Smallpox was declared eradicated by the World Health Organisation in 1980. It was a hugely devastating disease that claimed hundreds of millions of people’s lives in the 20th century alone, and was caused by the variola virus, a type of orthopoxvirus.

It’s thought that the virus reached humans tens of thousands of years ago, through an African rodent. Its mode of transmission is mainly airborne via infected patient droplets, and potentially via other intimate contact items such as bedding. The virus spreads through the respiratory system as it incubates, at which point it travels from cell to cell, relatively slowly. Initial symptoms include fever, fatigue, nausea, and other general flu-like symptoms.

When the virus has replicated and erupted from cells into the bloodstream, it is able to spread and replicate in lymph nodes and cause systemic disease. This is when the characteristic skin pustules develop over a few weeks, following similar ones on the mucosa first e.g. in the mouth. These release many more viruses in the body and can potentially infect a bystander.

They are fluid-filled pustules that erupt on the face and spread elsewhere on skin. The fluid becomes opaque and it contains tissue debris, not pus. Over time, scabs form and leave behind depigmented skin. There are multiple forms of the disease in terms of progression. The malignant and haemorrhagic types are more fatal. In the haemorrhagic type, no blisters form on the skin, as it remains flat, but vessels burst underneath and lead to…