For the first time in five years, Europe has had a polio outbreak, and it's serious enough that permanent damage has been done. Two children in Ukraine, aged four years and 10 months respectively, have been paralyzed, suggesting that larger numbers have been infected without (yet) developing symptoms.
As Oliver Rosenbaum, a spokesperson for the Polio Eradication Initiative at the World Health Organization (WHO) states:
"There are two cases of paralysis, but for sure they are not the only ones. That's one of the big dangers of the disease, there are a lot of asymptomatic cases."
As if that weren't worrisome enough, it's worth noting that only half of the children in Ukraine are fully immunized. This means that there is a high risk of the virus spreading through the country. The virus will have to be quickly contained to prevent further damage.
The outbreak is believed to have arisen from the weakened form of the polio virus used in vaccination. When immunization levels are too low, the virus used in the vaccine can mutate and spread. Usually the vaccine-derived virus is milder than the "wild" one, but in this case, as Rosenbaum has stated, the virus has become a "dangerous strain."
This is especially disheartening in light of the tremendous progress we've made in combating the disease on a global level.
In 2010, the last time an outbreak of this severity occurred in Europe, a wild polio strain imported from Tajikistan paralyzed 14 people in Russia.