Bats, Trypanosomes, and Triatomines in Ecuador: New Insights into the Diversity, Transmission, and Origins of Trypanosoma cruzi and Chagas Disease

The generalist parasite Trypanosoma cruzi has two phylogenetic lineages associated almost exclusively with bats—Trypanosoma cruzi Tcbat and the subspecies T. c. marinkellei. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasites at species and genotype levels through phylogenetic approaches based on 18S ribosomal RNA (18S rRNA) and cytochrome b (cytb) genes and conducted a comparison of nucleotide diversity of the cytb gene. We document for the first time T. cruzi Tcbat and T. c. marinkellei in Ecuador, expanding their distribution in South America to the western side of the Andes. In addition, we found the triatomines Cavernicola pilosa and Triatoma dispar sharing shelters with bats. The comparisons of nucleotide diversity revealed a higher diversity for T. c. marinkellei than any of the T. c. cruzi genotypes associated with Chagas disease. Findings from this study increased both the number of host species and known geographical ranges of both parasites and suggest potential vectors for these two trypanosomes associated with bats in rural areas of southern Ecuador. The higher nucleotide diversity of T. c. marinkellei supports a long evolutionary relationship between T. cruzi and bats, implying that bats are the original hosts of this important parasite

A new species of Andean microteiid lizard (Gymnophthalmidae: Cercosaurinae: Pholidobolus) from Peru, with comments on P. vertebralis.

Based on morphological and molecular evidence, herein is reported the discovery of a new species of Pholidobolus from the Andes of northwestern Peru. The new species is known from the montane forests of Cajamarca and Lambayeque departments, at elevations of 1,800– 2,300 m. It differs from other species of Pholidobolus in lacking prefrontal scales and having both strongly keeled dorsal scales and a diagonal white bar in the rictal region. Additionally, it is shown that records of P. vertebralis from Peru are based on misidentified specimens. The southernmost distribution records of P. vertebralis are from northwestern Ecuador. Also provided is an updated identification key for species of Pholidobolus

A new species of Andean microteiid lizard (Gymnophthalmidae: Cercosaurinae: Pholidobolus) from Peru, with comments on P. vertebralis.

Based on morphological and molecular evidence, herein is reported the discovery of a new species of Pholidobolus from the Andes of northwestern Peru. The new species is known from the montane forests of Cajamarca and Lambayeque departments, at elevations of 1,800– 2,300 m. It differs from other species of Pholidobolus in lacking prefrontal scales and having both strongly keeled dorsal scales and a diagonal white bar in the rictal region. Additionally, it is shown that records of P. vertebralis from Peru are based on misidentified specimens. The southernmost distribution records of P. vertebralis are from northwestern Ecuador. Also provided is an updated identification key for species of Pholidobolus

Influence of ecological factors on the presence of a triatomine species associated with the arboreal habitat of a host of Trypanosoma cruzi

Abstract Background The white-naped squirrel, Simosciurus nebouxii (previously known as Sciurus stramineus), has recently been identified as an important natural host for Trypanosoma cruzi in Ecuador. The nests of this species have been reported as having high infestation rates with the triatomine vector Rhodnius ecuadoriensis. The present study aims to determine the levels of nest infestation with R. ecuadoriensis, the ecological variables that are influencing the nest site selection, and the relationship between R. ecuadoriensis infestation and trypanosome infection. Results The study was carried out in transects in forest patches near two rural communities in southern Ecuador. We recorded ecological information of the trees that harbored squirrel nests and the trees within a 10 m radius. Manual examinations of each nest determined infestation with triatomines. We recorded 498 trees (n = 52 with nests and n = 446 without nests). Rhodnius ecuadoriensis was present in 59.5% of the nests and 60% presented infestation with nymphs (colonization). Moreover, we detected T. cruzi in 46% of the triatomines analyzed. Conclusions We observed that tree height influences nest site selection, which is consistent with previous observations of squirrel species. Factors such as the diameter at breast height and the interaction between tree height and tree species were not sufficient to explain squirrel nest presence or absence. However, the nest occupancy and tree richness around the nest were significant predictors of the abundance of triatomines. Nevertheless, the variables of colonization and infection were not significant, and the data observed could be expected because of chance alone (under the null hypothesis). This study ratifies the hypothesis that the ecological features of the forest patches around rural communities in southern Ecuador favor the presence of nesting areas for S. nebouxii and an increase of the chances of having triatomines that maintain T. cruzi populations circulating in areas near human dwellings. Additionally, these results highlight the importance of including ecological studies to understand the dynamics of T. cruzi transmission due to the existence of similar ecological and land use features along the distribution of the dry forest of southern Ecuador and northern Peru, which implies similar challenges for Chagas disease control

