Biology subjects

Hamer, S. A.

Publications and source records attributed to Hamer, S. A..

At least 19 recordsLinked to original sources

bioRxiv2026

An update on the mosquito fauna of Aguascalientes, Mexico: morphological and molecular identifications, host-feeding patterns, and the removal of Aedes idahoensis (Theobald) from Mexico

To better understand taxonomic identity and feeding patterns of mosquitoes in all physiographic regions and sub-regions of Aguascalientes, Mexico, we conducted surveillance followed by morphologic analysis and DNA metabarcoding. We targeted the Sierra Madre Occidental, Central Plateau, and Neo-Volcanic Axis. We sampled natural larval habitat for immature stages and adults were collected using Shannon and CDC light traps, mechanical aspirators, and human landing catch method. In addition, curated specimens from Aguascalientes deposited in a local institution were re-examined. Overall, 5,227 mosquito specimens consisting of 357 larvae, 199 larval exuviae, 373 pupal exuviae, 33 pupae, 3,000 females, 1,264 males, and 1 male genitalia were examined using taxonomic keys. Most immature and adult species (n = 20/34 species representing 58.8% coverage) were barcoded for molecular species designation, and a subsample (n = 64) of engorged female mosquitoes were analyzed for blood feeding patterns. Two subfamilies, four tribes, seven genera, 14 subgenera, and 34 species were identified, which one tribe, three genera, nine subgenera, and 22 species are new records. Phylogenetic analysis of specimens from Aguascalientes identified 20 species. Morphological observation of mosquitoes deposited in entomological collections resulted in the removal of Aedesidahoensis from Mexico, leaving the country with a total of 255 species documented. Bloodmeal metabarcoding was successful in 23 mosquitoes of five species, revealing evidence of feeding on more than a single vertebrate species in 17 individuals. Birds were the most common host with the cattle egret (Ardea ibis) found in 18 out of 23 mosquitoes. This update on the taxonomic identity and mosquito richness and feeding patterns from Aguascalientes affords a better understanding of the ecology of medically important mosquito species.

zoology↗

bioRxiv2026

RNA-seq analysis of Triatoma gerstaeckeri during mite infestation reveals increased metabolic demand and lower reproductive investment

Triatomine insects, also known as kissing bugs, serve as vectors for the Trypanosoma cruzi parasite, which can cause American trypanosomiasis, also known as Chagas disease. Triatomines are known to be parasitized by mites in natural and colony settings, where mites feed on the arthropod to obtain nutrients and resources for reproduction. This feeding, while necessary for the survival of the mites, likely occurs at the expense of their insect host. We examined the transcriptional response of Triatoma gerstaeckeri infested with mites (Pimeliaphilus spp.) and an uninfested group using Illumina-based RNA-seq, followed by targeted measurement of nutritional reserves in both groups. Our results show increased expression of factors involved in protein translation, but decreased expression of processes associated with cell development. These results are supported by declines in protein levels in mite-infested T. gerstaeckeri and lower expression of reproductive factors, suggesting a distinct reduction in nutrient reserves and reproductive output. These studies provide critical information on the interaction of mites and triatomines while considering the utility of mites as biological control of triatomines in nature or for husbandry protocols to minimize issues with mite infestations of colony individuals.

physiology↗

bioRxiv2026

Investigating the use of human COVID-19 rapid assays to detect antibody and antigen in domesticated dogs (Canis lupus familiaris) and cats (Felis catus)

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus that causes coronavirus disease-2019 (COVID-19) in humans, is also known to infect animals including dogs (Canis lupus familiaris) and cats (Felis catus). This study evaluated the efficacy of human COVID-19 rapid antigen and antibody tests in dogs and cats. Nasal/oral swabs from 60 animals (32 dogs, 28 cats) and serum from 40 animals (20 dogs, 20 cats) were tested. Rapid antigen tests used on respiratory swabs showed low-to-moderate sensitivity (75% dogs, 57% cats) and moderate-to-high specificity (79% dogs, 95% cats) compared to RT-PCR. Rapid antibody tests used on serum samples demonstrated low-to-moderate sensitivity (70% dogs, 50% cats) and moderate-high specificity (60% dogs, 100% cats) compared to PRNT. While imperfect, these test kits may have some utility for field surveillance studies, particularly when species-specific rapid SARS-CoV-2 assays for dogs and cats are unavailable. These test characteristics in dogs and cats are similar to the findings from studies of the same types of tests in humans which have found an average sensitivity and specificity of common commercially available kits in the US range from 50.0-84.3% and 64.5-74.3%, respectively, when used with human samples (1,2).

