The agency’s reactive approach to Legionnaires’ disease causes
thousands of preventable infections every year.
Recent revelations about
several instances of scientists’ mishandling of dangerous pathogens—including
potentially lethal anthrax bacteria and H5N1 bird flu–at the federal Centers
for Disease Control and Prevention (CDC) were bad enough. But testifying before
a subcommittee of the House Energy and Commerce Committee last week, CDC
Director Thomas Frieden confirmed that these were not isolated incidents. He
admitted that in spite of a spate of other similar incidents, “We missed the
broader pattern.”
Fortunately, no illnesses or
fatalities resulted from these mishaps, but the same cannot be said for other,
more deliberate actions of the CDC. Deaths have resulted from a conscious,
long-standing policy on how to address a common, potentially life-threatening
infection, Legionnaires’ disease, a type of environmentally acquired pneumonia.
There have been a number of recent fatalities: Six U.S. veterans at the VA
Hospital in Pittsburgh, six patients at an assisted living home in Ohio, three
hotel guests at a hotel in downtown Chicago and two patients at a major
university hospital in Birmingham, Alabama.
Legionella, the cause of
Legionnaires’ disease, was originally identified after an outbreak at an
American Legion Convention in a Philadelphia hotel in 1976 that killed 34 and
sickened 221. The bacterium lurks at low levels in natural fresh water sources
(such as rivers, lakes and streams) in virtually every part the world, most
often with little impact on humans. It becomes hazardous when it survives
municipal water treatments and subsequently contaminates and grows in man-made
building water systems such as hot tubs, decorative fountains, shower heads and
cooling towers. Left undetected in these locations, it can multiply to high
concentrations. People become sickened after inhaling contaminated aerosol
droplets generated from these sources.
Unlike most other pneumonias
caused by microorganisms, this disease is not transmitted person-to-person; it
is purely of environmental origin.
The only way to determine whether a water source is a high-risk
Legionella-contaminated system is to take samples of the water to see whether
the bacteria grow in a simple and inexpensive culture test in a laboratory.
Although they receive little
attention, outbreaks are not uncommon. By far, however, most cases of
Legionnaires’ disease are individual sporadic cases that are not known to be associated
with larger outbreak clusters, although this may be due to the fact that most
sporadic cases are never thoroughly investigated. (Legionnaires’ disease
symptoms are similar to other pneumonias and can only be diagnosed by specific
laboratory tests.) Estimates of the number of cases annually in the United
States range from 8,000 to more than 25,000.
An
obvious question is what federal health officials are doing to protect
Americans from this disease. The answer is both complicated and puzzling. The approach
of the CDC’s National Center for Immunization and Respiratory Diseases (NCIRD),
which has the responsibility for Legionnaires’ disease prevention, is flawed.
Perhaps that is not surprising, given that prevention appears not to be NCIRD’s
strong suit; its officials also recommended eliminating the fourth booster dose
for the childhood pneumococcal vaccine although that would reduce the efficacy
of vaccination and result in the death of children (the subject of a previous Forbes
article).
The CDC’s recommendations for
preventing Legionnaires’ disease have been predominantly focused on what might
termed a disease surveillance strategy–a reactive process that relies on
screening for disease after cases are detected, at which time a response is
quickly undertaken to prevent further infections. Although this strategy works
well for person-to-person transmissible diseases where the source of the
disease is another infected individual, it is not well suited to situations in
which the source of disease is in the environment.
Former
Assistant U.S. Surgeon General Dr. J. Donald Millar, who used the disease
surveillance approach successfully as the head of CDC’s renowned Smallpox
Eradication Program, has long been critical of CDC’s approach to Legionnaire’s
disease. In 1997 he warned that
disease surveillance was being misapplied to the prevention of Legionnaires’
disease because it is not transmitted from person to person but is contracted
solely by exposure to bacteria-contaminated aqueous sources. For such diseases
of environmental origin, proactive environmental surveillance, rather than
reactive disease surveillance, is the appropriate prevention strategy.
Others have echoed Millar’s views, but for decades CDC’s position has remained
unchanged.
Another
indicator that CDC was on the wrong track was the outcome of a 1991 lawsuit in
which the U.S. Government was sued following an outbreak of Legionnaires’
disease at a Social Security Administration (SSA) building in Richmond,
California. The U.S unsuccessfully relied on defense testimony from CDC experts
for its defense and was subsequently forced to pay an out of court settlement.
Clark W. Patten, the lead plaintiff attorney in the case,recounted that
his winning strategy was based on the premise that the U.S. Government
(specifically the CDC) should have known how to prevent the outbreak at the
federal building.
A
closer look at CDC policy over the years reveals the ways that a reactive
approach is illogical and ineffective. A recurring theme is that CDC
discourages environmental testing until an outbreak occurs. At that point,
however, CDC demands testing to demonstrate that all evidence of Legionella is
gone for up to a year after the outbreak. Inexplicably, CDC’s current
recommendation is still that “an epidemiological association with a probable
source should be established before intervention methods, such as
disinfection, are undertaken” [emphasis added].
This
contradiction–environmental surveillance not needed before an outbreak, but
required afterwards–in effect uses people as “canaries in the coal mine” to
detect high-risk water sources.
CDC
claims that a reason for not performing environmental surveillance is that
Legionella test results are uninterpretable in the absence of disease because
the concentration of Legionella in a water sample required to cause disease is
not fully understood. But Dr. David Krause, the former State Toxicologist for
the State of Florida, dismisses this claim: “one does not need to know the
concentration of Legionella required to cause disease to prevent it, one just
needs to know if amplification is being controlled in the system and a simple
periodic Legionella laboratory culture test can provide an answer.” Dr. Krause
added that “useful guidance to help building operators interpret Legionella
concentrations in water samples has been published for over 20 years by a
laboratory in the private sector and have [sic] long been cited in theOccupational
Safety and Health Organization (OSHA) Technical Manual.” Dr. W. Dana Flanders, Professor of Epidemiology and Biostatistics at Emory
University, wrote, “I am concerned CDC seems to be discouraging environmental
Legionella testing based on flawed assumptions…when I looked more closely at references
they use to support their position, I found that some of them instead actually
supported the opposite position concerning benefits of environmental testing.”
The problem, Dr. Flanders explained, is, “When CDC discourages proactive,
routine environmental testing, the result is that hazardous sources in building
settings with high counts may persist and go unrecognized until after an
association with disease.” CDC’s posture is puzzling. The number of cases since Legionnaire’s disease was
discovered is staggering–on the order of 900,000, and the number of reported
cases continues to increase each year. The yearly costs for
hospitalizing Legionnaires’ disease patients exceed $400 million, and yet CDC
still recommends through their website and scientific publications that
concerned parties wait for an outbreak before monitoring and disinfecting
building water sources.
Perhaps in CDC’s adherence to
this approach we are seeing a syndrome that is common, especially among
bureaucrats: the unwillingness of people to admit that they’ve been wrong.
In 1992 Congress changed the
official name of the CDC to the “Centers for Disease Control and Prevention,”
but at least for the Legionella Program within the NCIRD, that addendum doesn’t
seem to have made an impression.
In the aftermath of
the recent mishaps with dangerous pathogens at CDC, Director Frieden said at
a press conference, “Events like this should never happen, and that’s why I
will do everything in my power to make sure that nothing like this happens
again.” While he’s reviewing his agency’s miscues, Dr. Frieden should pay some
attention to his agency’s misguided approach to Legionnaires’ disease.
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