People who have travelled from parts of West Africa to Ireland are being asked to seek urgent medical attention if they develop a fever within 21 days of their return.

The call from the Health Protection Surveillance Centre (HPSC) is in response to the biggest outbreak of ebola virus disease (EVD) ever recorded. Over 1,200 cases of the disease have been recorded and more than 670 people have died as a result.

Currently, the countries affected are Guinea, Sierra Leone and Liberia. However, according to the World Health Organization (WHO), the Ministry of Health of Nigeria has now reported its first probable case.

"According to the Nigeria authorities, the case is a 40-year-old Liberian male national who recently travelled to Nigeria where he presented in hospital with symptoms of EVD. The patient travelled by air and arrived in Lagos, Nigeria, on July 20 via Lomé, Togo. He was symptomatic while traveling, was admitted to a private hospital immediately on arrival, and died on July 25," the WHO said.

EVD is a severe and often fatal illness. It is initially transmitted to humans from wild animals, but human-to-human transmission can then occur as a result of direct contact with the blood, secretions, organs or other bodily fluids of infected people, or indirect contact with environments that have been contaminated with these fluids.

According to the WHO, even burial ceremonies ‘in which mourners have direct contact with the body of the deceased person' can lead to the transmission of the disease.

Those affected require intensive care and there is currently no treatment or vaccine available. Where an outbreak occurs, the case fatality rate can reach 90%.

The WHO insists that it is ‘entirely likely that there still remain EVD cases to be identified', especially in Sierra Leone and Liberia.

The HPSC is calling on anyone returning from trips to Sierra Leone, Liberia and Guinea, or who have travelled through these areas, to seek urgent medical attention if they develop a fever of greater than 38 degrees Celsius within 21 days of their return.

For more information on EVD, click here