I am Dr. James M. Hughes, Director, National Center for Infectious Diseases, Centers for
Disease Control and Prevention (CDC). With me today is Dr. Richard Jackson, Director of
CDC's National Center for Environmental Health. We are here to discuss a very important topic:
the public health response to disease outbreaks caused by biological and chemical terrorism.
Our testimony summarizes the present system of public health surveillance and control at the
state, local, and Federal levels. I will focus primarily on terrorist events that involve biological
agents, and Dr. Jackson will address events that involve chemical agents.
U.S. Vulnerability to Terrorism
The bombings of the World Trade Center in New York and the Federal building in Oklahoma
City taught us how vulnerable we are to terrorist attacks within our own borders, even in times of
peace. We know that in addition to bombs, today's terrorists can choose among many highly
dangerous agents, including biological and chemical agents.
An attack with a biological or chemical weapon used to be considered very unlikely, but now
seems entirely possible. Many experts believe that it is no longer a matter of "if" but of "when"
such an attack will occur. They point to the accessibility of information on how to prepare
biologic and chemical weapons (on the Internet and elsewhere) and to activities by groups such
as Aum Shinrykyo, which, in addition to releasing nerve gas in Tokyo's subway, experimented
with botulism and anthrax. Moreover, the Federal Bureau of Investigation (FBI) recently
investigated a situation in Las Vegas where an individual was in possession of the organism
causing anthrax. Although the individual had an attenuated strain of anthrax used in an animal
vaccine rather than a virulent strain, the incident provided another reminder of how easily a
terrorist might cause serious illness and panic in a U.S. city.
The release of a biological agent or chemical toxin may not have an immediate impact because of
the delay between exposure and onset of illness, or incubation period. For example, when people
are exposed to a pathogen like anthrax or smallpox, they will not know that they have been
exposed, and they may not feel sick for some time. The incubation period may range from
several hours to a few weeks, depending on the microbe and the dosage. If a group of people in
an airport were exposed to the organism that causes anthrax in an aerosolized form, some of them
might be far away -- perhaps even overseas -- by the time they experienced the first symptoms.
Moreover, if an attack involved an organism like those causing plague or smallpox that is spread
from person to person, there could be a second or third wave of illness, and health care workers
treating patients would be at risk of infection. Each wave of illness could be larger than the one
before, as more and more people were exposed. In the best-case scenario, an observant health
worker would recognize that something out of the ordinary has occurred and alert public health
authorities. In the worst-case scenario, the first wave of cases may not appear to be connected --
or may be mistaken for other diseases -- and the outbreak would continue for some time before
the diagnosis is made and action is taken to contain it. We may have only a short window of
opportunity -- between the time the first cases are identified and a second wave of people become
ill -- to determine that an attack has occurred, to identify the organism, and to prevent further
Most people agree that investing in defense is imperative, even at a time when the average
American is not threatened by war, but defense is not solely through military means. As the
anthrax example illustrates, the initial response to a bioterrorist act is likely to be made by the
public health community rather than by the military. Protection against terrorism requires a
strong public health system at the local, state, and national levels.
Planning and Preparedness
Many Federal agencies are working together to formulate policies and strategic plans to ensure
prompt and effective responses to terrorist attacks that employ biological or chemical agents. In
his commencement address at the U.S. Naval Academy on May 22, 1998, President Clinton
announced his intention to upgrade our public health systems for disease detection and early
warning, both to improve our preparedness against terrorism and to help us cope with naturally
occurring infectious disease outbreaks. CDC and other agencies are assessing what is necessary
to implement such an upgrade.
CDC also is participating in a working group on domestic and international surveillance for
bioterrorism, conducted under the auspices of the Emerging Infections Task Force of the
Committee on International Science, Engineering, and Technology (CISET), National Science
and Technology Council. The Task Force is based in the White House Office of Science and
Technology Policy (OSTP). In addition, CDC works on bioterrorism issues with the Office of
Emergency Preparedness (OEP), OSTP, and the National Security Council.
Interagency planning will be especially important to ensure the availability of medical supplies
needed to respond to terrorist acts. In addition, CDC, the National Institutes of Health (NIH),
DOD, and other agencies need to collaborate on a research agenda to address scientific issues
related to bioterrorism.
To respond effectively to the threats of bioterrorism and epidemics, CDC and State and local
health departments must act together as they do in other areas of public health. CDC and State
and local health departments are the Nation's three-part shield of defense against public health
threats of all kinds. Public health response to terrorism requires recognition of the unique, yet
interdependent, roles that local, State, and Federal agencies play.
