Monrovia, Aug 23, (RHC), – The World Health Organization (WHO) has raised the alarm about the Ebola outbreak in the West African countries, warning of the epidemic’s “unprecedented” extent and speed.

Speaking at a news conference in the Liberian capital, Monrovia, on Friday, WHO’s Assistant Director-General for Health Security, Keiji Fukuda, expressed particular concern over the so-called “shadow zones” where patients are not being detected.

“We haven’t seen an Ebola outbreak covering towns, rural areas so quickly and over such a wide area,” Fukuda said.

The WHO doctor also noted that combating the disease will take “several months of hard work.”

Meanwhile, in a situation assessment issued on Friday, the WHO highlighted that the magnitude of West Africa’s Ebola outbreak has been “underestimated.”

The report came one day after Senegal closed its border with Guinea over Ebola outbreak fears.

More than 1,420 people have died in the outbreak so far, with the number of infection cases now standing at over 26,000. The worst-affected countries are Guinea, Liberia and Sierra Leone.

Ebola is a form of hemorrhagic fever whose symptoms are diarrhea, vomiting and bleeding. The virus spreads through direct contact with infected blood, feces or sweat. It can also be spread through sexual contact or the unprotected handling of contaminated corpses.

Ebola remains one of the world’s most virulent diseases, which kills between 25 to 90 percent of those who fall sick.