Smallpox is a fatal infectious disease caused by two virus strains - Variola major and Variola minor. The word 'smallpox' has been derived from the Latin word varius, meaning spotted. Around the 15th century, it was termed by the Europeans to distinguish it from the great pox; syphilis. The origin of this disease is disputed; some believe, it originated in the Asian subcontinent, while some have traced it to ancient Egypt. However, what can't be disputed is the devastation, this epidemic left behind, besides the millions that it killed prior to the 20th century. It was responsible for 300-500 million deaths before the 20th century ended. Causes It is caused by the Variola virus, which is a member of the orthopoxvirus genus. This virus is known to infect only humans and spreads through inhalation, person-to-person contact, and can also be transmitted from a mother to the fetus. The reason why this virus causes one of the most deadly diseases is that, the virus gets in the lungs and starts replicating inside the cells, eventually spreading to the skin, intestines, and kidneys. When this virus enters the skin, it causes red lesions to appear, gradually turning into vesicles, and then pustules. When the virus settles in the mucous membranes of the nose and throat, it releases large amounts of virus into the saliva, increasing its transmission rate. An infected person can spread the virus simply by sneezing, as the virus particles can remain on clothing, bedding, and/or any surfaces, for nearly a week. Symptoms The disease is of two types; Variola major and Variola minor. Variola major is fatal in nature, whereas Variola minor can cause serious illnesses, and in few odd instances, could even cause death. Signs of smallpox also depend upon its type. After a person has been infected, the virus starts to replicate itself within 72-96 hours, and most symptoms start to exhibit between 7-17 days. Body ache, fever, chills, and headache are the first indicators that the virus has begun to spread. A severe back pain is also experienced by many. Within 48 hours of being infected, the flat and colored rash appears, that turns into small blisters filled with vesicles and then pus. The rash initially appears in the mouth, nose, and throat, and then on the face, arms, and legs. Virus-filled sores do not break out like other infectious sores, they just tend to scab over. Scabbing means they spread and form underlying layers. It takes about another three weeks until the scabs fall off, leaving deep scars. The person stays infectious until the scabs fall off completely. People are generally isolated for some more days, as live virus is present in the scabs. Symptoms in children are quite similar to the ones mentioned above, except that it is known to cause seizures in some children. Children, however, have better chances of being left behind with lesser and lighter scars than adults. Treatment As soon one is diagnosed with the disease, the individual is isolated or quarantined and given the smallpox vaccine. Antibiotics are prescribed to treat secondary bacterial infections. The vaccine proves effective, if it is given within 96 hours of being infected. Smallpox has no cure besides vaccination. It has been eradicated as per the announcement made by the World Health Organization (WHO) in 1980. However, people must be aware of its symptoms and treatment, as its potential to spread and kill remains an ever-increasing threat to human life.