Trypanosoma cruzi, the etiologic agent of Chagas disease, is transmitted via the dejections of triatomine insects such as Triatoma infestans. Parasite development inside the vector depends on temperature, which determines the extrinsic incubation period (EIP) and modulates the parasite load. As global warming is expected to increase mean temperatures and thermal variability, these shifts may influence vector competence. Triatoma infestans individuals were experimentally infected with T. cruzi Dm28c strain and then exposed to four thermal regimes: two constant (18 °C and 27 °C) and two fluctuating (18 ± 5 °C and 27 ± 5 °C). Parasite load in the dejection samples was quantified by quantitative PCR over 42 days and the time to the first positive dejection determined to estimate the EIP. Higher temperatures significantly shortened the EIP, with mean values of 18.6 days at 18 ± 0 °C, 17.3 days at 18 ± 5 °C, 9.6 days at 27 ± 0 °C and 11.0 days at 27 ± 5 °C. Temperature variability did not affect the EIP but it did increase parasite load under cold conditions. Parasite load showed a bell-shaped curve, peaking earlier and at higher levels at warmer temperatures. A larger volume of ingested blood also reduced the EIP, especially under cold treatments. Rising temperatures accelerate T. cruzi development within T. infestans, potentially enhancing vector competence under climate change scenarios. Although temperature variability did not affect the EIP, it increased parasite load, particularly under cold conditions, which is a relevant result considering that low temperatures have historically limited the vector and Chagas disease transmission. Temperature variability—not only mean warming—can modulate parasite development. Our results therefore provide novel and relevant insights into how climate change may alter vector-borne disease dynamics.

Although pathogenic Leptospira DNA has been detected in water and soil from different climatic regions, information from Mediterranean-climate agricultural systems remains limited. This study characterized the environmental detection of pathogenic Leptospira DNA in water and soil samples from irrigated agroecosystems of central Chile, evaluating spatial and seasonal variation and associations with selected physicochemical variables. A total of 605 samples were collected from eight agricultural sites during spring 2019, summer 2020, and winter 2021. Samples were analyzed by real-time PCR targeting lipL32. Overall, 29.1% of samples were PCR-positive, and pathogenic Leptospira DNA was detected in all sites and seasons. Soil samples showed higher positivity than water samples (34.5% vs. 21.4%), and positivity was higher in summer (41.7%) than in spring (22.7%) or winter (19.3%). Water temperature and turbidity were the only physicochemical variables that differed between positive and negative samples, whereas the binomial generalized linear mixed model (GLMM) showed that season and sample type were associated with PCR positivity after accounting for site-level clustering. These results show that pathogenic Leptospira DNA can be widely detected in irrigated agricultural systems from a Mediterranean-climate region, suggesting that soil, seasonality, irrigation practices, and other site-level characteristics should be considered in future studies on the environmental ecology of pathogenic Leptospira.

Urban domestic dog populations can provide important clues about the eco-epidemiological characteristics of Trypanosoma cruzi, the causative agent of Chagas disease (ChD). Given the limited data on ChD from the Metropolitan Area of Mendoza, Argentina, a seroprevalence survey of 327 dogs across an urban–rural gradient was conducted between April 2018 and May 2019. Seropositive cases were analyzed considering host, social, and environmental factors, subtypes (DTUs), and bloodstream parasite load. Seroprevalence of infection by T. cruzi total antigens (ELISA-H) was similar in urban (18

