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Chagas disease, caused by the protozoan parasite Trypanosoma cruzi transmitted by blood-sucking insects of the subfamily Triatominae, is a major neglected tropical disease affecting 6 to 7 million of people worldwide. Rhodnius prolixus, one of the most important vectors of Chagas disease in Latin America, is known to be highly sensitive to environmental factors, including temperature. This study aimed to investigate the effects of different temperatures on R. prolixus development and life-cycle, its relationship with T. cruzi, and to gather information about the nutritional habits and energy consumption of R. prolixus. We exposed uninfected and infected R. prolixus to four different temperatures ranging from 24°C to 30°C, and monitored their survival, developmental rate, body and blood meal masses, urine production, and the temporal dynamics of parasite concentration in the excreted urine of the triatomines over the course of their development. Our results demonstrate that temperature significantly impacts R. prolixus development, life-cycle and their relationship with T. cruzi, as R. prolixus exposed to higher temperatures had a shorter developmental time and a higher mortality rate compared to those exposed to lower temperatures, as well as a lower ability to retain weight between blood meals. Infection also decreased the capacity of the triatomines to retain weight gained by blood-feeding to the next developmental stage, and this effect was proportional to parasite concentration in excreted urine. We also showed that T. cruzi multiplication varied depending on temperature, with the lowest temperature having the lowest parasite load. Our findings provide important insights into the potential impact of climate change on the epidemiology of Chagas disease, and can contribute to efforts to model the future distribution of this disease. Our study also raises new questions, highlighting the need for further research in order to understand the complex interactions between temperature, vector biology, and parasite transmission. Author summary: Chagas disease, caused by the parasite Trypanosoma cruzi and transmitted by blood-sucking kissing bugs, is a major neglected tropical disease affecting millions of people worldwide. The insect vector Rhodnius prolixus is highly sensitive to environmental factors, including temperature. In this study, we investigated the effects of different temperatures on R. prolixus and its interaction with T. cruzi, as well as the nutritional habits and energy consumption of the vector. We exposed uninfected and infected insects to various temperatures, and monitored their survival, development, body and blood meal weights, urine production, and T. cruzi infection over their lifespan. Our results revealed that temperature significantly influenced R. prolixus development, life-cycle, and its interaction with T. cruzi. Insects exposed to higher temperatures had shorter development time, increased mortality, and reduced ability to maintain weight. Infection further compromised the ability of the triatomines to retain weight gained by blood-feeding, and this effect correlated with parasite load. Additionally, T. cruzi multiplication varied with temperature, with lower temperatures associated with lower parasite concentration. Our findings have important implications for understanding the impact of climate change on Chagas disease epidemiology and contribute to modeling its future spread. [ABSTRACT FROM AUTHOR]

Background: The causative agent of plague, Yersinia pestis, is maintained in nature via a flea-rodent cycle. Western Iran is an old focus for plague, and recent data indicate that rodents and dogs in this region have serological evidence of Y. pestis infection. The purpose of this study was to conduct a large-scale investigation of Y. pestis infection in shepherd dogs, rodents, and their fleas in old foci for plague in Western Iran. Materials and methods: This study was conducted in Hamadan province from 2014 to 2020. Rodents and fleas were collected from various locations throughout this region. Y. pestis was investigated in rodent spleen samples and fleas using culture, serology, and real-time PCR methods. Additionally, sera samples were collected from carnivores and hares in this region, and the IgG antibody against the Y. pestis F1 antigen was assessed using an ELISA. Results: In this study, 927 rodents were captured, with Meriones spp. (91.8%) and Microtus qazvinensis (2.6%) being the most prevalent. A total of 6051 fleas were collected from rodents and carnivores, most of which were isolated from Meriones persicus. None of the rodents or fleas examined tested positive for Y. pestis using real-time PCR and culture methods. Meanwhile, IgG antibodies were detected in 0.32% of rodents. All serologically positive rodents belonged to M. persicus. Furthermore, none of the sera from the 138 carnivores (129 sheepdogs, five Vulpes vulpes, four Canis aureus), and nine hares tested positive in the ELISA test. Conclusion: This primary survey of rodent reservoirs shows serological evidence of Y. pestis infection. Western Iran is an endemic plague focus, and as such, it requires ongoing surveillance. Author summary: This article investigates the ongoing presence of the plague in Iran and stresses the importance of continuous monitoring in the western region, a major area for endemic plague. Rodents are the primary carriers of diseases in their natural habitats and contribute significantly to the ongoing presence of infectious cycles. The study focuses on the presence of Yersinia pestis, the bacteria responsible for the plague, in guard dogs, rodents, and fleas in the historical center of western Iran. The research confirms the presence of Y. pestis infection in rodents, specifically Meriones persicus, in western Iran through serological evidence. Given the new discoveries in Iran and the resurgence of the plague in neighboring countries, ongoing monitoring of plague infections in wildlife across various regions of the country is crucial for public health outcomes. [ABSTRACT FROM AUTHOR]

