TRYPANOSOMA CRUZI IN FREE-RANGING MAMMALIAN POPULATIONS IN SOUTH TEXAS, USA

Arthropod Ectoparasites of Two Rodent Species Occurring in Varied Elevations on Tanzania’s Second Highest Mountain

Climate change causes organisms, including species that act as parasite reservoirs and vectors, to shift their distribution to higher altitudes, affecting wildlife infestation patterns. We studied how ectoparasite distributions varied with altitude using two rodent species, Montemys delectorum and Rhabdomys dilectus, at different elevations (1500–3500 m). The ectoparasites infesting the two rodent species were influenced by the host sex, species, and temperature. We expected host density to predict parasite infestation patterns, because hosts in higher densities should have more parasites due to increased contact between individuals. However, temperature, not host density, affected ectoparasite distribution. Since temperatures decrease with elevation, parasite prevalences and abundances were lower at higher elevations, highlighting that the cold conditions at higher elevations limit reproduction and development—this shows that higher elevation zones are ideal for conservation. The rodents and ectoparasite species described in this study have been reported as vectors of diseases of medical and veterinary importance, necessitating precautions. Moreover, Mount Meru is a refuge for a number of endemic and threatened species on the IUCN Red List. Thus, the parasitic infection can also be an additional risk to these critical species as well as biodiversity in general. Therefore, our study lays the groundwork for future wildlife disease surveillance and biodiversity conservation management actions. The study found a previously uncharacterized mite species in the Mesostigmata group that was previously known to be a parasite of honeybees. Further investigations may shed light into the role of this mite species on Mount Meru.

Prevalence of Trypanosoma cruzi, the Etiologic Agent of Chagas Disease, Infection in Texas Skunks (Mammalia: Mephitidae)

Background: Chagas disease is one of the world's most neglected tropical diseases, infecting over six million people across the Americas. The hemoparasite Trypanosoma cruzi is the etiological agent for the disease, circulating in domestic, peridomestic, and sylvatic transmission cycles that are maintained by triatomine vectors and a diversity of wild and synanthropic hosts. Public health and wildlife management interventions targeting the interruption of T. cruzi transmission rely on an understanding of the dynamics driving the ecology of this zoonotic pathogen. One wildlife host that purportedly plays a role in the transmission of Chagas disease within the southern United States is the striped skunk (Mephitis mephitis), although infection prevalence in this species is poorly understood. Materials and Methods: To this end, we conducted a PCR-based surveillance of T. cruzi in 235 wild skunks, representing 4 species, across 76 counties and 10 ecoregions in Texas, United States, along with an evaluation of risk factors associated with the infection. Results: We recovered an overall T. cruzi prevalence of 17.9% for all mephitid taxa aggregated, ranging between 6.7% for plains spotted skunks (Spilogale putorius interrupta) and 42.9% for western spotted skunks (Spilogale gracilis). We report the first cases of T. cruzi infection in plains spotted and American hog-nosed skunks (Conepatus leuconotus), of important note for conservation medicine since populations of both species are declining within Texas. Although not statistically significant, we also detected trends for juveniles to exhibit greater infection risk than adults and for differential sex biases in T. cruzi prevalence between taxa, which align with variations in species-specific seasonal activity patterns. No geographic or taxonomic risk factors were identified. Conclusion: Our study contributed key data for population viability analyses and epidemiologic models in addition to providing a baseline for future T. cruzi surveillance among skunks and other wildlife species.

Trace mineral supplies for populations of little and large herbivores

Copper (Cu), iron (Fe), and zinc (Zn) are essential trace minerals for the reproduction, growth, and immunity of mammalian herbivore populations. We examined the relationships between Cu, Fe, and Zn in soils, common plants, and hepatic stores of two wild herbivores to assess the effects of weather, sex, and population density on the transfer of trace minerals from soils to mammals during the growing season. Soils, grasses, woody browse, hispid cotton rats (Sigmodon hispidus), and white-tailed deer (Odocoileus virginianus) were sampled across 19 sites. Concentrations of Cu, Fe, and Zn in grasses and browse species were not correlated with concentrations of those minerals in soils sampled from the same areas. Leaves of woody browse were higher in Cu, lower in Fe, and similar in Zn when compared with grasses. Available concentrations of soils were positively related to liver Cu and Zn in hispid cotton rats, which was consistent with the short lives and high productivity of these small mammals that rely on grass seed heads. Interactions between soil concentrations and weather also affected liver Cu and Fe in deer, which reflected the greater complexity of trophic transfers in large, long-lived, browsing herbivores. Population density was correlated with liver concentrations of Cu, Fe, and Zn in hispid cotton rats, and concentrations of Cu and Fe in deer. Liver Cu was < 5 mg/kg wet weight in at least 5% of animals at two of eight sites for hispid cotton rats and < 3.8 mg/kg wet weight in at least 5% of animals at three of 12 sites for deer, which could indicate regional limitation of Cu for populations of mammalian herbivores. Our data indicate that supplies of trace minerals may contribute to density dependence of herbivore populations. Local population density may therefore influence the prevalence of deficiency states and disease outbreak that exacerbate population cycles in wild mammals.

