Explanation: USDA researchers reported in 2021 that fewer than half of the white-tailed deer sampled exhibited antibodies indicative of prior SARS-CoV-2 infection. The actual figure reported was 40%.

Explanation: Contrary to the statement, a Penn State University study found that up to 80% of deer sampled in Iowa during the specified period tested positive for active SARS-CoV-2 infection, not necessarily 'nearly all'.

Explanation: Certain captive cervid facilities, characterized by high population densities and close proximity, have exhibited extremely high SARS-CoV-2 transmission rates, with active infection levels surpassing 90% in at least one instance.

Explanation: A nationwide USDA study from November 2021 to October 2022 indicated a decrease in active SARS-CoV-2 infections in white-tailed deer compared to earlier pandemic years, not a significant increase.

Explanation: According to USDA sampling in 2021, white-tailed deer in Michigan exhibited the highest percentage of SARS-CoV-2 antibodies, with 67% testing positive, followed by Pennsylvania at 44%.

Explanation: USDA researchers reported in 2021 that approximately 40% of sampled white-tailed deer exhibited evidence of SARS-CoV-2 antibodies.

Explanation: In the 2021 USDA sampling, Michigan reported the highest percentage of SARS-CoV-2 antibodies in white-tailed deer, with 67% of sampled deer testing positive.

Explanation: A Penn State University study indicated that up to 80% of deer sampled in Iowa between April 2020 and January 2021 tested positive for active SARS-CoV-2 infection, suggesting a significant prevalence.

Explanation: In at least one captive cervid facility, active SARS-CoV-2 infection levels were observed to exceed 90%, indicating extremely high transmission rates in such environments.

Explanation: A nationwide USDA study covering November 2021 to October 2022 observed a decrease in active SARS-CoV-2 infections in white-tailed deer compared to earlier pandemic periods.

Explanation: In March 2022, the WHO, FAO, and OIE jointly identified white-tailed deer as a newly formed wild animal reservoir for SARS-CoV-2, highlighting concerns about potential transmission dynamics and reinfection risks.

Explanation: Transmission among deer is primarily facilitated by close-contact social behaviors, such as sniffing, nuzzling, and sharing resources, rather than long-distance airborne droplets.

Explanation: Infected deer primarily shed SARS-CoV-2 through nasal secretions and feces; shedding through blood has not been identified as a primary route.

Explanation: An Ohio State University study provided evidence suggesting that humans transmitted SARS-CoV-2 to white-tailed deer on multiple occasions, and also identified deer strains with mutations uncommon in humans at the time. Evidence for deer-to-human transmission was suggested by other studies involving specific clades.

Explanation: A study conducted on Staten Island, New York City, revealed that wild white-tailed deer contracted the Omicron variant of SARS-CoV-2 shortly after its widespread prevalence in the human population.

Explanation: The Michigan mink spillover event, which resulted in human infections, was suggested to be linked to white-tailed deer, as two individuals infected with the mink strain reported recent hunting activities involving deer.

Explanation: A study analyzing spillover events identified approximately 109 independent instances of SARS-CoV-2 transmission from humans to white-tailed deer. The study also suggested potential deer-to-human transmission cycles.

Explanation: A USDA study confirmed that mule deer, similar to white-tailed deer, are capable of shedding live SARS-CoV-2 virus, indicating their potential role in transmission.

Explanation: 'Reverse zoonosis' specifically describes the transmission of a pathogen from humans to animals, initiating or sustaining an infection cycle within animal populations.

Explanation: While sniffing waste, sharing salt licks, and polygamous mating are mentioned as social behaviors facilitating transmission, grooming each other's fur is not explicitly listed as a contributing factor in the provided source.

Explanation: The Ohio State University study found evidence that humans transmitted SARS-CoV-2 to white-tailed deer on at least six distinct occasions.

Explanation: A study on Staten Island found that wild white-tailed deer contracted the Omicron variant of SARS-CoV-2 shortly after it became prevalent in the human population, with evidence suggesting potential for repeated reinfection.

Explanation: The Michigan mink spillover event, which led to human infections, was suggested to be linked to white-tailed deer, as two individuals infected with the mink strain reported recent hunting interactions with deer.

Explanation: A study analyzing spillover events identified approximately 109 independent instances of SARS-CoV-2 transmission from humans to white-tailed deer between November 2021 and April 2022.

