Small POX

Smallpox Disease Overview pox part of smallpox is derived from the Latin

word for “spotted” and refers to the raised bumps that appear on the face and body of an infected person.

Two clinical forms1. Variola major is the severe and most common form of smallpox, more extensive rash and higher fever. four types of variola major smallpox1. ordinary (the most frequent type, accounting for 90% or more of cases)2.modified (mild and occurring in previously vaccinated persons);3.flat,4. hemorrhagic (both rare and very severe). variola major has an overall fatality rate of about 30%; however, flat and

hemorrhagic smallpox usually are fatal. 2.Variola minor is a less common presentation of smallpox, and a much less

severe disease, with death rates historically of 1% or less

Incubation period.. Incubation Period

(Duration: 7 to 17 days)Not contagious

Initial Symptoms (Prodrome)(Duration: 2 to 4 days)Sometimes contagious*

Early Rash(Duration: about 4 days)Most contagious

Rash distribution: Pustular Rash

(Duration: about 5 days)Contagious

Pustules and Scabs(Duration: about 5 days)Contagious

Resolving Scabs(Duration: about 6 days)Contagious

Scabs resolvedNot contagious

Smallpox may be contagious during the prodrome phase,

most infectious during the first 7 to 10 days following rash onset.

Possible Ways of Getting Smallpox Prolonged face-to-face contact with

someone who has smallpox Direct contact with infected bodily fluids or

an object such as bedding or clothing that has the virus on it.

Exposure to an aerosol release of smallpox (the virus is put in the air).

Treatment There is no proven treatment for smallpox

best ways to prevent smallpox is through vaccination If given before exposure to smallpox – complete

protection within 3 days after exposure will prevent or greatly

lessen the severity of smallpox in most people. 4 to 7 days after exposure likely offers some

protection from disease or may decrease the severity of disease.

Vaccination will not protect smallpox patients who already have a rash

Eradication

one of the greatest triumphs in medicine

The global eradication of smallpox in 1977

the last naturally occurring case in the world was in Somalia in 1977.

Smallpox Eradication Timeline

Written descriptions occurred as early as 400 AD.

In science credit goes to the man who convinces the world, not the man to whom the idea first occurs..

Francis Galton

1796: The first smallpox vaccine was developed by Edward Jenner.

After WWI: Most of Europe smallpox-free. After WWII: Transmission interrupted in

Europe and North America

1940s the development of a freeze-dried vaccine was more stable in higher temperature and

humidity climates, the smallpox vaccine was available for wider

use throughout the world

1950: The Pan American Sanitary Organization,

undertook a program to eradicate smallpox in the Western Hemisphere.

1958: The first proposal for global eradication was

made to the World Health Assembly by the USSR in 1958.

They proposed a worldwide vaccination program to be completed in a 3-to-5 year period.

Some progress was made during the next 7 years, but the results overall were disappointing.

1966 The World Health Assembly decided to

intensify the eradication program by providing a special budget of $2.4 million per year specifically for this effort.

1967: The Intensified Global Eradication program began cases still occurred in 31 countries where the

disease was endemic. A major reservoir was Africa. A second major reservoir was in Asia, extending

from Bangladesh through India, Nepal, Pakistan, and Afghanistan.

The third was the Indonesian archipelago, The fourth was Brazil, which compromised half the

people of South America

Global Eradication Initiative

The initial eradication campaign was based on a two-fold strategy.

1.Mass vaccination campaigns in each country, using vaccine of ensured potency and stability, that would reach at least 80% of the population.

2.The development of surveillance systems to find cases and outbreaks so that more focused containment measures could be implemented.

Mass Vaccination In 1966, the Smallpox Eradication and

Measles Control Program was initiated in 18 West African countries to move toward eradication in this disease-endemic area.

Sierra Leone had the highest infection rates in the world

Efforts.. Through the use of vaccination guns,

government resources, and, most importantly, traditional health authorities, large numbers of people were vaccinated.

The program administered over 100 million vaccinations in a 5-year period.

Surveys showed that 90% of the population had been vaccinated.

Smallpox rates fell as a result of these efforts.

Ring vaccination-Key strategy of global eradication program great impact on smallpox transmission even in areas

where overall vaccination coverage was low by using a strategy called surveillance and containment, or ring vaccination.

The principle behind this strategy was to identify cases of smallpox,

vaccinate their household and other close contacts, vaccinate the close contacts of the primary

household and close contacts to the case

If the primary contacts developed smallpox despite vaccination, their close contacts would already be protected and the chain of transmission would have been broken.

Special surveillance teams… were recruited and trained to search for smallpox cases and

vaccinate their contacts. They visited each health unit in an area of endemic smallpox

to ensure that each week the health officer submitted a report indicating the number of cases seen.

When cases were reported, the teams worked with local health staff to find additional cases and to contain the outbreaks by vaccinating the contacts.

Although setbacks occurred, this surveillance and containment strategy proved to be the strategy that finally brought about the eradication of smallpox throughout the world.

Final Eradication

By the end of 1975, smallpox persisted only in the Horn of Africa

Conditions were very difficult in Ethiopia and Somalia, where there were few roads.

Civil war, famine, and refugees made the task even more difficult.

With the interruption of smallpox transmission in Asia, more resources were made available in Africa, including more staff and transport

world’s last indigenous patient with smallpox intensive surveillance and containment and

vaccination program was initiated in the spring and summer of 1977.

As a result, the world’s last indigenous patient with smallpox on earth was a hospital cook in Merka, Somalia, on October 26, 1977 with variola minor.