Surveillance of Trypanosoma cruzi infection in Triatomine vectors, feral dogs and cats, and wild animals in and around El Paso county, Texas, and New Mexico

The causative agent of Chagas disease, Trypanosoma cruzi, is transmitted by triatomine vectors. The insect is endemic in the Americas, including the United States, where epidemiological studies are limited, particularly in the Southwestern region. Here, we have determined the prevalence of T. cruzi in triatomines, feral cats and dogs, and wild animals, the infecting parasite genotypes and the mammalian host bloodmeal sources of the triatomines at four different geographical sites in the U.S.-Mexico border, including El Paso County, Texas, and nearby cities in New Mexico. Using qualitative polymerase chain reaction to detect T. cruzi infections, we found 66.4% (n = 225) of triatomines, 45.3% (n = 95) of feral dogs, 39.2% (n = 24) of feral cats, and 71.4% (n = 7) of wild animals positive for T. cruzi. Over 95% of T. cruzi genotypes or discrete typing units (DTUs) identified were TcI and some TcIV. Furthermore, Triatoma rubida was the triatomine species most frequently (98.2%) collected in all samples analyzed. These findings suggest a high prevalence of T. cruzi infections among triatomines, and feral and wild animals in the studied sites. Therefore, our results underscore the urgent need for implementation of a systematic epidemiological surveillance program for T. cruzi infections in insect vectors, and feral and wild animals, and Chagas disease in the human population in the southwestern region of the United States.

Chagas disease is caused by the parasite Trypanosoma cruzi and one of the major transmission routes is the contaminated feces of blood-feeding triatomine insect vectors, popularly known as kissing bugs. In recent years, this disease has become an important public health concern to the United States and other nonendemic regions of the world. Despite many studies about the prevalence of T. cruzi in triatomines, and domestic, feral and wild animals in central and southern Texas, there have been no studies in west Texas and New Mexico. In this study, we report the presence of triatomines in residences in El Paso County, TX, and surrounding communities in New Mexico (cities of Anthony and Las Cruces), as well as T. cruzi infections in feral and wild animals. Using two molecular techniques to analyze the bloodmeal source in triatomines, we detected 12 different mammalian bloodmeal sources, including human and canine. Finally, parasite genotyping showed that most (95%) of the samples belonged to the genotype TcI, which is prevalent in North America. Our findings indicate that the El Paso County and surrounding communities (>950,000 people) are high risk areas for T. cruzi transmission to humans, feral cats and dogs, and wild animals. Thus, there is an urgent necessity for a public health epidemiological surveillance program for T. cruzi infections in kissing bugs, feral and wild animals, and in the human population in the U.S.-Mexico border region.

Gastrointestinal parasite infestation in the alpine mountain hare (Lepus timidus varronis): Are abiotic environmental factors such as elevation, temperature and precipitation affecting prevalence of parasite species?

Information concerning factors regulating Alpine mountain hare (Lepus timidus varronis) populations such as host-parasite interactions is missing as only a few parasitological surveys exist of this subspecies. Parasites are not only dependent on their host but also on suitable environmental conditions for infestation. Abiotic environmental factors have an important regulating role on parasites in mammals. It is estimated that the elevation range of parasites is likely to shift in response to alternate host movement and changes in climate. Here we assess the parasitic infestation in the Alpine mountain hare by analysing the parasites in faeces and comparing the parasite infestation at different elevation ranges and at varied weather conditions for two years in the Austrian Alps. Almost half of the faecal samples were free of parasites (46.2%, n = 52). Most frequent was the infection by Coccidia (46.2%), whereas stomach intestine strongylids, Trichuris spp, and Cestoda were only found in 9.6% of all faeces. Hence, only Coccidia may be prevalent enough to regulate Alpine mountain hare populations in the Austrian Alps. Elevation had a significant positive effect on the infection of animals by Trichuris spp, whereas temperature had a significant negative effect on the infection by any parasite traceable in faeces and, when looking at the parasite groups individually, on Coccidia.

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Almost half of the Alpine mountain hare faecal samples were free of parasites.

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Coccidia was more frequent in our hare faeces than in other examined populations.

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Stomach intestine strongylids and Cestoda were only found in 9.6% of our samples.

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Only Coccidia may be prevalent enough to regulate this hare population.

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Temperature had a significant negative effect on the incidence of any parasite in the faecal samples.

Serological and molecular inquiry of Chagas disease in an Afro-descendant settlement in Mato Grosso do Sul State, Brazil

Furnas do Dionísio is a Brazilian Afro-descendant settlement in the city of Jaraguari, 21.4 miles from Campo Grande, Mato Grosso do Sul, Brazil. Approximately 96 families live in this quilombola (Maroon) settlement, also known in Brazil as a remnant community of descendants of African slaves. Recent studies found 20% of households were infested by triatomines, 18% of insects captured in the community were infected by Trypanosoma cruzi, and 22.7% of dogs presented T. cruzi antibodies. The low prevalence of Chagas disease observed in humans in Mato Grosso do Sul State is attributed to its arrival via colonist migration and subsequent transplacental transmission. In order to gain a better understanding of the T. cruzi cycle in residents of the study community, serological and molecular tests were carried out to diagnose Chagas disease. In the present study, 175 residents between 2 and 80 years old were included. A total of 175 participants were interviewed and 170 provided blood samples, which were tested for T. cruzi antibodies with serological tests. Molecular diagnosis was performed in 167 participants by PCR (KDNA) and NPCR (satellite DNA) tests. One of the 170 samples tested positive for all serological tests performed. The overall frequency of Chagas disease in the community was low (0.6%). Interview responses revealed that 66.3% knew of triatomine insects and 65.7% reported having had no contact with them. Physical improvements to residences, together with vector surveillance and control by the State and municipal governments and local ecological conservation contribute to the low frequency of the Chagas disease in this quilombola community.