Maalin was subsequently involved in the successful poliomyelitis eradication campaign in Somalia, and he died of malaria while carrying out polio vaccinations after the re-emergence of the poliovirus in 2013.

Maalin worked as a cook at the hospital in the port town of Merca in southern Somalia,[3] as well as an occasional vaccinator for a WHO smallpox eradication team.

[3][4][5] According to CDC epidemiologist Jason Weisfeld, one of the people who led the later containment effort in Merca, Maalin had received the smallpox vaccine but it had failed to take, and he had not been protected.

[10] On 12 October 1977, two children with smallpox symptoms were discovered at an encampment near the small inland settlement of Kurtunawarey, around 90 km (60 miles) from Merca.

[10][3][8] Maalin, then aged 23, served as a guide to the party taking them in a closed Land Cruiser from the hospital where he worked either to the home of a surveillance supervisor or directly to the isolation camp.

[10][3] The outbreak among the nomadic group was successfully contained by WHO workers by 18 October, but, critically, investigators failed to identify Maalin as a contact.

On 30 October, a nurse colleague reported him, possibly for the reward of 200 Somali shillings (around $35), and Maalin was transferred to the isolation camp.

[3][4][8] He was diagnosed with an infection of the Variola minor strain of smallpox, based on his symptoms and later confirmed by laboratory tests.

[3][4] Donald Henderson, who directed the WHO eradication programme from 1967 until 1976,[3] describes Maalin's case as "a classic one in depicting omissions and mistakes in program operations.

Police checkpoints on all exits to the town, including footpaths, were established to vaccinate anyone passing who had not been recently immunised.

[5] The containment efforts proved effective and, on 17 April 1978, WHO's Nairobi office sent a telegram stating: "Search complete.

"[1] Maalin worked for WHO as a local coordinator with responsibility for social mobilisation, and spent several years travelling across Somalia, vaccinating children and educating communities.

[16] After the 2013 reintroduction of poliovirus into Somalia, Maalin was again carrying out vaccinations in the Merca district when he developed a fever, and died days later, on 22 July 2013, of malaria.

[18] One of the most feared diseases of human history, smallpox was still causing an estimated 2 million deaths every year as late as 1967.

This involved active surveillance by case hunting, combined with rapid containment of infection in areas reporting outbreaks by intensive vaccination.

[22][23] The nomadic people of the Ogaden Desert retained endemic smallpox with an unusually mild form of the disease, which facilitated persistence in the population.

By June, when the outbreak peaked, 3,000 Somali health workers supervised by 23 international advisers were involved in the eradication efforts.