Potential Transmission Routes Research Articles

Infection Risk Assessment of COVID-19 through Aerosol Transmission: a Case Study of South China Seafood Market.

The Corona Virus Disease 2019 (COVID-19) is rapidly spreading throughout the world. Aerosol is a potential transmission route. We conducted the quantitative microbial risk assessment (QMRA) to evaluate the aerosol transmission risk by using the South China Seafood Market as an example. The key processes were integrated, including viral shedding, dispersion, deposition in air, biologic decay, lung deposition, and the infection risk based on the dose–response model. The available hospital bed for COVID-19 treatment per capita (1.17 × 10–3) in Wuhan was adopted as a reference for manageable risk. The median risk of a customer to acquire SARS-CoV-2 infection via the aerosol route after 1 h of exposure in the market with one infected shopkeeper was about 2.23 × 10–5 (95% confidence interval: 1.90 × 10–6 to 2.34 × 10–4). The upper bound could increase and become close to the manageable risk with multiple infected shopkeepers. More detailed risk assessment should be conducted in poorly ventilated markets with multiple infected cases. The uncertainties were mainly due to the limited information on the dose–response relation and the viral shedding which need further studies. The risk rapidly decreased outside the market due to the dilution by ambient air and became below 10–6 at 5 m away from the exit.

The WetNet: What the Oral Polio Vaccine Hypothesis Exposes about Globalized Interspecies Fluid Bonds.

The author analyzes the aftermath of EdwardHooper's suggestion that the trial of an oral polio vaccine (OPV) in the Belgian colonies of Africa engendered the pandemic form of the AIDS virus, HIV-1. In response toHooper's book,The River (1999),the Royal Society in London held a conference to debate the origins of HIV. Examination of the quick dismissal of the OPV theory opens a space for legitimately challenging the widely held belief that the vaccine contamination question was convincingly resolved. This article interrogates the relationship between historiography and the making of scientific facts and history, suggesting that historians have been too credulous of scientists' testimony. The further result of the lack of a thorough analysis of the evidence backing the OPV hypothesis has resulted in a missed opportunity to read The River as one of the few detailed accounts of the immense social, political, technological, and interspecies infrastructure constituted by Cold War vaccine production. This biomedical infrastructure dramatically changed the geographic and interspecies mobility of viruses in ways that may be impossible to reconstruct. Yet these potential transmission routes remain crucial to acknowledge. The COVID-19 pandemic draws attention to the critical importance of studying The WetNet, a concept coined by the author to name the conceptual and material infrastructures of inter- and intraspecies fluid bonding.

Recreational waters – A potential transmission route for SARS-CoV-2 to humans?

Coronavirus disease 2019 (COVID-19), the respiratory illness caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has lead to high morbidity and mortality rates worldwide, has been causing major public health concerns since first detected in late 2019. Following identification of novel pathogens, questions in relation to dissemination of the pathogen and transmission routes begin to emerge. This rapidly spreading SARS-CoV-2 virus has been detected in both faecal and wastewater samples across the globe, highlighting the potential for faecal-oral transmission of the virus. As a result, concerns regarding the transmission of the virus in the environment and the risk associated with contracting the virus in recreational waters, particularly where inadequately treated wastewater is discharged, have been emerging in recent weeks. This paper highlights the need for further research to be carried out to investigate the presence, infectivity and viability of this newly identified SARS-CoV-2 virus in wastewater effluent and receiving recreational waters.

Airborne SARS-CoV-2 Is Rapidly Inactivated by Simulated Sunlight.

Aerosols represent a potential transmission route of COVID-19. This study examined effect of simulated sunlight, relative humidity, and suspension matrix on stability of SARS-CoV-2 in aerosols. Simulated sunlight and matrix significantly affected decay rate of the virus. Relative humidity alone did not affect the decay rate; however, minor interactions between relative humidity and other factors were observed. Mean decay rates (± SD) in simulated saliva, under simulated sunlight levels representative of late winter/early fall and summer were 0.121 ± 0.017 min−1 (90% loss, 19 minutes) and 0.306 ± 0.097 min−1 (90% loss, 8 minutes), respectively. Mean decay rate without simulated sunlight across all relative humidity levels was 0.008 ± 0.011 min−1 (90% loss, 286 minutes). These results suggest that the potential for aerosol transmission of SARS-CoV-2 may be dependent on environmental conditions, particularly sunlight. These data may be useful to inform mitigation strategies to minimize the potential for aerosol transmission.

