JOHANNESBURG, South Africa — The West African coastal nation of Senegal has become the latest African country to ban poultry imports as the continent begins to take precautions against a feared arrival of bird flu.

Countries along the Rift Valley in eastern Africa — Kenya, Tanzania and Ethiopia, which are thought to be at greatest risk because of the millions of migratory birds that will arrive there in December — already had announced poultry bans or strengthened existing regulations. The neighboring countries of Congo, Sudan and Uganda also have announced bans, as has Ghana in West Africa.

In South Africa, where a milder strain of bird flu was detected on two farms last year, health officials said they had extended quarantines for imported poultry and had stepped up checks of the country's large ostrich population.

Health officials became concerned about Africa after bird flu was detected among migratory birds in Russia, Romania and Turkey. The virus currently poses little threat to humans, but officials are worried that infected birds flying south for the winter might not be detected quickly in Africa, where millions of people live in close contact with animals and public-health systems are ill-prepared to respond to emergencies.

Scientists worry that the virus, which has killed 67 people since 2003, could mutate into a strain that passes easily among people, spreading a potentially lethal disease across a wide swath of the population.

Health officials in Asia and Eastern Europe have ordered millions of birds suspected of having the flu to be killed. Domenech questioned whether such crucial early measures would be conducted in East Africa, "where veterinary services, due to various constraints, should have more difficulties to run efficient bird-flu campaigns based on slaughtering infected animals and vaccination."

The FAO plans to help East African countries monitor suspicious bird deaths and improve laboratories' ability to detect an outbreak.

Kenya's director of medical services, James Nyikal, said the country was prepared to take aggressive action, including quarantining or slaughtering birds that were suspected of being infected.