Biology subjects

Hamer, G. L.

Publications and source records attributed to Hamer, G. L..

17 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

Eastern equine encephalitis virus-vaccinated mice are protected against Madariaga virus despite negligible neutralizing antibody titers

Madariaga virus (MADV) is an understudied member of the eastern equine encephalitis virus (EEEV) complex that circulates widely in Latin America and may be geographically expanding. Spillover infections can cause severe disease in humans and equids. Despite these public and animal health concerns, no MADV vaccines or treatments are available. In this context, commercially available equine vaccines against the closely related North American EEEV (NA EEEV) could potentially provide heterologous protection against MADV. However, previous studies have shown weak or undetectable MADV-neutralizing antibody responses in equids and humans immunized with inactivated NA EEEV vaccines, and whether protection can occur despite these limited neutralizing antibody responses remains unknown. We evaluated a commercial equine trivalent inactivated NA EEEV vaccine against MADV challenge in NIH Swiss mice. Animals received two vaccine doses 14 days apart and were challenged 14 days later. Vaccination provided protection against lethal disease, whereas 36% mortality occurred in the unvaccinated group. Overall, vaccinated animals developed fewer and less severe clinical signs. MADV RNAemia was not detected following vaccination, and tissue dissemination was significantly reduced compared with the unvaccinated group. Central nervous system lesions were observed only in the unvaccinated group. Despite protection, most vaccinated mice had no detectable MADV-neutralizing antibody titers, and those that seroconverted developed only low titers, whereas most unvaccinated mice developed intermediate to high titers. These findings demonstrate that an inactivated NA EEEV-containing vaccine can protect against severe MADV disease despite limited MADV-neutralizing antibody responses.

systems biology↗

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

Transmission potential of Culex and Aedes species for Madariaga virus, a member of the eastern equine encephalitis virus complex

Madariaga virus (MADV), widely distributed in Latin America, can cause severe disease in humans and equids, yet, key aspects of its transmission cycle remain unclear. To identify mosquitoes that could act as MADV vectors, we assessed the vector competence of Aedes aegypti, Ae. albopictus, Ae. taeniorhynchus, Culex tarsalis, Cx. coronator, and Cx. quinquefasciatus, following oral exposure to MADV isolated in Panama (all species) or Brazil (Ae. taeniorhynchus only). MADV RNA and infectious virus were quantified from mosquito bodies, legs, and saliva. At 14 days post-exposure, five species had virus in all biological sample types. Culex quinquefasciatus was susceptible to infection and dissemination but had no positive saliva samples. Aedes taeniorhynchus showed higher infection probabilities with MADV-BR. Time-course analysis revealed distinct dynamics in Ae. aegypti and Ae. albopictus. Our findings indicate MADV may be compatible with mosquito species present in endemic regions and areas at risk of virus introduction.

molecular biology↗

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

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↗

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↗

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

Diel activity patterns of vector mosquito species in the urban environment: Implications for vector control strategies

Florida and Texas continue to be afflicted by mosquito-borne disease outbreaks such as dengue and West Nile virus disease and were the most affected states by the Zika outbreak of 2016-2017. Mathematical models have been widely used to study the population dynamics of mosquitoes as well as to test and validate the effectiveness of arbovirus outbreak responses and mosquito control strategies. The objective of this study is to assess the diel activity of mosquitoes in Miami-Dade, Florida and Brownsville, Texas, and to evaluate the effectiveness of simulated adulticide treatments on local mosquito populations. To assess variations in the diel activity patterns, mosquitoes were collected hourly for 96 hours once a month from May through November 2019 in Miami-Dade and Brownsville, Texas. We then performed a PERMANOVA followed by the SIMPER method to assess which species contributed the most to the observed differences. Finally, we used a mathematical model to simulate the population dynamics of 5 mosquito vector species to evaluate the effectiveness of the simulated adulticide applications. A total of 14,502 mosquitoes comprising 17 species were collected in Brownsville and 10,948 mosquitoes comprising 19 species were collected in Miami-Dade. Aedes aegypti was the most common mosquito species collected every hour in both cities and peaking in abundance in the morning and the evening. Our modeling results indicate that the effectiveness of adulticide applications varied greatly depending on the hour of the treatment. Overall, 9 PM was the best time for adulticide applications targeting all mosquito vector species in Miami-Dade and Brownsville. Our results indicate that the timing of adulticide spraying interventions should be carefully considered by local authorities based on the ecology of mosquito species in the focus area.

