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Epidemiology of COVID-19
Published in Srijan Goswami, Chiranjeeb Dey, COVID-19 and SARS-CoV-2, 2022
Rehab A. Rayan, Christos Tsagkaris, Imran Zafar, Aikaterini Tata
The R0 is a transmissibility measure, which indicates the theoretically expected number of secondary cases from each given case during an epidemic transmission period. An R0 > 1 is consistent with the spread of the epidemic. Considering the transmission period of the epidemic, R0 was estimated at 2–5, with the average ranging from 1.4–5.7. As expected, R0 has decreased since the outbreak of the pandemic in China and areas of Europe following the implementation of disease control measures (Xinhua, 2020).
Inflection points
Published in J. Michael Ryan, COVID-19, 2020
Two essential points are related to the question, why now? First, human-caused disruptions to the ecosystem bring animal viruses into closer contact with humans. Second, human technology and behavior are spreading pathogens more widely and more quickly (Quammen 2012). In 2008, researchers at the Zoological Society of London reviewed 300 emerging infectious diseases and found that 60% were zoonotic and that nearly 72% of these zoonotic diseases were caused by pathogens with a wildlife origin. They concluded, “Zoonoses from wildlife represent the most significant growing threat to global health” (Quammen 2012, 44). Why some outbreaks of zoonotic diseases disappear without causing devastation and others go viral has to do with the virus’s transmissibility and virulence. Transmission is traveling from one host to another, and transmissibility is how that is achieved. For example, shedding the virus by coughing or sneezing makes the virus highly transmissible. Influenzas are well adapted for airborne transmission, which is why SARS and COVID-19 have had such high rates of transmission. Ebola and HIV, on the other hand, are transmitted through direct contact with bodily fluids; other viruses are transmitted by airborne vectors, mosquitos, or tick bites.
Folie à deux (et folie à plusiers)
Published in David Enoch, Basant K. Puri, Hadrian Ball, Uncommon Psychiatric Syndromes, 2020
David Enoch, Basant K. Puri, Hadrian Ball
Many synonyms have been used, most reflecting the idea of the condition’s transmissibility, viz. “communicated insanity,” “contagious insanity,” “infectious insanity,” “psychosis of association” and “double insanity.” Although the condition usually involves two people, it can extend from the original subject to three, four, five persons, viz. folie à trois, folie à quatre, folie à cinq, or even a whole family, folie à famille (or folie en famille).
Problems related to measuring the transmissibility of anti-vibration gloves: possible efficacy for impact tools used in mining and quarrying activities
Published in International Journal of Occupational Safety and Ergonomics, 2023
Guido Alfaro Degan, Andrea Antonucci, Gianluca Coltrinari, Dario Lippiello
Dong et al. [52] also found that at each force level and for all of the frequency ranges, the grip-only action generally corresponds to the highest transmissibility, while the push-only action corresponds to the lowest. Another study [28] confirmed the aforementioned results, with a few differences in the frequency range behavior, probably due to the different materials used. This time, the experiment was conducted among six AV gloves with four different materials: gel pad, air bladder, neoprene and air bubbles. Here, as well, the results showed that increasing the hand force generally increased vibration transmissibility in the low frequency range (<50 Hz) but reduced the transmissibility in the middle frequency range (50–200 Hz). In this study, the transmissibility was also evaluated in the x and y direction. The results showed that in the z direction, vibration was affected more by force level than in the other two directions. These results are consistent with those reported by Gurram et al. [64], in which a slight average increase in the transmissibility was found among the main axis when different forces were applied to a sample of nine different gloves.
Modern vaccine strategies for emerging zoonotic viruses
Published in Expert Review of Vaccines, 2022
Atif Ahmed, Muhammad Safdar, Samran Sardar, Sahar Yousaf, Fiza Farooq, Ali Raza, Muhammad Shahid, Kausar Malik, Samia Afzal
The emergence of novel pathogens from the animal reservoir with enhanced capacity for dissemination is another potential threat to public health [1]. The occurrence of infectious diseases through zoonosis has significantly increased in number and severity over the last two decades [2]. Zoonotic pathogens are responsible for 65% of emerging infectious diseases in humans and are mostly related to viruses [3]. The cryptic transmission of zoonotic intracellular parasites is a unique property that promotes successful dissemination in the susceptible population until its proper diagnosis. These are mostly respiratory diseases and primarily spread in the human population through breathing; however, few viral particles follow alternate pathways of transmission, but their transmissibility is low. These infections originate from the spillover of pathogens from animal reservoirs that exhibit several new characteristics along with few previous features. Therefore, zoonotic viruses either reemerge in the same geographical regions with mutated genotypes or emerge in different geographical territories with similar gene sets. The emerging and reemerging viral diseases in different geographical locations through distinct animal reservoirs with unique transmission patterns are discussed in Table 1. However, the unpredictable nature, elevated case fatality rates, uncertainty in the determination of responsible animal reservoir, and unidentified modes of transmission are distinguished features of zoonotic organisms making it a global threat to human health [4].
COVID-19 and seasonal influenza
Published in Postgraduate Medicine, 2022
Aaron Lawson, Angel López-Candales
Even when implementation of current mitigation strategies has been for the most part efficacious; in reality their full benefit has been questioned. More importantly, objective, supportive data would have certainly been useful to support our efforts. The latter would have been very useful as we were initially told that SARS-CoV-2 was significantly more contagious than influenza. In order to clarify this controversial issue we can consider the explanation provided by Chen and associates as it relates to COVID and influenza spreading [17]. In their description, it is important to first describe transmissibility of infectious agents and for this we have to consider two important elements: (a) how many individuals in a susceptible population will be infected by someone with that disease and (b) variation in individual infectiousness [17]. In comparing COVID-19 and influenza, even though transmission of SARS-CoV-2 was highly overdispersed, as 60–75% of cases infect no one; superspreading events cause 80% of secondary infections [17]. In contrast, in the last H1N1 of 2009, a more uniform transmission of influenza A/H1N1pdm09 was seen with few instances of superspreading [17].