Rapid SARS-CoV-2 disinfection on distant surfaces with UV-C: The inactivation is affected by the type of material.

SARS-CoV-2 is responsible for the COVID-19 pandemic, which has caused almost 570 million infections and over six million deaths worldwide. To help curb its spread, solutions using ultraviolet light (UV) for quick virus inactivation inside buildings without human intervention could be very useful to reduce chances of contagion. The UV dose must be sufficient to inactivate the virus considering the different materials in the room, but it should not be too high, not to degrade the environment. In the present study, we have analyzed the ability of a 254 nm wavelength UV-C lamp to inactivate dried samples of SARS-CoV-2 exposed at a distance of two meters, simulating a full-scale scenario. Our results showed that virus inactivation was extremely efficient in most tested materials, which included plastic, metal, wood, and textile, with a UV-C exposure of only 42 s (equivalent to 10 mJ/cm2). However, porous materials like medium density fibreboard, were hard to decontaminate, indicating that they should be avoided in hospital rooms and public places.

Disseminated Histoplasmosis with Underlying Sarcoidosis-Rheumatoid Arthritis Overlap Syndrome: An Example of Diagnostic Test Threshold of Detection Affecting Test Results and Patient Care.

Histoplasmosis is common in many parts of the world but with areas of hyperendemicity. Disseminated histoplasmosis is the deadliest form of histoplasmosis and is most common among immunocompromised patients. Timely diagnosis is crucial to improve outcomes. We describe a patient on azathioprine and rituximab with disseminated histoplasmosis in which diagnosis was delayed in part because of negative early Histoplasma antigen testing, which was positive later in the course. This case serves as an example of the concept of "threshold of detection" in which a certain concentration of a microbe must be present for it to be detected by a diagnostic test that focuses on detection of a microbe or its components. This concept applies to many tests used to diagnose infectious diseases.

Evaluation of the Degradation of Materials by Exposure to germicide UV-C Light through Colorimetry, Tensile Strength and Surface Microstructure Analyses

Due to the COVID19 pandemic, solutions to automate disinfection using UV-C combined with mobile robots are beginning to be explored. It has been proved that the use of these systems highly reduces the risk of contagion. However, its use in real applications is not being as rapid as it needs to be. One of the main market input barriers is the fear of degrading facilities. For this reason, it is crucial to perform a detailed study on the degradation effect of UV-C light on inert materials. This experimental study proves that, considering exposition times equivalent to several work years in hospital rooms, only the appearance of the material is affected, but not their mechanical functionalities. This relevant result could contribute to accelerate the deployment of these beneficial disinfection technologies. For that purpose, a colorimetry test, tensile strength test, and analysis of the surface microstructure were carried out. The results showed that polymers tend to turn yellow, while fabrics lose intensity depending on the color. Red is hardly affected by UV-C, but blue and green are. Thus, this study contributes to the identification of the best materials and colors to be used in rooms subjected to disinfection processes. In addition, it is shown how the surface microstructure of the materials is altered in most of the materials, but not the tensile strength of the fabrics.