zoology↗

bioRxiv2026

Triatomine host preference in an experimental cafeteria: the impact of Trypanosoma cruzi infections

BackgroundHematophagous triatomine vectors of the Chagas disease parasite, Trypanosoma cruzi, have a wide bloodmeal host breadth yet mammals are the primary competent reservoirs for T. cruzi. Accordingly, the transmission of T. cruzi is dependent on triatomines encountering mammalian hosts. We hypothesized T. cruzi-infected triatomines exhibit a preference for mammalian versus non-mammalian hosts, as compared to uninfected triatomines. Methodology/Principal FindingsWe used a dual-choice olfactometer to present individual T. cruzi-infected and uninfected Triatoma gerstaeckeri- an important North American triatomine species- to pairwise combinations of no host, dog, human, or chicken. We found that uninfected T. gerstaeckeri preferred dogs over chickens and humans, but T. cruzi-infected T. gerstaeckeri had no host preference. Additionally, T. cruzi-infected T. gerstaeckeri took less time to begin advancing towards hosts (average of 522 s {+/-} 577 s vs 801 s {+/-} 704 s) and spent more time on both sides of the olfactometer compared to uninfected insects As a comparative group,we tested Rhodnius prolixus- a potent South American vector- and found no statistical preference among hosts, yet they advanced towards hosts more often (63.2% vs 47.1%) and faster compared to T. gerstaeckeri. Conclusions/SignificanceThe increased locomotion of R. prolixus and T. cruzi-infected T. gerstaeckeri toward hosts may promote increased transmission of T. cruzi. Dogs are a preferred host for T. gerstaeckeri and may be considered in future host-targeted interventions for triatomine control. Author SummaryVectors are often generalists or opportunists with a wide range of available hosts, yet the parasites they transmit may have a narrower host range. It is in the parasites best interest for the vectors they infect to interact with competent hosts, thereby introducing the setting for parasite manipulation of vectors. We aimed to understand the foraging behaviors of vectors and how those behaviors may be different when the vector is infected with a parasite. We studied the triatomine ( kissing bug) insect vectors of the Chagas disease parasite, Trypanosoma cruzi, using one of North Americas most important vector species in comparison to a potent South American vector species. We tested if parasite-infected triatomines exhibited a preference toward vertebrate hosts that are also competent reservoirs for the T. cruzi (i.e., mammals). We used an experimental cafeteria, in which individual vectors were introduced to a dual-choice olfactometer and allowed to walk toward hosts including restrained humans, dogs, or chickens. We found differences in apparent host preference between species of vectors and between infected vs. uninfected vectors. Uninfected vectors displayed a host preference toward dogs, yet this preference was not significant among infected vectors. Uninfected vectors had higher frequency of locomotion in the arena, suggesting the opportunity for more vector-host contact.

ecology↗

bioRxiv2025

Advancing the design of the kissing bug kill trap for surveillance of triatomines

Standardized surveillance and control of kissing bugs (Hemiptera: Reduviidae: Triatominae), the insect vectors of the Chagas disease parasite Trypanosoma cruzi, which causes Chagas disease, remains difficult. The Kissing Bug Kill Trap consists of solar powered LED lights mounted over a column of black funnels. It operates autonomously to capture, kill and preserve adult triatomines. We conducted experiments from 2022-2024 testing potential ways to improve trap performance, ease of deployment, and minimize cost. Thirteen prototypes evaluated in Texas, Guatemala, and Mexico captured 1,531 triatomines. In 2022-2023 we selected a six-funnel trap suspended from a single support pole with an angle bracket, and with four LED lights and a solar panel mounted above the rain-guard, as a reference trap. In 2023, traps with smaller funnels, blue funnels, and blue lights were inferior to the reference trap based on high by-catch of other arthropods and/or fewer triatomines caught per day. In 2024, traps with more or fewer than six funnels or with LED lights mounted on or below the rain guard did not outperform the reference trap. The experiments added five new triatomine species to the four already known to be caught by the Kissing Bug Kill Trap and revealed differences and similarities in phenology of dispersal flights of Triatoma gerstaeckeri over a three-year period in Texas. The reference trap was selected as the pre-commercial prototype, based on its suitability for triatomine surveillance and potential for reducing the risk of T. cruzi infection by intercepting dispersing adult triatomines before they reach human habitats.

