Trypanosoma caninum n. sp. (Protozoa: Kinetoplastida) isolated from intact skin of a domestic dog (Canis familiaris) captured in Rio de Janeiro, Brazil

Abstract

An unknown Trypanosoma species was isolated from an axenic culture of intact skin from a domestic dog captured in Rio de Janeiro, Brazil, which was co-infected with Leishmania (Viannia) braziliensis. Giemsa-stained smears of cultures grown in different media revealed the presence of epimastigotes, trypomastigotes, spheromastigotes, transitional stages, and dividing forms (epimastigotes or spheromastigotes). The highest frequency of trypomastigotes was observed in RPMI (15.2%) and DMEM (9.2%) media containing 5% FCS, with a mean length of these forms of 43.0 and 36.0 mum, respectively. Molecular analysis by sequential application of PCR assays indicated that this trypanosome differs from Trypanosoma cruzi and T. rangeli when specific primers were applied. On the other hand, a PCR strategy targeted to the D7 domain of 24salpha rDNA, using primers D75/D76, amplified products of about 250 bp in that isolate (stock A-27), different from the amplification products obtained with T. cruzi and T. rangeli. This organism differs from T. cruzi mainly by the size of its trypomastigote forms and kinetoplasts and the absence of infectivity for macrophages and triatomine bugs. It is also morphologically distinct from salivarian trypanosomes reported in Brazil. Isoenzyme analysis at 8 loci demonstrated a very peculiar banding pattern clearly distinct from those of T. rangeli and T. cruzi. We conclude that this isolate is a new Trypanosoma species. The name T. caninum is suggested.

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) .…”

“…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) . It appears to be nonpathogenic to dogs, in which the infection triggers a mild humoral immune response (7) (9) .…”

Accuracy of quantitative polymerase chain reaction in samples of frozen and paraffin-embedded healthy skin for the diagnosis of canine visceral leishmaniasis

“…The skin has proved to be a good site for parasitological confirmation (Madeira et al, 2009), and it is an important indicator, considering that the transmission of infection occurs during the blood feeding of the insect vector. Furthermore, the material collected from the same place on the skin can be used to perform other diagnostic tests, as the three used in this study as reference standard (parasitological culture, HE, and IHC), with no need to increase the number of biological specimens collected from the animal (Xavier et al, 2006).…”

Trypanosoma rhipicephalis sp. nov. (Protozoa: Kinetoplastida) isolated from Rhipicephalus microplus (Acari: Ixodidae) ticks in Rio de Janeiro, Brazil

“…However, Latif et al (2004) showed that Hyalomma anatolicum could be infected with a trypanosome described as T. theileri when feeding as nymphs on an infected calf and that T. theileri survived the moult and multiplied in the resulting unfed adult ticks. Another species with phylogenetic proximity to T. rhipicephalis is T. caninum isolated in axenic culture from the skin of domestic dogs captured in different states of Brazil, including Rio de Janeiro (Madeira et al 2009;Barros et al 2015). Although the vector of T. caninum is still unknown, it is possible that it is transmitted by ticks, which might validate the phylogenetic proximity of T. rhipicephalis to T. caninum.…”