ecology↗

bioRxiv2022

A Novel Regioselective Approach to Cyclize Phage-Displayed Peptides in Combination with Epitope-Directed Selection to Identify a Potent Neutralizing Macrocyclic Peptide for SARS-CoV-2

Using the regioselective cyanobenzothiazole condensation reaction with the N-terminal cysteine and the chloroacetamide reaction with an internal cysteine, a phage-displayed macrocyclic 12-mer peptide library was constructed and subsequently validated. Using this library in combination with iterative selections against two epitopes from the receptor binding domain (RBD) of the SARS-CoV-2 Spike protein, macrocyclic peptides that strongly inhibit the interaction between the Spike RBD and ACE2, the human host receptor of SARS-CoV-2, were identified. The two epitopes were used instead of the Spike RBD to avoid selection of nonproductive macrocyclic peptides that bind RBD but do not directly inhibit its interactions with ACE2. Antiviral tests against SARS-CoV-2 showed that one macrocyclic peptide is highly potent against viral reproduction in Vero E6 cells with an EC50 value of 3.1 M. The AlphaLISA-detected IC50 value for this macrocyclic peptide was 0.3 M. The current study demonstrates that two kinetically-controlled reactions toward N-terminal and internal cysteines, respectively, are highly effective in the construction of phage-displayed macrocyclic peptides, and the selection based on the SARS-CoV-2 Spike epitopes is a promising methodology in the identification of peptidyl antivirals.

biochemistry↗

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↗

bioRxiv2020

Natural SARS-CoV-2 infections, including virus isolation, among serially tested cats and dogs in households with confirmed human COVID-19 cases in Texas, USA

The natural infections and epidemiological roles of household pets in SARS-CoV-2 transmission are not understood. We conducted a longitudinal study of dogs and cats living with at least one SARS-CoV-2 infected human in Texas and found 47.1% of 17 cats and 15.3% of 59 dogs from 25.6% of 39 households were positive for SARS-CoV-2 via RT-PCR and genome sequencing or neutralizing antibodies. Virus was isolated from one cat. The majority (82.4%) of infected pets were asymptomatic. Re-sampling of one infected cat showed persistence of viral RNA at least 32 d-post human diagnosis (25 d-post initial test). Across 15 antibody-positive animals, titers increased (33.3%), decreased (33.3%) or were stable (33.3%) over time. A One Health approach is informative for prevention and control of SARS-CoV-2 transmission.

zoology↗

bioRxiv2020

Global patterns of aegyptism without arbovirus

The worlds most important mosquito vector of viruses, Aedes aegypti, is found around the world in tropical, subtropical and even some temperate locations. While climate change may limit populations of Ae. aegypti in some regions, increasing temperatures will likely expand its territory thus increasing risk of human exposure to arboviruses in places like Europe, Northern Australia and North America, among many others. Most studies of Ae. aegypti biology and virus transmission focus on locations with high endemicity or severe outbreaks of human amplified urban arboviruses, such as dengue, Zika, and chikungunya viruses, but rarely on areas at the margins of endemicity. Our objective in this study is to explore global patterns in the environmental suitability for Ae. aegypti and dengue virus to reveal deviations in the probability of the vector and human disease occurring. We developed a map showing one end of the gradient being higher suitability of Ae. aegypti with low suitability of dengue and the other end of the spectrum being equal and higher environmental suitability for both Ae. aegypti and dengue. The regions of the world with Ae. aegypti environmental suitability and no endemic dengue transmission exhibits a phenomenon we term aegyptism without arbovirus. We then tested what environmental and socioeconomic variables influence this deviation map revealing a significant association with population density, suggesting that locations with lower population density were more likely to have a higher probability of aegyptism without arbovirus. Characterizing regions of the world with established populations of Ae. aegypti but little to no autochthonous transmission of human-amplified arboviruses is an important step in understanding and achieving aegyptism without arbovirus.

ecology↗