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Tuesday, November 16, 2010

What is Smallpox?

Smallpox Symptoms
According to "House", high fever, vomiting, blood shot eyes. Wisely invest in Smallpox History Channel to better your understanding regarding Smallpox.
Here is a an elaborated article from http://skin-care.health-cares.net/smallpox-symptoms.php:
The initial symptoms of smallpox, 7 to 17 days after exposure, include the acute onset of fever, chills, headache, nausea, vomiting and severe muscle aches. During this time, the infected person feels fine and is not contagious. The symptoms of smallpox begin with high fever, head and body aches, and sometimes vomiting. A rash follows that spreads and progresses to raised bumps that crust, scab, and fall off after about three weeks, leaving a pitted scar. This stage generally lasts for two to four days and can be accompanied by flushing of the skin. By the fourth day of illness, the fever drops and the



characteristic smallpox rash appears. The rash starts out flat or slightly thickened spots (known as macules) and quickly progresses to raised spots (known as papules). These papules continue to enlarge and become filled with a clear fluid, then referred to as vesicles. The fluid in the vesicles gradually changes from clear to pus-like, and the lesions are then referred to as pustules. During the pustule stage, a fever is common and the pustules start to form into scabs. Over time, the dried scab material falls off of the skin. This entire process takes three to four weeks, and the areas affected by the rash can be permanently scarred.

There are two types of smallpox: variola major and variola minor. Variola major is the more severe form and has a 30-50% fatality rate among those who are unvaccinated (3% in vaccinated persons). Variola minor has a 1-2% fatality rate in unvaccinated individuals. There are two rare and more serious forms of smallpox. In the most severe, known as purpura variolosa or hemorrhagic-type smallpox, the initial stage of the illness (before the rash appears) is accompanied by a dark, purplish, blotchy flushing of the skin. People who developed purpura variolosa usually have a severe loss of blood into the skin and internal organs (hemorrhage), and die before the typical smallpox rash appears. About 3% of the persons with variola major develop purpura variolosa.

Another rare and deadly form of smallpox is referred to as flat-type smallpox affects about 5% of the persons with variola major. Persons with this form of the disease have lesions that develop more slowly, never raised above the surface of the skin, and feel soft to the touch. If people with flat smallpox survive, they rarely experience severe scarring. Both purpura variolosa and flat smallpox are virtually never seen in persons infected with variola minor.

Smallpox is an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning spotted, or varus, meaning "pimple". The term "smallpox" was first used in Europe in the 15th century to distinguish variola from the "great pox" (syphilis).

Smallpox localizes in small blood vessels of the skin and in the mouth and throat. In the skin, this results in a characteristic maculopapular rash, and later, raised fluid-filled blisters. V. major produces a more serious disease and has an overall mortality rate of 30–35%. V. minor causes a milder form of disease (also known as alastrim, cottonpox, milkpox, whitepox, and Cuban itch) which kills about 1% of its victims. Long-term complications of V. major infection include characteristic scars, commonly on the face, which occur in 65–85% of survivors. Blindness resulting from corneal ulceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common complications, seen in about 2–5% of cases.

Smallpox is believed to have emerged in human populations about 10,000 BC. The earliest physical evidence of smallpox is likely the pustular rash on the mummified body of Pharaoh Ramses V of Egypt, who died in 1157 BC. The disease killed an estimated 400,000 Europeans per year during the closing years of the 18th century (including five reigning monarchs), and was responsible for a third of all blindness. Of all those infected, 20–60%—and over 80% of infected children—died from the disease.

Smallpox was responsible for an estimated 300–500 million deaths during the 20th century alone. In the early 1950s an estimated 50 million cases of smallpox occurred in the world each year. As recently as 1967, the World Health Organization (WHO) estimated that 15 million people contracted the disease and that two million died in that year. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the eradication of smallpox in December 1979. Smallpox is one of only two infectious diseases to have been eradicated by humans, the other being Rinderpest, which was unofficially declared eradicated in October 2010. Source: http://en.wikipedia.org/wiki/Smallpox

Smallpox Causes
Smallpox is caused by infection with variola virus, which belongs to the genus Orthopoxvirus, the family Poxviridae and subfamily chordopoxvirinae. Variola is a large brick-shaped virus measuring approximately 302 to 350 nanometers by 244 to 270 nm, with a single linear double stranded DNA genome 186 kilobase pairs (kbp) in size and containing a hairpin loop at each end. The two classic varieties of smallpox are variola major and variola minor.

