Could international shipping spread Ebola?

What economic effects could the ongoing Ebola outbreak have on commercial and passenger shipping in the U.S.?

The potential for disruption is great, but only if the outbreak spreads and if maritime officials are unable to control the epidemic. The United Nations says about 90 percent of world trade is transported by sea, so just the rumor of Ebola on board a container ship or a freighter can be disruptive.

Earlier this month, for example, members of a longshoremen's union in Baltimore delayed loading cargo onto a ship bound for West Africa, reportedly out of concerns there might be Ebola on board. Work on the ship resumed after the vessel was cleared by the U.S. Coast Guard.

The Coast Guard, along with U.S. Customs and Border Protection, is legally authorized to help enforce any potential quarantine orders to "protect the public by preventing exposure to people who have or may have a contagious disease."

So far, such quarantines haven't been necessary, and officials say there are no restrictions on international, ocean-going trade due to the Ebola outbreak.

Citing recommendations from the World Health Organization, the International Maritime Organization (IMO) on Friday reiterated its stance that there should be no general, Ebola-related ban on trade or travel.And in accordance with those recommendations, according to Andy Winbow, the IMO's maritime safety division director, "the movement of ships, including the handling of cargo and goods, to and from the affected areas, should continue as normal in order to reduce the isolation and economic hardship of the affected countries."

Then there are concerns about how the Ebola could affect the cruise ship industry. The U.S. Centers for Disease Control and Prevention (CDC) has documented dozens of gastrointestinal illness outbreaks on board cruise ships in recent years, although most of those events were linked to the highly contagious Norovirus.

Earlier this month, following news that a cruise ship passenger might have been exposed to the virus, the Cruise Lines International Association (CLIA) said it has already developed and distributed to its member companies "strong protocols, and additional guidance, to reduce even further the already low risk of Ebola on a cruise ship."

The group adds its measures could evolve and that cruise lines are constantly evaluating the Ebola outbreak, as well as monitoring their passengers and employees. "Out of an abundance of caution and care for the well-being of our guests and crew members, our measures typically go beyond what is technically required," it noted in a statement.

Despite such precautions, the maritime industry is still using some procedures that date back to the "Age of Sail," when military and trading ships avoided any contact with any ships or ports where infectious disease was known, or suspected to be lurking.

In August, three global shipping and maritime workers organizations issued guidance to vessels traveling to ports affected or potentially affected by the Ebola crisis. The groups advised ships to be aware of any local risks for Ebola, keep unauthorized personnel off their vessels, not make crew changes in the ports of an affected country and to have the personnel in charge of shipboard medical care monitor their crews for any symptoms of the disease.

Analysts note that port entry procedures in a variety of countries, especially in the West African nations currently coping with the Ebola outbreak, have been tightened. And for now, the West African nations suffering through the Ebola epidemic could see their shipping come to a virtual halt.

"Depending on the severity of the outbreak in the coming months, trade from West Africa could be severely affected," said IHS Maritime and Trade analyst Gary Li, in a research note, "especially if other affected countries fall under the chaos of the epidemic."