Citing the experiences gleaned from responding to the SARS outbreak which impacted Singapore economically, the health ministy of Singapore announced the new restrictions which will become effective on Wednesday.
Singapore has negligible direct trade/ethnic ties to the affected west African nations, but did open a “trade and investment” outreach  office in Accra Ghana in an effort to secure a place as a clearing house/launching pad for west African trade with Asia and position itself at the head of the expected bow wave of development.
Citizens of Guinea, Liberia and Sierra Leone will need a visa to enter Singapore as part of measures against the spread of Ebola, the city-state’s health ministry said Monday.
 

The three West African countries are the worst-hit by the Ebola epidemic that has killed more than 4,900 people.
Singapore’s health ministry said the visa requirement for citizens of the three countries, who don’t currently need a visa to travel to the city-state, will take effect from Wednesday.
“The visa requirement will allow for better oversight of the entry of nationals from these countries, as well as facilitate possible contact tracing,” the ministry said in a statement.
https://www.breitbart.com/Breitbart-London/2014/11/03/Singapore-requires-visa-for-Ebola-hit-African-states