The current outbreak of Ebola Virus Disease (EVD) affecting countries in West Africa is now confirmed as the largest ever outbreak of the disease, according to the World Health Organization (WHO).

The latest WHO update published yesterday says there have been 1,603 confirmed, possible and suspected cases of EVD and 887 deaths in Guinea, Liberia, Nigeria and Sierra Leone since the outbreak first emerged at the end of last year.

The WHO says there have been 163 new cases of EVD and 61 deaths from the disease in these countries since July 31 reported in these countries. Three of these cases were in Nigeria and include two new probable cases - one in a healthcare worker and one in a Nigerian who travelled to Guinea - and a suspected case in a nurse.

It says the recent appearance of EVD cases in Nigeria is a worrying development. 

British Airways said it was suspending flights to and from Liberia and Sierra Leone until the end of this month due to concerns over the Ebola outbreak.

Doctors have been told a high index of suspicion must be maintained when assessing individuals presenting with fever and a history of travel, to, or through, the affected countries.

According to the HSE's Health Protection Surveillance Centre (HPSC) any traveller returning from a trip to (or travel through) the affected areas who develops a fever greater than 38 degrees centigrade within 21 days of their return should seek urgent medical attention.

The HPSC says the risk of infection for travellers is very low since most human infections result from direct contact with the body fluids or secretions of infected patients. Travellers should avoid all contact with infected patients.

However, the HPSC says as the situation in West Africa continues to evolve and as new cases are continuing to appear in the Region, the potential exists for cases to be imported into Ireland.

"Accordingly, a high index of suspicion must be maintained when assessing individuals presenting with fever and a history of travel, to, or through, countries on the Western Atlantic/Gulf of Guinea coast, and in particular Guinea, Liberia, and Sierra Leone."

There is a significant risk of transmission in a hospital setting in the affected areas as a result of unsafe medical procedures (such as accessing veins), use of contaminated medical devices (including needles and syringes) and unprotected exposure to contaminated body fluids.

Those who are providing medical care or are involved in the evaluation of an outbreak are advised to wear protective clothing, including masks, gloves, gowns, eye protection and practice proper infection prevention and control measures.

Ebola is an often fatal disease, transmitted through direct contact with blood or other bodily fluids (e.g. saliva, urine) from infected people, dead or alive. This includes unprotected sexual contact with patients up to seven weeks after they have recovered.

It can also be transmitted from from direct contact with blood and other bodily fluids from wild animals, dead
or alive, such as monkeys, forest antelopes and bats.

Ebola virus does not transmit through the air as flu does.

After two days and up to 21 days following exposure to the virus the disease may start suddenly with fever,
muscle aches, weakness, headache and sore throat.

The next stage of the disease is characterised by vomiting, diarrhoea, rash and malfunctioning of the liver and
kidneys. Some patients also have profuse internal and external bleeding and multi-organ failure.

There is no specific vaccine or treatment for the disease.

However, trials are expected to start in September on an Ebola vaccine that has shown promising results in animal testing.