Durham, N.C. — A largely unknown disease, deep-vein thrombosis (DVT), kills approximately 300,000 Americans each year – more than AIDS, breast cancer and traffic accidents combined.

One woman, though, has launched a personal campaign to raise awareness of DVT.

Melanie Bloom and her three daughters watched her husband, NBC correspondent David Bloom, beam back reports on the opening stages of the Iraq war in 2003.

"I watched those live reports of his with my heart in my throat," she said.

She feared bullets or bombs, "but rather the bomb was buried deep within David's own body," Bloom said.

David Bloom died from DVT when a blood clot developed in a deep vein of one leg, broke off and traveled through his heart to his lungs.

Melanie Bloom has since become the national spokeswoman for PreventDVT, a coalition of more than 50 groups that works to raise awareness of the disease among health-care professionals, policymakers and the public.

In a national advertisement, Bloom describe those at risk of DVT: "A businessman with a heart condition heads to his next out-of-town meeting." She also points out risk factors, such as obesity, advanced age, a hip or leg injury or hospitalization.

On top of dehydration and a genetic blood-clotting disorder, David Bloom had another risk factor: "Immobility (while) sleeping night after night with his knees pulled up to his chin in a tank," his wife said.

Although David Bloom experienced leg pain two days before his death, most DVT victims do not get warning signs, and diagnosis may come only after death.

"If you can't diagnose the disease in time, and sometimes you can't with this disease, you've got to use preventive measures," said Dr. Victor Tapson, with Duke Pulmonary Medicine. "That's crucial."

Hospital patients and people with hip or leg injuries may need blood-thinning medications, Tapson said. People who sit during long trips need regular walking breaks.

Awareness of the risks and preventive measures could save your life, Bloom said.

"I really don't want people to die from something that is preventable and treatable," she said.