Smallpox virus

There were two clinical forms of smallpox. Variola major was the severe and most common form, with a more extensive rash and higher fever. Variola minor was a less common presentation, and a much less severe disease, with historical death rates of one percent or less. Subclinical (asymptomatic) infections with Variola virus were noted but were not common. In addition, a form called variola sine eruptione (smallpox without rash) was seen generally in vaccinated persons. This form was marked by a fever that occurred after the usual incubation period and could be confirmed only by antibody studies or, rarely, by virus isolation.The incubation period between contraction and the first obvious symptoms of the disease was around 12 days. Once inhaled, variola major virus invaded the oropharyngeal (mouth and throat) or the respiratory mucosa, migrated to regional lymph nodes, and began to multiply. In the initial growth phase, the virus seemed to move from cell to cell, but by around the 12th day, lysis of many infected cells occurred and the virus was found in the bloodstream in large numbers (this is called viremia), and a second wave of multiplication occurred in the spleen, bone marrow, and lymph nodes.Smallpox was caused by infection with Variola virus, which belongs to the genus Orthopoxvirus, the family Poxviridae and subfamily Chordopoxvirinae.The clinical definition of smallpox is an illness with acute onset of fever equal to or greater than 38.3 °C (101 °F) followed by a rash characterized by firm, deep seated vesicles or pustules in the same stage of development without other apparent cause. When a clinical case was observed, smallpox was confirmed using laboratory tests.Smallpox virus lesions on the chorioallantoic membrane of a developing chick.In contrast to the rash in smallpox, the rash in chickenpox occurs mostly on the torso, spreading less to the limbs.An Italian female smallpox patient whose skin displayed the characteristics of late-stage confluent maculopapular scarring, 1965.The earliest procedure used to prevent smallpox was inoculation (known as variolation after the introduction of smallpox vaccine to avoid possible confusion), which likely occurred in India, Africa, and China well before the practice arrived in Europe. The idea that inoculation originated in India has been challenged, as few of the ancient Sanskrit medical texts described the process of inoculation. Accounts of inoculation against smallpox in China can be found as early as the late 10th century, and the procedure was widely practiced by the 16th century, during the Ming dynasty. If successful, inoculation produced lasting immunity to smallpox. Because the person was infected with Variola virus, a severe infection could result, and the person could transmit smallpox to others. Variolation had a 0.5–2 percent mortality rate, considerably less than the 20–30 percent mortality rate of the disease. Two reports on the Chinese practice of inoculation were received by the Royal Society in London in 1700; one by Dr. Martin Lister who received a report by an employee of the East India Company stationed in China and another by Clopton Havers.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 can offer 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. People with semi-confluent and confluent types of smallpox may have therapeutic issues similar to patients with extensive skin burns.The overall case-fatality rate for ordinary-type smallpox is about 30 percent, but varies by pock distribution: ordinary type-confluent is fatal about 50–75 percent of the time, ordinary-type semi-confluent about 25–50 percent of the time, in cases where the rash is discrete the case-fatality rate is less than 10 percent. The overall fatality rate for children younger than 1 year of age is 40–50 percent. Hemorrhagic and flat types have the highest fatality rates. The fatality rate for flat-type is 90 percent or greater and nearly 100 percent is observed in cases of hemorrhagic smallpox. The case-fatality rate for variola minor is 1 percent or less. There is no evidence of chronic or recurrent infection with Variola virus.The earliest credible clinical evidence of smallpox is found in the smallpox-like disease in medical writings from ancient India (as early as 1500 BCE), Egyptian mummy of Ramses V who died more than 3000 years ago (1145 BCE) and China (1122 BCE). It has been speculated that Egyptian traders brought smallpox to India during the 1st millennium BCE, where it remained as an endemic human disease for at least 2000 years. Smallpox was probably introduced into China during the 1st century CE from the southwest, and in the 6th century was carried from China to Japan. In Japan, the epidemic of 735–737 is believed to have killed as much as one-third of the population. At least seven religious deities have been specifically dedicated to smallpox, such as the god Sopona in the Yoruba religion in West Africa. In India, the Hindu goddess of smallpox, Sitala Mata, was worshipped in temples throughout the country.Having considered the development and results of the global program on smallpox eradication initiated by WHO in 1958 and intensified since 1967 … Declares solemnly that the world and its peoples have won freedom from smallpox, which was a most devastating disease sweeping in epidemic form through many countries since earliest time, leaving death, blindness and disfigurement in its wake and which only a decade ago was rampant in Africa, Asia and South America.The British used smallpox as a biological warfare agent at the Siege of Fort Pitt during the French and Indian Wars (1754–1763) against France and its Native American allies. The actual use of smallpox had official sanction. British officers, including the top British commanding generals, ordered, sanctioned, paid for and conducted the use of smallpox against the Native Americans. As described by historians, 'there is no doubt that British military authorities approved of attempts to spread smallpox among the enemy', and 'it was deliberate British policy to infect the Indians with smallpox'. On 24 June 1763, William Trent, a local trader and commander of the Fort Pitt militia, wrote, 'Out of our regard for them, we gave them two Blankets and an Handkerchief out of the Small Pox Hospital. I hope it will have the desired effect.' The effectiveness of this effort to broadcast the disease is unknown. There are also accounts that smallpox was used as a weapon during the American Revolutionary War (1775–1783).On Vozrozhdeniya Island in the Aral Sea, the strongest recipes of smallpox were tested. Suddenly I was informed that there were mysterious cases of mortalities in Aralsk. A research ship of the Aral fleet came to within 15 km of the island (it was forbidden to come any closer than 40 km). The lab technician of this ship took samples of plankton twice a day from the top deck. The smallpox formulation – 400 gr. of which was exploded on the island – 'got her' and she became infected. After returning home to Aralsk, she infected several people including children. All of them died. I suspected the reason for this and called the Chief of General Staff of Ministry of Defense and requested to forbid the stop of the Alma-Ata–Moscow train in Aralsk. As a result, the epidemic around the country was prevented. I called Andropov, who at that time was Chief of KGB, and informed him of the exclusive recipe of smallpox obtained on Vozrazhdenie Island.