Some individuals exhibit all four of these risk characteristics. Looking back over the past century and a half, we see a clear long-term trend toward lower risk and fewer cases of tuberculosis, beginning well before the advent of effective antibiotics. Improvement in socioeconomic and sanitary conditions has contributed to a general downward trend in incidence of tuberculosis. People who have a positive reaction to a TB skin test are often confused and misinformed about TB disease versus TB infection. McCurdy explained that active TB disease is an ongoing, advancing infection usually in the lungs, but it can involve virtually any part of the body.
Symptoms can include fever, loss of weight and a bloody cough.
Untreated, TB disease is often fatal. However, TB infection results from inhaling Mycobacterium tuberculosis, which establishes an infection that the immune system of a healthy host holds in check. McCurdy conducted a study of Northern California migrant workers in collaboration with Internal Medicine resident Desiree Arretz, M.D. and Yolo County Health Officer Robert Bates. Researchers decided that a social event would be the most effective method for involving the largest number of individuals, and organized health fairs at two Yolo County migrant worker housing camps. He indicated that somewhat fewer than 17 percent of the study participants showed positive TB skin tests.