Occurrence of Trypanosoma caninum in areas overlapping with leishmaniasis in Brazil: what is the real impact of canine leishmaniasis control?

Abstract

Trypanosoma caninum is a parasite of the Trypanosoma genus recently described in the natural infection of dogs in the municipality of Rio de Janeiro, Brazil. Suspecting the existence of a natural cycle and the circulation of this new species, the objective of this study was the taxonomic identification of samples of Trypanosoma spp. isolated from dogs in different Brazilian regions. Parasites were solely obtained from skin fragments culture and characterized by nested-PCR targeting the partial sequence of 18S rRNA gene and PCR products were sequenced. Thirty-three samples, obtained in São Paulo, Minas Gerais, Goiás, Mato Grosso and Rio de Janeiro states were analyzed. PCR and sequencing showed that the isolates were genetically identical or closely similar and confirmed T. caninum identity. This report broadens the geographical distribution of T. caninum in Brazil and discusses the impact of the presence of this parasite in areas of canine leishmaniasis occurrence.

Report of new cases of Trypanosoma caninum in Brazil

“…These animals are of particular interest with regard to the transmission cycle of Leishmania chagasi and Trypanosoma cruzi, because they are considered reservoirs for both agents and enhancers of transmission in the peridomicile, and consequently a risk factor for the human population (3) (4) . Trypanosoma caninum is the most recently described species of the Trypanosoma genus affecting dogs (5) , with 53 cases confirmed in different regions of Brazil (6) prior to this present study. The species has unique biological characteristics, including its isolation exclusively from intact skin fragments (5) (7) and the presence of afl agellate epimastigote forms in axenic cultures (8) .…”

“…Seven animals were from the municipality of Rio de Janeiro, one from the municipality of Barra Mansa, and another from the municipality of São João do Piauí (Figure 1). All isolates were identifi ed as T. caninum and exhibited 100% homology with T. caninum sequences from previous studies (6) . Rio de Janeiro B a r r a M a n s a Six months after the initial isolation, four dogs previously diagnosed with T. caninum infection were found and reevaluated.…”

“…However, the presence of T. caninum in areas overlapping with those affected by canine visceral leishmaniasis (CVL) has been identifi ed as a possible confounding factor for the accurate diagnosis of CVL. Thus, such overlap may have a negative impact on the control of this disease (6) . Culturebased testing has been an important tool for the diagnosis of T. caninum infection, although recent studies have demonstrated that polymerase chain reaction (PCR)-based tests that amplify specifi c regions of the 18S ribosomal DNA (rDNA) gene may be a valuable additional tool for diagnosis, particularly in areas overlapping with those affected by Leishmania chagasi (10) .…”

“…The cultureisolated strains were identifi ed using nested PCR with specifi c oligonucleotides to amplify a partial region of the 18S rDNA gene. Nucleotide sequences were analyzed as previously described (6) . Six months later, an active search for infected dogs was performed with the aim of re-isolating parasites from skin fragments in the same region where the previous isolations were performed.…”

“…Trypanosoma caninum is a recently described species, and its occurrence has been reported in different States of Brazil (6) . Herein, we describe new cases of infection with this agent in two new transmission areas: Barra Mansa, in the State of Rio de Janeiro, and São João do Piauí, in the State of Piauí.…”