The transmission and incidence of vector-borne diseases rely on vector distribution and life history traits such as survival, fecundity, and feeding. Since arthropod disease vectors are ectotherms, these vital rates are strongly influenced by temperature. Chagas disease is a neglected tropical disease caused by the protozoan parasite, Trypanosoma cruzi. This parasite is transmitted when the feces of the infected triatomine enter the bloodstream of the host. One of the most important vector-species of this disease in the Southern Cone region of South America is Triatoma infestans. In this study, we evaluated the role of constant and variable environmental temperature on the feeding behavior of T. infestans. Fifth-instar nymphs were acclimatized to 4 thermal treatments comprising 2 temperatures (27 degrees C and 18 degrees C) with and without diurnal thermal variability (27 +/- 5 degrees C and 18 +/- 5 degrees C). Individuals were fed weekly for 7 wk to quantify their feeding. Our results showed lower feeding frequency in nymphs acclimatized to cold temperature compared to those from warmer temperature treatments. However, treatments with thermal variability presented a nonlinear effect on feeding, with an increased feeding rate in the cold, variable treatment and a decreased feeding rate in the warm, variable treatment. Individuals maintained under cold treatments, the variable temperature exhibited a higher feeding rate and the lowest amount of ingested blood among all treatments. Thus, natural diurnal temperature variation cannot be ignored if we are to make more accurate T. cruzi transmission risk predictions now and in the future.

Trypanosoma cruzi is a protozoan parasite transmitted by triatomine insect vectors, which expel their infectious dejections when they feed, causing Chagas disease in humans. The transmission and incidence of this vector-borne disease depend on the vital traits of its vectors, including Triatoma infestans , the main vector in Southern South America. Being an ectothermic species, its metabolism and its vital traits respond to temperature fluctuations. Here, we evaluated if changes in the average and variability of temperature expected with climate change modify: (i) the extrinsic incubation period (EIP) of T. cruzi within the vector T. infestans , (ii) its parasitic load, and (iii) the probability that its dejections were T. cruzi -positive. We acclimated triatomines infected with Dm28c T. cruzi strain to two constant and two variable temperature treatments and measured T. cruzi in their dejections by qPCR over a 42-day period. We observed that individuals in warm-temperature treatments showed lower EIP and higher parasitic load than cold-temperature treatments. Also, temperature variability can increase the parasitic load peak in cold-temperature treatments. Consequently, in a climate change scenario, there might be an increase in the vector capacity of T. infestans and probably a change in the risk of vectorial transmission of T. cruzi .### Competing Interest StatementThe authors have declared no competing interest.

The transmission cycles of Trypanosoma cruzi, the causative agent of Chagas disease, include a wide variety of mammals and hematophagous triatomine insects. Infection with this blood parasite has been confirmed in many armadillo species; however, information on infection in Zaedyus pichiy, a small armadillo that inhabits areas endemic to Chagas disease, is scarce. Our objective was to determine the infection frequency and parasite load of T. cruzi in 49 wild Z. pichiy confiscated dead from poachers in Mendoza, Argentina, 2010-2017. We detected T. cruzi DNA in 32 of 49 armadillos (65%) using real-time PCR, confirming infection with T. cruzi in a high proportion of confiscated pichis. No differences were found related to sex, age, or ecoregion origin of the assessed pichis. Parasite loads ranged between <0.1 and 8.88 parasite equivalents/microgram cardiac tissue. Additional studies on the infection status of Z. pichiy are needed to determine their role in the maintenance of the sylvatic transmission cycle and the potential zoonotic risk from hunted pichis.

Background The COVID-19 pandemic, caused by SARS-CoV-2 infection, has become the most devastating zoonotic event in recent times, with negative impacts on both human and animal welfare as well as on the global economy. Although SARS-CoV-2 is considered a human virus, it likely emerged from animals, and it can infect both domestic and wild animals. This constitutes a risk for human and animal health including wildlife with evidence of SARS-CoV-2 horizontal transmission back and forth between humans and wild animals. Aim Molecular surveillance in different wildlife rehabilitation centers and wildlife associated institutions in Chile, which are critical points of animal-human interaction and wildlife conservation, especially since the aim of wildlife rehabilitation centers is to reintroduce animals to their original habitat. Materials and Methods The survey was conducted in six WRCs and three wildlife associated institutions. A total of 185 samples were obtained from 83 individuals belonging to 15 different species, including vulnerable and endangered species. Each specimen was sampled with two different swabs: one oropharyngeal or nasopharyngeal according to the nostril diameter, and/or a second rectal sample. RNA was extracted from the samples and two different molecular assays were performed: first, a conventional RT-PCR with pan-coronavirus primers and a second SARS-CoV-2 qPCR targeting the N and S genes. Results All 185 samples were negative for SARS-CoV-2.