ecology↗

bioRxiv2025

Field Evidence of Trypanosoma cruzi Infection, Diverse Host Use and Invasion of Human Dwellings by the Chagas Disease Vector in Florida, USA

Background: Triatomine bugs (Hemiptera, Reduviidae, Triatominae) are blood-sucking vectors of the protozoan parasite, Trypanosoma cruzi, which causes Chagas disease, a significant source of human morbidity and mortality in the Americas. Autochthonous transmission of Chagas disease in the United States is considered rare, despite evidence of Triatoma species harboring T. cruzi, invading homes, and biting occupants. In the southeastern United States, Triatoma sanguisuga is considered common, yet its distribution, host use, and T. cruzi infection are practically unknown in this region. Methodology/Principle Findings: Using field sampling and community science programs from 2013 to 2023, we collected triatomines from peridomestic and domestic settings, identified them to species, analyzed for bloodmeals, and screened for T. cruzi infection and Discrete Typing Units (DTUs) TcI - TcVI utilizing molecular techniques. Triatoma sanguisuga (n=310) were collected from 23 counties throughout the state, particularly in northern and central Florida. More than one third (34.6%) of T. sanguisuga were found inside a human dwelling, and 39.2% were collected by community members. T. cruzi infection was observed in 29.5% (88/298) of tested triatomines, with infection found in 12 of the 23 counties where triatomines had been collected. DTU-typing was successful for 47 of the T. cruzi-positive triatomines: 74.5% were infected with DTU TcI, 21.3% were infected with DTU TcIV, and 4.3% were co-infected with TcI and TcIV. Bloodmeal analysis of 144 T. sanguisuga found broad host use, including mammals (60%), ectothermic vertebrates (37%), and cockroaches (2.5%). Human blood meals contributed nearly a quarter (23%) of bloodmeals, indicating significant vector-human contact. Conclusion/Significance: Our field data from Florida demonstrate that T. sanguisuga is present near, and sometimes in, human dwellings, feeds upon humans, and is infected with multiple DTUs of T. cruzi. This indicates that the environment in the southeastern United States is suitable for autochthonous transmission of Chagas disease or that the human risk for T. cruzi infection is possible. The roles of ectotherms in T. sanguisuga and T. cruzi ecology also warrant further investigation. Author SummaryTriatomines, which can spread Chagas disease to humans and other animals, are found throughout many U.S. states. Little is known about triatomines in Florida - our study aimed to learn more about where triatomines can be found in Florida, how often they are infected with the parasite that causes Chagas disease, and which animals triatomines feed on in Florida, including humans. From 2013-2023, utilizing our own field work and community science programs, we collected 310 triatomines from various regions in Florida. Both adult and immature triatomines were found, and about one-third of the triatomines were found inside human homes (35%). About 30% of the triatomines tested were infected with the Chagas disease parasite, Trypanosoma cruzi. Blood-fed triatomines mostly fed on mammals (60%, including humans), amphibians (27%), and reptiles (11%), but not on birds. Nearly a quarter of bugs (23%) had fed on human blood. Our research raises concerns for possible transmission of Chagas disease to humans from triatomines in Florida.

ecology↗

bioRxiv2025

Active surveillance of cats and dogs from households with human COVID-19 cases reveals over one quarter of pets infected with SARS-CoV-2 in 2020-2021 in Texas, United States

