The number of infections from gastrointestinal viruses dropped but bacterial pathogen reports did not go down much in South Korea during the coronavirus pandemic, according to a study.

Such viruses are mainly caused by the fecal-to-oral route and require direct contact among people while bacterial pathogens have food transmission as the main cause of infection.

Researchers examined how the incidence of gastrointestinal infections changed since the start of COVID-19 using data released by the Korea Disease Control and Prevention Agency (KDCA) from March 2018 to February 2021. Findings were published in the Korean Academy of Medical Sciences journal.

Virus decline
From March 2020, when social distancing and personal hygiene were heavily emphasized, the scale of infection from each virus drastically decreased. Reduction rates compared to averages of the past two years were 31.9 percent for total viruses, 40.2 percent for norovirus, seven percent for astrovirus and 12. 2 percent for sapovirus.

From March 2018 to February 2019, there were 4,986 norovirus cases compared to 6,174 in March 2019 to February 2020 and 2,244 in March 2020 to February 2021.

Steps such as handwashing or wearing a mask may have led to the decline. However, gastrointestinal-related viruses did not show dramatic decreases like respiratory-related viruses did, suggesting the role of a foodborne infections for gastrointestinal-related viruses.

One study limitation is the data is not from all patients nationwide and it is possible other people did not visit the hospital or could not be treated because of the pandemic.

Bacterial infections steady
Infection rates of Campylobacter and Clostridium perfringens increased in some periods compared to the average of the past two years. Incidence of non-typhoidal Salmonella, Staphylococcus aureus, or enteropathogenic E. coli did decline but not significantly compared to the previous two years.

An outbreak of enterohemorrhagic E. coli (EHEC) was reported in June 2020 in Korea. EHEC increased from an average of 129 cases per year from March 2016 to February 2020 to 318 infections from March 2020 to February 2021 due to the large outbreak from June to August.

From March 2018 to February 2021, Campylobacter infection was the most common followed by Clostridium perfringens and non-typhoidal Salmonella. About 100 cases of Staphylococcus aureus and EPEC occurred each year.

From March 2018 to February 2019, there were 2,433 Clostridium perfringens infections recorded, 3,749 in 2019 to 2020 and 3,134 in 2020 to 2021. The totals for Campylobacter were 2,693, 3,479 and 3,329 as well as 2,386, 2,684 and 1,851 for non-typhoidal Salmonella.

From March 2018 to February 2019, 112 Staphylococcus aureus cases were reported, 156 in the following year and 75 in March 2020 to February 2021. The totals for EPEC were 132, 139 and 106.

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