Public Health AffairsThe threat of smallpox terrorism [Archives:2005/883/Health]

October 6 2005

By Dr. Saleh Al-Habshi
Msc. in Public Health

Following recent events that culminated in the deliberate and malicious use of anthrax to incite terror, the potential threat has returned. Suspicions that smallpox virus may be held somewhere else than the two officially designated institutes, have raised questions about whether the virus may be deliberately used to cause harm. Responding to current concerns about the possibility that terrorist organizations might deliberately infect populations with smallpox, World Health Organization (WHO) officials asked their smallpox advisory group to review the guidelines on smallpox vaccination. Current guidelines recommend vaccinating only individuals who are directly at risk of exposure, such as laboratory workers conducting smallpox research. But WHO considered changing these recommendations and take the potential use of smallpox virus for bioterrorism into account. Smallpox and other biological agents that might be deliberately used to cause harm are once again in the spot light. A single confirmed case of smallpox would set off an immediate global state of emergency. Although it spreads slowly, requiring direct personal contact, it is highly contagious. The incubation period is long: 12-14 days. Since 1979 immunity has waned and world population including the new generation are vulnerable. The current vaccine, though highly effective, has rare but serious and potentially fatal complications.

In 1967, when WHO launched its plan to eradicate smallpox within 10 years, the disease was common in 31 countries with total population of over one billion. Most of these countries presented formidable obstacles: Crowded cities, poor health care systems, fragile governments, civil unrest, famine, war and remote, inaccessible areas.

The global eradication of smallpox, certified in 1979, is one of the greatest public health achievements in history. It marked the end of a disease that in the past had killed 3 million people every year and scarred and blinded millions more. It also commemorated a decade, during the Cold War, when all countries united behind a common humanitarian cause. The United States was the largest donor that provided major logistic and staff support, and the Soviet Union was the largest supplier of vaccine. No effective treatment against smallpox was ever developed. Vaccination, supported by surveillance and containment, was the cornerstone of the eradication drive. When the last natural case occurred in Somalia in 1977, one of history's longest chains of transmission, at least 3000 years old, was broken.

In the immediate post eradication era, the commission responsible for certification of eradication charged WHO with ensuring that smallpox was gone and would have no chance to return. It also recommended that smallpox virus (variola virus) stocks be destroyed or given to WHO for safekeeping in two institutes. By 1983, smallpox virus stocks were officially kept only in the United States laboratory in Atlanta, Georgia, and the Research Institute of Viral Preparations in Moscow in the Soviet Union. Both are WHO collaborating centers (the first source of poxvirus), and a WHO team inspects these laboratories periodically.

The second source of poxvirus

Human infections with animal poxvirus have become a matter of considerable concern in recent years. Two poxviruses: the monkey poxvirus and the tana poxvirus have attracted considerable attention as potentially capable of infecting humans. Human monkey pox is not a new disease. It is very like smallpox, but being a rare disease, had never been recognized until smallpox was eradicated. Monkey pox virus is a distinct species from variola virus. Since 1970, over 400 patients suffering from monkey pox have been reported in 7 countries in Western and Central Africa; Zaire has accounted for 95% of them. Most victims have been young children. Human monkey pox is an infrequent and sporadic zoonosis. Humans can contract monkey pox by close contact with infected wild animals. However there have been episodes of person-to-person transmission. Infrequent contact with monkey pox virus, the low transmissibility of the virus, which may be an important factor limiting its spread among people living in enzootic areas. Human monkey pox does not pose a significant health problem. Smallpox vaccination protects against monkey pox infection. With elimination of vaccination and waning herd immunity against smallpox, an increase in human monkey pox cases may occur, as it occurred in Zaire in 1982 and 1983, but experts hold the view that monkey pox does not constitute a public health problem. This disease is now under WHO surveillance in West and Central Africa. Tana pox has been reported in East and Central Africa. Persons at risk are those entering wildlife habitats, and those in contact with pets or wild animals in urban environments. Smallpox vaccination does not protect against the tana poxvirus. Thus, animal poxvirus could be accessible to be used in a malicious bioterrorist attack in some suitable regions.

Smallpox eradication was a triumph for preventive medicine and for the power of international cooperation. The success of this global effort raised the profile of public health in the eye of politicians and economists as well as in medical and scientific circles. It provided guidance for other WHO-led programs aimed at curbing deaths from diarrhea and respiratory diseases. It spawned the expanded program on immunization and created momentum that has continued to swell. Expressed most recently in the creation of the Global Alliance for Vaccines and Immunization. The smallpox threat was consigned to history, a public health problem once and forever solved, that could now be forgotten. Vaccination of civilian populations ceased everywhere.

Action to face a suspected bioterrorist attack

In collaboration with the Center for Disease Control and Prevention and other partners around the world, WHO has reissued training materials for smallpox recognition, differential diagnosis, vaccination technique, and the management of an outbreak. Archival video films are available, showing how those who contracted this now-extinct disease looked and how containment operations worked. A global survey of smallpox vaccine stocks and vaccine seed virus has been conducted. Manufactures who supplied smallpox vaccine during the eradication program were contacted to gauge the world's production capacity. Meetings between experts and advisors were held to confirm that the search and containment strategy remains valid and to consider the continuing need for research using variola virus to produce safer vaccines and therapeutic drugs. To generally guide international preparedness an updated edition of a guide on the Public Health Response to Biological and Chemical Weapons was issued. The backbone of preparedness for a bioterrorist attack is a good system of disease surveillance and response designed to deal with known infectious disease risks. The epidemiological and laboratory techniques needed to detect, investigate and contain a deliberately caused outbreak are the same as those for natural outbreaks. Mechanisms for performing these functions on a global scale are firmly in place. The infrastructure for detecting and responding to outbreaks, natural or deliberate, is The Global Outbreak Alert and Response Network, a partnership that links more than 100 existing networks and operates within the framework of the International Health Regulations. Together, these networks possess much of the data, expertise and skill needed to keep the international community alert and ready to respond. A computer-driven tool for real-time gathering of disease intelligence supports the network, which was formalized in April 2000. The challenging question is whether developing countries are ready to face such threatening attacks?

Observing the current political, economic, social and health situation in many developing countries, it is doubtful that they can face and stand against such dreadful attacks. Developing countries are still suffering from contagious diseases. The WHO is continuously reporting about outbreaks of for instance poliomyelitis, cholera, yellow fever, rift valley fever, dengue fever and Ebola virus in developing countries and the efforts of the governments in addressing these issues are still weak, due to local constraints. Outcomes of such health problems increase the burden on each country in terms of human and economic losses. The existence of outbreaks is a result of poverty, inappropriate health planning, inefficient surveillance systems and improper resource allocation. Combating health problems and building preparedness to face outbreaks and bioterrorist attacks can not be achieved until a strong political commitment to accelerate prevention and control of diseases, potential policies, strategic planning, resource allocation and intention for action take place. It is more realistic in such situations, to start simply by giving priority to capacity building, improving surveillance system and strengthening collaboration with regional and international partners. Let us hope that the deliberate use of smallpox shall never come to pass. But if it should, there is a system in place, alert and prepared to respond.