Households where people have COVID-19 are high risk environments for companion animals that are susceptible to SARS-CoV-2. We sampled 579 pets from 281 households with one or more laboratory-confirmed person with COVID-19 in central Texas from June 2020 to May 2021. Nineteen out of 396 (4.8%) dogs and 21 out of 157 (13.4%) cats were positive for SARS-CoV-2 by RT-qPCR. Additionally, 95/382 (25%) dogs and 52/146 (36%) cats harbored SARS-CoV-2 neutralizing antibodies. Twenty-six companion animals of ten other species were negative. Overall, 164 (29%) pets were positive for SARS-CoV-2 by molecular and/or serological tests; a total of 110 (39%) out of 281 households had at least one animal with active or past SARS-CoV-2 infection. Cats were more likely to be infected by SARS-CoV-2 and had higher endpoint antibody titers than dogs. Through viral isolation from a subset of respiratory swabs, we documented 6 different lineages in dogs and cats, including the B.1.1 lineage in a cat one month prior to the first known human case in the country. We observed animal and human-pet interaction factors associated with higher risk of infection for dogs and cats, such as days after COVID-19 diagnosis and sharing food. Frequency of clinical signs of disease reported by owners of pets with active infections did not differ from uninfected ones, suggesting that not all reported signs are attributed to SARS-CoV-2 infection. Characterizing animal infections using active SARS-CoV-2 surveillance in pets at risk of infection may aid in One Health pandemic prevention, response, and management.

microbiology↗

bioRxiv2024

Investigating the Role of Management Decisions in Subspecies Hybridization Across the Wild Turkey's Range

The expanded geographic range and recovery to millions of wild turkeys across the country would not have been possible without management actions that included introducing and translocating individuals. However, the range-wide genetic impact of management decisions on one of North Americas greatest conservation success stories remains unknown despite the potential economic impact as hunters seek out easily identifiable subspecies for grand slams. In this study, we used DNA extracted from hunter-collected feathers from 29 states and Ontario to investigate genetic differences among turkeys in their historic and introduced ranges. Additionally, we compiled state-level management data to investigate how different management decisions are associated with the amount of admixture among subspecies. We found no difference in the amount of admixture in the turkeys historic range compared to the introduced range. However, management decisions like as the number of subspecies introduced and the number of unique source states resulted in an increased level of admixture detected, but there was no relationship in admixture and the number of unique relocated counties. This first investigation into the hybridization among subspecies of wild turkey provides evidence that individual states management actions have influenced the genetic makeup of subspecies in that state.

genomics↗

bioRxiv2024

Respiratory shedding of infectious SARS-CoV-2 Omicron XBB.1.41.1 lineage with increased evolutionary rate among captive white-tailed deer

White-tailed deer (Odocoileus virginianus) have high value for research, conservation, agriculture and recreation, and may be important SARS-CoV-2 reservoirs with unknown human health implications. In November 2023, we sampled 15 female deer in a captive facility in central Texas, USA. All individuals had neutralizing antibodies against SARS-CoV-2 and 11 had RT-qPCR-positive respiratory swabs; one also had a positive rectal swab. Six of 11 respiratory swabs yielded infectious virus with replication kinetics of most samples displaying lower growth 24-48 h post infection in vitro when compared to Omicron lineages isolated from humans in Texas in the same period. However, virus growth was similar between groups by 72 h, suggesting no strong attenuation of deer-derived virus. All deer viruses clustered in XBB Omicron clade, with more mutations than expected compared to contemporaneous viruses in humans, suggesting that crossing the species barrier to deer was accompanied by a high substitution rate.

microbiology↗

bioRxiv2024

Fluralaner treatment of chickens kills the southern house mosquito, Culex quinquefasciatus

The control of zoonotic and vector-borne pathogens is challenging due to the limited availability of intervention tools. West Nile virus (WNV) is an example of globally distributed zoonotic arbovirus that circulates between Culex species mosquitoes and avian hosts, with spillover transmission to humans, resulting in disease cases. Interventions delivering systemic insecticides to vertebrate hosts used by vector species, known as xenointoxication, are potential tools for managing vector populations by creating toxic bloodmeals. In this study, we evaluated the impact of three systemic insecticides on the mortality of Cx. quinquefasciatus: fenbendazole (Safe-Guard(R) Aquasol), ivermectin (Ivomec(R) Pour-On), and fluralaner (Bravecto(R)). We found no significant difference in the feeding rates of mosquitoes that fed on treated chickens compared to those fed on untreated chickens, suggesting that the treatment did not repel mosquitoes. The mortality of Cx. quinquefasciatus mosquitoes feeding on fluralaner-treated chickens was significantly higher (p < 0.01) than those fed on control chickens at 3 and 7 days post-treatment, but this effect was not observed in mosquitoes fed on chickens treated with fenbendazole or ivermectin. No differences in mortality were observed among the groups at 14, 26, or 56 days post-treatment. These data support fluralaner as a xenointoxication tool to control Cx. quinquefasciatus populations and decrease the risk of human exposure to their associated pathogens.

