- CHICAGO (AP) -- Even the most successful programs to combat tuberculosis
fail to eradicate as many as a third of new infections, pointing to the
need for new strategies, researchers said in a new report.
- A program implemented in Baltimore used
state-of-the-art techniques to cut the city's TB rate from one of the highest
in the nation to one of the lowest. It was among the first to implement
directly observed therapy and aggressive contact tracing.
- But the two techniques did not stop the
spread of the dangerous lung infection among casual contacts, researchers
concluded in a report in Wednesday's Journal of the American Medical Association.
- "It suggests that to bring TB rates
down from low to even lower, or if one wants to think of eradication, more
is going to be needed," Dr. William R. Bishai, the study's lead author,
said in a telephone interview Monday.
- In directly observed therapy, health
workers observe patients take each dose of medicine during months of treatment
to ensure none is missed. Patients may be required to take medicine daily
or several times a week.
- Contact tracing requires health workers
to question each patient to learn who he has exposed to the infection so
that they can be notified and given preventive therapy.
- TB spreads mainly when infected people
cough or sneeze bacteria into the air, where they are inhaled by others.
Incomplete therapy promotes drug-resistant bacteria, a growing problem.
- Fewer than 20,000 new TB cases were diagnosed
last year, but highly drug-resistant TB has turned up in 43 states. Tuberculosis
can be deadly if untreated. An estimated 15 million Americans are infected
with TB, but 85 to 90 percent are inactive and not infectious. No effective
vaccine is available.
- Baltimore implemented directly observed
therapy and contact tracing in 1981, and lowered its rate from more than
35 new cases per 100,000 people in 1981 to fewer than 15 cases per 100,000
people in 1996.
- But in the 2 1/2 years ending in 1996,
new infections still accounted for about one-third of all diagnoses, with
the remainder being old infections that had just begun to cause illness,
- The new cases clustered mostly in areas
with high rates of poverty, poor education, drug abuse, alcoholism and
the AIDS virus, where TB control has traditionally been difficult, the
- "A lot of the recently transmitted
TB appeared to be transmitted casually -- probably between people who didn't
know one another's identities," said Bishai, assistant professor of
international health at Johns Hopkins University School of Hygiene and
- Contract tracing wouldn't help those
people, Bishai said.
- An expert not involved in the study noted
that other cities have tried the same TB-control measures for shorter periods
and have found the same thing.
- Creative approaches will be needed, said
the expert, Dr. Peter F. Barnes of the University of Texas Health Center
- One technique could use DNA fingerprinting
to locate clusters of new infections, and then an old approach -- chest
X-rays -- to screen everyone in the cluster for unidentified active cases,
- By BRENDA C. COLEMAN, AP Medical Writer