Co-expression of SARS-CoV-2 entry genes in the superficial adult human conjunctival, limbal and corneal epithelium suggests an additional route of entry via the ocular surface

PurposeThe high infection rate of SARS-CoV-2 necessitates the need for multiple studies identifying the molecular mechanisms that facilitate the viral entry and propagation. Currently the potential extra-respiratory transmission routes of SARS-CoV-2 remain unclear. MethodsUsing single-cell RNA Seq and ATAC-Seq datasets and immunohistochemical analysis, we investigated SARS-CoV-2 tropism in the embryonic, fetal and adult human ocular surface. ResultsThe co-expression of ACE2 receptor and entry protease TMPRSS2 was detected in the human adult conjunctival, limbal and corneal epithelium, but not in the embryonic and fetal ocular surface up to 21 post conception weeks. These expression patterns were corroborated by the single cell ATAC-Seq data, which revealed a permissive chromatin in ACE2 and TMPRSS2 loci in the adult conjunctival, limbal and corneal epithelium. Co-expression of ACE2 and TMPRSS2 was strongly detected in the superficial limbal, corneal and conjunctival epithelium, implicating these as target entry cells for SARS-CoV-2 in the ocular surface. Strikingly, we also identified the key pro-inflammatory signals TNF, NFKβ and IFNG as upstream regulators of the transcriptional profile of ACE2+TMPRSS2+ cells in the superficial conjunctival epithelium, suggesting that SARS-CoV-2 may utilise inflammatory driven upregulation of ACE2 and TMPRSS2 expression to enhance infection in ocular surface. ConclusionsTogether our data indicate that the human ocular surface epithelium provides an additional entry portal for SARS-CoV-2, which may exploit inflammatory driven upregulation of ACE2 and TMPRSS2 entry factors to enhance infection.

Emerging details about COVID-19 and chronology of the pandemic in Turkey

Coronaviruses are found in all mammalian and avian species. Due to its mild infection on upper respiratory tract, this virus was not considered as a serious human pathogen until the outbreaks of SARS-CoV and MERS-CoV in 2002 and 2012, respectively. Recently the third and the biggest outbreak of coronavirus “COVID-19” or “SARS-CoV-2” has erupted and the world is now in a struggle to combat this disease. Although everything has not yet been fully clarified about this new type of virus, the data obtained from the studies conducted so far provides guidance on how to deal with SARS-CoV-2. In this context, this review provides information about pathogenesis, clinical symptoms, presence in animals, potential transmission routes of SARS-CoV-2 as well as the detection methods used in the world and Turkey.

Saliva is a non-negligible factor in the spread of COVID-19.

SARS‐CoV‐2, a novel emerging coronavirus, has caused severe disease (COVID‐19), and rapidly spread worldwide since the beginning of 2020. SARS‐CoV‐2 mainly spreads by coughing, sneezing, droplet inhalation, and contact. SARS‐CoV‐2 has been detected in saliva samples, making saliva a potential transmission route for COVID‐19. The participants in dental practice confront a particular risk of SARS‐CoV‐2 infection due to close contact with the patients and potential exposure to saliva‐contaminated droplets and aerosols generated during dental procedures. In addition, saliva‐contaminated surfaces could lead to potential cross‐infection. Hence, the control of saliva‐related transmission in the dental clinic is critical, particularly in the epidemic period of COVID‐19. Based on our experience of the COVID‐19 epidemic, some protective measures that can help reduce the risk of saliva‐related transmission are suggested, in order to avoid the potential spread of SARS‐CoV‐2 among patients, visitors, and dental practitioners.

Bee Viruses: Routes of Infection in Hymenoptera.

Numerous studies have recently reported on the discovery of bee viruses in different arthropod species and their possible transmission routes, vastly increasing our understanding of these viruses and their distribution. Here, we review the current literature on the recent advances in understanding the transmission of viruses, both on the presence of bee viruses in Apis and non-Apis bee species and on the discovery of previously unknown bee viruses. The natural transmission of bee viruses will be discussed among different bee species and other insects. Finally, the research potential of in vivo (host organisms) and in vitro (cell lines) serial passages of bee viruses is discussed, from the perspective of the host-virus landscape changes and potential transmission routes for emerging bee virus infections.

