HEADQUARTERS

INTELLIGENCE

(HQINT)

SMALLPOX INFORMATION PAPER

The Plague: A Deadly Opponent

HQ-IP-04

November 16, 2001

Smallpox Information Paper

Prepared: November 15, 2001

This product provides an overview of the threat posed by smallpox.

KEY POINTS:

Ø The discovery of a single suspected case of smallpox must be treated as an international health emergency and be brought immediately to the attention of national officials through local and state health authorities.

¨ Smallpox is a highly contagious human disease caused by the virus viriolae. There are two strains: viriole major, which have severe symptoms and a very high mortality (20-40 percent), and viriole minor, which had less severe symptoms and lower mortality (approximately 1 percent).

¨ The virus is known to have existed for thousands of years, and has probably killed up to 100 million people in its history, and left 200 million blind and scarred.

¨ In the 18th century, techniques were refined to inoculate persons with attenuated virus from open sores of those infected, and this made the inoculated immune to the disease, with some risk of side effects and mortality.

¨ In the 19th century a technique using cowpox vaccine instead of smallpox to perform inoculations reduced side effects and mortality.

¨ In the 20th century the virus was eliminated from the human population, the result of a successful World Eradication Program. Some virus remains in laboratory use and was originally to be destroyed.

¨ The last known stocks of the virus that causes smallpox are secured in labs in Atlanta, Georgia and in Russia. Their future is awaiting the outcome of a long-running debate over whether they should be permanently destroyed.

NOTES: Smallpox is a viral disease unique to humans. To sustain itself, the virus must pass from person to person in a continuing chain of infection and is spread by inhalation of air droplets or aerosols. Twelve to 14 days after infection, the patient typically becomes febrile and has severe aching pains and prostration. Some two to three days later, a papular rash develops over the face and spreads to the extremities. The rash soon becomes vesicular and later, pustular. The patient remains febrile throughout the evolution of the rash and customarily experiences considerable pain as the pustules grow and expand. Gradually, scabs form, which eventually separate, leaving pitted scars. Death usually occurs during the second week after infection.

Transmission: A person infected with smallpox and overtly sick usually transmits the virus face-to-face in a closed dwelling. There is no infectious subclinical state.

Progression: Smallpox is characterized in its classical form by the sudden onset of fever, headache, backache, vomiting, marked prostration and even delirium. At this early stage the patient may be very ill and compelled to take to his bed. Early in the illness there may appear in approximately 10 percent of patients a fleeting rash in the form of a reddening of the skin, not unlike the rash of German Measles. This is the so-called prodromal rash and, in the absence of a history of exposure to a source of infection, there is nothing about this rash to arouse suspicion of smallpox. The incubation period from exposure to the onset of this feverish illness is nearly always 12 days with very little variation either way.

About two to three days after the onset of illness the true smallpox rash appears. At this time any prodromal rash will be fading. This true, or so-called focal, rash is normally diagnostic of smallpox and is characteristic both in its evolution and distribution on the body. It begins as tiny discrete pink spots, macules, which enlarge and become slightly raised papules. Each of these progresses by the third day to become a tense blister, vesicle, 6mm in diameter, deep in the skin. After two more days the fluid inside becomes turbid and the lesions are not described as pustules or by the older term of pocks. In the following days these shrink and dry up to become hard lentil-like crusts in the skin. Eventually they separate leaving a sunken scar. The hard material, which comes away, contains smallpox virus in its substance.

The distribution of this focal rash is characteristic, affecting the head and extremities much more than the trunk. These features make classical smallpox easy to diagnose clinically when once the thought of the disease has entered the mind.

There is some correlation between severity of illness and extent of focal rash. Toxaemia may be so sever as to cause death even before the rash is fully developed, but more commonly death, if it occurs, will be between the 11th and 15th day of the rash. In severe cases the rash may cover the entire body and the individual lesions run into one another to become confluent.

Diagnosis: Great diagnostic difficulties arise through wide variations from this characteristic pattern. Very severe disease may result in death even before the focal rash is fully developed and sometimes, as in haemorrhagic smallpox, bleeding into the skin and from the body orifices wrongly focuses attention towards some severe and acute blood disease.

Mild smallpox naturally occurring or more likely modified in this direction by residual immunity resulting from an old vaccination also presents great difficulties in clinical diagnosis, so much so that it was described by one witness as "the clinicians nightmare." For example, a patient with only a single skin lesion on the wrist caused an outbreak of smallpox involving some 40 patients and several deaths in 1973. The extreme form of this modification is known as variola sine eruptione in which no rash follows the onset of illness. Even those patients may very occasionally be infectious through droplets from the mouth.