Cropland ecosystem functioning may be affected by human perturbations transmitted from adjacent ecosystems, such as freshwater systems. However, our limited knowledge of the ecological interactions within cropland–freshwater networks hinders projecting the consequences of anthropogenic pressures. We reviewed the information from freshwater and cropland communities in the Mediterranean zone of Chile and constructed an ecological metanetwork for characterizing the structure and projecting responses of this system facing environmental pressures. We performed a semi-qualitative analysis to identify the nodes that strongly influence other network components and (or) could significantly affect the transmission of effects within the system. Our analyses show that omnivore fish, amphibians, annual pollinated crops, and deciduous orchards are the most important groups. Although we expected that amphibious predators were the most important groups in transmitting perturbations between ecosystems, we also found groups of plants and pollinators performing this function. We stress that the fate of crop systems facing environmental disturbances should be assessed in a broader context rather than as an isolated system.

Armadillos are considered important reservoir hosts for Trypanosoma cruzi, the causative agent of Chagas disease. The first report of T. cruzi infection in pichis (Zaedyus pichiy), a small armadillo species endemic to central Argentina and Chile, dates back to 1935. However, more recent reports on T. cruzi in this species are scarce. The objective of this study was to assess T. cruzi infection and parasite load in Z. pichiy from Mendoza Province, an area endemic to human Chagas disease. Blood samples were obtained in 2014–2016 from pichis from Lavalle (low Monte), Malargüe (Patagonian steppe), and San Carlos (ecotone) departments, Mendoza Province, Argentina. The detection and quantification of T. cruzi was performed through qPCR amplification using satellite primers. Of the 265 analyzed samples, 201 (76

We investigated the co-occurrence of the nine of the most relevant canine vector-borne pathogens (CVBP) using conventional and real-time PCR and evaluated risk factors and potential non-apparent haematological alterations associated with co-infection in 111 rural, owned, free-ranging dogs in the Metropolitan Region of Chile.At least one pathogen was detected in 75% of the dogs. DNA of Anaplasma platys (Ap; 36%), Candidatus Mycoplasma haematoparvum (CMhp; 31%), Mycoplasma haemocanis (Mhc; 28%), Trypanosoma cruzi (17%), Leishmania spp. (4.5%), and Acanthocheilonema reconditum (1%) was detected. All dogs were negative for Ehrlichia spp., Rickettsia spp., Bartonella spp., Piroplasmida, and Hepatozoon spp. Thirty-eight dogs (34%) were coinfected. CMhp was involved in 71%, Mhc in 58%, and Ap in 50% of the co-infections. The most common co-infection pattern was CMhp-Mhc (37% of the cases). The prevalence of Ap was higher in juvenile than in adult dogs, whereas the opposite was found for CMhp and Mhc. Adult dogs were four times more likely of being co-infected than juveniles. Co-infected animals showed higher white blood cell count, segmented neutrophil count, and GGT levels than non-co-infected dogs. Clinically healthy but infected dogs may act as reservoirs of CVBP, and their free-ranging behavior would facilitate the spread of these pathogens to other dogs as well as human beings or wild carnivores.

AbstractTrypanosoma cruziis a protozoan parasite transmitted by triatomine insect vectors, which expel their infectious dejections when they feed, causing Chagas disease in humans. The transmission and incidence of this vector-borne disease depend on the vital traits of its vectors, includingTriatoma infestans, the main vector in Southern South America. Being an ectothermic species, its metabolism and its vital traits respond to temperature fluctuations. Here, we evaluated if changes in the average and variability of temperature expected with climate change modify: (i) the extrinsic incubation period (EIP) ofT. cruziwithin the vectorT. infestans, (ii) its parasitic load, and (iii) the probability that its dejections wereT. cruzi-positive. We acclimated triatomines infected with Dm28cT. cruzistrain to two constant and two variable temperature treatments and measuredT. cruziin their dejections by qPCR over a 42-day period. We observed that individuals in warm-temperature treatments showed lower EIP and higher parasitic load than cold-temperature treatments. Also, temperature variability can increase the parasitic load peak in cold-temperature treatments. Consequently, in a climate change scenario, there might be an increase in the vector capacity ofT. infestansand probably a change in the risk of vectorial transmission ofT. cruzi.

