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Modes of Transmission of Coronavirus
Published in Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma, Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
Mohd. Faiz Saifi, Colin E. Evans, Neha Gupta
The pathogen’s transmission is crucial to disease biology and epidemiology. Transmission of viral infections is believed to occur when the pathogen (virion) exits its reservoir or host through an exit portal [1] and is then carried further by some mode of transmission and then via an appropriate entry portal infects the susceptible host. The majority of newly emerging viral diseases are becoming a public health threat [1]. Particularly, viruses emerging from wildlife hosts become a cause of high-impact disease as found in SARS, Ebola fever, influenza, and lately emerging COVID-19 in humans. The transfer of infectious agents from animals to humans via the mechanism of cross-species transmission is primarily responsible for the development of these diseases [2]. Furthermore, the transmission of the infectious agent can occur either as a vertical disease agent or a horizontal disease agent [3]. Vertical disease transmission involves the transmission of pathogens from parent to offspring such as in prenatal transmission while Horizontal transmission involves the transmission of pathogens from one individual to another in the same generation through various ways including physical contact, contaminated food, body fluids, airborne inhalation or via vectors [3]. Pandemics such as SARS and COVID-19 are considered to occur as a result of the advent of highly transmissible pathogens and pathogenic coronaviruses (CoVs) viz. SARS-CoV and SARS-CoV-2, respectively [3]. These coronaviruses cause infections of the lower respiratory tract, and SARS-CoV was first identified in Guangdong province, China, in 2002, and later in Wuhan, China, in December 2019 as SARS-CoV-2 [1]. Both SARS-CoV and SARS-CoV-2 are known to be originated from their common natural host bat and then transmitted the infection to humans via some intermediate animal host possibly through the mechanism of cross-species transmission. The current chapter describes the various possible modes of transmission for the emergent SARS-CoV-2 with a discussion on the mechanism of cross-species transmission and factors associated with the spread of SARS-CoV and SARS-CoV-2 [3]. Information provided here shall provide an in-depth understanding of various factors that are responsible for different modes of transmission for CoVs among humans and animals and may prove beneficial towards designing the strategies to break the chains of infection [4].
Prevalence of Bovine Leukemia Virus (BLV) and Bovine Adenovirus (BAdV) genomes among air and surface samples in dairy production
Published in Journal of Occupational and Environmental Hygiene, 2020
Agata Stobnicka-Kupiec, Małgorzata Gołofit-Szymczak, Rafał L. Górny, Marcin Cyprowski
Zoonotic diseases are serious health outcomes caused by spread of germs between animals and people. Over the last 30 years infectious diseases have been recognized as one of the most significant public health problems, mainly due to the emergence of novel viral zoonotic diseases (Wang and Crameri 2014). Zoonotic pathogens can substantially impact public health both in terms of disease morbidity and in socioeconomic factors such as livestock productivity (McDaniel et al. 2014). According to available data, higher probability of zoonotic disease transmission occurs in case of domestic animals than in wildlife. Thus, it is important to focus research effort on their precise recognition (Morand et al. 2014; Warren and Sawyer 2019). It is worth to remember that RNA viruses usually pose higher zoonotic risk than DNA viruses, as they can emerge and spread very rapidly. The ability of RNA viruses to replicate in the cytoplasm (without nuclear entry) is the strongest single predictor of cross-species transmission, including probably human infections (Pulliam and Dushoff 2009; Tomley and Shirley 2009). Nevertheless, DNA viruses (e.g., Adenoviridae) may also be a risk factor for zoonoses and are suspected of being transmissible between humans and other mammals (Ghebremedhin 2014; Phan et al. 2006; Woolhouse et al. 2016).
The global epidemiology of Microsporidia infection in birds: A systematic review and meta-analysis
Published in International Journal of Environmental Health Research, 2023
Ali Taghipour, Sahar Ghodsian, Mahdi Jabbari, Vahid Rajabpour, Saeed Bahadory, Narges Malih, Kavous Solhjoo, Mohammad Zibaei, Amir Abdoli
Over the past decade, epidemiological knowledge of Microsporidia infections has improved with advances in diagnostic methods and molecular markers (Thellier and Breton 2008; Li et al. 2020). Traditionally, using different techniques of staining and microscopic observation is one of the cheapest diagnostic methods for Microsporidia spores, but these spores could be misdiagnosed with other microorganisms (i.e. small yeasts and bacteria) (Ghosh et al. 2014). Therefore, difficult detection by this method requires a skilled and experienced operator (Heyworth 2017). In the current study, the results of the microscopic prevalence are higher than the molecular methods, which may be due to misdiagnosis with other elements and microorganisms. In this review, most of the included studies used PCR-based molecular techniques. The major advantage of using molecular tools is their capability for species/genotype identification, which is critical to understand the epidemiology and zoonotic potential (Katzwinkel-Wladarsch et al. 1997; Nooshadokht et al. 2017). In our study, molecular methods showed that the highest number of reports were related to E. bieneusi with a pooled prevalence of 9.7% (95% CI: 7.4–12.7%). Considering E. bieneusi genotypes, most studies reported the D (nine studies) and Peru-6 (nine studies) genotypes. For this purpose, sequence analysis of the ITS region of E. bieneusi was defined as a standard genotyping tool that brings important information regarding the infection origin and the pathogenicity of this eukaryote (Li et al. 2019; Shen et al. 2020). At least 474 genotypes (based of the ITS gene) have been identified by sequencing of the ITS region of the ribosomal RNA (rRNA) gene (Li et al. 2019; Shen et al. 2020). These genotypes can be broken down into 11 groups (groups 1–11) phylogenetically (Li et al. 2019; Shen et al. 2020). At least 106 genotypes have been detected in humans, most of them applied to groups 1 and 2 (Li et al. 2019; Shen et al. 2020). A wide range of the hosts, including humans, numerous mammals, and bird species are host of the group 1 genotypes (Li et al. 2019; Shen et al. 2020). Hence, these genotypes have low host specificity and have potential for zoonotic or cross-species transmission (Li et al. 2019; Shen et al. 2020). The group 2 genotypes have been reported in cattle, chickens, and humans (Li et al. 2019; Shen et al. 2020). Genotype D is one of the most prevalent genotypes with a wide range of host variations, including humans and animals (Li et al. 2019; Shen et al. 2020). Although genotype D was the most common genotype in this systematic review, other genotypes (e.g. Peru 5, Peru 11, J, I, type IV (K), BEB6, and CHN3) which have zoonotic potential were found in humans and birds (Table 4) (Li et al. 2019; Shen et al. 2020). Table 4 demonstrates the prevalence of E. bieneusi genotypes in each bird according to the country. As such, sporadic cases of E. bieneusi genotypes of group 5 (CSW2), group 10 (CHB1, MJ5, SCB-I, and SCB-III), and group 11 (PtEb IX and CD9) were reported in birds (Li et al. 2019; Shen et al. 2020).