Two years after Nigerian militant group Boko Haram attacked his hometown of Gwoza – killing men and burning down houses – Ali Bello feared the worst when he received a panicked message from his wife.

The rickshaw driver – who works in the nearby town of Mubi in northeast Nigeria – raced home to find that their five-year-old son had been rushed to hospital after falling severely ill.

“When they told me the boy had polio, I did not believe it,” Bello told the Thomson Reuters Foundation by phone.