BACKGROUND:Mepraia spinolai, a wild vector of Trypanosoma cruzi in Chile, is an abundant triatomine species that is frequently infected by the parasite that causes Chagas disease. The aim of this study was to determine if the parasitic load of T. cruzi in M. spinolai is related to its blood meal source and the infecting DTUs of T. cruzi. METHODS:The vector was captured in rural areas. In the laboratory, DNA was extracted from its abdomen and T. cruzi was quantified using qPCR. Real time PCR assays for four T. cruzi DTUs were performed. Blood meal sources were identified by real-time PCR amplification of vertebrate cytochrome b gene sequences coupled with high resolution melting (HRM). RESULTS:Trypanosoma cruzi was detected in 735 M. spinolai; in 484 we identified one blood meal source, corresponding to human, sylvatic, and domestic species. From these, in 224 we were able to discriminate the infecting DTU. When comparing the parasitic loads between the unique blood meal sources, no significant differences were found, but infections with more than one DTU showed higher parasitic loads than single infections. DTU TcI was detected in a high proportion of the samples. CONCLUSIONS:Higher parasitic loads are related to a greater number of T. cruzi DTUs infecting M. spinolai, and this triatomine seems to have a wide span of vertebrate species in its diet.

Trypanosoma cruzi is the causal agent of Chagas disease, a parasitic zoonosis transmitted mainly through the feces of triatomine insects. Triatoma infestans is the main triatomine vector of this disease in South America. Previous research has shown that T. cruzi infection modifies the behavior of triatomines. We evaluated, for the first time, the effect of parasite load on feeding and defecation behavior, which we quantified by using real-time PCR. The detection time of the host was shorter in infected individuals, and the number of bites increased, while the dejection time was reduced when compared with the non-infected group. A significant correlation between the parasite load and the behavioral changes registered in the infected triatomines was found. These results would indicate that the intensity of T. cruzi infection modulates the feeding and defecation behavior of T. infestans, increasing the vector competence of this triatomine vector.

American trypanosomiasis is a disease caused by the flagellate protozoan Trypanosoma cruzi, which is transmitted mainly in endemic areas by blood-sucking triatomine vectors. Triatoma infestans is the most important vector in the southern cone of South America, exhibiting a nocturnal host-seeking behavior. It has been previously documented that the parasite produces changes in some triatomine species, but this is the first time that the behavior of a vector has been evaluated in relation to its parasite load. After comparing the movement events and distance traveled of infected and non-infected T. infestans, we evaluated the change produced by different T. cruzi parasite loads on its circadian locomotor activity. We observed differences between infected and non-infected triatomines, and a significant relation between the parasite load and the increase in locomotor activity of T. infestans, which was accentuated during the photophase. This could have direct implications on the transmission of T. cruzi, as the increased movement and distance traveled could enhance the contact of the vector with the host, while increasing the predation risk for the vector, which could both constitute a risk for vectorial and oral transmission to mammals.