Microbiological analyses of nasally guided catheters after less invasive surfactant administration \u2013 a pilot study

BackgroundRespiratory distress syndrome (RDS) is a frequent complication of premature birth. Treating RDS by continuous positive airway pressure and less invasive surfactant administration (LISA) may reduce bronchopulmonary dysplasia. Surfactant, however, can be inactivated by bacterial infection. Therefore, potential routes of microbe transmission into the airway are of interest. The aim of this study was to evaluate microbiological contamination of catheters used for LISA procedures and its association with postnatal age.MethodsCatheter tips used for LISA procedures via the nasal route (LISA-n) in infants with RDS were placed into a sterile eSwab container directly after the procedure, cultured and examined for microbiological contamination.ResultsInterpretable results could be collected from 20 catheter tips. Four showed positive culture results (20%) with microbes potentially associated with the development of early onset neonatal sepsis. Risk of positive microbe detection increased with postnatal age (< 4 h: 10%; 4–18 h: 20%; > 18 h: 40%).ConclusionsIn this pilot study, the risk of tracheal microbe transmission following the LISA-n procedure increased with postnatal age. Although the clinical relevance of this finding is unclear, earlier surfactant administration might reduce the risk of catheter contamination.Trial registration numberSubstudy of the registered Trial: feasibility study – Neofact: NCT04086095, www.ClinicalTrials.gov, September 11, 2019.

Routes of Transmission of Newly Emerging SARS-CoV-2: A Systematic Review

Background: In December 2019, a novel corona virus (SARS-CoV-2) causes atypical pneumonia now known as “corona virus disease 2019” (COVID-19) emerged in Wuhan, China and spread rapidly throughout the world.&#x0D; Objective: The purpose of the present study was to identify the different plausible routes of transmission of SARS-CoV-2 into the human body.&#x0D; Methodology: We searched electronic databases (MEDLINE, EMBASE, Science Citation Index and Chinese database) checked documents and references. We included all the studies regarding potential routes of transmission of SARS-CoV-2. All reviewers independently screened titles and abstracts, assessed studies for inclusion, appraised quality, and extracted data.&#x0D; Result: SARS-CoV-2 has been found to have higher level of transmissibility than other two pathogenic CoVs. Sustained human to human transmission of SARS-CoV-2 has already been established though the exact route of transmission is yet to be determined. Similar to other CoVs, respiratory droplet and contact with contaminated surfaces are considered as principle route of transmission of SARS-CoV-2 whereas aerosol, feco-oral, perinatal, ocular surface and transfusion transmissions are the plausible route of spreading of this highly pathogenic CoVs.&#x0D; Conclusion: In the current review, we summarize the potential route of transmission of SARS-CoV-2 in the light of previous SARS-CoV and MERS-CoV outbreaks to solidify the scientific basis on which important decisions can be made.&#x0D; Bangladesh Journal of Infectious Diseases, April 2020;7(suppl_1):S18-S31

Strengthening basic and clinical research on ocular infection caused by coronavirus

This article was published ahead of print on the official website of Chinese Jounal of Ophthalmology on February 19, 2020. The prevention and treatment of coronavirus disease 2019 (COVID-2019) has reached the critical stage in China. Ocular surface represents a possible route for infection. Based on the previous studies and our own research, we summarize the potential transmission route and clinical symptoms of COVID-2019 in the eye, as well as the further prevention and research, with the expectation of contributing to the development in the field of infectious eye disease in China. (Chin J Ophthalmol, 2020, 56:250-252).

Airborne Transmission of COVID-19: Epidemiologic Evidence from Two Outbreak Investigations

SARS-CoV-2, the pathogen causing COVID-19, first emerged in humans in late 2019 in Wuhan, China. Much remains unknown about COVID-19 transmission dynamics hampering the ability to implement effective preventive interventions. Understanding the mechanisms of COVID-19 transmission is critical to the prevention and containment of the disease. Several case studies have demonstrated transmission routes through close contact and respiratory droplets produced when an infected person coughs or sneezes. Evidence on whether SARS-CoV-2 can be transmitted as an aerosol (i.e., airborne) is highly sought after, and has profound public health implications during the global pandemic. To inform the knowledge gap and investigate potential transmission routes of COVID-19, we present the result from an outbreak investigation of COVID-19 among lay Buddhists worshiping in a temple. The attack rate on an enclosed bus containing an individual with COVID-19 was 34.3% while no one on a second similar bus was infected. The natural experiment provided convincing evidence that the disease transmission largely occurred during the bus rides. Through further epidemiologic investigation, we determined that the possibility of transmission by direct contact on the exposed bus was low. The absence of a significantly increased risk in the part of the bus closer to the index case suggested that the risk was fairly evenly distributed throughout, and thus, airborne spread of the virus may, at least partially, explain the extraordinarily high attack rate observed. This finding has important public health significance and future efforts at prevention and control should consider the potential for airborne spread of COVID-19, particularly in enclosed spaces with re-circulating air conditioning systems.

