Temporal Variation in the Abundance and Timing of Daily Activity of Chagas Disease Vector Triatoma gerstaeckeri (Stål, 1859) in a Natural Habitat in the Lower Rio Grande Valley, South Texas

Case Report: Neurologic Presentation of West Nile Virus: Difficult Diagnosis

West Nile virus infections have surged across the globe. South Texas, located on the path of bird migration, with Culex quinquefasciatus and other Culex species, and biotic primers that predispose the area to epidemics (floods, amplifying hosts, and lack of mosquito control and prevention) remains a highly endemic area for arbovirus spread. West Nile virus infection ranges from mild febrile illness to severe central nervous system involvement. The purpose of this report is to highlight complex presentations of WNV and how confounding presenting symptoms delay diagnosis. The secondary goal is to describe how pandemics, such as SARS-CoV-2, can overwhelm the system and result in medical decision bias errors.

Modelling geospatial distributions of the triatomine vectors of Trypanosoma cruzi in Latin America

Approximately 150 triatomine species are suspected to be infected with the Chagas parasite, Trypanosoma cruzi, but they differ in the risk they pose to human populations. The largest risk comes from species that have a domestic life cycle and these species have been targeted by indoor residual spraying campaigns, which have been successful in many locations. It is now important to consider residual transmission that may be linked to persistent populations of dominant vectors, or to secondary or minor vectors. The aim of this project was to define the geographical distributions of the community of triatomine species across the Chagas endemic region. Presence-only data with over 12, 000 observations of triatomine vectors were extracted from a public database and target-group background data were generated to account for sampling bias in the presence data. Geostatistical regression was then applied to estimate species distributions and fine-scale distribution maps were generated for thirty triatomine vector species including those found within one or two countries and species that are more widely distributed from northern Argentina to Guatemala, Bolivia to southern Mexico, and Mexico to the southern United States of America. The results for Rhodnius pictipes, Panstrongylus geniculatus, Triatoma dimidiata, Triatoma gerstaeckeri, and Triatoma infestans are presented in detail, including model predictions and uncertainty in these predictions, and the model validation results for each of the 30 species are presented in full. The predictive maps for all species are made publicly available so that they can be used to assess the communities of vectors present within different regions of the endemic zone. The maps are presented alongside key indicators for the capacity of each species to transmit T. cruzi to humans. These indicators include infection prevalence, evidence for human blood meals, and colonisation or invasion of homes. A summary of the published evidence for these indicators shows that the majority of the 30 species mapped by this study have the potential to transmit T. cruzi to humans.

Daily activity patterns of movement and refuge use in Triatoma gerstaeckeri and Rhodnius prolixus (Hemiptera: Reduviidae), vectors of the Chagas disease parasite

Transmission risk for vector borne disease is greatest during periods of heightened vector activity. Triatomine bugs (Hemiptera: Reduviidae), which transmit Trypanosoma cruzi, the causative agent of Chagas disease, are generally considered nocturnal, but their patterns of activity in controlled settings have rarely been studied. We quantified activity patterns across a 24-hour period in nymphs of two triatomine species: (1) Triatoma gerstaeckeri Stål, a North American triatomine which is closely associated with sylvatic and peridomestic hosts, and (2) Rhodnius prolixus Stål, a Central and South American triatomine that thrives in the domestic environment. T. gerstaeckeri showed activity throughout the night, with peaks around midnight, 3:00, and again around dawn. Refuge use was highest in the pre-dawn hours then again after the dawn activity peak. We hypothesize that the dawn activity peak may represent a period of host seeking for this sylvatic species that targets nocturnal hosts returning to their home at dawn. In contrast, R. prolixus displayed high activity near 23:00 and again around noon. This study provides a baseline understanding of diel activity for future behavioral experiments and identifies periods of time that may represent the greatest risk of host exposure to triatomines and T. cruzi.