GENEVA (AP) _ A meningitis outbreak sweeping across Africa has killed at least 3,500 people, the International Red Cross said Wednesday.

It said 38,000 cases of the membrane infection had been documented, but that ``many more are likely to have gone unreported,'' said the International Federation of Red Cross and Red Crescent Societies.

A statement said it was the worst outbreak of the disease in the last decade and has caused a serious shortage of vaccine worldwide.

``There is definitely a crisis,'' said Dr. Hakan Sandbladh, the federation's emergency health coordinator.

The federation and international health organizations are trying to provide supplies to the most affected areas, Sandbladh said.

The federation provided a million doses of vaccine to Ethiopia last month and is sending 400,000 more to Burkina Faso, one of the centers of the outbreak in West Africa, the statement said.

Burkina Faso has reported 1,525 deaths since the beginning of the year, the statement said.

Unless vaccination is widespread, bacteria are likely to continue spreading the disease until seasonal rains arrive in several months, Sandbladh said.

Meningitis, an infection of the membranes that protect the brain and spinal cord, often surfaces in Africa during annual dry seasons.