One of the two Ebola testing labs in Sierra Leone has been closed by the World Health Organization (WHO) following the infection of one of its staff.

The announcement was made on Tuesday that the lab had been vacated as the result of a Senegalese epidemiologist contracting the virus. The remaining lab will be left open but the reduction in aid to the area could hinder containment efforts for the nasty virus.

Sierra Leone is among the hardest hit areas for what is being called the worst outbreak of Ebola in recorded history. This country alone has reported more than 800 confirmed cases of the virus and over 350 deaths confirmed to be caused by the virus. For both infection and death, there are a number of cases still awaiting confirmation of the presence of the virus.

According to the WHO, 1,427 deaths are either confirmed or suspected to be related to the outbreak in West Africa. The survival rate is around 47 percent, which is considered high as the virus has been known to claim up to 90 percent of those who contract it. The most recent numbers from the WHO show that 1,528 people are known to have the virus and another 1,087 are considered “suspect” or “probable” for infection.

Liberia has experienced the hardest hit from the outbreak. Government interventions to contain the virus have included quarantining an entire slum in its capital, Monrovia. President Ellen Johnson Sirleaf has responded to reports of officials abandoning their government positions and even leaving the country with mandates that all government employees return to work or lose their jobs permanently.