Smallpox and biological warfare: a disease revisited.

T his is the second article in a series of papers addressing issues related to biological warfare and bioterrorism. As outlined in the historical review of biological warfare (1), smallpox is one of the most devastating diseases that could potentially be used as a biological weapon. In fact, smallpox was for many centuries devastating to mankind. However, the remarkable efforts of the World Health Organization led to its eradication in 1977. With the developments in more recent years, the threat of biological and chemical warfare has reemerged. In particular, the events surrounding the attack on the World Trade Center on September 11, 2001, as well as the recent developments in Afghanistan and the Middle East, have shown that the threat of biological weapons is real and present in today's time. The Centers for Disease Control and Prevention (CDC) in Atlanta has classified various organisms and diseases that could potentially be used as biological weapons. These diseases are grouped in three categories according to their possibility of use and their impact on public health (Table 1). Smallpox is listed in group A, indicating that it is easily disseminated and transmitted from person to person and results in high mortality rates. In this article, I outline the epidemiology, microbiology, and clinical features of a disease not known to many people in the 21st century. The recommendations and conclusions are based on extensive research and the summary statement of the Working Group on Civilian Biodefense. Those recommendations presented herein represent the best professional judgment of the working group at the time the data were published. The conclusions and recommendations need to be regularly reassessed as new information becomes available. BRIEF HISTORY OF SMALLPOX Smallpox was introduced to Europe sometime between the fifth and seventh centuries and was frequently epidemic during the Middle Ages. Smallpox continued to be a problem throughout the 17th and 18th centuries, affecting populations on a large scale. Variolation was a semi-effective measure to prevent the disease; however, the procedure was not without risk. With Edward Jenner's demonstration in 1796 that inoculation with cowpox provided protection against smallpox, the potential threat of the disease was greatly diminished (2). The procedure of vaccination, as Jenner named it, was rapidly introduced in England, Europe, and North America. In later years, it was also introduced in many of the other European colonies. The history of smallpox and variolation is discussed in more detail …