Surveys of horse serum are a useful method of surveillance for Brazilian spotted fever in areas where humans are exposed to Amblyomma cajennense ticks.

In serum samples obtained from all the healthy humans, horses, dogs, and donkeys present on three farms in the Pedreira Municipality, an endemic area for Brazilian spotted fever, an indirect immunofluorescence assay (IFA) detected antibodies against Rickettsia rickettsii in 17 (77.3%) horses, 5 (31.3%) dogs (titers ranging from 64 to 4,048), and none of 4 donkeys or 50 humans. Five canine and eight equine sera with high antibody titers to R. rickettsii were also tested by IFA against R. bellii, R. akari, and R. africae antigens. Sera from two horses and two dogs that showed similar high antibody titers against two rickettsial antigens were evaluated after cross-absorption. Sera from seven horses and two dogs contained antibodies specific for R. rickettsii, and one dog serum had antibodies against a Rickettsia species very closely related to R. africae. The latter may have been caused by infection with the recently identified COOPERI strain.

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Ehrlichiosis is a disease caused by rickettsial organisms belonging to the genus Ehrlichia. In Brazil, molecular and serological studies have evaluated the occurrence of Ehrlichia species in dogs, cats, wild animals and humans. Ehrlichia canis is the main species found in dogs in Brazil, although E. ewingii infection has been recently suspected in five dogs. Ehrlichia chaffeensis DNA has been detected and characterized in mash deer, whereas E. muris and E. ruminantium have not yet been identified in Brazil. Canine monocytic ehrlichiosis caused by E. canis appears to be highly endemic in several regions of Brazil, however prevalence data are not available for several regions. Ehrlichia canis DNA also has been detected and molecularly characterized in three domestic cats, and antibodies against E. canis were detected in free-ranging Neotropical felids. There is serological evidence suggesting the occurrence of human ehrlichiosis in Brazil but its etiologic agent has not yet been established. Improved molecular diagnostic resources for laboratory testing will allow better identification and characterization of ehrlichial organisms associated with human ehrlichiosis in Brazil.

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Recent studies have been conducted in Brazil using molecular techniques for the detection of hemotrophic mycoplasmas in several mammals. In domestic cats, Mycoplasma haemofelis, 'Candidatus M. haemominutum', and 'Candidatus M. turicensis' infections have been identified. These species have also been found in free-ranging and captive neotropical felid species. Two canine hemoplasmas, Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum', have been identified in dogs. In commercial swine populations, Mycoplasma suis was found to be highly prevalent, especially in sows. Moreover, novel mycoplasma species have been identified in Brazilian commercial pigs and domestic dogs. A hemoplasma infection in a human patient infected with the human immunodeficiency virus (HIV) was also recently documented. In conclusion, hemoplasma species are common and important infectious agents in Brazil. Further studies should be conducted to better understand their impact on pets, production animals, and wildlife fauna, as well as their role as zoonotic agents, particularly in immunocompromised patients.Keywords: Hemoplasma, Mycoplasma haemofelis, Mycoplasma suis, HIV. ResumoEstudos recentes utilizando técnicas moleculares para a detecção de micoplasmas hemotróficos em diferentes mamíferos têm sido conduzidos no Brasil. Em gatos domésticos, infecções por Mycoplasma haemofelis, 'Candidatus M. haemominutum' e 'Candidatus M. turicensis' foram identificadas. Estas espécies também foram encontradas em felídeos neotropicais de vida livre e de cativeiro. Dois hemoplasmas caninos, Mycoplasma haemocanis e 'Candidatus Mycoplasma haematoparvum', foram identificados em cães domésticos. Em populações comerciais de suínos, Mycoplasma suis possui alta prevalência, especialmente em porcas. Além disso, novas espécies de hemoplasmas foram detectadas em suínos comercias e cães. Infecção por um hemoplasma em um paciente humano infectado com o vírus da imunodeficiência humana (HIV) foi recentemente documentada. Em conclusão, espécies de hemoplasmas são comuns e importantes agentes de infecções no Brasil. Estudos futuros devem ser conduzidos para melhor entender seu impacto em cães e gatos, animais de produção e na fauna silvestre, e também para determinar o seu papel como agentes zoonóticos, particularmente em pacientes imunocomprometidos.Palavras-chave: Hemoplasma, Mycoplasma haemofelis, Mycoplasma suis, HIV.