Sure, the major indexes are all down again this week. Europe's in another recession. Middle East tensions are rising. The U.S. is rolling ahead toward the fiscal cliff.

But not everyone is experiencing such gloom, doom, and misery. We always have some cheerful news in the world of health care. Here are three bright spots from the past week.

To infinity and beyond
Infinity Pharmaceuticals (INFI) shares skyrocketed by 20% this week. The market was all abuzz after the company announced good results from a phase 1 study of its experimental rheumatoid arthritis drug, IPI-145.

The study found that the drug worked well even with low doses. Importantly, data also showed that IPI-145 was well tolerated. That's good news for the company as it seeks to move forward with a phase 2 study for rheumatoid arthritis. Another phase 2 study for the drug in treating asthma is already under way.

Infinity's hopes don't rest entirely on IPI-145, though. The company also has another drug in phase 2 -- retaspimycin hydrochloride. The drug targets non-small-cell lung cancer and is used in combination with Sanofi's (NYSE: SNY) Taxotere. 

Who's in the 100%?
Gilead Sciences (GILD 0.07%) announced very good news over last weekend that sent its shares flying high starting at Monday's market open. Shares climbed more than 14% for the week.

The company shared interim data from its ongoing phase 2 study of a combination treatment for the hepatitis C virus. The preliminary results showed that 100% of patients remained free of HCV four weeks after taking a combination of sofosbuvir, NS5A inhibitor GS-5885 and ribavirin.

That's great potential news for patients with HCV. It's really good news for Gilead. However, it's also bad news for competitors such as Achillion Pharmaceuticals (ACHN). Achillion is also testing an HCV drug, but its results haven't been as spectacular as Gilead's.

Thanksgiving comes early
Sarepta Therapeutics (SRPT 6.09%) saw its shares jump nearly 14% this week without even trying. Shareholders might want to send a thank-you note in advance of the Thanksgiving holiday to Liisa Bayko, senior analyst with JMP Securities.

Bayko wrote that GlaxoSmithKline (GSK -0.92%) and its partner Prosensa don't expect approval for Duchenne muscular dystrophy drug Dispersen until 2014 at the earliest. That would benefit Sarepta, which has phase 2 studies in progress for eteplirsen. Shares traded higher on Bayko's comments.

Sarepta's results for eteplirsen have been promising so far. A phase 2b extension trial found that patients with Duchenne muscular dystrophy who took eteplirsen achieved significant improvement in the six-minute walk test compared with those taking a placebo. The patients taking eteplirsen also had increased levels of dystrophin, a protein important in preventing damage to muscles.

Don't worry, be happy
Despite the gloomy outlook in general these days for the market, opportunities still exist for investors to find nice returns. While many worried about the dropping Dow and the shrinking S&P 500, those who owned shares in any of the companies mentioned here had reasons to be happy this week. I extend my apologies if you find yourself whistling the Bobby McFerrin tune all weekend.