RESUMEN
Delhi, the national capital of India, has experienced multiple SARS-CoV-2 outbreaks in 2020 and reached a population seropositivity of over 50% by 2021. During April 2021, the city became overwhelmed by COVID-19 cases and fatalities, as a new variant B.1.617.2 (Delta) replaced B.1.1.7 (Alpha). A Bayesian model explains the growth advantage of Delta through a combination of increased transmissibility and partial reduction of immunity elicited by prior infection (median estimates; x1.5-fold, 20% reduction). Seropositivity of an employee and family cohort increased from 42% to 86% between March and July 2021, with 27% reinfections, as judged by increased antibody concentration after previous decline. The likely high transmissibility and partial evasion of immunity by the Delta variant contributed to an overwhelming surge in Delhi. One-Sentence SummaryDelhi experienced an overwhelming surge of COVID-19 cases and fatalities peaking in May 2021 as the highly transmissible and immune evasive Delta variant replaced the Alpha variant.
RESUMEN
Objective Castor possesses the medicinal properties. Hence, castor extract has the reducing power agent was used in nanoparticles synthesis. Extract of castor also produces secondary metabolites (phenolics, reducing agent) and exhibits anti-oxidant property, which was used as larvicide and antimicrobial agent. In the present study the silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of castor. Methods The synthesized AgNPs were characterized with UV-visible spectroscopy and transmission electron microscopy (TEM). The phenolics, reducing sugar and total sugar were evaluated performing Folin-Ciocalteu reagent method, DNS method and Phenol-sulphuric acid method. Anti-oxidant activity of synthesized nanoparticles was evaluated using DPPH assay. The larvicidal activity of synthesized AgNPs was evaluated against the third instar of Anopheles stephensi and Aedes aegypti. The mortality was observed after 24 h by probit analysis. Further, the antimicrobial activity was reported against Staphylococcus aureus (Gram positive) and Pseudomonas aeruginosa (Gram negative). Results The UV spectra showed maximum absorbance at 445 nm and TEM analysis indicated spherical shape of nanoparticles with average size of 8.96 nm. The synthesized nanoparticles also possessed anti-oxidant potentials. Thus, it could be used as potential free radical scavenger. The larvae of A. stephensi were found more susceptible to AgNPs than larvae of A. aegypti. Conclusion Due to the medicinal properties and reducing power activity, in the present study AgNPs have been synthesized using the aqueous leaves extract of castor and access their phytochemical, anti-oxidant, larvicidal and antimicrobial properties.