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CDC
HISTORY
Long before the nineteenth century many tribes and
kingdoms were devastated by the smallpox virus. This disease had a hugh
impact on the political balance of power : wars were disrupted, battles
were lost, reigning monarchies were ended, and the deaths of countless
millions of people from smallpox was so common that it was an expected
part of life.
Many cultures in Africa, China , India and Europe were affected by the smallpox virus . In eighteenth century Europe, as many as 400,000 people died each year and a third of the blindness in the continent resulted from smallpox. Epidemics such as this have had a great impact on the economy of European development. Because smallpox had a high mortality rate, it prevented a rapid increase in population.
The first recognizable description of the disease was written by Ko Hung, who lived in China during A.D. 265-313, but smallpox was not documented until 1122. The common name for this virus was variola and didn't become known as smallpox until around 1666 during a smallpox epidemic in England. The English continued the spread of smallpox when they colonized the Americas in 1792. The native American Indians had no immunities against this horrible killer and were devastated by the disease.
Smallpox has been responsible for over 2 million deaths per year during major outbreaks. In more recent history, an outbreak of smallpox occurred in 1939 in Johannesburg South Africa. The most recent outbreak was in 1977 in Somalia. This outbreak sparked action from the World Health Organization to stop any more devastation by the disease and smallpox was finally eradicated in December of 1977.
The variola virus, as seen in an electron microscope, is a brick-shaped or ovoid shaped cell. It is about 200 x 400nm in size and enclosed in a complex double membrane. This is a very hardy virus and is able to survive for a considerable amount of time outside the host.
The central core of the virus contains a single molecule of double-stranded DNA, which is enclosed by an external layer of lipid and protein.
In an infected host cell, formations of intracytoplasmic inclusions can be seen. These inclusions are called the Guarnieri bodies and are caused specifically by the virus.
Influenza is another viral infection that is caused by orthomyoxoviruses.
TREATMENT
The eradication of the (Variola) smallpox virus is
one of the greatest achievements of all time. Smallpox was the first disease
ever to be eradicated! The war on smallpox won it's first battle in the
late 1800's when an English physician, Edward Jenner first recognized that
milk-maids who were infected with cowpox, a relatively mild infection,
never contracted smallpox. Dr. Jenner did the first cowpox virus injection
on an eight year old boy. The child developed the expected reactions and
then was inoculated with the smallpox virus. He showed no sign of the disease.
Inoculation of any weakened pathogen came to be known as a vaccination
from the latin word vacca, for cow.
Prior to the vaccinations, countless millions died from smallpox virus. There is no specific treatment for smallpox but chances of survival was increased by keeping the sores clean and prevent secondary infection with antibiotics and sulfa drugs. In the unlikely event that a victim survives the disease, they are now fully immunized. Isolation of a person with smallpox has always been the first line of defense against the spread of the disease. One of these isolation hospital sites , Rietfontein, established 100 years ago in Johannesburg, South Africa is now being developed for residential use. They believe it is possible that under ideal conditions and dry temperate climates, the smallpox virus could theoretically live up to 100 years.
The variola virus was transmitted from person to person. An infected person would expel droplets from the nose and mouth, thereby infecting another person to happened to inhale the droplets.
These droplets from the upper respiratory tract secretions contained the virus shed from lesions of the oropharyngeal mucous membrane. There were also virus - laden particles from skin lesions that could break off and become airborne.
It was not unusual to see the virus being spread to doctors, nurses, and persons caring for the infected individual. Smallpox was usually spread among household members and intimate contact with infected persons.
SYMPTOMS
The basic symptoms
of smallpox was fever, severe headaches, and a rash that develops from
macules to papules to vesicles to pustules. There are two forms of smallpox:
variola major and variola minor. It was easier to determine which type
of smallpox the patient had when a large group of people were infected.
Variola major was a more serious illness with a higher mortality rate than variola minor which was a milder illness with a lower mortality rate. There are five categories that variola major can be classified in: Ordinary type, Modified type, Variola sine eruption, Flat type, and Hemorrhagic type.
The majority of the patients that got the Ordinary type, developed pustular skin lesions. There were three types of skin lesions. The first and most frequent type was a confluent rash which appears mainly on the face and forearms. The second was a semi confluent rash which appeared mainly on the face and discrete areas. The third was a discrete rash which appeared on normal skin between pustules, this was the more rare form.
The Modified type was more like regular smallpox except that the course was more accelerated and pustular lesions were smaller. This was most common with patients who had been vaccinated or who had been infected before.
The Flat type often appeared in children and the pustules remained flat and in confluent or semi confluent form.
The last type was hemorrhagic type, when the skin lesions and mucous membranes become hemorrhagic. The word hemorrhagic means that blood escapes from a blood vessel causing heavy bleeding. This type of smallpox acquired the nickname, "sledgehammer smallpox", because those who were infected died within 3 to 4 days after getting this strain of the virus.
In ordinary cases, the incubation period lasts 7 to 9 days. In 10%
of patients who were infected got diarrhea and in 50% vomiting occurs.
By day 14, the rash would begin to heal, leaving depigmented areas over
the body.
STATUS OF SMALLPOX AT
PRESENT
Smallpox, the worlds most violent killer has been
condemned to die on July 30th 1999. The judge and jury that convicted the
final laboratory stocks of smallpox to be destroyed is an organization
called W.H.O. , World Health Organization
. W.H.O. has tracked the smallpox virus for the last 20 years to all four
corners of the earth and finally succeeded in eradicating this deadly virus
on December 9, 1979. The eradication of smallpox is a picture of collaboration
and co-operation between nations, but now in the final chapter of this
virus there are those that are against the formal destruction of
smallpox by autoclave.
Now that the control of smallpox has been accomplished there are some scientist who believe we still have much to learn from this enemy. They have discovered that this virus has astonishingly diverse strategies to evade the host's attacks. Understanding these adapted strategies could possibly lead to cures for auto-immune diseases and cancer. They want to keep the virus alive for further study!
Those who are for the total destruction of the virus believe that escape of the virus could be used for terrorist purposes and argue that further research could in fact continue using cloned DNA fragments of full genome strains of variola.
The debate of whether to eradicate smallpox from destruction comes
down to weighing the potential risks of the virus escaping, against the
potential benefits to science through research.
REFERENCES
INFECTIOUS
DISEASES THAT HAVE SHAPED
For more information, contact
jackiesr@dcccd.edu