Mortality: There is no treatment recognized as effective once the illness has started.

Patient care: There is no treatment per se once a patient has taken ill with smallpox. Treatments should concentrate on reducing secondary infections, preventing malnutrition, and increasing patient comfort, applying cold to reduce fever, and analgesics for pain.

Isolation & Debriefing: Isolation prevents propagation of the disease. It is also useful to ask the patient to generate a list of contacts during their infectious period so they can be tracked down and vaccinated, as well as the possible source of the patient's exposure, so it can be eliminated.

Secondary infections: Secondary infections which can include hemorrhaging and gangrene may be reduced by keeping linen clean, covering burst pustules, and providing nutrition.

Disposal: There is some evidence that the variola virus is extremely hardy and can survive decades or centuries of desiccation or freezing. Although this has not been proven, the disposal of remains should be by cremation. However, it is not always possible to convince relatives to do this because of social or religious traditions. Burial should be immediate.

Inoculation: Inoculation is a technique whereby a substance is introduced to a patient in order to create immunity to a specific illness. In the case of smallpox immunity, a patient is introduced to attenuated smallpox – or more recently, the related vaccinia virus (thus the expression 'vaccinate') - and a trivial infection occurs. If the procedure has been successful, subsequent exposure to the virus does not infect the patient. Variolation is inoculation with smallpox (variola) and vaccination is inoculation with vaccinia.

NOTE: Canada and the United States discontinued the practice of vaccination in 1973, but it is still practiced in the military and some countries require it for travel.

Eradication: In 1967 the World Health Organization embarked on a World Eradication

Program. In the prior year, 10-15 million people had died of smallpox.

Smallpox is a good candidate for eradication because:

· Smallpox virus has a single, stable, serotype

· There is no animal reservoir and humans are the only hosts

· The antibody response is prompt, so that exposed persons can be protected

· The disease is easily recognized clinically, so that exposed persons can be immunized promptly

· There is no carrier state or subclinical infection

The last recorded natural case was in Somalia in 1977, but laboratory exposure has caused several small epidemics since. The World Health Organization (WHO) declared the disease eradicated in 1980.

In its 1996 session, the World Health Assembly recommended that the last smallpox stocks be destroyed in 1999.

Smallpox as a biological weapon

The value of any biological weapon is that it serves both a tactical and strategic function:

Tactical because it can quickly destroy enemy troops, and disrupts production and distribution of equipment. Friendly troops and citizens can be protected through inoculation.

Strategic because it can act as a major psychological factor, even if its tactical success is limited. Further, unlike nuclear weapons, there is no destruction of property. An attacker only has to clean up the bodies when they move into an unoccupied city.

Smallpox sources include:

· US and former USSR medical research archives (known, certain)

· Hostile regimes that may have preserved samples (unknown, unlikely)

· Published genome (known, certain)

· Wild samples (unknown, unlikely)

NOTE: The use of smallpox as a tactical weapon against a Western nation is unlikely, for the following reasons:

Access: Hostile regime may have preserved samples and may attempt to generate stocks from the genome.

Deployment: It is unlikely to be able to infect large numbers of people at a single time. To act as a weapon of mass killing, it would have to be distributed in significant quantities to many people simultaneously. This is not practical without a sophisticated distribution system. For example, outbreaks could be caused by a missile impact, but they would be localized to the impact zone.

Indiscriminate: The West can inoculate themselves, and third-world regimes cannot. Smallpox could spread and engulf the attacker's community with a much higher casualty rate.

Retaliation: The West is capable of producing much more deadly bioweapons, and is capable of deploying them more effectively, and protecting itself. If the West is attacked with biological weapons, the gloves will come off, and there is no strategic advantage to a hostile country to escalate hostilities to this point.

Nevertheless, it remains possible that terrorists, whose objective is to spread fear, would find even a few deaths gratifying. Consequently, the employment of smallpox as a psychological weapon cannot be ruled out.

SOURCES: Centers for Disease Control. Atlanta, Georgia

Roberts, K.B. Smallpox: An Historic Disease. Memorial University of Newfoundland. St. John's Newfoundland, Canada. 1979.

Levinson, Warren E. and Jawetz, Ernest. Medical Microbiology & Immunology. Appleton & Lange Norwalk, Conneticut. 1994.

Miguel Leon-Portilla, the Broken Spears. Beacon Press Boston Massachusetts, 1992.

Brock, Thomas D. Microogranisms from Smallpox to Lyme Disease. W.H. Freedman and Co. New York, New York, 1990.

MacNeil, William H. Plagues and Peoples. History Book Club, New York, New York, 1976.