biochemistry↗

bioRxiv2024

Evaluation of a novel Tc-24 recombinant antigen ELISA for serologic testing for Trypanosoma cruzi in dogs

Chagas disease is a parasitic infection caused by Trypanosoma cruzi. Diagnosis of chroni Chagas disease in dogs relies on limited serological test options. This study used a new Tc-24 recombinant antigen ELISA on an archival set of 70 dog serum samples from multi-dog kennel environments in Texas subjected to three existing Chagas serological tests. Tc-24 ELISA produced a quantitative result and could detect anti-T. cruzi antibodies in dogs with high sensitivity and specificity. Comparing individual tests to Tc-24 ELISA resulted in strong associations and correlations, which suggest that Tc-24 ELISA is a reliable and accurate diagnostic tool for dogs with a single test.

zoology↗

bioRxiv2023

Bloodmeal metabarcoding of the argasid tick (Ornithodoros turicata Duges) reveals extensive vector-host associations

Molecular methods to understand host feeding patterns of arthropod vectors are critical to assess exposure risk to vector-borne disease and unveil complex ecological interactions. We build on our prior work discovering the utility of PCR-Sanger sequencing bloodmeal analysis that work remarkably well for soft ticks (Acari: Argasidae), unlike for hard ticks (Acari: Ixodidae), thanks to their unique physiology that retains vertebrate DNA from prior bloodmeals viable for years. Here, we capitalize on this feature and apply bloodmeal metabarcoding using amplicon deep sequencing to identify multiple host species in individual Ornithodoros turicata soft ticks collected from two natural areas in Texas, United States. Of 788 collected O. turicata, 394 were evaluated for bloodmeal source via metabarcoding, revealing 27 different vertebrate host species (17 mammals, 5 birds, 1 reptile, and 4 amphibians) fed upon by 274 soft ticks. Information on multiple hosts for individual O. turicata was derived from 168 of these (61%). Metabarcoding revealed more mixed vertebrate bloodmeals in O. turicata previously processed using Sanger sequencing. These data reveal wide host range of O. turicata and demonstrate the value of bloodmeal metabarcoding for understanding the ecology for known and potential tick-borne pathogens circulating among humans, domestic animals and wildlife such as relapsing fever caused by Borrelia turicatae. Our results also document, for the first time an off-host soft tick collected to have evidence of prior feeding on wild pig which is a critical observation in the context of the threat of enzootic transmission of African swine fever virus if it were introduced to the US. This research enhances our understanding of vector-host associations and offers a promising perspective for biodiversity monitoring and disease control strategies.

ecology↗

bioRxiv2023

Validation of a multiplex microsphere immunoassay for detection of Trypanosoma cruzi antibodies in dogs

The vector-borne protozoan parasite Trypanosoma cruzi causes Chagas disease in humans, dogs, and many other mammalian hosts. Canine Chagas disease is increasingly diagnosed in dogs of the southern US where triatomine insect vectors occur, and there are limited veterinary diagnostic options; currently, only the indirect fluorescent antibody (IFA) test is offered at a single accredited diagnostic laboratory. This study evaluated a multiplex microsphere immunoassay (MIA) for detecting antibodies against T. cruzi in dogs and compared with existing serological methods to establish cut-off values and relative sensitivity/specificity. Dog sera (n=135) which were previously characterized using the IFA and off-label use of two commercial rapid assays were tested on the multiplex MIA against 12 different antigens: nine T. cruzi antigens, a negative control recombinant protein (green fluorescent protein), a Leishmania antigen, and a canine parvovirus antigen (used as an antibody control given near-ubiquitous parvovirus vaccination). For each sample, the ratio of median fluorescence intensity (MFI) for each T. cruzi antigen to that of GFP was calculated. Samples with an antigen/GFP ratio greater than 4 standard deviations above the mean of 25 known negative sera were considered positive on that antigen. Samples testing positive on 2 or more antigens were considered positive for T. cruzi antibodies. Compared to the IFA, the multiplex MIA demonstrated a relative sensitivity of 100% and specificity of 96.97%. Given its precision, high-throughput format, potential for automation, and lack of subjective interpretation, the multiplex MIA should be considered a valid and improved assay for T. cruzi antibodies in dogs.

