What percentage of white-tailed deer sampled by USDA researchers in 2021 showed evidence of SARS-CoV-2 antibodies, and where were the highest percentages found?

In 2021, USDA researchers found that 40% of sampled white-tailed deer exhibited evidence of SARS-CoV-2 antibodies. The highest concentrations of these antibodies were detected in Michigan, where 67% of the sampled deer tested positive, and in Pennsylvania, with 44% testing positive.

How did international health organizations characterize the role of white-tailed deer in relation to SARS-CoV-2 in March 2022?

In March 2022, the World Health Organization (WHO), Food and Agriculture Organization (FAO), and World Organisation for Animal Health (OIE) jointly issued a statement identifying white-tailed deer as an example of a newly formed wild animal reservoir for SARS-CoV-2.

What did a 2023 study reveal about the evolution rate of SARS-CoV-2 in white-tailed deer?

An August 2023 study confirmed that SARS-CoV-2 evolves at an accelerated pace in white-tailed deer, approximately three times faster than the rate of viral evolution observed in humans. This study also found high SARS-CoV-2 positivity rates in deer even in rural areas, suggesting widespread infection.

How long can white-tailed deer maintain active SARS-CoV-2 infections compared to humans?

White-tailed deer can maintain active SARS-CoV-2 infections for significantly longer periods than humans, with infections lasting anywhere from six to nine months.

How do white-tailed deer contribute to the spread of SARS-CoV-2 among themselves?

Infected deer can shed the virus through nasal secretions and feces for 5-6 days. Their social behaviors, such as sniffing each other's waste, nuzzling noses, engaging in polygamous mating, and sharing salt licks, create conditions conducive to viral transmission within the deer population.

Where in the deer's body does SARS-CoV-2 primarily replicate, and in which other tissues has it been found?

Similar to humans, SARS-CoV-2 replicates within the upper respiratory tract of deer, particularly in nasal structures. The virus has also been detected in the tonsils, lymph nodes, and central nervous system tissue of infected deer.

What transmission rates have been observed in captive cervid facilities?

Captive cervid facilities, where deer are kept in close proximity for breeding or hunting purposes, have shown extremely high transmission rates of SARS-CoV-2, with active infection levels exceeding 90% in at least one such facility.

Why might European deer species not have shown significant SARS-CoV-2 infection rates compared to North American white-tailed deer?

While European deer species like roe, red, and fallow deer possess the ACE2 receptor susceptible to SARS-CoV-2, they did not show significant cases of infection in the first two years of the pandemic. This suggests that the high density of white-tailed deer populations in North America and their frequent interactions with humans are key factors contributing to the widespread outbreaks observed there.

What did an Ohio State University study find regarding human-to-deer transmission and deer mutations?

A 2021 study from Ohio State University found that humans had transmitted SARS-CoV-2 to white-tailed deer on at least six separate occasions. Notably, the deer in their study exhibited six mutations that were uncommon in human strains at that time.

How has the Alpha variant of SARS-CoV-2 persisted in white-tailed deer populations?

Test data from Pennsylvania revealed the presence of a divergent Alpha variant strain in white-tailed deer in November 2021, long after it had ceased to be dominant in humans. Further studies in 2023 showed the Alpha variant persisting in deer over a year after its last detection in local human populations, suggesting independent evolution within deer.

What evidence suggests that SARS-CoV-2 variants can evolve independently in deer?

Studies in New York State found Alpha and Gamma strains in white-tailed deer more than a year after their last detection in local human populations. These older variants, which had nearly disappeared in humans, showed greater genetic divergence in deer than recent human strains found in wild deer, indicating independent evolution pathways.

What did Canadian researchers observe regarding SARS-CoV-2 variants in wild deer populations?

Canadian researchers identified the older Alpha and Delta variants among wild deer populations. They also noted a strain circulating among white-tailed deer that had previously only been observed in humans in the United Kingdom.

What was discovered about the Omicron variant in New York City's white-tailed deer population?

A study of white-tailed deer on Staten Island, New York City, starting in December 2021, found that wild deer had contracted the Omicron variant shortly after it became prevalent in humans. The presence of high antibody levels in one infected deer suggested that deer can be repeatedly reinfected with SARS-CoV-2.

What is the significance of the 'Ontario WTD clade' discovery?