Laboratory accident-1978 Searches for additional cases continued in

Africa for more than 2 years, during which time thousands of rash illnesses were investigated. None proved to be smallpox

Although 2 cases of smallpox occurred in England in 1978 as a result of a laboratory accident, smallpox was gone as a naturally transmitted disease

Eradication Declared.. The World Health Organization officially

certified that smallpox had been eradicated on December 9, 1979, 2 years after the last case in Somalia.

In 1980 the World Health Assembly recommended that all countries cease routine vaccination

Small pox virus today kept in two approved labs in the U.S. and

Russia.

bronze grouping symbolizes the coming together of peoples

from all nations to solve a major health scourge that plagued

the human family since the beginning of recorded history.

Together, the peoples of the world achieved this unprecedented success of eradicating smallpox

Why Smallpox is a Concern today??

smallpox virus, Today, credible concern exists that the virus was

made into a weapon by some countries and that terrorists may have obtained it.

CDC calls it a “Category A” agent. Category A agents are believed to present the greatest potential threat for harming public health

After 9/11 the U.S. govt improved its level of

preparedness against terrorism. be prepared for an intentional release of the

smallpox virus updating and releasing a smallpox response

plan.

bioterrorism Category A

can be easily disseminated or transmitted from person to person;

result in high mortality rates and have the potential for major public health impact;

might cause public panic and social disruption; and require special action for public health preparedness

Category A Bacillus anthracis) Botulism (Clostridium botulinum toxin) Plague (Yersinia pestis) Smallpox (variola major) Tularemia (Francisella tularensis) Viral hemorrhagic fevers (filoviruses [e.g.,

Ebola, Marburg] and arenaviruses [e.g., Lassa, Machupo])

Category B

Brucella species) Epsilon toxin of Clostridium perfringens Food safety threats (e.g., Salmonella species, Escherichia coli O157:H7,

Shigella) Glanders (Burkholderia mallei) Melioidosis (Burkholderia pseudomallei) Psittacosis (Chlamydia psittaci) Q fever (Coxiella burnetii) Ricin toxin from Ricinus communis (castor beans) Staphylococcal enterotoxin B Typhus fever (Rickettsia prowazekii) Viral encephalitis (alphaviruses [e.g., Venezuelan equine encephalitis,

eastern equine encephalitis, western equine encephalitis]) Water safety threats (e.g., Vibrio cholerae, Cryptosporidium parvum)

How Public Health Officials will Respond to a Smallpox Outbreak CDC has a detailed plan to protect Americans

against the use of smallpox as a biological weapon.

If a smallpox outbreak happens1.public health officials will use television,

radio, newspapers, the Internet and other channels to inform members of the public about what to do to protect themselves and their families.

2. Officials will tell people where to go for care if they think they have smallpox.

3. Smallpox patients will be isolated and will receive the best medical care possible. Isolation prevents the virus from spreading to others.

4.Anyone who has had contact with a smallpox patient will be offered smallpox vaccination as soon as possible.

Then, the people who have had contact with those individuals will also be vaccinated.

Following vaccination, these people will need to watch for any signs of smallpox.

People who have been exposed to smallpox may be asked to take their temperatures regularly and report the results to their health department.

5.The smallpox vaccine may also be offered to those who have not been exposed, but would like to be vaccinated.

At local clinics, the risks and benefits of the vaccine will be explained and professionals will be available to answer questions.

No one will be forced to be vaccinated, even if they have been exposed to smallpox.

To prevent smallpox from spreading, anyone who has been in contact with a person with smallpox but who decides not to get the vaccine may need to be isolated for at least 18 days. During this time, they will be checked for symptoms of smallpox.

People placed in isolation will not be able to go to work. Steps will be taken to care for their everyday needs (e.g., food and other needs)

The Smallpox Vaccine The vaccine is made from a virus called

vaccinia which is a “pox”-type virus related to smallpox. The smallpox vaccine contains the “live” vaccinia virus

Length of Protection Smallpox vaccination provides high level

immunity for 3 to 5 years and decreasing immunity thereafter.

If a person is vaccinated again later, immunity lasts even longer.

Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated. In

Receiving the Vaccine The vaccine is given using

a bifurcated (two-pronged) needle that is dipped into the vaccine solution. When removed, the needle retains a droplet of the vaccine. The needle is used to prick the skin a number of times in a few seconds.

.

Anyone directly exposed to smallpox… regardless of health status, would be offered

the smallpox vaccine

because the risks associated with smallpox disease are

far greater than those posed by the vaccine

Smallpox Vaccine Availability Until recently, the U.S.

government provided the vaccine only to a few hundred scientists and medical professionals working with smallpox and similar viruses in a research setting.

Vaccine availability.. the U.S. government has enough vaccine to

vaccinate every person in the United States in the event of a smallpox emergency

Smallpox Vaccination May Have Protected Against HIV Infection

Weinstein RS et al. Significantly reduced CCR5-tropic HIV-1 replication in vitro in cells from subjects previously immunized with Vaccinia virus. BMC Immunology 2010, 11: 23.

Small pox vs HIV As the HIV virus enters T cells, it makes use of a

cell-surface receptor called CCR5. The smallpox virus also uses this receptor. when the smallpox virus grabs hold of this CCR5

receptor to penetrate the T cell, it alters it in some way.

The HIV virus may then subsequently find it harder to gain entry and therefore replicate in the cells

Weinstein’s study is based on a small number of subjects,

these results are intriguing enough to warrant further investigation

scientists are focusing on understanding the effects that the smallpox virus, Vaccinia, has on the immune system and how those effects may influence HIV infection rates and progression to full-blown AIDS

…it stands as a reminder of the power of international health cooperation to do great and lasting good

Dr Margaret Chan