State and federal health officials are investigating how a rare and virulent bacteria strain appears to have killed a young researcher at a VA Hospital’s infectious diseases lab in San Francisco, setting off alarms that the man’s friends and fellow researchers also may have been exposed.

The 25-year-old laboratory researcher at San Francisco Veterans Affairs Medical Center died Saturday morning shortly after asking friends to take him to the hospital. For the week and months before his death, he had been handling a bacteria linked to deadly bloodstream infections at the VA Hospital’s Northern California Institute for Research and Education, said Peter Melton, a spokesman for the California Occupational Safety and Health Administration.

The man, whose name has not been released, was working with fellow researchers to develop a vaccine for a bacterial strain that causes septicemia and meningitis. Hours after he left work, however, the germ that he was studying took his own life.

“He left the lab around 5 p.m. (Friday),” said Harry Lampiris, chief of the VA Hospital’s infectious diseases division. “He had no symptoms at all.”

Two hours later, however, the Treasure Island resident reported to his girlfriend he was feeling sick with a headache, fever and chills, Lampiris said. Not until Saturday morning did the symptoms grow worse with a body rash. He asked friends to take him to the hospital but fell unconscious in the car and had no pulse by the time he arrived. He died later in the morning.

“It starts out so non-specifically, people don’t think it’s anything serious,” Lampiris said. “Obviously, he didn’t suspect it.”

The San Francisco Department of Public Health is trying to identify everyone who had close contact with the worker during the time he was infected, said city health spokeswoman Eileen Shields.

His friends and co-workers are getting preventive antibiotics, as are some 60 health workers who treated him at the hospital, Shields said.

The bacteria spreads through respiratory exposure such as sneezing and coughing or kissing.

Cal-OSHA confirmed Wednesday that it is investigating the lab worker’s death and whether the lab where he worked followed safety protocols.

The federal Centers for Disease Control and Prevention also is helping state and city authorities to determine what occurred, a spokeswoman said.

“We’re not certain how this death happened, but hopefully the investigation will turn up some answers to help prevent it from ever happening again,” CDC spokeswoman Alison Patti wrote in an email.

A state laboratory has confirmed that the San Francisco worker was infected with the Neisseria meningitidis bacterium, the same germ he had been handling at the laboratory for weeks and months before his death. It also confirmed that the rare strain he and fellow researchers were studying — Serogroup B — was the same one found in his body.

The germ can cause two separate but equally deadly conditions. One is septicemia, a bloodstream inflammation that causes bleeding into the skin and organs and is believed to be the cause of the man’s death.

The other is meningitis, which inflames the thin layer of tissue surrounding the brain and spinal cord and can lead to hearing loss, brain damage and death. It was not immediately clear to researchers if he was afflicted by both conditions or just the septicemia.

Researchers at the San Francisco facility had been studying the B strain for years because it is the only one of five major strains causing meningitis and septicemia for which no vaccine is available. The VA hospital partners with UC San Francisco for scientific and clinical research. The nonprofit institute where the researcher worked gets about $47 million annually in federal grants and contracts.

The researcher who died was a biology major who had joined the laboratory in October as an associate. Colleagues described him as a smart and conscientious researcher who took safety precautions, Lampiris said.

About 1,000 cases of meningococcal disease, or meningitis, are reported in the United States each year, Patti said.

But it is rare for a research lab worker to be infected by the deadly germs he is studying.

“This is an organism that merits rigorous safety precautions in a research laboratory,” Patti said.

Lampiris said workers at the San Francisco facility are expected to wear gloves, gowns and do their work behind a protective “safety cabinet,” or hood, while isolating the bacteria.

“His co-workers felt he was highly competent and that he was adequately supervised to do the level of work,” Lampiris said.

Sixteen laboratory workers worldwide contracted meningitis between 1985 and 2001, including six in the United States, according to a 2005 study by the Journal of Clinical Microbiology. Half of them died. Most did not have sufficient respiratory protection, the study said.

Signs of the disease include a stiff neck, fever, nausea and other flu-like symptoms, but the incubation period can be as short as three days.