigate the presence of N. risticii in samples collected from horses (n = 187). Five positive samples were found in the molecular screening. Hypoalbuminemia and high levels of creatine kinase and lactate dehydrogenase were the predominant findings in the biochemical analysis. The sequences were similar to those of N. risticii. Phylogenetic analysis revealed genotype segregation based on the geographical distribution in the N. risticii sequence clade. Dendrograms constructed with five hypervariable regions revealed that V4 distinguished Neorickettsia at the species level and produced a phylogeny that best represented the phylogeny obtained with the complete 16S rDNA sequence. This is the first report of N. risticii DNA in the blood of Brazilian horses based on sequences deposited in GenBank. Further studies are necessary to clarify the epidemiological chain of this vector-borne parasite in order to determine and establish appropriate preventive measures in the equine trading market.

To characterize phylogenetically the species which causes canine hepatozoonosis at two rural areas of Rio de Janeiro State, Brazil, we used universal or Hepatozoon spp. primer sets for the 18S SSU rRNA coding region. DNA extracts were obtained from blood samples of thirteen dogs naturally infected, from four experimentally infected, and from five puppies infected by vertical transmission from a dam, that was experimentally infected. DNA of sporozoites of Hepatozoon americanum was used as positive control. The amplification of DNA extracts from blood of dogs infected with sporozoites of Hepatozoon spp. was observed in the presence of primers to 18S SSU rRNA gene of Hepatozoon spp., whereas DNA of H. americanum sporozoites was amplified in the presence of either universal or Hepatozoon spp.-specific primer sets; the amplified products were approximately 600bp in size. Cloned PCR products obtained from DNA extracts of blood from two dogs experimentally infected with Hepatozoon sp. were sequenced. The consensus sequence, derived from six sequence data sets, were blasted against sequences of 18S SSU rRNA of Hepatozoon spp. available at GenBank and aligned to homologous sequences to perform the phylogenetic analysis. This analysis clearly showed that our sequence clustered, independently of H. americanum sequences, within a group comprising other Hepatozoon canis sequences. Our results confirmed the hypothesis that the agent causing hepatozoonosis in the areas studied in Brazil is H. canis, supporting previous reports that were based on morphological and morphometric analyses.

Transmission of Hepatozoon spp. to dogs was investigated using four species of ixodid ticks: Rhipicephalus sanguineus, Amblyomma aureolatum, Amblyomma ovale and Amblyomma cajennense. We collected completely or partially engorged adult ticks of these species from dogs that were naturally infested and positive for Hepatozoon spp. We selected some of these ixodids and inoculated them orally in four negative dogs. The other ticks were dissected and examined for oocysts. Of all dogs inoculated orally with R. sanguineus, A. aureolatum, A. cajennense and A. ovale, only the animal that received the macerate of A. ovale was positive; evidence (gametocytes in peripheral blood) of infection was found 63 days after inoculation. Among all dissected ticks, we found only two oocysts; these were similar to those of Hepatozoon canis, and both were recovered from a single A. ovale specimen. We inoculated sporozoites recovered from the oocysts intraperitoneally into a Hepatozoon spp. negative dog, and circulating gametocytes were detected 84 days later. Our study demonstrated that A. ovale can be a vector of Hepatozoon spp. in Brazil.

Hepatozoon canis is a tick-borne protozoan that infects dogs and has been reported throughout the world. Manifestation of H. canis infection varies from being sub-clinical in apparently healthy dogs to severe illness. The main vector of the infection is the dog tick, Rhipicephalus sanguineus although other species may also transmit this agent. H. canis has been reported previously in Brazil, but mostly as an occasional finding during laboratory exams and always associated with other diseases. The prevalence of H. canis in dogs of rural areas of Brazil has been little studied. For this study, 250 dogs from seven counties of Rio de Janeiro state were examined. All the dogs were from rural areas, near forest. Of the dogs examined, 26 dogs were from Seropédica, 82 from Itaguaí, 41 from Paracambi, 26 from Mangaratiba, 32 from Barra do Piraí, 32 from Piraí and 11 from Miguel Pereira. Blood smears from the peripheral blood of the ear were taken and ticks found on the dogs were collected for identification in the laboratory. Using blood smear evaluation, H. canis was identified in 39.2% of the animals examined. Other hemoparasites identified were Babesia canis (5.2%) and Ehrlichia canis (4.8%). Four tick species were found parasitizing the dogs: Amblyomma cajennense (23.6%), R. sanguineus (12.4%), Amblyomma aureolatum (2.8%) and Amblyomma ovale (2.0%). There was a positive correlation between the presence of A. cajennense and H. canis infection.

American tegumentary leishmaniasis (ATL) is endemic in the State of Rio de Janeiro, with the highest incidence observed in the municipalities along the Southern coast. A total of 169 human cases were reported from 1993 to 1995 in the municipality of Paraty, representing 15% of all case reports in the State of Rio de Janeiro during that period. From March to December, 1996, a survey was conducted in endemic american tegumentary leishmaniasis (ATL) areas (Praia Grande, Taquari, Várzea do Machado, and Graúna) in Paraty. 326 households with 215 pet dogs were surveyed. The initial study consisted of taking venous blood samples to perform RIFI and ELISA tests. The canine skin test was performed during the same visit and was positive in 8.8% of dogs. Of the 215 dogs, 5 presented lesions suspected of ATL; biopsies and the vacuum aspiration technique were performed on these cases. Correlating the study areas with the results obtained, some dogs presented sub-clinical infection, highly relevant to studies on canine ATL infection in the State of Rio de Janeiro.

Current methods for the control of the cattle tick Boophilus microplus infestations are not effective and the parasite remains a serious problem for the cattle industry in tropical and sub-tropical areas. Recent advances have introduced the possibility for the immunological control of the parasite through the use of recombinant vaccines. Recently, it was shown that the recombinant vaccine Gavac (Heber Biotec S.A.) is able to control B. microplus populations in artificially infected grazing dairy cattle in Cuba. To assay the effect of the vaccine on a different B. microplus strain and under different ecological conditions, we conducted a trial in Brazil on grazing dairy and beef pure and cross-bred cattle under natural infestation conditions. A farm in the northeast of the state of Sao Paulo was selected and two groups of animals per breed were included in the experiment and were maintained grazing on separate but similar pastures. For each breed, one group was vaccinated with the vaccine Gavac and the second group was not vaccinated and was employed as a control. In vaccinated cattle, during 36 weeks of experiment, the average infestation rate was maintained below 78 ticks per animal while average infestation peaks (mean +/- S.E.) of 144 +/- 44 ticks per animal (for dairy cross-bred cattle) and 195 +/- 42 ticks per animal (for beef cross-bred cattle) were recorded in the control groups. Tick infestation rates showed statistical significant differences (p = 0.04) between both experimental groups throughout the experiment. These results clearly showed, as in the Cuban study, that the vaccine controlled tick numbers in successive generations in the field.

An extremely polymorphous intraerythrocytic microorganism occurring in naturally infected turkeys, ducks and fowls has been discovered in the states of Minas Gerais, Rio de Janeiro and Espirito Santo. 2. Studies on the morphology and biology have shown that it is a hitherto undescribed heteroxenous parasite for which the name Neitziella rezendei gen. nov., sp. nov. is proposed. 3. Its morphological features permit its inclusion in the class Microtatobiotes and order Rickettsiales. 4. Microscopical examination of blood films have shown that the parasitic carrier state in turkeys persists for more than 200 days (endpoint not determined). 5. The natural mode of transmission needs to be determined. 6. The suspicion that the parasite may cause illthrift and deaths in poultry requires confirmation.