As the Nation's prevention agency, CDC's mission is to monitor the health of the U.S.
population and investigate and contain disease outbreaks, including those that are due to
deliberate acts of terrorism. In 1994, CDC issued a strategic plan, Addressing Emerging
Infectious Disease Threats: a Prevention Strategy for the United States, which launched a major
effort to rebuild the component of the U.S. public health system that protects U.S. citizens
against infectious diseases. The plan focuses on four goals, each of which has direct relevance to
preparedness for bioterrorism: disease surveillance and outbreak response; applied research to
develop diagnostic tests, drugs, vaccines, and surveillance tools; disease prevention and control;
and infrastructure and training. Through fiscal year 1998, $59 million has been appropriated to
implement the plan incrementally, with the help of many partners, beginning with the most
critical areas and programs, and the President's fiscal year 1999 budget includes an additional
$20 million to continue this effort.
CDC intends to issue an updated version of the plan later this year. Like the 1994 plan, the new
plan emphasizes that we must always be prepared for the unexpected -- whether it be a naturally
occurring influenza pandemic, multiply antibiotic resistant infections, or the deliberate release of
anthrax by a terrorist.
Investigating Diseases of Unknown Cause
CDC is often asked to assist State public health authorities or foreign health ministries when the
cause of an outbreak is unknown. Early in an investigation, it may not be possible to know
whether an outbreak is caused by an infectious agent or a chemical toxin. For example, a recent
outbreak of acute kidney failure in children in Haiti was thought to be infectious, but
investigation revealed that the illnesses were caused by chemical contamination of a medication
used in children.
In recent years, it has become more common for outbreak investigators to consider the possibility
of a terrorist event when they investigate the cause of an outbreak. This possibility arose during
the investigations of the 1993 outbreak of hantavirus pulmonary syndrome in the United States,
the 1994 outbreak of plague in India, and even the 1995 outbreak of Ebola hemorrhagic fever in
the Democratic Republic of the Congo (then Zaire).
Whether an outbreak has a natural or man-made cause is not always clear in the first stages of an
epidemiologic investigation. This point is well illustrated by what happened during the first days
of the hantavirus outbreak in 1993. In May of that year, a physician at the Indian Health Service
(IHS) in a southwestern State reported that two previously healthy young people had died from
acute respiratory failure. Over the next few days, additional cases were identified by the State
medical examiner's office and by other IHS physicians. The epidemiologists ruled out leakage
of an air-borne toxic chemical from a nearby munitions depot. Microbiologists conducted
laboratory tests for pneumonic plague, inhalational anthrax, and pulmonary tularemia, and were
able to rule out these diseases. These three infections, though rare, occur sporadically in the
southwestern United States, where they are endemic in the local animal populations. All three
could have been biological weapons. Throughout the investigation, there were rumors that a
biological agent had been released as an act of genocide against the Navajo people who lived in
the affected area.
As public health investigators proved, the outbreak was not caused by a chemical or biological
weapon, but by a newly identified, highly lethal virus spread by rodents. Fortunately, CDC's
application of sophisticated molecular biologic techniques led to the rapid identification of a
previously unrecognized hantavirus as the cause of this illness five months before the virus was
finally cultured using conventional techniques. The investigative skills, diagnostic techniques,
and physical resources required to detect and diagnose this outbreak were similar to those that
would be needed to identify and respond to a bioterrorist attack.
Our experience with the hantavirus outbreak shows that a strong public health system for disease
surveillance, outbreak investigation, and laboratory diagnosis is essential to protect the nation.
With each outbreak investigation, public health personnel become better trained and more
experienced in addressing cases of unexplained illness.
Public Health Response to Terrorism
Four components of the public health response to disease outbreaks are important to U.S.
preparedness to address acts of terrorism in a coordinated fashion: detection of usual events,
investigation and containment of potential threats, laboratory capacity, and coordination and
Detection of unusual events. The public health effort to combat infectious diseases in the
United States is based on the early detection of unexpected cases or clusters of illnesses, so that
small outbreaks can be stopped before they become big ones. In its recent interim report,
"Improving Civilian Medical Response to Chemical or Biological Terrorist Incidents," the
Institute of Medicine (IOM) cites public health departments' existing mission to promptly
identify and control infectious disease outbreaks. The IOM report recommends expansion of
CDC's emerging infections initiative as a means of improving State and local surveillance
In the case of a bioterrorist attack, the initial detection of a disease is likely to take place at the
local level. It is essential to work with members of the medical community who may be the first
to recognize unusual diseases, and with State and local health departments, who are most likely
to mount the initial response -- especially if the intentional nature of the outbreak is not
immediately apparent. Strong communication links between clinicians, emergency responders,
and public health personnel are important.
As mentioned, an astute physician -- on the basis of only two unusual cases -- alerted health
authorities to what turned out to be an outbreak of hantavirus pulmonary syndrome. In contrast,
during the 1995 Ebola outbreak in Zaire, there was no surveillance system in place, and the
outbreak was not detected until at least two waves of infection had passed and many people,
including a large number of health care workers, had died. Thus, early detection and response is
As part of the implementation of CDC's plan for emerging infections, CDC has established the
Epidemiologic and Laboratory Capacity (ELC) program to help State and large local health
departments develop the skills and resources to address whatever unforeseen infectious disease
challenges may arise in the twenty-first century. One of the specific aims of the ELC program is
the development of innovative systems for early detection and investigation of outbreaks. By
July, thirty State and large local health departments will receive support from the ELC program.
