China
Africa
Explore chapters and articles related to this topic
Herpes
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Over 90% of HSV episodes in pregnancy are either recurrent or nonprimary first-episode HSV. Intimate contact between a susceptible person (without antibodies against the virus) and an individual who is actively shedding the virus, or with body fluids containing the virus is required for HSV infection to occur. Contact must involve mucous membranes or open or abraded skin. HSV invades and replicates in neurons as well as in epidermal and dermal cells. Virions travel from the initial site of infection on the skin or mucosa to the sensory dorsal root ganglion, where latency is established. Viral replication in the sensory ganglia leads to recurrent clinical outbreaks. These outbreaks can be induced by various stimuli, such as trauma, ultraviolet radiation, extremes in temperature, stress, immunosuppression, or hormonal fluctuations. Viral shedding, leading to possible transmission, occurs during primary infection, during subsequent recurrences, and during periods of asymptomatic viral shedding.
Identifying Airborne Transmission as the Dominant Route for the Spread of COVID-19
Published in William C. Cockerham, Geoffrey B. Cockerham, The COVID-19 Reader, 2020
Renyi Zhang, Yixin Li, Annie L. Zhang, Yuan Wang, Mario J. Molina
Several parameters likely influence the microorganism survival and delivery in air, including temperature, humidity, microbial resistance to external physical and biological stresses, and solar ultraviolet (UV) radiation (7). Transmission and infectivity of airborne viruses are also dependent on the size and number concentration of inhaled aerosols, which regulate the amount (dose) and pattern for respiratory deposition. With typical nasal breathing (i.e., at a velocity of –1 m·s−1) (4), inhalation of airborne viruses leads to direct and continuous deposition into the human respiratory tract. In particular, fine aerosols (i.e., particulate matter smaller than 2.5 μm, or PM2.5) penetrate deeply into the respiratory tract and even reach other vital organs (14, 15). In addition, viral shedding is dependent on the stages of infection and varies between symptomatic and asymptomatic carriers. A recent finding (16) showed that the highest viral load in the upper respiratory tract occurs at the symptom onset, suggesting the peak of infectiousness on or before the symptom onset and substantial asymptomatic transmission for SARS-CoV-2.
Obstetrics: Answers
Published in Euan Kevelighan, Jeremy Gasson, Makiya Ashraf, Get Through MRCOG Part 2: Short Answer Questions, 2020
Euan Kevelighan, Jeremy Gasson, Makiya Ashraf
This patient should be informed that most recurrent episodes are short-lived and resolve within 7–10 days (1). Antiviral treatment and cultures of lesions (to predict viral shedding) are not usually required (1). Supportive treatment with saline bathing and simple analgesia is appropriate (1). She should be informed that the risk of her baby having neonatal herpes is very small and that CS is not indicated (2). If rupture of membranes occurs, delivery should be expedited by the most appropriate method, e.g. intravenous oxytocin; or, if the cervix is very unfavourable, CS can be considered (1). Invasive procedures, e.g. insertion of fetal scalp electrode and fetal blood sampling, should be avoided. The neonatologist should be aware that the baby’s mother has recurrent GH (1).
Prolonged SARS-CoV-2 shedding in a person living with advanced HIV and diffuse large B-cell lymphoma: a case report
Published in Infectious Diseases, 2022
Irfaan Maan, Stavroula Maria Paraskevopoulou, Kate Cwynarski, Meena Shrestha, Laura Waters, Robert Miller, Nadia Ahmed
Effective isolation of positive cases to prevent onward virus transmission relies on knowledge of the periods of infectious viral shedding. A literature review by Walsh et al. found little to no difference in viral load between symptomatic, asymptomatic and pre-symptomatic patients and the median duration of detectable virus on PCR testing was 14.5 days [2]. Detectable virus on PCR cannot be used alone as a surrogate for infectivity as it could be due to detection of non-viable virus or fragments. La Scola et al. found no viable virus in culture after day 8 of illness despite ongoing high viral loads [11]. There is evidence of a link between the cycle threshold (Ct) value and successful viral culture suggesting patients with higher Ct values are less likely to be infectious [11]. However, the authors caution extrapolating these findings to other centres due to differences in equipment, reagents and procedures and the need for individual centres determining their own threshold for infectivity based on Ct values. Several different assays are used in our diagnostic virology lab (and throughout the UK) reflecting the need for high-volume 24-hour testing. This makes the interpretation of serial positive PCR results challenging. Viral cultures are currently primarily used in research setting and they were never taken for this case. Furthermore, it is unclear if this data on Ct values can be extrapolated to immune suppressed individuals.
Clinical course of SARS-CoV-2 infection in patients with severe acquired brain injury and a disorder of consciousness: an observational study
Published in Brain Injury, 2021
Antonio Caronni, Emanuele Liaci, Anna Bianchi, Alessandro Viganò, Francesco Marenco, Angela Comanducci, Daniela Maria Cabrini, Mario Meloni, Margherita Alberoni, Elisabetta Farina, Mariangela Bianco, Silvia Galeri, Guya Devalle, Jorge Navarro
Another interesting finding seems the clearance time of SARS-CoV-2, which was on median more than 50 days, i.e. longer than usually reported. Viral load in throat swabs progressively decreases after symptoms onset and reaches the detection limit after about three weeks (42). Even if a median shedding time of about 21 days has been reported by different Authors (43), prolonged viral shedding has been reported as well with isolated cases showing detectable levels of the virus up to 47 days (44). Note that even when this very long threshold is applied, three of the six positive patients would be considered prolonged shedders. Longer times to negative test seem in line with the view according to which patients with SABI have a weak immune response to SARS-CoV-2. Under this hypothesis, patients with SABI could be weak in eradicating the virus, eventually becoming long-term carriers.
Microsurgery in the era of COVID-19
Published in Baylor University Medical Center Proceedings, 2021
Jesse I. Payton, Stacy Wong, Nicholas F. Lombana, Michel S. Saint-Cyr, Andrew M. Altman, Sebastian M. Brooke
Transmission of COVID-19 occurs through droplets and contact. Droplets spread 1 to 2 meters and infect mucous membranes.3,4 Certain operations and techniques aerosolize the virus, potentiating transmission at greater distances.5 The incubation period ranges from 1 to 14 days, with a median of 3 to 7 days, and patients are infectious during this time.3,4,6 Viral shedding is known to have occurred from 4 to 37 days.7,8 The most common symptoms are fever, cough, ageusia, anosmia, expectoration, myalgia or fatigue, and shortness of breath.4,9,10 However, 8.3% to 58.3% of patients remain asymptomatic based on two studies in Japan looking at evacuees from Wuhan and patients from the Diamond Princess cruise ship.11,12