Human perceptions vary between rural and urban environments, determining the degree to which people are able to coexist with biodiversity. It is important to identify the sociodemographic factors that determine these local perceptions to adjust amphibian conservation strategies in recognition of the particular conditions of different human communities. In this research, the effect of the urban or rural location where people live and sociodemographic variables in the knowledge and perceptions about amphibians was determined. The data were collected through individual semi-structured surveys of 401 participants. We measured seven response variables through the Likert scale, which ranges from 1 (totally disagree) to 5 (totally agree). For each response variable, a multivariate analysis of variance was performed. Ninety-two percent of people correctly recognized frogs and toads as amphibians, but there was confusion in classifying caecilians and salamanders within this group or including reptiles within amphibians. This confusion was more evident for women from urban locality. Positive perceptions of amphibians varied between urban and rural locality for young adults, people with a high school education level, and people without formal education. Negative beliefs varied between urban and rural locations for women, adolescents, young adults, and professionals. Half of the people accepted information on the conservation of amphibians. Positive perceptions of people about amphibians should be used as a flag to strengthen environmental educational strategies, mainly in urban locations. The results suggest that amphibian conservation plans that aim to inform and educate the public should be focused differently for age groups, genders, and educational level for people in urban and rural locations.

Mepraia spinolai, (Porter) 1934, is a diurnal triatomine endemic to Chile and a wild vector of the protozoan Trypanosoma cruzi, (Chagas) 1909, which causes Chagas disease. Behavioral changes in M. spinolai induced by this parasite have been reported previously, which include detection of a potential host, defecation latency, and some life history traits. In this study we assessed changes in locomotor and daily activity due to infection with T. cruzi. No difference was detected in distance traveled between infected and uninfected individuals. However, the groups differed in their daily activity patterns; infected individuals showed significant reduction of movements during the light phase and concentrated their activity in the dark phase. Uninfected individuals showed no differences in locomotor activity between the phases. The results suggest that T. cruzi induces a displacement in the activity of M. spinolai toward the dark phase of the circadian cycle, which may improve its vector competence.

Vector-borne diseases (VBD) are particularly susceptible to climate change because most of the diseases' vectors are ectotherms, which themselves are susceptible to thermal changes. The Chagas disease is one neglected tropical disease caused by the protozoan parasite, Trypanosoma cruzi. One of the main vectors of the Chagas disease in South America is Triatoma infestans, a species traditionally considered to be restricted to domestic or peridomestic habitats, but sylvatic foci have also been described along its distribution. The infestation of wild individuals, together with the projections of environmental changes due to global warming, urge the need to understand the relationship between temperature and the vector's performance. Here, we evaluated the impact of temperature variability on the thermal response of T. infestans. We acclimated individuals to six thermal treatments for five weeks to then estimate their thermal performance curves (TPCs) by measuring the walking speed of the individuals. We found that the TPCs varied with thermal acclimation and body mass. Individuals acclimated to a low and variable ambient temperature (18°C ± 5°C) exhibited lower performances than those individuals acclimated to an optimal temperature (27°C ± 0°C); while those individuals acclimated to a low but constant temperature (18°C ± 0°C) did not differ in their maximal performance from those at an optimal temperature. Additionally, thermal variability (i.e., ± 5°C) at a high temperature (30°C) increased performance. These results evidenced the plastic response of T. infestans to thermal acclimation. This plastic response and the non-linear effect of thermal variability on the performance of T. infestans posit challenges when predicting changes in the vector's distribution range under climate change.

Chagas disease is caused by Trypanosoma cruzi and transmitted by the triatomine Mepraia spinolai in the southwest of South America. Here, we examined the T. cruzi-infection dynamics of field-caught M. spinolai after laboratory feeding, with a follow-up procedure on bug populations collected in winter and spring of 2017 and 2018. Bugs were analyzed twice to evaluate T. cruzi-infection by PCR assays of urine/fecal samples, the first evaluation right after collection and the second 40 days after the first feeding. We detected bugs with: the first sample positive and second negative (+/-), the first sample negative and second positive (-/+), and with both samples positive or negative (+/+; -/-). Bugs that resulted positive on both occasions were the most frequent, with the exception of those collected in winter 2018. Infection rate in spring was higher than winter only in 2018. Early and late stage nymphs presented similar T. cruzi-infection rates except for winter 2017; therefore, all nymphs may contribute to T. cruzi-transmission to humans. Assessment of infection using two samples represents a realistic way to determine the infection a triatomine can harbor. The underlying mechanism may be that some bugs do not excrete parasites unless they are fed and maintained for some time under environmentally controlled conditions before releasing T. cruzi, which persists in the vector hindgut. We suggest that T. cruzi-infection dynamics regarding the three types of positive-PCR results detected by follow-up represent: residual T. cruzi in the rectal lumen (+/-), colonization of parasites attached to the rectal wall (-/+), and presence of both kinds of flagellates in the hindgut of triatomines (+/+). We suggest residual T. cruzi-infections are released after feeding, and result 60-90 days after infection persisting in the rectal lumen after a fasting event, a phenomenon that might vary between contrasting seasons and years.