The 'Ontario WTD clade' is a new SARS-CoV-2 variant identified in Ontario white-tailed deer. Its discovery is significant because it infected a person with close deer contact, suggesting a potential deer-to-human transmission. The variant also possessed 76 mutations, indicating it likely evolved in an intermediate animal host, accumulating significant divergence.

What was the nature of the SARS-CoV-2 spillover event involving Michigan mink and its connection to deer?

A SARS-CoV-2 spillover event involving mink in Michigan resulted in four human infections, which were only publicly announced months after their discovery. Two individuals infected with the Michigan mink strain reported recent interactions with white-tailed deer while hunting, suggesting a possible link between mink, deer, and human transmission.

What are 'Deltacron' strains in the context of SARS-CoV-2 in deer?

'Deltacron' strains refer to hybrid variants that may arise when Delta strains pick up Omicron mutations through co-infection in animals like mink and deer. Scientists are monitoring these strains due to the potential combination of Delta's increased fatality rate with Omicron's enhanced transmissibility.

What did a study on spillover events reveal about human-to-deer and deer-to-human transmission cycles?

A study from November 2021 to April 2022 identified 109 independent spillover events from humans to white-tailed deer. It also suggested three instances of double-spillover, where the virus went from human to deer, back to human, and then to deer again. Additionally, 18 deer samples could not be traced to closely related human strains in the sampling regions.

What did a nationwide USDA study reveal about SARS-CoV-2 infection trends in white-tailed deer from 2021 to 2022?

A nationwide USDA study conducted from November 2021 to October 2022 across 29 states found widespread prior SARS-CoV-2 infection in white-tailed deer. However, the number of active infections had decreased compared to earlier pandemic years, possibly due to seasonal variations or the transmissibility rates of recent Omicron strains in deer.

What is 'seroconversion' and why is it relevant to SARS-CoV-2 transmission in deer?

Seroconversion is the development of antibodies in response to an infection. The possibility of rapid seroconversion in deer, occurring as quickly as one week post-infection, highlights the need for continued research into transmission pathways and management strategies for disease spillover between humans and deer.

What was the first detection of SARS-CoV-2 in mule deer, and where did it occur?

The first detection of SARS-CoV-2 in mule deer was announced by Utah wildlife officials following a November-December 2021 field study. A female mule deer in Morgan County, Utah, was found to have an active Delta variant infection, while several other deer showed evidence of antibodies.

How has the migration of white-tailed deer potentially influenced SARS-CoV-2 spread in mule deer habitats?

White-tailed deer have been migrating into traditional mule deer habitats, including Morgan County, Utah, since the early 2000s. This overlap in populations may facilitate the transmission of SARS-CoV-2 between the two species, as white-tailed deer can mate and hybridize with mule deer.

Did SARS-CoV-2 exposure extend to other cervid species like elk and moose in Canada?

Canadian researchers expanded testing to cervids beyond white-tailed deer. While both white-tailed deer and mule deer tested positive for variants circulating in the United States, elk and moose did not show evidence of exposure to SARS-CoV-2.

What did a USDA study find about mule deer's ability to shed SARS-CoV-2?

A USDA study found that mule deer, similar to white-tailed deer, are capable of shedding live SARS-CoV-2 virus. This indicates that mule deer also possess the potential to infect other animals with the virus.

Where was the first instance of SARS-CoV-2 infection found in European deer populations?

In a study published in 2023, free-ranging European fallow deer in Dublin, Ireland, were identified as the first deer population outside of North America to have contracted SARS-CoV-2, raising concerns about further spread.

What is the significance of white-tailed deer being identified as a 'natural reservoir' for SARS-CoV-2?

Identifying white-tailed deer as a natural reservoir means the virus can persist and potentially circulate indefinitely within the deer population, independent of human infections. This raises concerns about the virus evolving new variants within deer that could potentially re-transmit to humans.

What role do ACE2 receptors play in SARS-CoV-2 infection in deer?

White-tailed deer possess ACE2 receptors that are similar to those in humans, which SARS-CoV-2 uses to enter cells. This similarity in cellular structure is a key reason why the virus can infect deer.

What is the potential risk associated with SARS-CoV-2 evolving in deer populations?

The primary risk is that SARS-CoV-2 could evolve into new variants within deer populations. These variants might possess mutations that enhance transmissibility, virulence, or immune evasion, potentially posing a greater threat upon re-transmission to humans or other animal species.

What is 'reverse zoonosis' in the context of SARS-CoV-2 and deer?