Bats, Trypanosomes, and Triatomines in Ecuador: New Insights into the Diversity, Transmission, and Origins of <i>Trypanosoma cruzi</i> and Chagas Disease

<div><p>The generalist parasite <i>Trypanosoma cruzi</i> has two phylogenetic lineages associated almost exclusively with bats—<i>Trypanosoma cruzi</i> Tcbat and the subspecies <i>T</i>. <i>c</i>. <i>marinkellei</i>. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasites at species and genotype levels through phylogenetic approaches based on 18S ribosomal RNA (18S rRNA) and cytochrome b (cytb) genes and conducted a comparison of nucleotide diversity of the cytb gene. We document for the first time <i>T</i>. <i>cruzi</i> Tcbat and <i>T</i>. <i>c</i>. <i>marinkellei</i> in Ecuador, expanding their distribution in South America to the western side of the Andes. In addition, we found the triatomines <i>Cavernicola pilosa</i> and <i>Triatoma dispar</i> sharing shelters with bats. The comparisons of nucleotide diversity revealed a higher diversity for <i>T</i>. <i>c</i>. <i>marinkellei</i> than any of the <i>T</i>. <i>c</i>. <i>cruzi</i> genotypes associated with Chagas disease. Findings from this study increased both the number of host species and known geographical ranges of both parasites and suggest potential vectors for these two trypanosomes associated with bats in rural areas of southern Ecuador. The higher nucleotide diversity of <i>T</i>. <i>c</i>. <i>marinkellei</i> supports a long evolutionary relationship between <i>T</i>. <i>cruzi</i> and bats, implying that bats are the original hosts of this important parasite.</p></div

Constructions in Ecuador where <i>Cavernicola pilosa</i> and <i>Triatoma dispar</i> were found in association with bats.

<p><b>A.</b> House with cinderblock walls at Rancho Alegre, Zamora Chinchipe where <i>C</i>. <i>pilosa</i> (inset) was inhabiting a roost of <i>Myotis</i> sp. <b>B.</b> Adobe barn in Chinguilamaca, Loja where <i>T</i>. <i>dispar</i> (inset) was found associated with <i>Molossus molossus</i> and <i>Myotis</i> sp. Arrows indicate the entrances to the bat roosts where the insects were collected.</p

Mitochondrial diversity of <i>Trypanosoma cruzi</i>.

<p>Nucleotide diversity (π) of mitochondrial lineages of <i>Trypanosoma cruzi</i> calculated for the haplotypes of the cytb gene. The subspecies <i>T</i>. <i>c</i>. <i>marinkellei</i> shows larger nucleotide diversity than the other examined lineages. Whiskers in each bar indicate the standard error.</p

Results of PCR screenings for <i>Trypanosoma cruzi</i> and <i>Trypanosoma rangeli</i>.

<p>Results of PCR screenings for <i>Trypanosoma cruzi</i> and <i>Trypanosoma rangeli</i>.</p

Network genealogy using partial 18S rRNA gene sequences

<p>from eight new trypanosomes characterised in this study (in bold) plus 70 other sequences from all DTUs (TcI-TcVI and Tcbat) of <i>T</i>. <i>cruzi</i> and 22 sequences from <i>T</i>. <i>c</i>. <i>marinkellei</i>. Network constructed with the NeighborNet algorithm excluding all conserved sites and with uncorrected p-distance. Numbers in nodes correspond to bootstrap support values using the same parameter optimized for network inferences.</p