Background: Canine vector-borne pathogens (CVBP) comprise a relevant and globally distributed group of disease agents. The aim of this study is to determine de co-occurrence of the most relevant CVBP of veterinary and zoonotic interest, in free-ranging, owned, rural dogs of central Chile, and to evaluate risk factors and potential non-apparent hematological alterations associated to pathogen co-infection by two or more agents.Methods: Nine groups of canine vector-borne pathogens (CVBP) were molecularly investigated in 111 free-ranging, owned rural dogs in the Metropolitan Region of Chile. Results: At least one pathogen was detected in 75% of the dogs. The most prevalent agent was Anaplasma platys (36%), followed by Candidatus Mycoplasma haematoparvum (CMhp; 31%), Mycoplasma haemocanis (Mhc; 28%), Trypanosoma cruzi (17%), Leishmania spp. (4.5%) and Acanthocheilonema reconditum (1%). DNA of Ehrlichia spp., Rickettsia spp., Bartonella spp., Piroplasmida and Hepatozoon spp. was not detected. Thirty-eight dogs (34%) were coinfected, either by two (n=20), three (n=7), or four agents (n=1). The most common co-infection pattern was CMhp – Mhc (n=14). CMhp was involved in 71%, Mhc in 58%, and A. platys in 50% of the co-infections. Prevalence of A. platys was higher in juvenile than in adult dogs, whereas the opposite was found for CMhp and Mhc. Adult dogs had five times more probabilities of being coinfected than young animals. Dogs positive for A. platys were infested by a larger number of Rhipicephalus sanguineus sensu lato ticks than uninfected individuals. At clinical evaluation, most of the animals were considered healthy, with only eight dogs (7%) presenting pale mucous membranes. Co-infected animals showed higher white blood cell count, segmented neutrophil count and GGT levels than non-co-infected dogs. Conclusions: Widespread occurrence of and co-infection by CVBP was found in rural free-ranging dogs of central Chile. This study represents the first report of Leishmania spp. in Chile. Clinically healthy but infected dogs as those studied here may act as reservoirs of CVBP, potentially contributing to the spread of these pathogens to other tick-exposed dogs as well as human beings or wild carnivores.

We present a review on the natural infection by trypanosomatids of nonhuman vertebrates in Chile, aiming to synthesize and update the knowledge on the diversity of trypanosomatids infecting native and alien vertebrate species. To this end, we conducted a systematic review of literature records published from 1900 to April 2020 on four databases, focusing on the 21 genera of trypanosomatids and Chile. The methods and findings of our review have been based on the preferred reporting items for systematic reviews and meta-analysis (prisma) checklist. We found 29,756 records but only 71 presented relevant information for this review. Overall, there are only two reported trypanosomatid genera infecting vertebrate species in Chile, the genera Trypanosoma and Leishmania. The former is mostly represented by Trypanosoma cruzi (90% of the total records) and to a much lesser extent by Trypanosoma avium, Trypanosoma humboldti, Trypanosoma lewisi, and a couple of unidentified trypanosomatids. A total of 25 mammals have been reported as being infected by T. cruzi, including 14 native and 11 alien species from Orders Artiodactyla, Carnivora, Chiroptera, Didelphimorphia, Lagomorpha, Perissodactyla, and Rodentia. Extensive screening studies using new analytical tools are necessary to grasp the whole potential diversity of trypanosomatid species infecting vertebrates in Chile.