. >> sreenivasan: dalene von delft was leading a happy life. the young south africanys phian was married to a classmate from medical school, and well on her way to being a pediatric surgeon, when she got what felt like a bad cold, including a cough that wouldn't go away. >> i think i just decided, i must go for an x-ray. i can remember walki into the dark room and just seeing my x-ray and i got such a fright. i could see the whole left top part of my lung. there was a hole, and it was just destroyed. i couldn't believe it's my x-ray, because it looked bad. >> sreivasan: it was tuberculosis, or t.b.: a b contagioterial infection that most commonly attacks the lungs. it spreads from peon to person through the air, through coughing or speaking. for dalene, the news was even worse. >> i was at home and this email came through, unfortunately, with the news that i got multidrug-resistant t.b. >> sreenivasan: for zolelwaar sifumba, it std with a swollen lymph node when she was still in medical school. >> there's a certain way t.b. looks when it's in y

. >> reporter: gerald dalen said whatever is in the air has kept his nose running all day, rain, sunshine and wind. the combination has turned the green diablo hills with their long waving grasses into a pollen factory sending their microscopic nose missiles straight into cities like concord and walnut creek. >> pollen is able to travel sometimes 20 miles and it is certainly being spread evenly around the county. >> reporter: allergy specialist dr. bruce patterson says patients come to his concord offices before they start sneezing to get allergy shots. each one is specially tailored to the individual. >> so the shots are working to train the body to develop its own protection against the things that someone is allergic to and that's a process that's done over years. >> reporter: carrie borgen swears by it. her allergies worsened when she moved here from southern california, but after years of suffering she began a series of twice a week injections and now follows a regular maintenance schedule. >> i will tell you it has changed my life as far as allergies go. i don't have the issues anym