microbiology↗

bioRxiv2023

Frequency variation and dose modification of benznidazole administration for the treatment of Trypanosoma cruzi infection in mice, dogs and non-human primates

Trypanosoma cruzi naturally infects a broad range of mammalian species and frequently results in the pathology that has been most extensively characterized in human Chagas disease. Currently employed treatment regimens fail to achieve parasitological cure of T. cruzi infection in the majority of cases. In this study, we have extended our previous investigations of more effective, higher dose, intermittent administration protocols using the FDA-approved drug benznidazole (BNZ), in experimentally infected mice and in naturally infected dogs and non-human primates (NHP). Collectively these studies demonstrate that twice-weekly administration of BNZ for more than 4 months at doses that are [~]2.5-fold that of previously used daily dosing protocols, provided the best chance to obtain parasitological cure. Dosing less frequently or for shorter time periods was less dependable in all species. Prior treatment using an ineffective dosing regimen in NHPs did not prevent the attainment of parasitological cure with an intensified BNZ dosing protocol. Furthermore, parasites isolated after a failed BNZ treatment showed nearly identical susceptibility to BNZ as those obtained prior to treatment, confirming the low risk of induction of drug resistance with BNZ and the ability to adjust the treatment protocol when an initial regimen fails. These results provide guidance for the use of BNZ as an effective treatment for T. cruzi infection and encourage its wider use, minimally in high value dogs and at-risk NHP, but also potentially in humans, until better options are available.

microbiology↗

bioRxiv2022

Collection of triatomines from sylvatic habitats by a Chagas-positive, trained scent-detection canine in Texas, USA

BackgroundTriatomine insects, vectors of the etiologic agent of Chagas disease (Trypanosoma cruzi), are challenging to locate in sylvatic habitats. Collection techniques used in the United States often rely on methods to intercept seasonally dispersing adults or on community scientists encounters. Neither method is suited for detecting nidicolous habitats, which is important for vector control. Furthermore, manual inspection of suspected harborages is unlikely to reveal novel locations and host associations. Similar to a team that used a trained dog to detect sylvatic triatomines in Paraguay, we worked with a trained scent detection dog to detect sylvatic locations of triatomines across Texas. Principle methodology/FindingsZiza, a 3-year-old German Shorthaired Pointer previously naturally infected with T. cruzi, was trained to detect triatomines. Over the course of 6 weeks in the fall of 2017, the dog and her handler visited 18 sites across Texas. The dog detected 60 triatomines at 7 locations; an additional 50 triatomines were contemporaneously collected at these sites without the assistance of the dog. Approximately 0.98 triatomines per hour were found when only humans were conducting searches; when working with the dog, approximately 1.71 triatomines per hour were found. In total, 3 adults and 107 nymphs of four species (Triatoma gerstaeckeri, Triatoma protracta, Triatoma sanguisuga, and Triatoma indictiva) were collected. PCR testing of a subset revealed T. cruzi infection, including DTUs TcI and TcIV, in 28% of nymphs (n=100) and 66% of adults (n=3). Blood meal analysis of a subset of triatomines (n=5) revealed feeding on Virginia opossum (Didelphis virginiana), Southern plains woodrat (Neotoma micropus) and eastern cottontail (Sylvilagus floridanus). Conclusion/SignificanceA trained scent detection dog enhanced triatomine detections in sylvatic habitats. This approach is especially effective at detecting triatomine nymphs and nidicolous locations. With new knowledge of specific sylvatic habitats and key hosts fed upon by triatomines, there are opportunities for continued exploration of novel vector control methods to block the transmission of T. cruzi to humans and domestic animals. Author summaryTriatomine insects, also known as kissing bugs, are vectors of Trypanosoma cruzi, the parasite that causes Chagas disease in humans, dogs, and other mammals. Triatomines are found throughout the Americas, but little is known about where these blood-sucking insects spend their early life stages. Knowing more is important to vector control initiatives aimed at interrupting Chagas disease transmission. Scent detection dogs have been trained to detect many pests, including one study of a triatomine detection dog in South America. In this study, we used a dog to detect triatomines in their natural environments throughout Texas. Over 6 weeks, the dog identified 60 triatomines at 7 different locations; an additional 50 triatomines were collected without the dogs assistance. Nearly twice as many triatomines were collected per hour when the dog was searching as compared to only humans searching. Of all the triatomine nymphs collected, 28% were positive for T. cruzi, and the blood meal analysis revealed kissing bugs had fed on Southern plains woodrat, opossum, and eastern cottontail. This study outlines a strategy that can be replicated in the United States to enhance the detection and control of habitats where triatomines spend their early life stages.

