By Tom Wilemon / The Tennessean
Maryland might be expected to have a higher case count of fungal
meningitis than Tennessee because more people there were exposed to
recalled medicine linked to the outbreak, but illnesses from Tennessee
easily quadrupled those reported from the Chesapeake Bay State.
article published Wednesday in The New England Journal of Medicine showed
wide variations in attack rates, but provided no firm conclusion as to
the reason. Tennessee had an attack rate of 10.9 infections per 100
people, compared to just 2.4 for Maryland. The national attack rate was
4.7. Both Tennessee and Michigan had attack rates more than double the
"These attack rates are most certainly
underestimates, because this outbreak is certainly not over," said Dr.
Rachel M. Smith, an epidemiologist with the U.S. Centers for Disease
Control and Prevention, who is the lead author of the article.
the death rate turned out to be much less than CDC officials initially
feared, she said. As of Dec. 10, it was 6 percent of those who became
ill. Officials worried it might go as high as 40 percent based on
outcomes from much smaller outbreaks of fungal meningitis traced to
contaminated spinal injections. Efforts by the CDC, state health
departments and health care facilities to contact patients for early
diagnosis and treatment saved lives, Smith said.
given for the variation in state attack rates include differences in the
degree of contamination in the medicine shipments, the storage times
for the medicine and injection practices at the clinics.
Smith said CDC staff do not believe some states are missing infections.
More than 99 percent of the 13,534 potentially exposed patients had been
contacted by Oct. 19.
Another article about the outbreak
published in The New England Journal of Medicine last month drew a
correlation between storage times and attack rates. Dr. Marion Kainer,
state director of healthcare-associated infections for the Tennessee
Department of Health, was its lead author.
"We found a strong
association between the age of the methylprednisolone vials and the rate
of infection in one clinic," the prior article stated. "One possible
explanation for this observation is that the level of contamination in
the vials may have increased over time, with subsequent high fungal
burdens present in older vials."
Today's article in the medical
journal includes authors from the CDC and state epidemiologists from
Tennessee, Michigan, Indiana, Virginia, Maryland, New Jersey, Florida
and North Carolina.
With input from multiple locations and
national data compiled by the CDC, it offers the broadest picture of the
outbreak thus far. The median age for someone sickened in the outbreak
was 64. The youngest meningitis victim was 16, while the oldest was 92.
accounted for 61 percent of meningitis cases and 60 percent of all
fungal infections. While meningitis has been the most deadly illness
associated with the outbreak, patients have also been sickened with
injection site infections.
The median incubation period from exposure to illness was 20 days, but some patients didn't get sick until 120 days later.
The peak period for new infections was late September to early October.
batch of the three recalled lots of methylprednisolone acetate a
patient got has been identified as risk indicator. The one linked to the
most infections was twice as likely to make a patient sick as a second
lot and more than five times as likely to cause an infection as the
However, Smith said the reason for the variation in
attack rates in the three lots is unclear. For instance, one of the lots
might have had a higher attack rate if it had been more widely used,
The majority of the 20 to 50 new cases being reported
each week are injection site infections. These present diagnosis
challenges because pain is a symptom that patients already suffer.
coming out at the CDC with a health alert that kind of talks a little
bit more explicitly about guidance in terms of using MRIs in patients
with new or worsening pain or even a baseline amount of pain because
many of these patients have chronic pain," Smith said. "It's very hard
for clinicians to know if their pain is getting worse or just not
resolving. We just want to be clear. Some patients even with baseline
pain may have evidence of infection on MRI."