Rarest disease

The rarest contagious disease is smallpox, a once-widespread virus which was eradicated by a concerted global vaccination programme between 1967 and 1977. The World Health Assembly formally declared that smallpox had been eradicated around the world on 8 May 1980.

Smallpox is caused by the variola virus, and symptoms include a high fever, fatigue and a distinctive rash. The rash causes spots which fill with fluid and pus. These later crust over, dry out and fall off.

The last natural case was recorded in Somalia in 1977, where a hospital cook named Ali Maow Maalin caught smallpox from two patients in a vehicle. Maalin made a full recovery. He died in 2013 while working towards the polio eradication campaign.

The last known cases of smallpox were identified in 1978 in Birmingham, England. Janet Parker was a medical photographer at the Birmingham University Medical School, working on the floor above a smallpox research laboratory. Somehow she caught smallpox while working nearby and later died.

The World Health Assembly formally announced the world free of smallpox on 08 May 1980. The World Health Organisation continues to carry out surveillance and provides guidance to governments, to help protect the world from any new outbreak of smallpox.