ecology↗

bioRxiv2022

Persistence of SARS-CoV-2 neutralizing antibodies longer than 13 months in naturally-infected, captive white-tailed deer (Odocoileus virginianus), Texas

After identifying a captive herd of white-tailed deer (WTD) in central Texas with >94% seroprevalence with SARS-CoV-2 neutralizing antibodies in September 2021, we worked retrospectively through archived serum samples of 21 deer and detected seroconversion of all animals between December 2020 and January 2021. We then collected prospective samples to conclude that the duration of persistence of neutralizing antibodies is at least 13 months for 19 (90.5%) of the animals, with two animals converting to seronegative after six and eight months. Antibody titers generally waned over this time frame, but three deer had a temporary 4 to 8-fold increases in PRNT titers over a month after seroconversion; anamnestic response cannot be ruled out.

zoology↗

bioRxiv2022

High seroprevalence of SARS-CoV-2 in white-tailed deer (Odocoileus virginianus) at one of three captive cervid facilities in Texas

Free-ranging white-tailed deer (Odocoileus virginanus) across the United States are increasingly recognized as involved in SARS-CoV-2 transmission cycles. Through a cross-sectional study of 80 deer at three captive cervid facilities in central and southern Texas, we provide evidence of 34 of 36 (94.4%) white-tailed deer at a single captive cervid facility seropositive for SARS-CoV-2 by neutralization assay (PRNT90), with endpoint titers as high as 1280. In contrast, all tested white-tailed deer and axis deer (Axis axis) at two other captive cervid facilities were seronegative, and SARS-CoV-2 RNA was not detected in respiratory swabs from deer at any of the three facilities. These data support transmission among captive deer that cannot be explained by human contact for each infected animal, as only a subset of the seropositive does had direct human contact. The facility seroprevalence was more than double of that reported from wild deer, suggesting that the confined environment may facilitate transmission. Further exploration of captive cervids and other managed animals for their role in the epizootiology of SARS-CoV-2 is critical for understanding impacts on animal health and the potential for spillback transmission to humans or other animal taxa. ImportanceAs SARS-CoV-2 vaccine coverge of the human population increases and variants of concern continue to emerge, identification of the epidemiologic importance of animal virus reservoirs is critical. We found that nearly all (94.4%) of the captive white-tailed deer at a cervid facility in central Texas had neutralizing antibodies for SARS-CoV-2. This seroprevalence is over double than that which has been reported from free-ranging deer from other regions of the US. Horizontal transmission among deer may be facilitated in confinement. Tracking new infections among wild and confined deer is critical for understanding the importance of animal reservoirs for both veterinary and human health.

zoology↗

bioRxiv2021

Unprecedented incidence of Trypanosoma cruzi infections in a cohort of dogs directly detected through longitudinal tracking at multi-dog kennels, Texas, USA

Canine Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is increasingly recognized as a health concern for dogs in the USA, and infected dogs may signal geographic regions of risk for human disease. Dogs living in multi-dog kennel environments where triatomine vectors are endemic may be at high risk for infection. We monitored a cohort of 64 T. cruzi-infected and uninfected dogs from across 10 kennels in Texas, USA, to characterize changes in infection status over time. We used robust diagnostic criteria in which reactivity on multiple independent platforms was required to be considered positive. Among the 30 dogs enrolled as serologically- and/or PCR-positive, all but one dog showed sustained positive T. cruzi diagnostic results over time. Among the 34 dogs enrolled as serologically- and PCR-negative, 10 new T. cruzi infections were recorded over a 12-month period. The resulting incidence rate was 30.7 T. cruzi infections per 100 dogs per year. This study highlights the risk of T. cruzi infection to dogs in kennel environments, despite multiple vector control methods employed by kennel owners. To protect both dog and human health, there is an urgent need to develop more integrated vector control methods as well as prophylactic and curative antiparasitic treatment options for T. cruzi infection in dogs.

zoology↗