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Smallpox: The Weapon That Knows No Borders
[Medscape Infectious Diseases, 2001. © 2001 Medscape, Inc.]
Harry Goldhagen
Introduction
Stanley O. Foster, MD, MPH (
http://www.sph.emory.edu/ih/foster.html), Visiting Professor of International Health at Rollins School of Public Health, Emory University, Atlanta, Georgia, jokingly states that he is a recipient of the OBN -- the Order of the Bifurcated Needle. For those too young to remember such things as smallpox vaccination, this tool was used to inoculate vaccinia, the relatively benign relative of smallpox that saved generations from this disfiguring and sometimes fatal disease. Dr. Foster was a key "warrior" in the successful battle to eradicate smallpox, working in Bangladesh, Nigeria, and Somalia during the 1960s and 1970s.
With the looming threat of additional bioterrorist attacks on the United States, we spoke with Dr. Foster to hear his views, based on his extensive experience with this and other communicable diseases, on the best approaches to preparedness and the risk that smallpox might be used as a biological weapon.
Smallpox Has No Borders
Medscape: Do you think smallpox is likely to be used as a bioterrorist agent?
Foster: I think the risk of smallpox being used as a weapon is very, very small.
Medscape: Why do you think the risk is so low?
Foster: The release of a live agent is totally different from the release of anthrax. In 1960, there were about 15 million cases of smallpox globally and 2 million deaths a year. Should smallpox be released in the United States, we have the knowledge and resources to control it. Should it get back into areas of the developing world, such as the Indian subcontinent or subsaharan Africa, it would become a global disaster. This is significantly different from when you use anthrax, which is essentially limited to people that are exposed. The possibility of somebody getting smallpox and reseeding it is a much more horrifying scenario than whatever anthrax could do in this country.
Medscape: So you think that the deterrent is that if somebody were to use it, it would affect everyone, including the terrorists' own people. That would hopefully be what keeps them from using such a weapon. Of course, these terrorists are obviously willing to die.
Foster: Yes, they are willing to die, but they also have children and loved ones.
The Risks of Universal Vaccination
Medscape: Nevertheless, one has to prepare for a bioterrorist attack with smallpox.
Foster: Yes. I think the odds of anything happening are very, very small, but we still have to be prepared. However, mass vaccination is not the preparedness that one should do at this time. Vaccination carries a certain amount of risk, about 1 death per million vaccinees, as shown by the articles by Lane and Neff.[1-3] Those articles led to the decision in the United States to stop routine immunization in 1971. In other words, the risk of vaccination exceeded the risk of importation of smallpox.
Medscape: Like when we switched from live oral polio vaccine (OPV) to inactivated polio vaccine (IPV)?
Foster: Exactly right. It's a risk assessment. For example, if I had vaccine, I would not vaccinate my grandchildren.
There's some feeling that you have to have high levels of coverage for surveillance containment to work. We have 2 good sets of data, which show that is not true: data by Don Hopkins, who wrote 2 articles on his experience in Sierra Leone,[4,5] and data from my own experience in Bangladesh.[6,7] The coverage in Bangladesh in 1972 was about 55%. We had 100,000 cases. In 1976, when there were zero cases, vaccination coverage was 45%.
Medscape: So, the coverage level doesn't matter?
Foster: It certainly helps. The way to stop smallpox is to find the cases -- surveillance; to identify and vaccinate all contacts -- containment; and to search for any other undetected cases. When eradication activities started in Bangladesh, a country with 60 million people in an area about the size of the state of Georgia, the density of susceptibles was much higher than in the United States today. Despite many obstacles, surveillance containment succeeded. Smallpox does not spread like measles -- it spreads primarily among close, identifiable contacts.
Surveillance/Containment
Medscape: Do you feel that our surveillance capabilities are sufficient right now? Will front-line physicians be able to recognize the rashes, or the extreme illness that precedes the rash? Will they recognize smallpox?
Foster: The differential diagnosis in the early stage is not specific at all. Once the vesicles develop and the diagnosis becomes clear, vaccination of immediate contacts can modify or prevent disease. Vaccination within 2-3 days of exposure is highly protective. The Centers for Disease Control and Prevention (CDC) is in the process of rolling out materials so that people will recognize the disease, and developing strategies to address different types of exposure. [Dr. Foster and the WHO have made his smallpox slide presentation available on the internet, either as a web-based presentation or for download. You can reach the presentation through his
web site at Emory. The CDC will be broadcasting clinical information about smallpox on Dec 13, and this Webcast will be archived on Medscape and the CDC site. -- Editor]
There's been a lot of talk that the medical infrastructure is not there. If you look at the ability of the Web and other media to communicate with the public, I am convinced that we could rapidly mobilize to meet any situation that we find.
Medscape: Did the public assist in recognizing smallpox during the eradication effort?
Foster: Forty-four of the last 119 cases of smallpox in Bangladesh were identified by the public, many of whom were nonliterate.[8] We actually searched 12 million houses and showed them a picture of smallpox, and we'd say, "if you've seen a case like that you get 50 taca or 250 taca," a month or 2 months' wages.
Medscape: What a huge effort!
Foster: Yes. We had 10,000 workers, and each one visited 1200 houses. We did an assessment afterwards to see how many houses had, in fact, been visited, and I think we got up to around 87%. In 1972, there was great hiding of smallpox; we knew of only 10,000 of the 100,000 cases. At the end of the program, we knew about 98% of the cases. That was largely because the public knew about smallpox, the reward, and where to report.
