A large drop in intussusception rates during Australia’s lockdown suggests that common respiratory viruses have been overlooked as a major cause of acute bowel obstruction in infants, researchers say.

A study led by Murdoch Children’s Research Institute (MCRI)  found that hospital admissions for intussusception decreased substantially during the period of the 2019-2020 COVID-19 pandemic public health measures that led to significant decreases in communicable disease prevalence.

Compared to previous years, hospital admissions for infant bowel obstruction fell by almost two thirds (63%) in Victoria and by 67% in metropolitan Melbourne, which had the most extensive  lockdown period, according to their study, published in Clinical Infectious Diseases (link here).

Similarly, NSW metropolitan centres experienced a 40% decline in hospital admissions for intussusception among children under two during lockdowns.

Victoria experienced the greatest lockdown duration, with Melbourne having six lockdown periods, for a total of 263 days. Greater Sydney had 159 days.

Rates of intussusception cases returned to normal levels after lockdown measures were lifted, the researchers noted.

For their study, 12 years of data was analysed across Victoria, and NSW, with a total of 5,589 intussusception cases recorded between January, 2010 and April, 2022. Of those, 3,179 were children under the age of two.

The researchers said it had previously been shown that respiratory viruses such as adenovirus were associated with rates of idiopathic intussusception, which is the primary cause of acute bowel obstruction in infants. However, prior to the study it had been thought that viruses were responsible for only a minority (about 30%) of cases of idiopathic intussusception.

“The unexpected magnitude of the reductions [in this study] suggests that the true proportion of infectious disease-caused idiopathic intussusception is greatly underestimated,” they wrote.

MCRI and Monash University researcher Dr Ben Townley said the magnitude of the decline supported the hypothesis that common respiratory diseases such as colds, the flu and respiratory syncytial virus (RSV), were behind a significant proportion of intussusception cases.

“Reductions in intussusception hospital admissions were seen in all age groups, however most occurred in children less than two years of age,” he said.

He added that other countries with prolonged COVID-19 lockdowns and suppression strategies saw reductions in common respiratory viruses, which influenced the drop in intussusception admissions.

“Intussusception is the leading cause of acute bowel obstruction in infants and young children and without prompt diagnosis and management, can be fatal,” Dr Townley noted.

MCRI researcher Professor Jim Buttery said the decrease in intussusception cases was greater than expected given previous research into the causes of the condition.

“Our analysis found commons viruses play a larger role than previously recognised in triggering intussusception. Infectious triggers were thought to comprise only a minority, about 30 per cent, of cases.”

Professor Buttery said the findings raised the possibility that emerging vaccines like the new RSV vaccines may help prevent intussusception.

“When a new vaccine against common childhood respiratory viruses is introduced, we may find there are some unexpected benefits, like protecting more children from intussusception,” he said. “We last saw this in 2007, when introducing the rotavirus vaccine against gastroenteritis, also reduced febrile convulsions in young children.”