Gastrointestinal symptoms of 95 cases with SARS-CoV-2 infection

ObjectiveTo study the GI symptoms in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients.DesignWe analysed epidemiological, demographic, clinical and laboratory data of 95 cases with SARS-CoV-2 caused coronavirus disease...

Abstracts

Abstracts of the following articles:&#x0D; Preliminary Findings Regarding the Reproductive Performance in First Calving Dairy Heifers Associated With the Prevalence of Milk Antibodies to Bovine Viral Diarrhoea Virus and Leptospira hardjo&#x0D; Visits to Farm Buildings and Cattle Troughs by Badgers (Meles meles ): a Potential Route forTransmission of Bovine Tuberculosis 1 (Mycobacterium bovis) Between Badgers and Cattle

Detecting extra-ocular Chlamydia trachomatisin a trachoma-endemic community in Ethiopia: Identifying potential routes of transmission.

BackgroundTrachoma elimination efforts are hampered by limited understanding of Chlamydia trachomatis (Ct) transmission routes. Here we aimed to detect Ct DNA at non-ocular sites and on eye-seeking flies.MethodsA population-based household survey was conducted in Oromia Region, Ethiopia. Ocular and non-ocular (faces, hands, clothing, water containers and sleeping surfaces) swabs were collected from all individuals. Flies were caught from faces of children. Flies, ocular swabs and non-ocular swabs were tested for Ct by quantitative PCR.ResultsIn total, 1220 individuals in 247 households were assessed. Active trachoma (trachomatous inflammation—follicular) and ocular Ct were detected in 10% and 2% of all-ages, and 21% and 3% of 1–9-year-olds, respectively. Ct was detected in 12% (95% CI:8–15%) of tested non-ocular swabs from ocular-positive households, but in none of the non-ocular swabs from ocular-negative households. Ct was detected on 24% (95% CI:18–32%) of flies from ocular-positive households and 3% (95% CI:1–6%) of flies from ocular-negative households.ConclusionCt DNA was detected on hands, faces and clothing of individuals living in ocular-positive households suggesting that this might be a route of transmission within Ct infected households. In addition, we detected Ct on flies from ocular-positive households and occasionally in ocular-negative households suggesting that flies might be a vector for transmission within and between Ct infected and uninfected households. These potential transmission routes may need to be simultaneously addressed to suppress transmission.

Experimental infection of Egyptian rousette bats (Rousettus aegyptiacus) with Sosuga virus demonstrates potential transmission routes for a bat-borne human pathogenic paramyxovirus

In August 2012, a wildlife biologist became severely ill after becoming infected with a novel paramyxovirus, termed Sosuga virus. In the weeks prior to illness, the patient worked with multiple species of bats in South Sudan and Uganda, including Egyptian rousette bats (ERBs: Rousettus aegyptiacus). A follow-up study of Ugandan bats found multiple wild-caught ERBs to test positive for SOSV in liver and spleen. To determine the competency of these bats to act as a natural reservoir host for SOSV capable of infecting humans, captive-bred ERBs were inoculated with a recombinant SOSV, representative of the patient’s virus sequence. The bats were inoculated subcutaneously, sampled daily (blood, urine, fecal, oral and rectal swabs) and serially euthanized at predetermined time points. All inoculated bats became infected with SOSV in multiple tissues and blood, urine, oral, rectal and fecal swabs tested positive for SOSV RNA. No evidence of overt morbidity or mortality were observed in infected ERBs, although histopathological examination showed subclinical disease in a subset of tissues. Importantly, SOSV was isolated from oral/rectal swabs, urine and feces, demonstrating shedding of infectious virus concomitant with systemic infection. All bats euthanized at 21 days post-inoculation (DPI) seroconverted to SOSV between 16 and 21 DPI. These results are consistent with ERBs being competent reservoir hosts for SOSV with spillover potential to humans.

