A spike in tuberculosis cases has caught the attention of Washtenaw County Health Department.

Three individuals were diagnosed with tuberculosis in March.

Normally, about one case of tuberculosis is diagnosed every month in Washtenaw County, and about 60 percent of cases are found in the foreign-born population, said Laura Bauman, Health Department epidemiologist.

What’s strange about the recent cases is that two out of three of the individuals diagnosed were born in the United States. But they had been living internationally, Bauman noted. The additional cases are not considered an outbreak because they are not related, she added.

If anything, the cases serve as a reminder that tuberculosis is alive and well in the world.

Mycobacterium tuberculosis, the bacterium behind tuberculosis, is estimated to infect one-third of the world’s population, or 2 billion people, according to the World Health Organization. One in 10 of those people will become ill. The rest may carry the germs, but they won’t spread them.

“It could stay dormant for their entire lives,” Bauman said.

Locally, the newest cases are stretching the already-busy nursing staff at the Health Department. Staffers are required to witness individuals take their medicine. And, they have to test the sputum - phlegm from inside the lungs - every few days initially to see if the infected individual is still contagious. The Health Department is responsible for screening for tuberculosis in people the infected individual has been around; in one case, 60 people had to be screened at a workplace of one of those infected. Richard Fleece, health officer for the Health Department, can arrest an individual who refuses to take their medicine. He’s never had to, he said.

Individuals infected can’t work and have to stay in isolation at their homes for three or four weeks. The antibiotic regimen is intense and can last as long as nine months - longer for strains of drug-resistant tuberculosis.

Tuberculosis is most infectious when it takes root in the lungs, Bauman said. But it can infect other places in the body - such as the kidneys, brain or spine, and it can be deadly if left untreated.

A vaccination for TB in the United States isn’t widely used, according to the Centers for Disease Control and Prevention, but some countries where tuberculosis is more prevalent vaccinate for the disease. According to the CDC, there were 11,181 cases of TB reported in the U.S. in 2010, with those cases disproportionately impacting foreign-born and minorities.

Juliana Keeping covers general assignment and health and the environment for AnnArbor.com. Reach her at julianakeeping@annarbor.com or 734-623-2528. Follow Juliana Keeping on Twitter