Urinary Tract Infection, Other Common Infections Identified as Possible Stroke Triggers
Researchers find that urinary tract infection (UTI) has the strongest link with increased likelihood of a stroke event.
Most of us are familiar with several factors that can increase stroke risk, such as smoking, high blood pressure, and high cholesterol. New research published June 27, 2019, in the American Heart Association’s journal Stroke explores how several infections, including urinary tract infections (UTIs) are possible triggers that can make a stroke more likely.
It’s long been suspected that there could be a relationship between infection and stroke events, says Mona Bahouth, MD, an assistant professor of neurology at Johns Hopkins School of Medicine in Baltimore, who was not involved in this research. “By using a large data set, this report adds some additional information about that relationship, including findings about how the timing of the infection impacts stroke type,” says Dr. Bahouth.
Previous work on infection and stroke focused on acute infections with ischemic stroke, but this research looked at a wider range of infections and included hemorrhagic strokes, according to the study authors.
Is Infection a New Risk Factor for Stroke?
In the short term, an infection can increase the tendency of the blood to clot, or can affect the functioning of the blood vessels and make them more vulnerable to blockage or rupture, both of which could lead to a stroke, says Mandip Dhamoon, MD, an associate professor of neurology at the Icahn School of Medicine at Mount Sinai in New York City and the senior author of the research. “Healthcare providers need to be aware that stroke can be triggered by infections,” says Dr. Dhamoon.
Ischemic Stroke Versus Hemorrhagic Stroke: What’s the Difference?
Every year, more than 795,000 people in the United States have a stroke, according to the Centers for Disease Control and Prevention (CDC), and about 140,000 strokes result in death every year. There are two main types of stroke: ischemic stroke, which is caused by blood clots, and hemorrhagic stroke, caused by bleeding around the brain. About 87 percent of strokes are ischemic.
Findings Shed Additional Light on the 'Why Now?' Question About What Triggers a Stroke
Using the New York State Inpatient Databases and Emergency Department Databases from 2006 to 2013, researchers identified hospital and emergency room visits for stroke and infections. Types of infections included skin, urinary tract, septicemia (blood infection), abdominal, and respiratory. Researchers then compared hospitalizations for infections for 7, 14, 30, 60, 90, and 120 days before the strokes occurred. Risk was estimated for each infection type by comparing the group with infections to a control group during the same period.
RELATED: The Best Diet to Prevent Stroke
Every infection type was found to be linked with an increased likelihood of ischemic stroke. The greatest association was with urinary tract infection, which was associated with a five times greater risk for stroke within the 7-day window and a three times greater risk within 30 days of the infection. For all infection types, the association with stroke decreased over time after the infection, adding support to the theory that the potential for infection to trigger a stroke is greatest over a shorter time window, according to researchers.
Researchers divided hemorrhagic stroke into two categories, intracerebral hemorrhage, caused by a ruptured blood vessel in the brain, and subarachnoid hemorrhage, a stroke that happens when the inner lining of the brain bleeds.
For intracerebral hemorrhage, the association was strongest for UTIs, septicemia, and respiratory infections. Respiratory infection was the only infection linked to the occurrence of subarachnoid hemorrhage.
“Exploring the relationship between infection and stroke is important especially when superimposed on top of known risks factors. This could be something else to help understand the ‘why now?’ question when it comes to stroke,” says Bahouth. Although this study didn’t show why some types of infections might be more related to stroke than others, it did show a relationship between odds of stroke and infection in the preceding days and weeks, she says.
Immune System Takes Time to Normalize Post-Infection
Once the infection is treated, body systems begin to normalize, says Bahouth. The relationship between infection and what happens to the body afterward isn’t an on-off switch, says Bahouth. When your immune system is activated it does take time to settle back down into its more normal state, she says.
Controlling Risk Factors to Prevent Stroke
While this research on the association of infection with stroke risk is interesting, infection doesn’t rival some of the more well-known risk factors just yet, says Bahouth. Those include high blood pressure, high cholesterol, diabetes, atrial fibrillation, smoking, poor diet, and low exercise, she says. Taking the appropriate medicines, not smoking, exercising, and eating a healthy diet can all help reduce those risks, says Bahouth.
Using commonsense measures like good handwashing techniques and extra precautions when you’re around people who are ill can help you avoid infection, she says.
If you do get sick with an infection, drinking a lot of water to prevent the dehydration that comes with infections is good idea, says Bahouth. “We know that when a person is dehydrated it affects the blood vessel wall, and that creates lots of opportunity for the blood to get thicker and for the platelets to clot together,” she says.
Be aware that some over-the-counter cold medications can increase blood pressure, which can be an additional risk for people who are prone to high blood pressure, says Bahouth. If you have high blood pressure, talk to your pharmacist or healthcare provider about your condition so they may recommend an OTC symptom-relieving medication that's safe for you, she says.
Next Steps in Understanding the Link Between Infection and Stroke
“Our study shows that we need to do more to understand why and how infections are associated with the occurrence of different kinds of stroke, and that will help us to determine what we can do to prevent these types of strokes,” says Dhamoon. These findings suggest that there could be implications for vaccination, antibiotic regimens or intensive antithrombotic treatments not only to prevent the infections but to prevent stroke in those who are deemed high-risk, he adds.
“More research is needed on the mechanisms or reasons that infections can cause both ischemic and hemorrhagic strokes,” says Dhamoon. There are plans to look not only at stroke outcomes, but other thrombotic events as well, he says.