HOUSTON — A massive recall has brought more attention and put more pressure on a century-old Texas ice cream company that has been searching to discover how its products became linked to a deadly string of listeria cases.

Blue Bell Creameries said Tuesday, a day after recalling all its products, it is getting closer to pinpointing the cause of the contamination. Amid those efforts, the Centers for Disease Control and Prevention said Tuesday the number of illnesses linked to the company’s products has increased to 10.

“As each day passes, we are getting closer and closer to figuring out how this listeria was introduced into our facilities. ... It’s a matter of doing the work and not making excuses,” said Blue Bell spokesman Joe Robertson. He said consumers “are our No. 1 concern.”

The company said a team of microbiologists it hired is working with federal officials at its four facilities in Texas, Oklahoma and Alabama to identify the cause of the listeria. Blue Bell is also expanding its cleaning and sanitization system, beefing up its employee training, expanding its swabbing system by 800 percent to include more surfaces and is sending daily samples to a microbiology laboratory for testing.

Blue Bell, which has been in business for 108 years, also said under a new policy it will test all products produced at its facilities before sending them out to retailers.

Listeria primarily affects pregnant women and their newborns, older adults and people with immune systems weakened by cancer, cancer treatments, or other serious conditions.

Two more illnesses have now been confirmed in Oklahoma and Arizona. The CDC had previously reported eight illnesses in Kansas and Texas, including three deaths in Kansas linked to ice cream contaminated with listeria.