CDC has also entered into agreements with seven State health departments, in collaboration with
local academic, government, and private sector organizations, to establish Emerging Infections
Program (EIP) sites that conduct active, population-based surveillance for selected diseases, as
well as for unexplained deaths and severe illnesses in previously healthy people.
CDC has also helped establish sentinel surveillance systems that involve local networks of
clinicians and other health care providers. One such network includes emergency departments at
eleven hospitals in large U.S. cities. Another includes fourteen travel medicine clinics in the
United States, plus seven overseas. A third network includes over 500 infectious disease
specialists throughout the country. CDC is using these and other provider-based networks to
alert and inform the medical community so that health workers can help recognize and assess
unusual infectious disease threats.
Investigation and response. As is the case for any naturally-occurring infectious disease
outbreak, the initial response to an outbreak caused by an act of bioterrorism is likely to take
place at the local level. In the most likely scenario, CDC -- as well as DOD and security
agencies -- will be alerted only after a State or local health department has recognized a cluster of
cases that is highly unusual or of unknown cause. CDC is working with State and large local
health departments through the ELC program and other efforts to provide tools, training, and
financial resources for local outbreak investigations.
CDC's Epidemic Intelligence Service (EIS) trains personnel to respond to outbreaks and other
disaster situations to aid state and local officials in the identification of potential causes and
implement appropriate solutions. It is interesting to remember that the EIS was established
during the Cold War in response to the threat of biological warfare. In addition, CDC trains
Public Health Prevention Service (PHPS) specialists who can provide on-site programmatic
support to extend the manpower of state and local public health staff.
Once the cause of a terrorist-sponsored outbreak has been determined, specific drugs, vaccines,
and antitoxins may be needed to treat the victims and to prevent further spread. However,
depending upon the pathogen that causes the outbreak, appropriate medical supplies may not be
readily available since these organisms are uncommon causes of disease in the United States.
This is an important issue that is being addressed collaboratively by a number of Federal
agencies, including CDC, OEP, FDA, and other parts of the Department of Health and Human
Services; DOD; FEMA and the Department of Veterans Affairs.
In his May 22 speech, the President also announced that the United States would create
stockpiles of medicines and vaccines to protect our civilian population against biological agents
our adversaries are most likely to develop. A number of Federal agencies are working
collaboratively to address this important issue as well.
Laboratory Support. In the event of a bioterrorist attack, rapid diagnosis will be critical to the
immediate implementation of prevention and treatment measures. However, because none of the
biological agents considered most likely to be used as bio-weapons are currently major public
health problems in the United States, we have limited capacity to diagnose them, either at the
State and local or Federal level.
We must also prepare for the possible use of other agents as bioterrorist threats. This was
illustrated by a 1984 foodborne outbreak of salmonellosis in Oregon caused by followers of
Bhagwan Shree Rajneesh and a 1996 foodborne outbreak of shigellosis in Texas caused by a
single perpetrator. Future events could involve organisms that have been genetically engineered
to increase their virulence, manifest antibiotic resistance, or evade natural or vaccine-induced
In recent years, CDC has helped State health departments acquire the capacity to detect naturally
occurring outbreaks of foodborne diseases. In 1997, the success of that effort was underscored
when the Colorado State Health Department, using DNA fingerprinting techniques
developed/standardized at CDC, detected a small cluster of cases of E. coli infection caused by
consumption of a single brand of frozen hamburger patties. Twenty-five million pounds of
ground beef were recalled, and a potential nationwide outbreak was averted. Providing state
health departments with the capacity to detect outbreaks of diseases caused by terrorists may
avert disasters with even greater potential to devastate our country.
Coordination and Communications. One of the major objectives in CDC's emerging infections
plan is to improve CDC's ability to communicate with State and local health departments, U.S.
quarantine stations, health care professionals, other public health partners, and the public. In the
event of an intentional release of a biological agent, rapid and secure communications will be
especially crucial to ensure a prompt and coordinated response. Each hour's delay will increase
the probability that another group of people will be exposed, and the outbreak will spread both in
number and in geographical range.
CDC may also need to communicate with WHO and with the ministries of health of other
nations, especially if persons exposed in the United States have traveled to another country.
Because of the ease and frequency of modern travel, an outbreak caused by a bioterrorist could
quickly become an international problem.
In conclusion, a strong and flexible public health infrastructure is the best defense against any
disease outbreak -- naturally or intentionally caused. CDC's on-going initiatives to strengthen
disease surveillance and response at the local, State, and Federal levels can complement efforts to
detect and contain diseases caused by the biological agents that might be used as weapons.
Thank you very much for your attention. I will be happy to answer any questions you may have.