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Volume CXXXIII, Number 15 |
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Ask Dr. Jeff
JEFF BENSON, M.D.
CONTRIBUTOR
Dear Dr. Jeff: I've heard that there may be meningitis
on campus. Is that true? And does that mean we should all get vaccinated
or take antibiotics? B.G.
Dear B.G.: First and foremost, there have been NO cases
of meningitis on campus. No known cases of viral meningitis, and no known
cases of bacterial-meningococcal-meningitis (by far, the more serious
of the two).
Meningococcal meningitis is an infection of the central nervous system
(brain + spinal cord) caused by the bacterium Neisseria meningitides.
It often begins as a vague, flu-like illness, but can progress extremely
rapidly, with the development of headache, fever, stiff neck, and vomiting.
A characteristic rash appears late, usually just prior to collapse and
coma. If treated promptly, meningococcal meningitis is highly curable.
Untreated, it is likely fatal.
Fortunately, meningococcal meningitis is quite rare. There
are about 3,000 sporadic cases per year in this country. Between 100 and
125 of them occur on college campuses.
The natural reservoir of meningococcus is the back of our
throats. In fact, Neisseriae can be cultured from up to 15 percent of
randomly selected healthy individuals. These "asymptomatic carriers"
do not themselves develop meningitis. They may spread the bacteria by
sneezing or coughing, however, and others may be more susceptible. Carriage
rates rise to 40 percent, among close contacts of people with active meningitis.
During a meningitis outbreak, the carriage rate in "closed populations"
like college dormitories or military barracks will likely be higher still
-- up to 75 percent.
Carriers can be treated with antibiotics, and cleared of Neisseria, for
at least some period of time. That's the reason for treating all close
contacts of people with active meningitis. The same rationale underlies
treating all residents of dormitories and barracks, during a meningitis
outbreak.So: why not test everyone - and treat all carriers - before there's
an outbreak?
Meningococcal meningitis is rare. The risk of disease among
college freshmen in residence is about 1 in 300,000. For purposes of comparison,
that's about three times as likely as their lifetime risk of being struck
by lightning. From a public health point of view, it makes little sense
to test 100 percent of a population, then treat up to 15 percent, in order
to prevent an illness that will affect only 0.00033 percent. Plus, you
never know when you might become a carrier, or for how long.
Of course, there IS a meningococcal vaccine. It's about
90 percent protective against four of the five serotypes of Neisseria
that cause meningitis. These four serotypes are responsible for about
70 percent of meningitis cases. If everyone were vaccinated, then almost
2 out of every 3 meningococcal meningitis cases could be prevented.
The vaccine has no significant side effects or risks. Its
protective effects last 3-4 years. It is currently manufactured under
patent by one company. The vaccine is quite expensive, and is being aggressively
marketed to college health centers.
The Centers for Disease Control have made the following
calculation. Vaccination of all first-year college students would likely
prevent 37-69 cases of disease, and 2-4 deaths, each year. The cost per
case prevented would be about $3 million, and the cost per death prevented,
about $48 million. That's many, many orders of magnitude more expensive
than any other public health intervention.
The Health Center's cost for the vaccine, on the other hand,
is $59, and that's what you would pay if you chose to be vaccinated here.
To return to your original question: should you get vaccinated against
meningococcal meningitis or take antibiotics preventively? The only "down
sides" to the vaccine are the cost and a mildly sore arm. On the
"upside," you'll be protected against four of the five serotypes
of Neisseria for a few years, and so reduce your risk of infection by
almost two thirds. That is a significant reduction.
You should take antibiotics preventively only if you've
been exposed to someone with active meningitis.
There is one final wrinkle to consider. In the event of
an actual case of meningococcal meningitis on campus, all close contacts
would need to take antibiotics whether or not they had been vaccinated.
The serotype of the infecting Neisseria would take days to determine.
Antibiotics are immediately effective against all five strains of meningocococcus.
All of us at the Health Center would be happy to discuss
any questions or concerns you may have. The final decisions, of course,
are yours.
Jeff Benson, M.D.
Dudley Coe Health Center