Four orthopoxviruses cause infection in humans: variola, vaccinia, cowpox, and monkeypox. Variola virus infects only humans in nature, although primates and other animals have been infected in a laboratory setting. Vaccinia, cowpox, and monkeypox viruses can infect both humans and other animals in nature.

The lifecycle of poxviruses is complicated by having multiple infectious forms, with differing mechanisms of cell entry. Poxviruses are unique among DNA viruses in that they replicate in the cytoplasm of the cell rather than in the nucleus. In order to replicate, poxviruses produce a variety of specialized proteins not produced by other DNA viruses, the most important of which is a viral-associated DNA-dependent RNA polymerase. Both enveloped and unenveloped virions are infectious. The viral envelope is made of modified Golgi membranes containing viral-specific polypeptides, including hemagglutinin. Infection with either variola major or variola minor confers immunity against the other.

Transmission
Transmission occurs through inhalation of airborne variola virus, usually droplets expressed from the oral, nasal, or pharyngeal mucosa of an infected person. It is transmitted from one person to another primarily through prolonged face-to-face contact with an infected person, usually within a distance of 6 feet (1.8 m), but can also be spread through direct contact with infected bodily fluids or contaminated objects (fomites) such as bedding or clothing. Rarely, smallpox has been spread by virus carried in the air in enclosed settings such as buildings, buses, and trains. The virus can cross the placenta, but the incidence of congenital smallpox is relatively low. Smallpox is not notably infectious in the prodromal period and viral shedding is usually delayed until the appearance of the rash, which is often accompanied by lesions in the mouth and pharynx. The virus can be transmitted throughout the course of the illness, but is most frequent during the first week of the rash, when most of the skin lesions are intact. Infectivity wanes in 7 to 10 days when scabs form over the lesions, but the infected person is contagious until the last smallpox scab falls off.

Smallpox is highly contagious, but generally spreads more slowly and less widely than some other viral diseases, perhaps because transmission requires close contact and occurs after the onset of the rash. The overall rate of infection is also affected by the short duration of the infectious stage. In temperate areas, the number of smallpox infections were highest during the winter and spring. In tropical areas, seasonal variation was less evident and the disease was present throughout the year. Age distribution of smallpox infections depends on acquired immunity. Vaccination immunity declines over time and is probably lost in all but the most recently vaccinated populations. Smallpox is not known to be transmitted by insects or animals and there is no asymptomatic carrier state. Source: http://en.wikipedia.org/wiki/Smallpox

Smallpox vs Chickenpox
Chickenpox was commonly confused with smallpox in the immediate post-eradication era. Chickenpox and smallpox can be distinguished by several methods. Unlike smallpox, chickenpox does not usually affect the palms and soles. Additionally, chickenpox pustules are of varying size due to variations in the timing of pustule eruption: smallpox pustules are all very nearly the same size since the viral effect progresses more uniformly. A variety of laboratory methods are available for detecting chickenpox in evaluation of suspected smallpox cases.

In the 9th century the Persian physician, Rhazes, provided one of the most definitive observations of smallpox and was the first to differentiate smallpox from measles and chickenpox in his Kitab fi al-jadari wa-al-hasbah (The Book of Smallpox and Measles)

Smallpox Treatment
Smallpox vaccination within three days of exposure will prevent or significantly lessen the severity of smallpox symptoms in the vast majority of people. Vaccination four to seven days after exposure likely offers some protection from disease or may modify the severity of disease. Other than vaccination, treatment of smallpox is primarily supportive, such as wound care and infection control, fluid therapy, and possible ventilator assistance. Flat and hemorrhagic types of smallpox are treated with the same therapies used to treat shock, such as fluid resuscitation. Patients with semi-confluent and confluent types of smallpox may have therapeutic issues similar to patients with extensive skin burns.

No drug is currently approved for the treatment of smallpox. However, antiviral treatments have improved since the last large smallpox epidemics, and studies suggest that the antiviral drug cidofovir might be useful as a therapeutic agent. The drug must be administered intravenously, however, and may cause serious renal toxicity. Source: http://en.wikipedia.org/wiki/Smallpox

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