Bioterrorism threat: Matter of concern

With current technology, an enemy could complete a BW attack before the local commander or medical officer would know anything had happened. Increasing numbers of casualties would be present in a shorter period than a natural epidemic

The grim specter of biological warfare and bioterrorism is real. Biological warfare is the intentional use of micro-organisms, and toxins, generally of microbial, plant or animal origin to produce disease and death in humans, livestock and crops. No one is free from the potential consequences. Biological warfare (BW) is defined as the employment of biological agents to produce casualties in man or animals or damage to plants. Bioterrorism is the deliberate use of bacteria, viruses or other germs (agents) to cause illness or death in people, animals, or plants and spread fear.

Terrorists may use biological agents because they can be extremely difficult to detect and do not cause illness for several hours to several days. In bioterrorist attacks, only a small number of people may be injured or affected, but many more become afraid and change their behavior because of their fear.

Bioterrorism is used to attack and intimidate people, governments and countries. Thus, terrorists’ use of biological agents could kill many people to create an unparalleled medical, political, and social crisis. Biological attacks against large populations would most likely be disseminated by aerosol. It could be attempted by contaminating food and water supplies. While intact skin is an excellent barrier to most biological warfare, agents such as trichothecenemycotoxin can penetrate the integument and cause systematic illness. Ingestion and cutaneous penetration are currently considered unimportant potential routes of exposure. Agents can be easily produced from the environment, universities, biological supply houses and clinical specimens.

In the 14th century during the siege of Kaffa, on the Black sea (now Feodosiya, Ukraine), epidemic plague occurred among the attacking tartars. They catapulted the cadavers of their dead into the city to initiate a plague epidemic. They apparently were successful, and this may have been a factor in the second plague pandemic. Another attempted use of biological warfare occurred between 1754 and 1767 when the British Ind decimated the Indians, but it is unclear if the contaminated blankets or endemic disease brought by the Europeans caused these epidemics.

In World War I, Germany was thought to have used Bacillus anthracis and Brukholderia mallei to covertly contaminate animal feed and animals of neutral trading partners of the Allies. Between 1932 and 1945, Japan had a biological weapons development program in Harbin, China. There were 150 buildings, 5 satellite camps and 3,000 scientific staff. At least 11 Chinese cities were attacked with the agents of anthrax, cholera, Shigellosis, Salmonella and plague. Food and water were contaminated from the culture thrown into houses. Aerosols were sprayed from airplanes. Plague infected fleas, 15 million per attack, were released from airplanes. Ten thousand prisoners died from experimental infections. Japanese troops had 10,000 casualties and 170 deaths.

The biological warfare program in Iraq began in 1900 and was expanded in 1985. Two pathogenic bacteria namely B. anthracis and Clostridium perfringens five viruses (Enterovirus 17, human rotavirus, camel pox virus yellow fever virus and Congo-Crimean hemorrhagic virus); toxins (aflatoxin, ricin, tricothecene mycotoxins) were studied and by 1991, the Iraqis have weaponized anthrax, botulinum toxin and aflatoxin.

The person to person aerosol infectivity, high mortality and stability make small pox (Variola) a potential BW threat. Small pox has been eradicated, but at least two sites, the centres for Disease Control and Prevention in Atlanta and the Russian State Research Center of Virology and Biotechnology in Koltsovo Russia still maintain viable variola virus strain. The extent of clandestine stockpiles remains a matter of debate and concern. WHO has set June 30, 1999 as the day all variola stocks are to be destroyed. If variola were ever released by an enemy or by terrorists, morbidity and mortality could be considerable. Yersinia pestis would most likely to be aerosolized for a BW attack. The possibilities of rapid death combined with possible person to person transmission (in contrast to anthrax) makes plague an ominous BW threat. Botulinum toxin was first developed as a biological weapon over 60 years ago, it can be aerosolized or used to contaminate food and the estimated lethal oral dose is 70 kg. Hemorrhagic fever viruses cause high morbidity and in some cases high mortality.

With current technology, an enemy could complete a BW attack before the local commander or medical officer would know anything had happened. Large and steadily increasing numbers of casualties would be present in a shorter period than a natural epidemic. There may be a large number of rapidly fatal cases with few recognizable signs and symptoms. Multiple diseases could occur simultaneously. Vector-borne diseases will appear without natural outbreaks in animals, BW agents would likely have a high attack rate among exposed individuals and the disease would often be unusual for the geographic area. Because most agents would be delivered in aerosol clouds many patients would have pulmonary diseases caused by agents that don’t usually cause pulmonary disease (anthrax, plague, staphylococcal enterotoxin B).

Rayamajhee is MSc in Medical Microbiology