As a young missionary doctor, Bill Foege was sent with his family to eastern Nigeria in 1966, where they lived in a mud hut without plumbing, 145 km from the nearest telephone. He immediately faced an outbreak of smallpox in the midst of the looming civil war in Biafra. He characterized smallpox as a disease with the characteristic smell of death. Due to insufficient vaccination, he introduced a circular vaccination strategy, first used in England in the 19th century, which suppressed the outbreak. This method used contacting missionaries by ham radio to identify four affected villages within 24 hours and then vaccinate the residents. The strategy led authorities to adopt it throughout the campaign to eradicate smallpox, the only human infectious disease eradicated in 1980. Smallpox killed an estimated 300 million people in the 20th century. Foege became director of the CDC's smallpox eradication program and later director of the CDC.