STORY BYSummertime brings yet another-and rather surprising-reason to lower your blood pressure:
People with hypertension who become infected with West Nile Virus (WNV) are at greater risk for developing encephalitis, or inflammation of the brain, than those with normal blood pressure, according to a recent study. People who use drugs such as cocaine and amphetamines, which cause high blood pressure, are also at greater risk.
The study was led by Kristy M. Lillibridge, DVM, assistant professor of epidemiology at The University of Texas School of Public Health at Houston. Lillibridge is also a former US Centers for Disease Control and Prevention epidemic intelligence service officer who worked on the first outbreak of WNV in the United States in New York City in 1999.
Lillibridge, along with researchers from several local and national centers, analyzed data from 90 hospitalized WNV patients in a Houston WNV outbreak in 2002. Besides high blood pressure, other significant risk factors identified were age (being over 51) and being male.
"Prior to our study, the only significant risk factor identified was advanced age, that an older person was more likely to develop encephalitis," said Lillibridge.
In the New York City outbreak, diabetes was found to be a risk factor, also, Lillibridge says. "In this study, diabetes was not significant; and all diabetics who had developed encephalitis also had a history of high blood pressure ," Lillibridge says.
For most, risk is low. Less than 1 percent of
people who are bitten by mosquitoes develop any
symptoms of the disease and relatively few
mosquitoes actually carry WNV.
What Are the Symptoms of WNV?
WNV affects the central nervous system.
Symptoms vary.
Symptom information provided by the CDC
website: http://www.cdc.gov/ncidod/dvbid/
westnile/wnv_factSheet.htm
Not only did the study find a high proportion of patients with a history of high blood pressure who developed encephalitis, results also pointed to a higher proportion of encephalitis is persons using amphetamines or cocaine (eight percent), which are drugs known to cause high blood pressure.
"When we performed the statistical model using the data collected from all hospitalized patients, high blood pressure remained a significant risk factor, even when we adjusted for age and gender," Lillibridge says.
In the Houston outbreak, 59 patients developed encephalitis, 25 patients developed meningitis (inflammation of the membranes enclosing the brain and spinal cord), and six patients developed fever.
Although 60 percent of fatal cases involved women, 66 percent of the patients were men. Of the individuals who got WNV encephalitis, 76 percent had a history of high blood pressure or took drugs that cause high blood pressure.
Five children under 18 were also among the 90 patients studied. Of two who developed encephalitis, one had been taking amphetamines for attention deficit hyperactivity disorder; and one had a history of a head injury. When compared to the adults, the children had different symptoms, including seizures, rash, paralysis and diarrhea.
It is not known exactly why people with high blood pressure may be more susceptible to developing a more severe form of the disease. However, researchers hypothesize that it may be that high blood pressure allows the virus to cross more easily from the blood into the brain, resulting in the more serious symptoms associated with encephalitis.
Two other studies are about to be underway, according to Lillibridge. One will focus on the homeless population in Houston (10 percent of those who developed encephalitis in the original Houston group studied were homeless).
The other will be a national study of clinical features and risk factors for encephalitis in children.
"These studies help us better understand who is susceptible to serious disease, which will allow us to know who to target with messages about protection against mosquitoes bites," said Lillibridge. "People with high blood pressure and those who use drugs that produce high blood pressure should be especially careful to avoid infection by following simple precautions."
Lillibridge suggests
Last Updated: 4-05-2004
The most comprehensive academic health center in Texas, The University of Texas Health Science Center at Houston (UTHealth) is home to six schools devoted to medicine, nursing, public health, dentistry, health informatics and graduate studies in biomedical science. UTHealth, founded in 1972, is part of The University of Texas System. It is a state-supported health institution whose state funding is supplemented by competitive research grants, patient fees and private philanthropy.
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Dr. Kristy Murray is an assistant professor in epidemiology at the UT School of Public Health.
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Easy remedy
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One of the easiest ways to help curb your hunger is on-tap right in front of you. Water!
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