A new study published in the journal Neurology suggests minor infections, including colds and flu, may temporarily raise a child's risk of stroke.

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Minor infections such as colds and flu may temporarily raise a child's stroke risk, the new study finds.

However, study author Dr. Heather J. Fullerton, of the University of California-San Francisco (UCSF) Benioff Children's Hospital, and colleagues note that the increased risk is small and that routine vaccinations may provide some protection against stroke.

While stroke is commonly associated with older adults, it affects almost 11 in every 100,000 children in the US each year. Stroke is even one of the top 10 causes of death among children.

Common risk factors for pediatric stroke include congenital heart defects, artery disease, immune disorders and head or neck trauma. But in August 2014, Dr. Fullerton and colleagues first suggested that colds and other minor infections may be short-term risk factors for child stroke.

This latest study builds on those findings, incorporating a larger study sample that represents a wider population. This study also involved children whose stroke was confirmed via brain imaging.

Six times higher stroke risk for children with past-week infection

The study involved 709 children under the age of 18 who were part of the Vascular Effects of Infection in Pediatric Stroke Study. Of these, 355 had experienced arterial ischemic stroke (AIS) - as confirmed by brain magnetic resonance imaging (MRI) - and 354 were free of stroke.

Fast facts about pediatric stroke
  • Among children, stroke is most common in those under the age of 2 years
  • African-American children have a higher stroke risk than other racial/ethnic groups
  • In newborns and infants, seizures, extreme sleepiness and a tendency to only use one side of the body are common signs of stroke.

Learn more about pediatric stroke

Infection exposure and vaccine history of the children were assessed through the analysis of medical charts and parental interviews.

The team found that 18% of children with AIS had an infection a week before their stroke, while 3% of the stroke-free children had an infection a week before interviews were conducted. Upper respiratory infections - such as colds and flu - were most common.

Compared with children who did not have a stroke, those who experienced stroke were around six times more likely to have had an infection within the previous week.

Stroke risk was not increased for children who had an infection 1-6 months previously, indicating that minor infections only increase stroke risk in the short term, according to the authors.

Children who had received none, few or some routine vaccinations were around seven times more likely to experience stroke than those who had received most or all of their vaccinations, the team found, suggesting that good vaccination adherence may reduce short-term stroke risk associated with minor infections.

"If our results hold up in further studies, controlling infections like colds and flu through handwashing and vaccines may be a strategy for preventing stroke in children," notes Dr. Fullerton.

While these findings warrant further investigation, Dr. José Biller, of the Loyola University Chicago Stritch School of Medicine, IL, writes in a linked editorial that parents should not be overly worried about stroke risk if their child catches a cold:

"Parents should be reassured that while the risk was increased, the overall risk of stroke among children is still extremely low.

It is possible that changes in the body as a result of these infections, such as inflammation and dehydration, could tip the balance in a child who is already at a higher risk for stroke. Parents should not be alarmed if their child has a cold that it will lead to a stroke."

Earlier this year, a Spotlight feature from Medical News Today investigated the risk factors for stroke among children and looked at the different treatment options for the condition.