First Case of Identification of Candida kefyr and Pichia kluyveri in Lebanese Water

Candida kefyr (Kluyveromyces marxianus) is a clinically important infectious yeast. It is found in nature, and is known to cause diseases in humans. No previous studies known have shown the detection of Candida kefyr in water sources of any country, and no studies have detected it anywhere in Lebanon. This present study is carried out to assess the quality of Lebanese water in terms of yeast pollution. The occurrence of Candida spp. (species) was inspected in 84 water samples that tested positive for containing Candida. Out of all isolates, 12 isolates were of C. kefyr and two were of P. kluyveri. The identification of Candida sp. was carried out by using HiCrome™ M1297A and M1297AR chromogenic media. Isolates identified were confirmed by MALDI-TOF MS and 26S rRNA sequencing. The isolates varied from sensitive to resistant to common antifungal agents, including Itraconazole, clotrimazole, fluconazole, miconazole, and nystatin, via disk diffusion assay. These results are the first to confirm the presence of C. kefyr in Lebanese water supplies and suggest that water consumed in Lebanon may be a potential transmission route for serious Candida-based infections.

A numerical study of ventilation strategies for infection risk mitigation in general inpatient wards.

Aerial dispersion of human exhaled microbial contaminants and subsequent contamination of surfaces is a potential route for infection transmission in hospitals. Most general hospital wards have ventilation systems that drive air and thus contaminants from the patient areas towards the corridors. This study investigates the transport mechanism and deposition patterns of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) within a typical six bedded general inpatient ward cubicle through numerical simulation. It demonstrates that both air change and exhaust airflow rates have significant effects on not only the airflow but also the particle distribution within a mechanically ventilated space. Moreover, the location of an infected patient within the ward cubicle is crucial in determining the extent of infection risk to other ward occupants. Hence, it is recommended to provide exhaust grilles in close proximity to a patient, preferably above each patient’s bed. To achieve infection prevention and control, high exhaust airflow rate is also suggested. Regardless of the ventilation design, all patients and any surfaces within a ward cubicle should be regularly and thoroughly cleaned and disinfected to remove microbial contamination. The outcome of this study can serve as a source of reference for hospital management to better ventilation design strategies for mitigating the risk of infection.

Zoonotic Diseases from Horses: A Systematic Review.

Background: Worldwide, horses play critical roles in recreation, food production, transportation, and as working animals. Horses' roles differ by geographical region and the socioeconomic status of the people, but despite modern advances in transportation, which have in some ways altered humans contact with horses, potential risks for equine zoonotic pathogen transmission to humans occur globally. While previous reports have focused upon individual or groups of equine pathogens, to our knowledge, a systematic review of equine zoonoses has never been performed. Methods: Using PRISMA's systematic review guidelines, we searched the English literature and identified 233 previous reports of potential equine zoonoses found in horses. We studied and summarized their findings with a goal of identifying risk factors that favor disease transmission from horses to humans. Results: These previous reports identified 56 zoonotic pathogens that have been found in horses. Of the 233 articles, 13 involved direct transmission to humans (5.6%).The main potential routes of transmission included oral, inhalation, and cutaneous exposures. Pathogens most often manifest in humans through systemic, gastrointestinal, and dermatological signs and symptoms. Furthermore, 16.1% were classified as emerging infectious diseases and thus may be less known to both the equine and human medical community. Sometimes, these infections were severe leading to human and equine death. Conclusions: While case reports of zoonotic infections directly from horses remain low, there is a high potential for underreporting due to lack of knowledge among health professionals. Awareness of these zoonotic pathogens, their disease presentation in horses and humans, and their associated risk factors for cross-species infection are important to public health officials, clinicians, and people with recreational or occupational equid exposure.

Manure Compost Is a Potential Source of Tetracycline-Resistant Escherichia coli and Tetracycline Resistance Genes in Japanese Farms.

Manure compost has been thought of as a potential important route of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) from livestock to humans. To clarify the abundance of ARB and ARGs, ARB and ARGs were quantitatively determined in tetracycline-resistant Escherichia coli (harboring the tetA gene)-spiked feces in simulated composts. In the simulated composts, the concentration of spiked E. coli decreased below the detection limit at day 7. The tetA gene remained in manure compost for 20 days, although the levels of the gene decreased. Next, to clarify the field conditions of manure compost in Japan, the quantities of tetracycline-resistant bacteria, tetracycline resistance genes, and residual tetracyclines were determined using field-manure-matured composts in livestock farms. Tetracycline-resistant bacteria were detected in 54.5% of tested matured compost (6/11 farms). The copy number of the tetA gene and the concentrations of residual tetracyclines in field manure compost were significantly correlated. These results suggest that the use of antimicrobials in livestock constitutes a selective pressure, not only in livestock feces but also in manure compost. The appropriate use of antimicrobials in livestock and treatment of manure compost are important for avoiding the spread of ARB and ARGs.