In moves that appear counter to the advice of the World Health Organization (WHO), Zambia and the Ivory Coast have issued bans on air travel between their territories and three West African countries in which Ebola outbreaks have occurred. Meanwhile, Nigeria has suspended all flights by Gambia Bird Airlines into its airports, citing the carrier’s failure to take sufficient measures to contain the spread of the virus. Although health officials have reported no cases of Ebola in Gambia, Gambia Bird flies to the stricken countries of Sierra Leone, Liberia and Guinea.

In a statement, Gambia Bird insisted it has exercised all proper precautions against spreading the disease, including “general measures” and mandatory procedures regarding passenger screening at check-in, on-board disinfection and reporting systems.

WHO guidelines call for states to conduct exit screening for illness consistent with potential Ebola infection of everyone at international airports, seaports and major land crossings. The exit screening should consist of, at a minimum, a questionnaire, a temperature measurement and, in the case of fever, an assessment of the risk that the Ebola virus caused the fever. Authorities should deny anyone with an illness “consistent with EVD (Ebola Virus Disease)” from traveling except in the case of an appropriate medical evacuation. The guidelines also instruct officials to restrict those in contact with confirmed Ebola victims from domestic travel and bar them from international travel for 21 days after exposure.

However, the WHO and the International Civil Aviation Organization have stopped short of recommending any blanket travel bans. “There should be no general ban on international travel or trade,” said the WHO in a statement, adding that states should provide travelers to Ebola affected and at-risk areas with relevant information on risks, measures to minimize the risk and advice for managing potential exposure.

In its own statement, the International Air Transport Association (IATA) said it would “monitor developments closely in the Ebola outbreak in close coordination with the WHO and ICAO.”

“In the rare event that a person infected with the Ebola virus was unknowingly transported by air, WHO advises that the risks to other passengers are low,” said IATA. “Nonetheless, WHO does advise public health authorities to carry out contact tracing in such instances.”