The number of deaths and confirmed cases of ebola in west Africa has been vastly underestimated, the World Health Organisation (WHO) says.
The death toll from the outbreak currently stands at 1,069 people. There have been 1,975 confirmed, probable or suspected cases.
The majority of the cases have occurred in Guinea, Sierra Leone and Liberia. Four deaths have also been reported in Nigeria.
But the WHO said there is evidence that the number of reported cases underestimates the scale of the suffering.
“The outbreak is expected to continue for some time. WHO’s operational response plan extends over the next several months,” the WHO said in a statement.
“Staff at the outbreak sites see evidence that the numbers of reported cases and deaths vastly underestimate the magnitude of the outbreak.”
It comes after several does of the experimental drugZMapparrived in Liberia this week.
Officials say only three people will receive the drug, which could prove life-saving, ineffective or even harmful.
The Liberian government previously said two doctors would receive ZMapp, but it remains unclear who else will be treated.
The ebola outbreak was first identified in Guinea in March and has since spread to Liberia, Sierra Leone and Nigeria.
The spread of the disease has overwhelmed strained health systems in west Africa.
As there is no licenced treatment for Ebola – which is transmitted by contact with bodily fluids – doctors have turned to the limited supply of untested drugs to treat some cases.
Two Americans and one Spaniard have so far received ZMapp.
The Americans have since shown signs of improvement, however it remains unclear what role the drug has played in their recovery. The Spaniard died within days.
As the human cost continues to rise, there are concerns about the wider economic threat caused by the outbreak.
The Moody’s ratings agency warned on Thursday that the virus could have “significant economic” ramifications for a number of west African countries.