Reverse zoonosis refers to the transmission of a pathogen from humans back to animals. In this context, it describes how humans infected with SARS-CoV-2 can transmit the virus to white-tailed deer, initiating the cycle of infection within the deer population.

How does the long duration of infection in deer (6-9 months) compare to humans?

The extended duration of active SARS-CoV-2 infection in white-tailed deer, lasting six to nine months, is considerably longer than the typical infection period in humans. This prolonged shedding period could increase opportunities for transmission and viral evolution within the deer population.

What is the implication of finding older SARS-CoV-2 variants like Alpha and Gamma in deer populations long after they declined in humans?

The persistence of older variants in deer suggests that these animals can act as a reservoir for strains that are no longer dominant in humans. This raises concerns because these archived strains could potentially re-emerge or evolve further within the deer population, possibly leading to new challenges for human immunity.

What is the significance of the 'triple rate' of viral evolution in deer mentioned in the text?

The statement that SARS-CoV-2 evolves at triple the rate in white-tailed deer compared to humans implies that the virus undergoes genetic changes much more rapidly within the deer population. This accelerated evolution increases the likelihood of new variants emerging that could potentially impact human health.

Sars-cov-2 In White-tailed Deer Wiki: Viral Dynamics in Wildlife: SARS-CoV-2 and White-Tailed Deer

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Introduction

Initial Findings

Research conducted by the USDA in 2021 revealed significant SARS-CoV-2 exposure in white-tailed deer populations. Blood samples indicated that approximately 40% of deer tested had antibodies, suggesting prior infection. States like Michigan (67%) and Pennsylvania (44%) showed particularly high percentages.^[1]

Potential Reservoir Identified

A subsequent study by Penn State University and Iowa wildlife officials indicated that up to 80% of Iowa deer sampled between April 2020 and January 2021 tested positive for active SARS-CoV-2 infection, not just antibodies. This discovery, confirmed by the National Veterinary Services Laboratory, alerted scientists to the possibility that white-tailed deer might serve as a natural reservoir for the virus, potentially acting as a "variant factory" for transmission back to humans.^[2]

Global Health Consensus

In March 2022, a joint statement from the World Health Organization (WHO), Food and Agriculture Organization (FAO), and World Organisation for Animal Health (OIE) specifically highlighted white-tailed deer as an example of a newly formed wild animal reservoir for SARS-CoV-2.^[3]

Transmission Dynamics

Viral Shedding and Spread

Infected deer can shed the virus through nasal secretions and feces for approximately 5–6 days. Their natural behaviors, such as sniffing intermingled food and waste, nuzzling, and sharing salt licks, create conditions conducive to viral transmission within populations.^[7] The virus primarily replicates in the upper respiratory tract, specifically nasal structures, but has also been detected in tonsils, lymph nodes, and central nervous system tissue.^[8]

Receptor Similarity

White-tailed deer possess an ACE2 receptor similar to humans, which SARS-CoV-2 utilizes for cell entry. While other deer species in Europe (roe, red, fallow deer) also exhibit this susceptibility, they have not shown widespread infection, suggesting that the high population density and frequent human interactions characteristic of North America are key factors in the observed outbreaks.^[10]

High Transmission in Captivity

Facilities housing captive cervids (deer farms, hunting preserves) have demonstrated exceptionally high transmission rates, with some studies showing active infection levels exceeding 90% in specific locations due to the close proximity of animals.^[9]

Mutations and Variants

Accelerated Evolution

Studies indicate that SARS-CoV-2 evolves at an accelerated rate within white-tailed deer, reportedly three times faster than in humans.^[4] An Ohio State University study identified six mutations in the deer virus strains that were uncommon in humans at the time of the study.^[11]

Persistence of Older Strains

Evidence suggests that older variants, such as the Alpha and Delta strains, which had largely disappeared from human circulation, have persisted and continued to evolve independently within deer populations. For instance, Alpha variant strains were detected in Pennsylvania deer long after their last detection in local human populations.^[10]^[12] Similarly, findings in New York and Canada confirmed the presence of these older variants, alongside strains previously seen only in the UK, indicating distinct evolutionary pathways in deer.^[13]^[14]

Omicron and Reinfection

The Omicron variant was detected in New York deer populations shortly after its emergence in humans. High antibody levels in some infected deer suggest they can be repeatedly reinfected.^[15] Furthermore, a novel variant, termed the "Ontario WTD clade," was identified in Canadian deer, exhibiting significant divergence (76 mutations compared to the original virus) and potentially arising from an intermediate host.^[17]

