Diseases including foodborne infections declined after public health measures were introduced because of the coronavirus pandemic, according to a preliminary analysis in Australia.

Researchers have analyzed Nationally Notifiable Diseases Surveillance System (NNDSS) data to determine the effect of COVID-19 measures on some nationally notifiable diseases in Australia.

Implementation of health actions related to the virus in Australia beginning in mid-March 2020 such as physical distancing, travel restrictions and emphasis on hygiene, likely contributed to the lower than expected notification numbers, according to the study in the Communicable Diseases Intelligence journal.

Yearly comparisons
Scientists said quantifying the impact COVID-19 public health measures had on communicable diseases in Australia was “difficult” because of many confounding factors.

The study focused on social diseases such as influenza and rotavirus, imported infections such as measles, and foodborne diseases such as salmonellosis.

In the first six months of 2020, there were 50 percent fewer notifications reported to the NNDSS than in the same period in 2019 and 20 percent fewer than the 5-year average from 2015 to 2019.

From January to June 2020, Campylobacteriosis reports were down 12 percent to 14,845 compared to the same period in 2019, but they were up 11 percent based on the 5-year average of 13,389. Listeriosis reports fell from 27 in 2019 and the 5-year average of 41 to 15 in 2020.

Shiga toxin producing E. coli (STEC) declined slightly in 2020 to 315 patients compared to 329 in 2019 but was up on the 5-year average. Five hemolytic uremic syndrome (HUS) cases were reported compared to 11 in the same period in 2019 and the 5-year average of eight.

Factors influencing Salmonella decline
The almost 8,000 reports of salmonellosis between January and June 2020 were 17 percent lower than the 5-year average for the same period and 2 percent lower than 2019.

Most cases in the first six months of 2020 were caused by Salmonella Typhimurium at 3,375. The 5-year average of 3,583 was reported for the same period.

In February 2020, notifications of salmonellosis were 61 percent higher than for the same month in 2019 at 2,545 from 1,583 and 36 percent higher than the average for the previous five years. The increase was because of an outbreak of Salmonella Typhimurium investigated between late January and May, according to the report.

There was a decrease in salmonellosis infections compared with previous years between March and June. Declines largely followed seasonal trends but researchers said they were likely magnified by physical distancing measures that saw the closure of dine-in services at businesses such as restaurants, cafés and bars, and the rise in people eating at home.

Changes in priorities, including laboratory resourcing for testing fecal specimens shifting to COVID-19, and in health-seeking behaviors and encouraged use of telehealth services, are all likely to have contributed to the decline in notified salmonellosis cases, according to the study.

Financial impacts such as income loss and ability to afford healthcare will have also impacted notification numbers.