Explanation: A USDA study confirmed that mule deer, analogous to white-tailed deer, possess the capability to shed live SARS-CoV-2 virus, indicating their potential role in transmission.

Explanation: In the context of SARS-CoV-2 and deer, 'reverse zoonosis' refers specifically to the transmission of the virus from humans to animals, initiating infection cycles within animal populations.

Explanation: The source indicates that a 2023 study found 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, contradicting the assertion of slower evolution.

Explanation: Research indicates that white-tailed deer possess the capacity to sustain active SARS-CoV-2 infections for extended durations, typically between six and nine months, which is considerably longer than observed in humans.

Explanation: Data from Pennsylvania confirmed the detection of a divergent Alpha variant strain of SARS-CoV-2 in white-tailed deer in late 2021, persisting long after it ceased to be dominant in human populations.

Explanation: Studies in New York State indicated the persistence of older SARS-CoV-2 variants, such as Alpha and Gamma, in white-tailed deer populations for over a year after their decline in local human populations, suggesting independent evolutionary pathways.

Explanation: The 'Ontario WTD clade' is a SARS-CoV-2 variant identified in white-tailed deer. Its significant number of mutations suggests it likely evolved in an intermediate animal host before infecting deer, rather than originating directly in humans.

Explanation: 'Deltacron' strains, which are hybrid variants potentially combining mutations from Delta and Omicron, are a concern not only for human-to-human transmission but also due to their potential evolution in animal hosts like mink and deer.

Explanation: Identifying white-tailed deer as a 'natural reservoir' implies the opposite: that the virus *can* persist and circulate indefinitely within the deer population, independent of human infections.

Explanation: A primary risk of SARS-CoV-2 evolution in deer is the potential development of variants with enhanced transmissibility, virulence, or immune evasion, posing greater threats upon re-transmission to humans.

Explanation: The extended duration of active SARS-CoV-2 infection in white-tailed deer, ranging from six to nine months, significantly increases opportunities for viral transmission and subsequent evolution within the deer population.

Explanation: The persistence of older SARS-CoV-2 variants, such as Alpha and Gamma, in deer populations suggests that these animals can serve as a reservoir for strains that are no longer dominant in humans, potentially leading to their re-emergence or further evolution.

Explanation: The 'triple rate' of viral evolution in deer signifies that the speed of genetic change in SARS-CoV-2 is approximately three times faster in white-tailed deer compared to humans, increasing the likelihood of new variant emergence.

Explanation: A 2023 study confirmed that SARS-CoV-2 evolves at an accelerated pace in white-tailed deer, approximately three times faster than the rate observed in humans.

Explanation: White-tailed deer can maintain active SARS-CoV-2 infections for extended periods, ranging from six to nine months, which is significantly longer than typical human infection durations.

Explanation: The Ohio State University study observed that SARS-CoV-2 strains detected in deer exhibited mutations that were uncommon in human strains circulating concurrently, suggesting potential evolutionary divergence.

Explanation: Pennsylvania test data indicated that a divergent Alpha variant strain of SARS-CoV-2 persisted in white-tailed deer populations in November 2021, long after this variant had ceased to be dominant in human populations.

Explanation: Studies in New York State revealed that older SARS-CoV-2 variants, such as Alpha and Gamma, persisted in white-tailed deer for over a year after their disappearance from local human populations, exhibiting greater genetic divergence in deer.

Explanation: The 'Ontario WTD clade' is significant because it infected a person with close deer contact, indicating potential deer-to-human transmission, and possessed numerous mutations suggesting evolution in an intermediate host.

Explanation: 'Deltacron' strains refer to hybrid variants that may arise from co-infections, potentially combining mutations from Delta and Omicron, and are a concern due to their possible evolution in animal hosts.

Explanation: The primary concern with white-tailed deer being identified as a 'natural reservoir' is the potential for SARS-CoV-2 to persist indefinitely and evolve new variants within the deer population, which could then be re-transmitted to humans.

Explanation: The primary risk associated with SARS-CoV-2 evolving new variants within deer populations is the potential emergence of strains with enhanced transmissibility, virulence, or immune evasion capabilities, which could pose greater risks to human health.

Explanation: The extended duration of SARS-CoV-2 infection in deer (6-9 months), compared to humans, implies increased opportunities for viral transmission within the deer population and for subsequent viral evolution.

Explanation: The persistence of older SARS-CoV-2 variants, such as Alpha and Gamma, in deer populations suggests that these animals can serve as a reservoir for strains that are no longer dominant in humans.

