Infant RSV linked to vitamin D deficiency: study

There could be a direct link between respiratory syncytial virus (RSV) in babies and a vitamin D deficiency in pregnant women, according to a new medical study.

The Dutch study, published Monday on the website of the journal Pediatrics, tested vitamin D levels in blood that was collected from the umbilical cord of 156 newborns in the Netherlands.

More than half of the newborns in the study did not receive enough vitamin D in the womb, according to researchers.

The babies were then tracked for a year, and researchers found that the infants who were born with low levels of vitamin D were six times more likely to contract a respiratory infection than babies who had enough of the vitamin.

"What we found is that [a deficiency of] vitamin D levels in the cord blood is associated with an increased risk of RSV bronchiolitis," Dr. Louis Bont, a pediatric infectious disease specialist at Wilhelmina Children's Hospital in Utrecht, Netherlands, and one of the study's lead authors, told CBC News.

"This is the first evidence that vitamin D intake during pregnancy is not only related, not only important, for bone health, but also to prevent the most frequent cause of infant disease."

High RSV rate in Nunavut

RSV is the most common cause of lower respiratory tract infections among young children worldwide, but it is especially common among young Inuit children in Nunavut, where many people do not get enough vitamin D.

RSV has led to a hospitalization rate of 484 per 1,000 Inuit infants, aged six months or younger, in Nunavut's Baffin region, making itone of the highest RSV-related rates in the world, according to the Canadian Paediatric Society.

Cases of RSV tend to come in waves, with some years being worse than others. Nunavut health officials say there has not been an abnormally high number of RSV infections so far this year.

"The numbers of RSV cases that are being reported to us are pretty much the same as last year. We are not seeing an outbreak," said Dr. Geraldine Osborne, Nunavut's chief medical officer of health.

About90 per cent of Nunavut's population is vitamin D deficient, according to preliminary results from a field study that was recently conducted by the territory's Health Department.

The field study also found that only seven per cent of pregnant women in Nunavut's Baffin Island region are getting enough vitamin D.

While a lack of sunlight during the winter months is a factor, Osborne has said many Nunavummiut are not eating enough foods that are rich in vitamin D, and some are reluctant to take vitamin supplements.

The low intake of vitamin D intake among pregnant womenhas been a major factor behind a high rate of rickets a softening of bones that leads to fractures and deformities in children in Nunavut.

The Health Department does provide vitamin D supplements to pregnant and nursing mothers, but officials have not determined how many mothers are actually taking them.