Roqia holds her young son, who was reported through the local surveillance network in Bamyan, Afghanistan, as having acute flaccid paralysis. ©WHO Afghanistan

The poliovirus remains in just a few small pockets around the world. However, these final hiding places are some of the most challenging settings on earth in which to eradicate a disease. Finding and stopping a virus whose special power is staying hidden is no mean feat, especially in remote or inaccessible places.

Disease detectives around the world are working tirelessly to find every last virus in these hard to reach places. Some areas are vast and sparsely populated, such as the broad plains and river beds making up areas of the Lake Chad region. Others are densely packed residential areas of Afghanistan, where security issues can sometimes make immunization difficult. In areas of Syria, civil war continues to rage through towns, communities, and families. Yet these challenges are not enough to stop the surveillance system.

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