Vector-borne diseases remain a significant public health threat in many regions of the world. Traditional vector surveillance and control methods have relied on active and passive surveillance programs, which are often costly and time-consuming. New internet-based vector surveillance systems have shown promise in removing some of the cost and labor burden from health authorities. We developed and evaluated the effectiveness of a new internet-based surveillance system, "AlertaChirimacha", for detecting Triatoma infestans (known locally by its Quechua name, Chirimacha), the Chagas disease vector, in the city of Arequipa, Peru. In the first 26 months post-implementation, AlertaChirimacha received 206 reports of residents suspecting or fearing triatomines in their homes or neighborhoods, of which we confirmed, through pictures or inspections, 11 (5.3%) to be Triatoma infestans. After microscopic examination, none of the specimens collected were infected with Trypanosoma cruzi. AlertaChirimacha received 57% more confirmed reports than the traditional surveillance system and detected 10% more infested houses than active and passive surveillance approaches combined. Through in-depth interviews we evaluate the reach, bilateral engagement, and response promptness and efficiency of AlertaChirimacha. Our study highlights the potential of internet-based vector surveillance systems, such as AlertaChirimacha, to improve vector surveillance and control efforts in resource-limited settings. This approach could decrease the cost and time horizon for the elimination of vector-mediated Chagas disease in the region. Author summary: Insects that spread diseases are still a problem in many parts of the world. Monitoring and controlling them can be expensive and time-consuming, but new internet-based methods have shown promise in reducing workload and costs. We developed AlertaChirimacha, an internet-based surveillance system to detect Triatoma infestans, a species of insect that spreads Chagas disease. AlertaChirimacha was tested in Arequipa, Peru, and in the 26 months after it was implemented, it received 206 reports from residents who suspected they had these insects in their homes, 11 were confirmed by our team. AlertaChirimacha detected more infested homes than the traditional methods combined. AlertaChirimacha was also effective in reaching people, getting them to engage, and respond to reports. This approach can improve efforts to control insect-borne diseases in places with limited resources and make it less expensive to eliminate vector-mediated Chagas disease. [ABSTRACT FROM AUTHOR]

Anthropogenic land-use change, such as deforestation and urban development, can affect the emergence and re-emergence of mosquito-borne diseases, e.g., dengue and malaria, by creating more favourable vector habitats. There has been a limited assessment of how mosquito vectors respond to land-use changes, including differential species responses, and the dynamic nature of these responses. Improved understanding could help design effective disease control strategies. We compiled an extensive dataset of 10,244 Aedes and Anopheles mosquito abundance records across multiple land-use types at 632 sites in Latin America and the Caribbean. Using a Bayesian mixed effects modelling framework to account for between-study differences, we compared spatial differences in the abundance and species richness of mosquitoes across multiple land-use types, including agricultural and urban areas. Overall, we found that mosquito responses to anthropogenic land-use change were highly inconsistent, with pronounced responses observed at the genus- and species levels. There were strong declines in Aedes (-26%) and Anopheles (-35%) species richness in urban areas, however certain species such as Aedes aegypti, thrived in response to anthropogenic disturbance. When abundance records were coupled with remotely sensed forest loss data, we detected a strong positive response of dominant and secondary malaria vectors to recent deforestation. This highlights the importance of the temporal dynamics of land-use change in driving disease risk and the value of large synthetic datasets for understanding changing disease risk with environmental change. Author summary: An understanding of the response of disease vectors to anthropogenic activities can aid in the control of mosquito-borne disease transmission. However, regional assessments of these responses are lacking, especially in areas where mosquito-borne diseases are emerging and re-emerging. We assembled a synthetic dataset of mosquito abundance and species richness across multiple land-use types in Latin America and the Caribbean, using data from peer-reviewed published studies. We then used this dataset to explore whether mosquito abundance and species richness changed, compared to a baseline of minimal anthropogenic activity, depending on the type of land use. Overall, we observed a decline in mosquito biodiversity in urban areas. We detected distinct species-specific responses in abundance to land use, with some important disease vectors, such as Aedes aegypti, increasing in abundance in anthropogenic environments. Finally, we also demonstrated by coupling our dataset with forest loss data that the abundance of dominant malaria vectors in the region increases with deforestation. [ABSTRACT FROM AUTHOR]

