News Briefs

Diseases of Bioterrorism

In the wake of the devastating events of September 11, Americans have had to contend with the very disturbing possibility of bioterrorism. By releasing clouds of bacteria or viruses into the air, small groups of fanatics might trigger widespread outbreaks of deadly diseases. To harness and deliver these bio-weapons would be very difficult, but federal officials have made it clear that the threat of such an attack is being taken seriously.

Although several diseases are potential tools of bioterrorism, the ones most often mentioned are anthrax, botulism, smallpox, and plague. What are some of the things we know about these diseases?

Anthrax

Anthrax is an infectious disease caused by the bacterium Bacillus anthracis. It is most common in farmlands and it usually affects animals. Human infection can result from contact with infected livestock or by eating undercooked meat from infected animals.

There are three forms of Anthrax: cutaneous (through the skin), inhalation, and gastrointestinal. In most cases, the bacteria enter the body through a cut or abrasion in the skin (cutaneous). About 20 percent of these cases, when untreated, will result in death. With antibiotic therapy, however, deaths are rare with cutaneous anthrax. Inhalation anthrax is another matter. It begins with symptoms that resemble a common cold, but progress to severe breathing problems and shock. It is usually fatal if not treated with antibiotics soon after exposure, before symptoms appear. Intestinal anthrax, with symptoms of nausea, vomiting, fever, vomiting of blood, and severe diarrhea, may respond to antibiotic therapy but may also be life-threatening.

A Michigan-based vaccine company manufactures and distributes an anthrax vaccine that is reported to be 93 percent effective in protecting against this infection. However, it has been used to date only by military personnel and people whose jobs put them at high risk, because manufacturing capacity of this one company is quite limited.

Anthrax doesn't appear to be passed from person to person. According to NORD's new book, The NORD Guide to Rare Diseases, to be published by Lippincott, Williams & Wilkins next spring, There have been no confirmed cases of person-to-person transmission of cutaneous, gastrointestinal, or inhalational anthrax. The authors of that chapter, Kristy Murray, DVM, and David Ashford, DVM, MPH, DSc, of the Centers for Disease Control and Prevention (CDC), point out that any suspected anthrax case in the U.S. warrants a rapid public health investigation and should be reported immediately to local public health authorities. B. anthracis is considered a potential agent of biological terrorism.

As of this writing, a highly publicized case of a Florida man who died in October 2001 from inhalation anthrax had triggered an intensive investigation by law and public health officials. The cause of the Florida case of inhalation anthrax is still unknown, but a co-worker was diagnosed with anthrax after the first man died.

An antibiotic made by the Bayer Corporation, ciprofloxacin (Cipro) has been approved by the U.S. Food and Drug Administration (FDA) for treating people who have been exposed to inhaled anthrax. Cipro needs to be taken soon after exposure to be effective, but taking the drug as a preventive measure before exposure to anthrax is NOT advised and may cause harm.

Botulism

Botulism results from exposure to Clostridium botulinum, a common bacterium in soil. Most cases in the United States are due to improperly home-processed foods, but the bacteria may also enter the body through wounds.

In 1999, 173 cases of botulism were reported in the United States. Foodborne and wound botulism begin with nausea, vomiting, and diarrhea, followed by paralysis that starts in the chest and upper extremities and spreads downward. Respiratory failure may result. There is also a form known as infantile botulism caused by eating foods containing C. botulinum spores. It most often occurs during the second month of life.

With appropriate medical support, mortality from botulism is 5 to10 percent, although recovery may take weeks or months. Intravenous equine antitoxin administered as early as possible in the course of illness is the only specific treatment available for foodborne and wound botulism. (This antitoxin is available to physicians on a 24-hour basis from the CDC.) Equine antitoxin is not recommended for infants, but an investigational, human-derived product, human botulism immune globulin, is being developed for that purpose through the California Department of Health Services Infant Botulism Program. It is available to physicians under a Treatment Investigational New Drug protocol.

Smallpox

The last recorded natural case of smallpox worldwide occurred in Somalia in 1977, and the World Health Organization declared the disease eradicated in 1980. Officially, stocks of the virus are known to exist at only two locations: the Centers for Disease Control and Prevention (CDC) in Atlanta and Russian government laboratories near Moscow. However, government officials believe that stocks are being maintained elsewhere, including in Iraq, and may be considered as a biological weapon.

Smallpox is caused by the variola virus, and the diseases itself is sometimes known by that name. It is spread from one person to another through droplets of saliva. The incubation period averages about 12 days. The first symptoms include fever, fatigue, headache and backache. After ad few days, a characteristic rash appears on the face, arms and legs, with flat, red lesions that later become filled with pus, form a crust, and develop a scab. Most people ultimately recover from smallpox, but the disease is deadly in up to 30 percent of cases.

Until 1973 Americans were routinely vaccinated against smallpox. That practice ended when the disease was eradicated, but now federal health officials say they are producing a new smallpox vaccine that will be kept in government stockpiles for the purpose of protecting Americans against bioterrorism. Also, the Department of Defense has been asked to develop a long-range plan for producing vaccines against all biological warefare agents.

There is no treatment for smallpox other than to treat secondary infections and provide comfort. Although it hasn't been proven, there is some evidence that the virus is extremely hardy and may survive for many years in a frozen state.

Plague

In the United States, there are approximately 10 human cases of plague per year, with most occurring in the southwestern U.S. Typically, these infections occur when people are bitten by infected rodent fleas, handle infected animal carcasses or tissues, or inhale respiratory secretions from infected cats.

The bacterium that causes plague, Y. Pestis, lives in the digestive tracts of fleas. Often, those fleas are carried by rats, but they can also be transmitted by household or farm animals.

Plague may spread from one person to another when droplets from a coughing patient are inhaled by someone else. Therefore, it can be extremely contagious. Symptoms may include chills, weakness, headache, cough, the presence of sputum (sometimes bloody), and gastrointestinal distress. With bubonic plague, the most common form, lymph nodes may be swollen and painful. Plague can be treated with antibiotics, but when treatment is delayed, it may be life-threatening.

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