History is brimming with the wrath smallpox wrecked on the human race. It was counted as the deadliest disease humans have ever encountered. It used to claim millions of lives worldwide each year. Smallpox is a highly contagious viral disease. It is also known as variola. Luckily due to extensive vaccination against this disease, it has been now completely eradicated. Due to the absence of this virus now this vaccine is not administered because it can be toxic. Only people who are at high risk are recommended to receive this vaccine. Show More
It is known that it used to start with flu-like symptoms after an incubation period of 7-17 days.