Background: Chagas is a complex and multidimensional socio-environmental health phenomenon, in which different components converge and interact. Historically, this disease was associated with insect vectors found in the rural environment. However, in the Americas, we are currently facing a new paradigm, in which different scenarios allow maintaining the vectorial transmission of the parasite through triatomine populations that either occasionally enter the dwellings or colonize urban environments. Methodology/Principal findings: Records of scientific reports available in the PubMed and LILACS search engines were retrieved, using three criteria according to the main triatomine genera of epidemiological importance and to the general scientific production on Chagas disease in urban contexts. Results showed that records on the occurrence of vectors in urban dwellings began to increase in the last three decades. Results also showed that the main species of triatomines collected inside dwellings (18 in total) belong mainly to the genera Triatoma and Panstrongylus, with most species (16/18, 88.8%) infected with the parasite, and that infestation of triatomine species occurs in all types of cities (small, medium and large, including megalopolises), from Argentina to the USA. Conclusions/Significance: Urban Chagas represents a new challenge that adds a different dimension to the problem of Chagas disease due to the particular characteristics of the lifestyle in urban agglomerates. The new scenario will require adaptations of the programs of control of vector to this shift from rural to urban settlements. Author summary: Chagas disease is caused by the parasite Trypanosoma cruzi and transmitted to humans through insects called triatomines, which feed on warm-blooded animals. Although this disease has been historically associated with the rural environment, in the last years, triatomines have been found either entering urban dwellings intrusively or colonizing urban environments of Latin American cities. In this study, we reviewed publications referring to urban Chagas that include the presence of the main vectors of this disease to find out how important the occurrence of triatomines in large cities is, which triatomine species involved are, whether or not these insects are infected with the parasite, and what the geographical distribution of the vectors and the parasite is. The results confirmed the existence of vectors in urban areas of Latin America and showed that records began to increase in the last three decades. Species of the genera Triatoma and Panstrongylus were the ones mainly recorded in the dwellings and the ones most infected with the parasite. Records of infected triatomine species have been reported from Argentina to the USA. This new scenario of Chagas disease raises the need to adapt the control of urban populations of the vectors found in these areas. [ABSTRACT FROM AUTHOR]

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. Author summary: In the vector-borne transmission of Chagas disease, approximately 150 species of triatomine bugs are potential vectors for the parasite Trypanosoma cruzi. A competent vector must fulfill several features such as the ability to host, amplify, and differentiate the parasite, allowing T. cruzi persistence within the insect vector. Our aim was to describe the dynamics of T. cruzi infection in a competent triatomine species collected in two contrasting seasons—with different environmental temperatures—of 2017 and 2018. We used a follow-up procedure including T. cruzi detection right after collection and 40 days later; both detections were performed after laboratory feeding. Most infected bugs were T. cruzi positive on both occasions. However, infected bugs from winter 2018 presented switches from T. cruzi negative at collection to T. cruzi positive 40 days later. The results suggest infections with T. cruzi attached to the hindgut wall as the colonization site, caused by infections that persist there after a fasting event, are released after a second feeding. [ABSTRACT FROM AUTHOR]

Background: Phlebotomine sand flies are prominent vectors of Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly chemical-based vector control is a key component of leishmaniasis control efforts. Methods and findings: We performed a literature review on the current interventions, primarily, insecticide-based used for sand fly control, as well as the global insecticide resistance (IR) status of the main sand fly vector species. Indoor insecticidal interventions, such as residual spraying and treated bed nets are the most widely deployed, while several alternative control strategies are also used in certain settings and/or are under evaluation. IR has been sporadically detected in sand flies in India and other regions, using non-standardized diagnostic bioassays. Molecular studies are limited to monitoring of known pyrethroid resistance mutations (kdr), which are present at high frequencies in certain regions. Conclusions: As the leishmaniasis burden remains a major problem at a global scale, evidence-based rational use of insecticidal interventions is required to meet public health demands. Standardized bioassays and molecular markers are a prerequisite for this task, albeit are lagging behind. Experiences from other disease vectors underscore the need for the implementation of appropriate IR management (IRM) programs, in the framework of integrated vector management (IVM). The implementation of alternative strategies seems context- and case-specific, with key eco-epidemiological parameters yet to be investigated. New biotechnology-based control approaches might also come into play in the near future to further reinforce sand fly/leishmaniasis control efforts. Author summary: Phlebotomine sand flies, mainly aggregated in the tropics and subtropics, are prominent vectors Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly vector control is a key component of leishmaniasis prevention and control efforts. Here, we review the current methods and active ingredients applied for sand fly chemical control, as well as the IR data (bioassay and underlying mechanisms) available for dominant sand fly vector species worldwide. Future perspectives for improving the efficiency and sustainability of sand fly control applications, in the genomics era, including the use of molecular diagnostics for evidence-based IRM and the introduction of alternative biotechnology-based approaches, are discussed. [ABSTRACT FROM AUTHOR]