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West Nile Hits Some Harder, Study Says: Diabetes, Hypertension Tied to Severe Virus Risk.

Posted on: Sunday, 18 June 2006, 09:00 CDT

By Barbara Anderson, The Fresno Bee, Calif.

Jun. 18--West Nile virus poses a greater health risk for people with diabetes and high blood pressure than to other Californians, and these two vulnerable groups should protect themselves from mosquito bites this summer, say state health officials.

An analysis of West Nile virus cases in 2005 found diabetics and people with hypertension were more likely to have severe neurological problems resulting from the bite of an infected mosquito, said Cynthia Jean, coordinator of the West Nile virus surveillance program for the state Department of Health Services.

"Hypertension and diabetes appears to be a risk factor for developing the more severe form of West Nile virus illness," Jean said.

Jean said people developing neurological complications from West Nile were four times more likely to have diabetes than those who developed the less severe West Nile fever. Those who developed severe health problems from the virus were twice as likely to have hypertension.

It's already known that people older than 50 and those with weakened immune systems are at greater risk for complications from West Nile, but the study is the first in California to show an increased risk for diabetics and people with high blood pressure.

About 7% of California's population -- about 2 million people -- have diabetes, and the problem is worse in the central San Joaquin Valley.

Diabetes affects as many as 10.4% of adults in Tulare County. Other Valley counties also struggle with high rates of diabetes: 8.2% of adults in Kings County; 7.2% in Fresno and Merced counties, and 6.7% in Madera County, according to the state Diabetes Information Resource Center.

California hopes to have its study published in medical literature, Jean said. An increased risk from West Nile for diabetics and people with high blood pressure was found earlier in New York and Texas, she said.

The California study included 880 reported cases of West Nile virus. About two-thirds of the people infected answered questions about their diabetes and hypertension status. Researchers studied this group.

They found 33% of the people who had developed severe complications from West Nile had diabetes. Of the people who had the less dangerous cases of West Nile fever, 11% were diabetic.

Among those who developed neurological problems such as encephalitis, meningitis or poliolike syndrome, 46% had high blood pressure. In comparison, 29% who had milder cases of West Nile fever had high blood pressure.

The study doesn't mean diabetics and people with high blood pressure are more likely to be bitten by infected mosquitoes, Jean said. But if they are, they're at a higher risk of complications from the infection.

Thus far this year, there have been no reports of West Nile infections in people or horses statewide, but infected mosquitoes have been found, including a pool of infected mosquitoes reported in Merced earlier this month.

Last year in California, 935 people and 456 horses became infected with the virus, which is transmitted by mosquitoes that have feasted on infected birds. Nineteen Californians died in 2005 after becoming infected. Seven of the 19 deaths were in the central San Joaquin Valley.

The majority of people infected with West Nile develop no outward problems from the disease. About one in five get West Nile fever, which can cause flulike symptoms, lingering fatigue and weakness. But less than 1% become seriously ill with complications.

Theories exist as to why diabetics and people with high blood pressure are at greater risk for severe problems.

Dr. Carol Glaser, chief of the viral disease laboratory branch at the state Department of Health Services, said weakened blood vessels in diabetics and people with high blood pressure may allow the virus access through the blood-brain barrier and into the central nervous system. The blood-brain barrier -- walls of small vessels in the brain -- normally prevents diseases in the blood from escaping into the nervous system.

Another possibility is that subtle changes in the immune system of diabetics may allow the virus to overwhelm the body's natural defenses.

With summer less than a week away, mosquito control officials say it's important for people to check backyards for standing water and window screens for tears.

Statewide, 28 dead birds have tested positive this year for West Nile, including one in Sacramento. None of the birds was found in the central San Joaquin Valley.

Infected mosquitoes have been found in Riverside, Los Angeles and Merced counties.

Heavy spring rains in the Valley created perfect conditions for mosquitoes.

"The last two months, we had mosquitoes everywhere through the city," said David Farley, manager of the Fresno Mosquito and Vector Control District.

Hotter weather dried out the Valley, but the risk of mosquitoes infecting people with West Nile virus remains, Farley said. "There are still going to be people who get sick from it and possibly die from it."

Elmo Vance, 76, hasn't seen many mosquitoes on the evenings he sits outside his Senior Citizens Village apartment in Fresno, but he applies mosquito repellent anyway.

Vance is a diabetic and has high blood pressure. He wasn't surprised to learn he's at greater risk of complications from West Nile.

"I did know with diabetes you are subject to a lot of different diseases and you have to be very careful," he said.

Glaser said "nobody is at zero risk" from West Nile, but state health officials recognize the need to target the elderly, people with hypertension and diabetics with messages about wearing insect repellent to ward off mosquito bites.

"It's hard to tell 36 million people to wear DEET all summer," Glaser said. "At least it tells us these are the groups that really need to think about it."

The reporter can be reached at banderson@fresnobee.com or (559) 441-6310.

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Copyright (c) 2006, The Fresno Bee, Calif.

Distributed by Knight Ridder/Tribune Business News.

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Source: The Fresno Bee

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