Hawai'i public health officials are turning their focus to spotting signs that might indicate a mutation and strengthening of the H1N1 virus, following a doubling of swine flu cases here in the past two weeks and Hawai'i's first death in which the virus was deemed a factor.

The state has 616 known cases of the H1N1 virus, according to the latest national count by the Centers for Disease Control and Prevention.

That's an increase of 113 cases since a June 24 tally by the state Department of Health, and double the number of illnesses from two weeks ago.

The increase is not surprising, said Dr. Sarah Park, chief of the Health Department's Disease Outbreak Control Division. From the beginning of the Hawai'i outbreak in May, she has said she expects more cases, hospitalization and deaths.

The only death here so far linked to the virus was that of a woman in her late 60s who died June 19 at Tripler Army Medical Center. The flu was a contributing factor, but the woman's health was already in decline because of multiple serious health issues.

The Health Department continues to monitor the disease's progress but has reduced testing and is focusing on priority groups that might be the first indicators that the virus is mutating and becoming more severe, Park said.

"It's a fear and it will be a fear until we pass through the fall," Park said, adding that a sure sign of change might be 50 hospitalized cases at once or a cluster of deaths.

The priority groups are patients with severe cases of the flu, people with high-risk conditions, people in high-risk occupations such as health care workers, travelers and people who are part of an outbreak investigation.

In the beginning, Park said, testing each suspected case was important to determine when the swine flu arrived in the Islands and how quickly it spread. With those answers the department can now focus its resources on tracking the possible changes in the disease that could blend with other flu strains, she said.

"There's always concerns that if it mixes with the regular seasonal flu ... that it could pick up worse genes," Park said, adding that it could all fizzle out but the state cannot count on that and neither should residents.

The CDC said swine flu is the predominant flu type circulating currently, with 10 states, including Hawai'i, reporting widespread cases. The other states are California, Connecticut, Delaware, Georgia, Maine, New York, Pennsylvania, Rhode Island and Virginia.

For a state-by-state count of swine flu cases in the United States, go to the CDC Web site at www.cdc.gov/h1n1flu/update.htm.

Park said she worries that some Hawai'i residents are still going to school and work when they are sick, which could worsen their condition and spread disease.

Individuals should treat this like hurricane preparedness and have enough food and drink to stay home for seven days, the recommended time to recuperate, Park said.

"I'd say the biggest task and the biggest hurdle is trying to get our community to prepare," she said.