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Mesocestoides is a controversial tapeworm with significant lack of data related to systematics and life cycles. This helminth has an indirect life cycle with vertebrates, mostly carnivorous mammals, as definitive hosts. Theoretically, a coprophagous arthropod would be the first intermediate host, and herptiles, mammals, and birds, which prey on these insects, would represent the second intermediate hosts. However, recent evidence suggests that this life cycle would require only two hosts, with no arthropods involved. In the Neotropics, although there are records of mammals and reptiles as hosts for Mescocestoides, no molecular analyses have been performed. This work aimed to record an additional intermediate host and molecularly characterize the isolated larvae. Thus, 18 braided tree iguanas (Liolaemus platei) from Northern Chile were collected and dissected during 2019. One lizard was parasitized by three morphotypes of larvae compatible with tetrathyridia of Mescocestoides. To achieve its specific identity, a molecular approach was performed: 18S rRNA and 12S rRNA loci were amplified through cPCR. The inferred phylogenies confirmed the morphological diagnosis and stated that all morphotypes were conspecifics. The sequences for both loci formed a monophyletic clade with high nodal support, representing a sister taxon to Mescocestoides clade C. This study represents the first molecular characterization of any taxon of Mescocestoides from the Neotropics. Future surveys from potential definitive hosts would help to elucidate its life cycle. Furthermore, an integrative taxonomic approach is required in additional studies from the Neotropical region, which would contribute to a better understanding of the evolutionary relationships of this genus.

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Chagas disease is caused by Trypanosoma cruzi. Vector survival is an important variable affecting vectorial capacity to determine parasite transmission risk. The aims of this study are to evaluate vector survival under fasting/starvation conditions of wild-caught Mepraia spinolai after feeding and fasting, the pathogenicity of T. cruzi infection, the parasite burden and seasonal variation in parasite discrete typing units (DTU). The survivorship of M. spinolai nymphs after two continuous artificial feedings was evaluated, assessing their infection with microscopic observation of fecal samples and PCR. Later, insects were fasted/starved until death. We performed qPCR analyses of parasite load in the fecal samples and dead specimens. T. cruzi genotyping was performed using conventional PCR amplicons and hybridization tests. Infection rate was higher in M. spinolai nymphs in summer and spring than in fall. Parasite burden varied from 3 to 250,000 parasites/drop. Survival rate for starved nymph stage II was lower in insects collected in the spring compared to summer and fall. TcII was the most frequent DTU. Mainly metacyclic trypomastigotes were excreted. We conclude that M. spinolai infection rate in nymphs varies among seasons, suggesting higher transmission risk in warmer seasons. However, nymphs stage II collected in spring are more sensitive to starvation compared to other seasons. TcII in single or mixed infection does not seem relevant to determine vector pathogenicity. These results of vector survivorship after fasting/starvation are important to determine the competence of M. spinolai as a vector of T. cruzi, since they excrete metacyclic trypomastigotes and the parasitism with T. cruzi seems to be poorly pathogenic to the vector under a severe fasting/starvation condition.

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Several reports have described host species diversity and identity as the most important factors influencing disease risk, producing either dilution or amplification of the pathogen in a host community. Triatomine vectors, mammals and the protozoan Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) Chagas are involved in the wild cycle of Chagas disease, in which infection of mammals occurs by contamination of mucous membranes or skin abrasions with insect-infected faeces. We examined the extent to which host diversity and identity determine the infection level observed in vector populations (i.e. disease risk in humans). We recorded infection in triatomine colonies and on the coexisting host mammalian species in semi-arid Chile. Host diversity, and total and infected host species densities are used as predictor variables for disease risk. Disease risk did not correlate with host diversity changes. However, the densities of each infected rodent species were positively associated with disease risk. We suggest that the infected host density surrounding the vector colonies is a relevant variable for disease risk and should be considered to understand disease dynamics. It is crucial to pay attention on the spatial scale of analysis, considering the pattern of vector dispersal, when the relationship between host diversity and disease risk is studied.

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In this study, we performed a phylogenetic analysis of 35 species of the tribe Triatomini by means of available 16S ribosomal DNA and cytochrome b (Cyt b) gene sequence data, adding taxa of the spinolai complex, to clarify phylogenetic relationships of this complex and related triatomines. The phylogenetic analysis suggests a monophyletic clustering of the spinolai complex related to the South American species of triatomines.

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The aim of this work was to determine the impact of specific hosts on a population of Mepraia spinolai (Porter) (Hemiptera, Reduviidae), a sylvatic vector of Chagas' disease in Chile. We assessed whether a recently introduced host could be an important epidemiological factor in maintaining Chagas' disease in Chile. The study stressed the variations in survival, individual weight and fecundity in the insect population when the vector was raised with a species-specific food supply. The study compared the European rabbit Oryctolagus cuniculus, introduced in Chile

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One important paradigm in host-parasite evolutionary biology is the ability of parasites to manipulate the phenotype of their hosts to facilitate transmission. In this paper, I examine whether the protozoan parasite Trypanosoma cruzi modifies the developmental time, body size, and survival of its vector, the bloodsucking insect Mepraia spinolai (Hemiptera; Reduviidae). M. spinolai nymphs were experimentally infected when fed on T. cruzi-infected mice (infected group) or kept uninfected when fed on healthy mice (control group). T. cruzi-infected insects showed a retarded developmental time and reduced survival compared with uninfected individuals. The impact of the parasite on the vector was age-dependent as the last three insect molts were the most affected stages. The presence of T. cruzi decreased significantly the weight of male and female insects in the three last stages. When insect sex was taken into account, infected female bugs took longer than infected males to develop into the adult stage, which implies that the impact of T. cruzi is sex-dependent. Results from this study indicate that T. cruzi has a strong impact on life history traits of M. spinolai and provide strong evidence of age- and sex-dependent parasite-induced phenotype modification for insect vectors. The implications of this study along with previously reported feeding behavioral alterations in this insect vector-parasite system suggest that T. cruzi-induced modifications could translate into an enhanced transmission to definitive mammal hosts.

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This paper examines the association of ethnicity and birthweight, adjusted for other maternal and infant characteristics, among black women who gave birth in Massachusetts from 1987 through 1989. Data are drawn from the standard certificate of live birth, which includes questions on race and ethnicity/ancestry as well as birthweight; maternal sociodemographic and biological characteristics; access to prenatal care; and infant characteristics. The study cohort consists of 18,571 black infants and a comparison group of 206,358 non-Hispanic white infants. Infants whose mothers reported their race as black were further categorized into six ethnic groups: American, Haitian, West Indian, Cape Verdean, Hispanic, and other black. In addition to descriptive analyses, we used multiple linear regression to measure the association between ethnicity, other characteristics, and birthweight; and we used multiple logistic regression to measure the odds ratio of low birthweight (ranging from 500 g to 2499 g) for the six black ethnic groups, adjusted for other characteristics. Results indicate that Americans have lower mean birthweight and generally higher levels of risk than other black ethnic groups. Compared to the reference group of non-Hispanic whites, Americans (OR = 1.49), other blacks (OR = 1.41), and West Indians (OR = 1.37) have significantly elevated relative risks of low birthweight.

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