The Irish Health Service Executive (HSE) have asked doctors to stay vigilant despite there being a “low threat” that the Ebola virus, with no known cure, would reach Ireland.

Health authorities in Hong Kong and Birmingham, England, quarantined passengers showing possible symptoms of the Ebola virus. They both tested negative for the virus.

So far the virus has killed 660 people in West Africa. The Ebola virus has no known cure and kills 90 percent of those infected. It causes diarrhea, vomiting and internal and external bleeding.

Last week a Liberian official Patrick Sawyer flew to Lagos, Nigeria via Lome in Togo and died of the disease at a hospital in the Nigerian capital. He began displaying symptoms while in flight.

Sawyer was able to board an international flight while ill. This raised fears that the disease could spread beyond Liberia, Guinea and Sierra Leone, the three countries affected. Sawyer, an American citizen, had been planning to visit his wife and three children in Minnesota in August.

The hospital in Lagos where Sawyer died has been evacuated and is being decontaminated

Following the outbreak in West Africa the Ireland's Health Protection Surveillance Centre (HPSC), a branch of the national Health Serivce Executive (HSE), alerted hospital clinicians and general practioners around the country. Similarly, health officials in the United Kingdom have been warned to remain vigilant for symptoms of the virus.

A spokesperson for the HSE said, “The HSE HPSC was alerted to this EVD Outbreak in March 2014 and the HPSC immediately alerted hospital clinicians and GPs around the country of the outbreak.

“While the outbreak of EVD in West Africa is the largest ever such outbreak on record, the likelihood of the disease appearing in Ireland is very low.”

They added that Ireland is "well equipped and its doctors and nurses supplied with specialist knowledge" to deal with a case of the virus effectively.

“Ireland has a National Isolation Unit (NIU) located at the Mater Misericordiae Hospital in Dublin and is the national referral centre for high risk suspected and confirmed cases of VHF and other serious infectious diseases,” the spokesperson added.

Ebola was first recorded during two simultaneous outbreaks in 1976 Nzara, Sudan, and Yambuku, a village in the Democratic Republic of Congo (DRC) situated near the Ebola River.

Fruit bats are believed to have been the natural hosts of the virus and it was passed to humans through close contact with blood, organs or other bodily fluids.

Healthcare workers are at the highest risk of infection as the virus spreads through direct contact with bodily fluids.