(McClatchy-Tribune Information Services) -- As the numbers of swine flu cases increase nationally, scientists say underlying medical conditions such as heart or lung problems, asthma and obesity have been linked to serious infections.

Lynn Lane, the mother of a 24-year-old Sacramento woman who died Tuesday of the H1N1 virus, said Wednesday her daughter was healthy and energetic but overweight.

Beth Kizere died in the UC Davis Medical Center after being hospitalized for 11 days. She was the first in Sacramento County to die of swine flu and the ninth in California.

Lane said hospital personnel gave her daughter excellent care. She said they didn't focus on her daughter's weight or discuss a connection between H1N1 and overweight people.

"Actually, they said her being overweight was kind of a plus because she had reserve fat to sustain her" during her illness, Lane said. "Plus, she was so young. But it didn't help."

Kizere did have allergies, Lane said, and she suspected her daughter might have had asthma. But Lane added that her daughter didn't smoke or have a disease such as emphysema. In general, she said, her daughter's health was robust.

Lane, who lives in the Arden Arcade area, said it is unclear when or where her daughter contracted the virus.

Kizere traveled with her brother and friends to Las Vegas on June 4 and became ill during the trip. Lane said the group returned home June 8, and Kizere was admitted to the medical center June 13.

"They thought she had pneumonia," Lane said. "But it just progressed downward. When she went in, she was running a high temperature."

Tests for pneumonia were negative, so doctors continued the search for her illness, eventually determining Kizere was suffering from swine flu.

Dr. Glennah Trochet, Sacramento County's public health officer, and Joe Quimby, senior press officer for the Centers for Disease Control in Atlanta, declined to comment on the specifics of Kizere's case.

More generally, however, they discussed analyses of cases in Mexico and the United States linking various conditions to severe swine flu infections.

Quimby said a survey of hospitals released Friday showed that their patients with H1N1 were recorded as most often having underlying conditions of asthma, chronic obstructive pulmonary disease or obesity.

The single biggest risk factor varies from week to week, Quimby said.

The latest sampling showed asthma in 32 percent of the hospitalized patients. Those with chronic obstructive pulmonary disease were tied, at 32 percent, and obesity was reported in 27 percent of the patients, he said.

"In 90 percent of all the deaths that we're aware of, patients had underlying health conditions," Quimby said.

Trochet said that in Mexico, the secretary of health recently reported that among 106 deaths tied to the virus, 34 percent of the patients had metabolic problems, listing diabetes mellitus and obesity, she said.

Since being overweight increases the likelihood that someone has diabetes, the diabetes may have been an underlying cause in the surveys, not the obesity, she said.

"I think before we start talking about this, there needs to be a lot more study," she said. "We need bigger numbers."

Lane said the reasons her daughter succumbed to swine flu remain a mystery.

Kizere was tired, probably from the coughing and fever, but had no aches or pains. "At the last, she had a headache. But she thought that was from coughing so much," Lane said.

Lane described her daughter as "very talented." She created beautiful bead work and loved to sculpt, draw and use the computer to produce art. "The world is going to miss out on that," Lane said.

She urged others in the community to "be very aware of any symptoms that are flu-like" and to take precautions.

"Whatever you do," said Lane, her voice breaking, "wash your hands, wash your hands, wash your hands.

"It doesn't matter how many times a day you don't think it is necessary. Just do it, because this is a very aggressive, nasty virus, and that is one way to prevent it."

Trochet agreed that people can impede the spread of H1N1 by hand washing. She said they should cover their mouths when coughing and sneezing and stay home when ill.

Kizere attended Bella Vista High School. Services are pending.

Copyright (C) 2009, The Sacramento Bee, Calif.