The Centers for Disease Control and Prevention said in a health advisory earlier this month that a common paediatric virus called parechovirus,
which may cause serious illness in newborns under three months, is spreading throughout the country.
The CDC has just released information on a recent and "unusually large" cluster of the infection.
In Tennessee, 23 infants aged between 5 days and 3 months contracted the illness between April 12 and May 24 of last year.
All but one of the infants were hospitalised after developing parechovirus meningoencephalitis, which causes swelling of the brain or brain lining.
The majority of the infants, 21, have recovered completely, although one continues to have seizures and another appears to have hearing loss.
According to Dr. Ritu Banerjee, an author of the new report and professor of paediatric infectious diseases at Vanderbilt University Medical Center in Nashville,
"what surprised us, and why we put this report together, is that we saw a higher than usual number of babies with this infection than we've seen in prior years."
To put things in perspective, the hospital only saw seven instances from 2019 to 2021, although she said that this was partly because
to pandemic lockdowns, and she believes the recent spike in cases may be related to the relaxation of these restrictions.
The majority of the babies had older siblings or were around children, and one of them became ill while being treated in the neonatal intensive care unit.
Fever, fussiness, poor feeding, odd drowsiness, and congestion were among the newborns' complaints. One started having seizures.