Spillover and Spillback Cycles

Human-to-Deer Transmission

Genomic analysis has identified numerous instances of SARS-CoV-2 spilling over from humans to white-tailed deer. One study documented 109 independent spillover events.^[22]

Potential Deer-to-Human Transmission

Concerns exist regarding the potential for deer-to-human transmission. The discovery of the "Ontario WTD clade" variant in a deer population, followed by its detection in a human who had close contact with local deer, suggests this possibility.^[16] Additionally, some human infections linked to a Michigan mink-associated strain reported recent interactions with deer, further fueling these concerns.^[20]

Complex Transmission Pathways

The data suggests complex transmission cycles, including potential "double-spillover" events where the virus moves from humans to deer, back to humans, and then again to deer. Furthermore, some viral sequences found in deer could not be traced to closely related human strains in the same geographic areas, indicating independent evolution or undetected transmission chains.^[23]

Infection Variability

Nationwide Prevalence

A nationwide USDA study covering 29 states (most of the US white-tailed deer range) from November 2021 to October 2022 indicated widespread prior infection. However, the number of active infections appeared lower compared to earlier pandemic periods. This decrease might be influenced by seasonal factors and the transmissibility of recent Omicron strains in deer.^[24]

Rapid Seroconversion

The potential for rapid seroconversion—developing antibodies within a week of infection—highlights the need for ongoing research into transmission pathways and effective management strategies for human-animal viral exchange.^[24]

Hybrid Strains

The potential exists for "Deltacron" strains, hybrids resulting from co-infections of Delta and Omicron variants in intermediate hosts like mink and deer. Such strains could theoretically combine the increased fatality of Delta with the enhanced transmissibility of Omicron.^[21]

Related Species

Mule Deer and Others

The first case of SARS-CoV-2 in mule deer was detected in Utah in late 2021, with active Delta variant infection found in one deer. White-tailed deer, known to hybridize with mule deer, have been migrating into mule deer habitats, potentially facilitating virus spread.^[25]^[26]

European Fallow Deer

In 2023, a study confirmed SARS-CoV-2 infection in free-ranging European fallow deer in Dublin, Ireland, marking the first documented instance outside North America.^[29]

Canadian Observations

Canadian research identified Alpha and Delta variants in wild deer populations, similar to US findings. They also observed strains previously seen only in the UK.^[14] Studies confirmed that mule deer, like white-tailed deer, can shed live virus, posing a similar risk for animal-to-animal transmission.^[28] Elk and moose, however, did not show evidence of exposure in Canadian studies.^[14]

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References

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Viral Dynamics in Wildlife

💡 Dive in with Flashcard Learning! 💡

Introduction ℹ️

🔬 Initial Findings

⚠️ Potential Reservoir Identified

🌍 Global Health Consensus

Transmission Dynamics 🦌

💨 Viral Shedding and Spread

🧬 Receptor Similarity

🏢 High Transmission in Captivity

Mutations and Variants 🔄

📈 Accelerated Evolution

⏳ Persistence of Older Strains

❓ Omicron and Reinfection

Spillover and Spillback Cycles ↔️

➡️ Human-to-Deer Transmission

👤 Potential Deer-to-Human Transmission

🔄 Complex Transmission Pathways

Infection Variability 📊

📉 Nationwide Prevalence

⏱️ Rapid Seroconversion

❓ Hybrid Strains

Related Species 🐾

🦌 Mule Deer and Others

🌎 European Fallow Deer

🇨🇦 Canadian Observations

Teacher's Corner 🧑‍🏫

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References

📜 References

Feedback & Support 👍

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Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

Introduction

Initial Findings

Potential Reservoir Identified

Global Health Consensus

Transmission Dynamics

Viral Shedding and Spread

Receptor Similarity

High Transmission in Captivity

Mutations and Variants

Accelerated Evolution

Persistence of Older Strains

Omicron and Reinfection

Spillover and Spillback Cycles

Human-to-Deer Transmission

Potential Deer-to-Human Transmission

Complex Transmission Pathways

Infection Variability

Nationwide Prevalence

Rapid Seroconversion

Hybrid Strains

Related Species

Mule Deer and Others

European Fallow Deer

Canadian Observations

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice