U.S. military troops are exposed to mosquito-borne pathogens when deployed to endemic regions. Personal protective measures such as permethrin-treated uniforms and dermal repellents are the cornerstones of mosquito-borne disease prevention for the U.S. military. These measures have limitations and additional personal protection tools, such as spatial repellent devices to decrease the risk of vector-borne pathogen transmission, are required. Novel spatial repellent controlled-release devices formulated with metofluthrin were evaluated in an outdoor setting in the northern Amazon of Peru to evaluate performance under field conditions. The metofluthrin emitting devices lowered the number of mosquitoes captured in protected human landing collections (HLC) compared to blank devices, although there were effect differences between Anopheles spp. and species in other mosquito genera. A computational-experimental model was developed to correlate HLC and active ingredient (AI) concentrations as a function of time and space. Results show a strong correlation between the released AI and the decrease in HLC. This model represents the first effort to obtain a predictive analytical tool on device performance using HLC as the entomological endpoint.

Ticks are obligatory hematophagous ectoparasites that transmit pathogens among various vertebrates, including humans. The microbial and viral communities of ticks, including pathogenic microorganisms, are known to be highly diverse. However, the factors driving this diversity are not well understood. The tropical horse tick, Dermacentor nitens, is distributed throughout the Americas and it is recognized as a natural vector of Babesia caballi and Theileria equi, the causal agents of equine piroplasmosis. In this study, we characterized the bacterial and viral communities associated with partially fed Dermacentor nitens females collected using a passive survey on horses from field sites representing three distinct geographical areas in the country of Colombia (Bolivar, Antioquia, and Cordoba). RNA-seq and sequencing of the V3 and V4 hypervariable regions of the 16S rRNA gene were performed using the Illumina-Miseq platform (Illumina, San Diego, CA, USA). A total of 356 operational taxonomic units (OTUs) were identified, in which the presumed endosymbiont, Francisellaceae/Francisella spp., was predominantly found. Nine contigs corresponding to six different viruses were identified in three viral families: Chuviridae, Rhabdoviridae, and Flaviviridae. Differences in the relative abundance of the microbial composition among the geographical regions were found to be independent of the presence of Francisella-like endosymbiont (FLE). The most prevalent bacteria found in each region were Corynebacterium in Bolivar, Staphylococcus in Antioquia, and Pseudomonas in Cordoba. Rickettsia-like endosymbionts, mainly recognized as the etiological agent of rickettsioses in Colombia, were detected in the Cordoba samples. Metatranscriptomics revealed 13 contigs containing FLE genes, suggesting a trend of regional differences. These findings suggest regional distinctions among the ticks and their bacterial compositions.

Integrated One Health studies are essential for assessing the risks of leishmaniasis transmission. In Honduras, the most prevalent clinical presentation of leishmaniasis is the non-ulcerated cutaneous form caused by Leishmania infantum; however, research on its transmission dynamics remains limited. This study aimed to characterize the eco-epidemiology of leishmaniasis and identify potential zoonotic risk factors in the municipality of Ojos de Agua, Department of Comayagua, central Honduras, using a One Health approach. We collected sand flies using CDC light traps placed in intra- and peridomestic settings of households with a history of leishmaniasis. Concurrently, we evaluated domestic dogs and collected blood samples for serological and molecular testing. We also conducted active surveillance among community residents to identify human infections. We collected a total of 644 phlebotomine sand flies, including 186 females. We identified eight sandfly species, with Lutzomyia (Lutzomyia) longipalpis as the predominant species, followed by Pintomyia (Pifanomyia) evansi. Among the 64 engorged females screened, the overall PCR positivity rate for Leishmania spp. was 14.1% (9/64). Blood meal analysis of PCR-positive sand flies identified humans and pigs as blood and meal sources. Additionally, 18.6% (8/43) of domestic dogs were seropositive for Leishmania spp., and 23.3% (10/43) tested positive by PCR. DNA sequencing identified the infecting species as Leishmania infantum. We detected no active human cases during the study period. These findings highlight the value of a One Health approach for improving transmission risk monitoring in newly emerging areas with a history of ulcerative cutaneous leishmaniasis in Honduras.

Endemic and (re)emerging infectious diseases pose a major threat to public health and military readiness in Central and South America. The high biodiversity and the differing transmission pathways require the use of highly sensitive methods to track the emergence and spread of these diseases. High-throughput sequencing technologies have become a critical resource for the field of infectious disease monitoring, specifically for tracking pathogen evolution, antimicrobial resistance, and transmission. This review provides an overview of the implementation of genomics-informed infectious disease surveillance conducted by the U.S. Naval Medical Research Unit SOUTH, focusing on operational, infrastructural, and logistical challenges in resource-limited settings and outlining strategies for building sustainable regional capacity. Selected case studies focused on prominent biothreats including dengue, Oropouche, malaria, and antimicrobial resistance demonstrate the significance and applicability of targeted and agnostic sequencing approaches to elucidate transmission pathways, pathogen discovery, and guide public health responses and field-deployable applications.