Explanation: The 'triple rate' of viral evolution in deer signifies that the speed of genetic change in SARS-CoV-2 is approximately three times faster in white-tailed deer compared to humans.

Explanation: A potential consequence of SARS-CoV-2 evolving in deer populations is the emergence of variants with increased transmissibility, virulence, or immune evasion capabilities, which could pose greater risks to human health.

Explanation: The study involving the 'Ontario WTD clade' suggested that this variant likely evolved in an intermediate animal host before infecting deer, evidenced by its numerous mutations and divergence.

Explanation: European deer species, such as roe and red deer, did not exhibit widespread SARS-CoV-2 infections in the initial phases of the pandemic, unlike North American white-tailed deer. This is attributed to factors like lower population density and less frequent human interaction.

Explanation: Canadian researchers identified older variants, specifically Alpha and Delta, circulating among wild deer populations. The Omicron variant was not explicitly mentioned as being widely found in Canadian wild deer in the provided source.

Explanation: The initial detection of SARS-CoV-2 in mule deer was reported by Utah wildlife officials, involving a Delta variant infection in Morgan County in late 2021.

Explanation: The migration of white-tailed deer into mule deer habitats may facilitate SARS-CoV-2 spread between species due to population overlap and potential interbreeding, rather than hindering it.

Explanation: Canadian researchers found that elk and moose populations did not show evidence of SARS-CoV-2 exposure, unlike white-tailed and mule deer.

Explanation: The first identified instance of SARS-CoV-2 infection in free-ranging European deer occurred in fallow deer in Dublin, Ireland, not in red deer in Germany.

Explanation: The initial detection of SARS-CoV-2 in mule deer in Utah involved the Delta variant, identified in Morgan County in late 2021.

Explanation: The first free-ranging European deer population identified with SARS-CoV-2 infection was in Dublin, Ireland, specifically among fallow deer.

Explanation: European deer species like roe and red deer exhibited fewer significant SARS-CoV-2 cases compared to North American white-tailed deer, likely due to lower population densities and less frequent human interactions, despite possessing susceptible ACE2 receptors.

Explanation: Canadian researchers identified the Alpha and Delta variants of SARS-CoV-2 circulating among wild deer populations. They also noted a strain previously observed only in the UK.

Explanation: The first active SARS-CoV-2 (Delta variant) infection in mule deer was detected in Morgan County, Utah, in late 2021.

Explanation: The migration of white-tailed deer into mule deer habitats may facilitate SARS-CoV-2 transmission between species due to increased population overlap and potential interbreeding.

Explanation: Canadian researchers found that elk and moose populations did not show evidence of SARS-CoV-2 exposure, unlike white-tailed and mule deer.

Explanation: The first free-ranging European deer population identified with SARS-CoV-2 infection was in Dublin, Ireland, specifically among fallow deer.

Explanation: A key factor contributing to widespread SARS-CoV-2 outbreaks in North American white-tailed deer is their high population density and frequent interactions with humans, contrasting with European deer populations.

Explanation: Research indicates that SARS-CoV-2 primarily replicates in the upper respiratory tract of deer, particularly nasal structures, rather than the lower respiratory tract.

Explanation: The Ohio State University study identified six mutations in deer strains of SARS-CoV-2 that were uncommon in human strains circulating at that time, indicating potential independent evolution within the deer population.

Explanation: Seroconversion, defined as the development of antibodies in response to infection, can occur rapidly in deer following SARS-CoV-2 exposure, potentially within one week post-infection.

Explanation: The ACE2 receptors in deer are structurally similar to those in humans, which facilitates SARS-CoV-2 entry into deer cells and is a key factor in the virus's ability to infect these animals.

Explanation: In March 2022, the World Health Organization (WHO), Food and Agriculture Organization (FAO), and World Organisation for Animal Health (OIE) jointly identified white-tailed deer as a newly formed wild animal reservoir for SARS-CoV-2.

Explanation: Research indicates that SARS-CoV-2 primarily replicates within the upper respiratory tract of deer, specifically in nasal structures, and has also been detected in tonsils and lymph nodes.

Explanation: In the context of SARS-CoV-2 infection in deer, 'seroconversion' refers to the development of antibodies in response to the infection, which can occur rapidly.

Explanation: The structural similarity of ACE2 receptors between deer and humans is significant because it allows SARS-CoV-2 to utilize the same cellular entry mechanism in both species, facilitating infection.