Detection and quantification of Leishmania braziliensis in ectoparasites from dogs

Quantitative Detection of Leishmania in Rhipicephalus microplus and Amblyomma sabanerae in the Peruvian Amazon Basin

Leishmaniasis is a disease of public importance with a complex transmission cycle. A quantitative PCR was developed by using the small subunit of the ribosomal RNA gene (SSU rRNA) as a DNA target, which is conserved in all Leishmania species. A TaqMan ^® probe was designed to have a high specificity. In all, 22 out of 23 (95.7%) ticks classified as R. microplus tested positive for Leishmania sp. The quantification was between 34.1 and 2197.1 parasites per tick in a range of 12 to 769 fg/uL. In addition, 9 out of 10 (90%) ticks classified as Amblyomma sabanerae tested positive for Leishmania sp. The quantification was between 448.6 and 5428.6 parasites per tick in a range of 157 to 1900 fg/µL. Leishmania sp. was identified in very high percentages in Rhipicephalus microplus and Amblyomma sabanerae from wild Pecari tajacu and Chelonoidis denticulata, in quantities of 34.1 and 5428.6 parasites per arthropod, and this could suggest that the ticks were parasitized by sucking blood from the animals from which they were collected. This is the first report about Leishmania parasites found in wild Rhipicephalus microplus and Amblyomma sabanerae, adding new information about the distribution and epidemiology of the parasite in sylvatic areas.

RNA Viruses in Blechomonas (Trypanosomatidae) and Evolution of Leishmaniavirus

In this work, we analyzed viral prevalence in trypanosomatid parasites (Blechomonas spp.) infecting Siphonaptera and discovered nine species of viruses from three different groups (leishbunyaviruses, narnaviruses, and leishmaniaviruses). Most of the flagellate isolates bore two or three viral types (mixed infections). Although no new viral groups were documented in Blechomonas spp., our findings are important for the comprehension of viral evolution. The discovery of bunyaviruses in blechomonads was anticipated, since these viruses have envelopes facilitating their interspecific transmission and have already been found in various trypanosomatids and metatranscriptomes with trypanosomatid signatures. In this work, we also provided evidence that even representatives of the family Narnaviridae are capable of host switching and evidently have accomplished switches multiple times in the course of their evolution. The most unexpected finding was the presence of leishmaniaviruses, a group previously solely confined to the human pathogens Leishmania spp. From phylogenetic inferences and analyses of the life cycles of Leishmania and Blechomonas, we concluded that a common ancestor of leishmaniaviruses most likely infected Leishmania first and was acquired by Blechomonas by horizontal transfer. Our findings demonstrate that evolution of leishmaniaviruses is more complex than previously thought and includes occasional host switching.IMPORTANCE Flagellates belonging to the genus Leishmania are important human parasites. Some strains of different Leishmania species harbor viruses (leishmaniaviruses), which facilitate metastatic spread of the parasites, thus aggravating the disease. Up until now, these viruses were known to be hosted only by Leishmania Here, we analyzed viral distribution in Blechomonas, a related group of flagellates parasitizing fleas, and revealed that they also bear leishmaniaviruses. Our findings shed light on the entangled evolution of these viruses. In addition, we documented that Blechomonas can be also infected by leishbunyaviruses and narnaviruses, viral groups known from other insects' flagellates.

Natural transovarial and transstadial transmission of Leishmania infantum by naïve Rhipicephalus sanguineus ticks blood feeding on an endemically infected dog in Shiraz, south of Iran

BACKGROUND

The visceral leishmaniasis parasite, Leishmania infantum, is naturally transmitted through the bites of phlebotomine sand flies. Alternative routes of transmission are questioned. The main aim is to verify the passage of L. infantum kDNA in ticks, Rhipicephalus sanguineus, blood feeding on a parasitemic dog in Shiraz, south of Iran.

METHODS

A total of 180 Leishmania-free ticks collected from fields and bred on lab rodents, were divided into eight groups and allowed to feed on a dog (Canis familiaris) for fixed periods of time. These and all third generation stages of ticks were checked for L. infantum kDNA using conventional PCR protocol.

RESULTS

The infection rate was significantly higher in female than male ticks (p=0.043). The rates were higher among nymphs (25/60; 42%) than adult ticks (37/120; 30.8%). The kDNA of L. infantum was not detected in ticks 24 h post-feeding. It was, however, positive among the second to fourth groups of nymphs (4/10; 40%, 10/20; 50% and 11/20; 55%) and adult (12/30; 40%, 14/30; 46.6% and 11/30; 36.6%) ticks. Eggs and unfed larvae recovered from the third and fourth adult groups (2 weeks, 4 weeks) were 100% PCR-positive. The data revealed the passage of L. infantum kDNA in nymphs and adults of brown dog tick following fixed time intervals post blood feeding on an infected dog.

CONCLUSIONS

The natural transovarial and transstadial passage of kDNA through ticks was shown by PCR.

Detection of Leishmania (V) guyanensis in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) collected from Pecari tajacu

INTRODUCTION

Previous studies identified the presence of Leishmania infantum in Rhipicephalus sanguineus and indicated the possibility that it could transmit leishmaniasis to a variety of hosts.

OBJECTIVE

To identify parasites of Leishmania (Viannia) spp. in ticks collected from wild animals in an endemic area for leishmaniasis.

MATERIALS AND METHODS

We performed 81 individual DNA extractions from ticks collected from three Tapirus terrestris and three Pecari tajacu in Madre de Dios, Perú. Ticks were taxonomically identified and they were subsequently prepared to identify Leishmania (Viannia) spp. kDNA by PCR and the species of Leishmania by HRM-PCR.

RESULTS

Leishmania (Viannia) kDNA was detected in three wild ticks of the species R. microplus, collected from a collard peccary (P. tajacu) hunted in the forests of Madre de Dios. The HRM-PCR showed that one of the positive samples had a kDNA curve compatible with L. (V) guyanensis.

CONCLUSION

The results showed the presence of L. (V) guyanensis DNA in R. microplus possibly acquired after biting a collarde peccary. Therefore, it is important to design future studies to clarify R. microplus involvement in the transmission of leishmaniasis.