Pandemic Puzzles: The Sudden Silence and Resurgence of Gastrointestinal Viruses

 

Following the first United States stay-at-home recommendations to combat the spread of COVID-19, gastrointestinal viruses such as norovirus, rotavirus, and adenovirus almost vanished from Californian communities, remaining at a low level for over two years. The study was published in the American Society for Microbiology publication publication of Clinical Microbiology.

According to Niaz Banaei, M.D., professor of Pathology and Medicine (Infectious Diseases) at Stanford University and Medical Director of Clinical Microbiology Laboratory at Stanford Health Care, these viruses surged back to pre-pandemic levels in late 2022. "Adenovirus F40/41, the most common adenovirus strain associated with gastroenteritis, actually increased to levels twofold higher than pre-pandemic levels."

Banaei believes that the increase in viral infections was caused by a loss of collective community immunity as a result of the pandemic's lack of exposure. "Something similar has been described for the surge in respiratory syncytial virus infections in 2022," he explained.

The researchers analysed detection rates for community-acquired gastrointestinal infections before, during, and after California's COVID-related shelter-in-place programme to determine changes in the prevalence of gastrointestinal pathogens. To that goal, they employed the BioFire FilmArray GI panel, which tests for 22 of the most prevalent bacteria that cause diarrhoea, and analysed around 18,000 tests taken between January 2018 and December 2022.

According to Banaei, the reason for the study was a shift in the rate of positives for particular viruses during the COVID-19 pandemic. "It became clear almost immediately that the pandemic lockdown and shelter-in-place had created a natural experiment to investigate the transmission dynamics of pathogens causing gastroenteritis."

According to Banaei, the study provides a unique perspective into the biology of gastrointestinal infections and raises some new research issues. "Why did some vanish while others remained unaffected during the lockdown?" Why are some suddenly soaring to previously unseen heights?" Improved knowledge of these processes may lead to methods to halt pathogen transmission, particularly in low- to middle-income nations where gastroenteritis is still a major source of disease and death, particularly among children. "It may also help us prepare for future unforeseen pandemics."