We learned by our mistakes rather than our successes.[9] For example, we introduced a single reward in Bangladesh, and the health workers wouldn't tell the public about the reward because they were afraid the public would claim the money; the knowledge of the reward was limited to about 30% or 35%. So realizing the mistake, we doubled the reward to pay both the health worker and the public, and in about a couple of months, knowledge of the reward went from 35% to close to 75% to 80%. They said, "Okay, if you see a picture of that, you come to my house and tell me."
When Vaccination Is Necessary
Medscape: I see. But what about the Dark Winter scenario (
http://www.hopkins-biodefense.org/), in which smallpox spread to millions of people in a short period?
Foster: Yes, well, there are differences of opinion. I recently attended a meeting of 15 smallpox warriors: we were unanimous in identifying surveillance containment as the initial response to addressing this threat. To go beyond that -- that is, to mass vaccination -- we would have to have evidence of broad-scale exposure to the disease.
Medscape: Do you think that, once we have sufficient vaccine stocks available, we could rapidly vaccinate the population if we detect cases of smallpox?
Foster: I would say that under most scenarios, surveillance and containment will be adequate. There are some potential scenarios where you would have to go to mass vaccination, and if so, with an adequate supply of vaccine, you could vaccinate the country in 1-2 weeks.
Medscape: I've heard that some new technologies are being examined for safer smallpox vaccines.
Foster: We can't make the vaccine the way we used to because it would never pass Food and Drug Administration requirements. We're moving from a vaccine that was relatively dirty, made on the sides of cows, to one made in tissue culture. With our current technology, one would hope that we could develop a totally safe vaccine, and then the risk/benefit issue changes.
The Role of the CDC
Medscape: That seems quick enough for a disease that takes a few weeks to get established, and makes your approach to handling this attack scenario very clear.
Foster: It's not my approach. There are a lot of actors in this business, but the main defense in the United States is CDC working with state and local health departments. If you look at other emergencies, especially newly emerging emergencies such as Legionnaire's disease and toxic shock syndrome, and stuff like that, the CDC has a basic discipline and ability to partner with organizations and is the main resource that this country has. I worked for CDC for 30 years and retired in 1991. I have observed their mobilization for crises, including the current anthrax terrrorism, and I'm totally confident that they have the commitment and vision to handle any form of terrorism, including smallpox.
Medscape: Who will set this policy for the nation? Will it be the Department of Health and Human Services as guided by the CDC? Congress? Who will listen to people like you?
Foster: I think that there are a number of people with different agendas. My message is that CDC, with its mechanisms of consultation with official bodies making decisions, has a far greater probability of success.
Those of us who have spent a lot of time in smallpox-infected villages know our enemy. . . When you feel and you smell smallpox, you respect it; you know what worked and what didn't work, and you also know that vaccination carries small but significant risks. The important thing is that we try to make the decision-making process transparent, and allow policy to evolve from science, not headlines.
References: These MAY or MAY NOT resolve into clickable addresses....
:
Talking About Bioterrorism - Smallpox: The Weapon That Knows No Borders
[Medscape Infectious Diseases, 2001. © 2001 Medscape, Inc.]
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Lane JM. Hazards of smallpox vaccination. JAMA. 1982;247:2709. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=7200533&dopt=Abstract.
Goldstein JA, Neff JM, Lane JM, Koplan JP. Smallpox vaccination reactions, prophylaxis, and therapy of complications. Pediatrics. 1975;55:342-347. Available at:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=238178&dopt=Abstract.
Neff JM. The case for abolishing routine childhood smallpox vaccination in the United States. Am J Epidemiol. 1971;93:245-247. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=5550339&dopt=Abstract.
Hopkins DR, Lane JM, Cummings EC, Millar JD. Smallpox in Sierra Leone. I. Epidemiology. Am J Trop Med Hyg. 1971;20:689-696. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=5106525&dopt=Abstract.
Hopkins DR, Lane JM, Cummings EC, Thornton JN, Millar JD. Smallpox in Sierra Leone. II. The 1968-69 eradication program. Am J Trop Med Hyg. 1971;20:697-704. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=5093667&dopt=Abstract.
Foster SO, Ward NA, Joarder AK, et al: Smallpox surveillance in Bangladesh: I - Development of surveillance containment strategy. Int J Epidemiol. 1980;9:329-334. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=7203775&dopt=Abstract.
Hughes K, Foster SO, Tarantola D, et al. Smallpox surveillance in Bangladesh: II - Smallpox facial scar survey assessment of surveillance effectiveness. Int J Epidemiol. 1980;9:335-340. Available at:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=7203776&dopt=Abstract.
Foster SO. Participation of the public in global smallpox eradication. Public Health Rep. 1978;93:147-149. Available at:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=635088&dopt=Abstract.
Foster SO. Smallpox eradication: lessons learned in Bangladesh. WHO Chron. 1977;31:245-247. Available at:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=898942&dopt=Abstract.
Sidebar - Further Reading
Henderson DA, Inglesby TV, Bartlett JG, et al. Smallpox as a biological weapon: medical and public health management. JAMA. 1999;281:2127-2137. Available at:
http://jama.ama-assn.org/issues/v281n22/ffull/jst90000.html.
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