Vector species richness predicts local mortality rates from Chagas disease.

Vector species richness may drive the prevalence of vector-borne diseases by influencing pathogen transmission rates. The dilution effect hypothesis predicts that higher biodiversity reduces disease prevalence, but with inconclusive evidence. In contrast, the amplification effect hypothesis suggests that higher vector diversity may result in greater disease transmission by increasing and diversifying the transmission pathways. The relationship between vector diversity and pathogen transmission remains unclear and requires further study. Chagas disease is a vector-borne disease most prevalent in Brazil and transmitted by multiple species of insect vectors of the subfamily Triatominae, yet the drivers of spatial variation in its impact on human populations remain unresolved. We tested whether triatomine species richness, latitude, bioclimatic variables, human host population density, and socioeconomic variables predict Chagas disease mortality rates across over 5000 spatial grid cells covering all of Brazil. Results show that species richness of triatomine vectors is a good predictor of mortality rates caused by Chagas disease, which supports the amplification effect hypothesis. Vector richness and the impact of Chagas disease may also be driven by latitudinal components of climate and human socioeconomic factors. We provide evidence that vector diversity is a strong predictor of disease prevalence and give support to the amplification effect hypothesis.

Scorpion envenomation in the neotropical savannah: Environmental predictors and years of lost life.

Scorpion stings envenomation (SSE) is a growing medical concern in Brazil, particularly in the state of Minas Gerais, which has recorded a significant number of incidents. This study aimed to investigate the potential predictors of scorpion sting incidence and evaluate the cost-effectiveness of interventions in Minas Gerais. Generalized Estimating Equations (GEE) models were constructed using socioeconomic and environmental variables as predictors and scorpion sting incidence as the response variable. The analysis revealed that mean annual temperature and major land use type were significant predictors of scorpion sting incidence, while precipitation and socioeconomic variables showed no relationship with incidence. The total number of cases and annual incidence of scorpion stings overlapped with regions experiencing higher forest conversion and agricultural land use, as well as higher temperatures. The estimated Disability-Adjusted Life Years (DALY) for scorpion sting incidents in Minas Gerais was substantial, indicating the need for effective prevention and treatment measures. The cost per DALY averted varied among municipalities, with some requiring minimal investment while others needing significant funding to address the scorpion risk. Mean annual temperature emerged as the main risk factor for scorpion stings, contributing to increased costs associated with antivenom treatment. These findings highlight the importance of considering environmental factors and implementing targeted interventions to mitigate scorpion sting incidents and reduce associated morbidity and mortality.

Progression of Gait Changes in Older Adults With Mild Cognitive Impairment: A Systematic Review.

BACKGROUND AND PURPOSE: The identification of altered gait and its progression over time is important to gaining a better understanding of the clinical aspects of mild cognitive impairment (MCI) in older adults. The aim of the present systematic review was to determine changes in gait variables over time among older adults with MCI. METHODS: The PubMed, Web of Science, Scopus, and Science Direct databases were searched for relevant articles using the following keywords and Medical Subject Headings: Aged AND "Mild cognitive impairment" AND (gait OR locomotion). A hand search was also performed of the reference lists of the selected articles in an attempt to find additional records. The following were the inclusion criteria: longitudinal studies and clinical trials involving a control group without intervention; samples of individuals 65 years or older; and characterization of gait using a single or dual task. RESULTS AND DISCUSSION: The initial search led to the retrieval of 6979 studies, 9 of which met the inclusion criteria. The duration of follow-up among the studies ranged from 6 months to 2 years. Most trials investigated gait speed. Other gait variables were step length, time required to walk a given distance, and mean weekly gait speed. Altered gait progressed in older adults with MCI. The main alterations were gait speed and variability in daily number of steps in follow-up periods lasting more than 1 year. No significant changes in gait variables were found in shorter follow-up periods (up to 6 months). CONCLUSIONS: The progression of gait changes in older adults with MCI has been underinvestigated. MCI leads to reduced gait speed in longer follow-up periods. Such information can contribute to the determination of motor interventions for older adults with MCI, especially in the early stages.

Recent and future environmental suitability to dengue fever in Brazil using species distribution model.

BACKGROUND: Dengue fever is a mosquito-borne disease that affects more than 2.5 billion people worldwide. Here, we used the dataset of municipality infestation level from the Brazilian Health Ministry with the aim of building vector distribution models to identify epidemiological hotspots. METHODS: Maxent software was used to predict the environmental suitability of the vector under current and 2050 climatic conditions. We built potential risk maps for current and future epidemiological scenarios in order to provide data for vector control planning. RESULTS: The results showed that the current epidemiological status is critical in the coastal region, with 80% of the population in risk areas and 30% in epidemiological outbreak areas. Our results also suggest that the area covered by the vector distribution in Brazil will decrease in future projections in the north, but will spread to the south. CONCLUSIONS: The results may provide useful information for health agencies and policymakers in focusing efforts in epidemiological hotspots. Therefore, understanding the niche distribution dynamics of Aedes aegypti is an important step towards public health planning for vector control.