no problem. >> reporter: zhang surgeon, stanford liver surgeon samuel so was concerned about a c.t.n that revealed several new growths. >> on this side, you can see one, two, three, four. >> reporter: the hepatitis-b virus is found in blood and bodily fluids. many people can live with the virus and never get sick, but 25% of those infected get severe liver damage or cancer. the virus can be transmitted by unsafe sex and unsterile needles, but most people who suffer from the disease-- like zhang, who was born in china-- became infected at birth from their mothers. >> this is my brother with his two kids. >> reporter: his younger brother haiyang also became infected at birth but, like many of those with the disease, he had no symptoms until it was too late. to two years ago at the age of 42, he went to see a doctor about a pain in his side. he was told he had advanced liver cancer and there was thing that doctors could do. zhang flew his brother to shanghai to try to get a liver transplant, but he died three days after arriving there. >> well, he passed away. my sister-in-law and his