Africa has marked a full year since its last recorded case of polio, a key step in the future eradication of the disease.
The last recorded case of polio in the continent was in Somalia last year, following an outbreak in the Horn of Africa region two years ago that left more than 200 people paralyzed.
The Somali government is not yet declaring the disease completely eradicated from the country.
"The chance for re-emergence is there, but we will be vigilant," Dr. Abdiqani Omar, director general of Somalia's Health Ministry, said in an interview with VOA's Somali service.
Omar says health workers have not been able vaccinate or spread awareness campaigns to areas controlled by the al-Shabab militant group.
Experts warn that continued success in the battle against polio depends on the continuation of vaccination campaigns and the close monitoring of suspected cases.
“Surveillance for polio virus has improved considerably," Dr. Hamid Jafari, director of a global polio eradication program at the World Health Organization, said. "However, in the past we've had year-long periods when we thought the polio virus had gone from the Horn of Africa and central Africa, only to find out that we were simply missing transmission because our surveillance systems were not strong enough to spot cases."
Nigeria marked one year since its last recorded case of polio in July. Afghanistan and Pakistan remain the only two countries in the world that have active cases of the disease.
Polio, short for poliomyelitis, is a highly infectious disease transmitted person to person, often through fecal matter and contaminated water. It mainly affects children, causing permanent paralysis and even death. Polio is easily prevented through vaccination, but there is no cure.