Fewer than half of major firms are prepared for potential disturbances to their supply chains as a result of disasters such as bird flu or floods like the one in New Orleans last year.
Analyst AMR Research said only 33% of firms had made specific contingency plans for the potential spread of bird flu, based on a survey of 200 firms with a combined revenue of over $1bn (£580m).
But the analyst added that 43% of firms surveyed had a risk management plan in place, to identify alternative sources of supply when needed.
For instance, before Hurricane Katrina hit the coast of the Gulf of Mexico, Dell had already identified New Orleans as a high-risk entrepot and had begun to move some in-bound shipments to other local ports. Dell was not a survey respondent.
AMR said supply chain disruption has occurred every year for the past five. There has been the Asian outbreak of severe acute respiratory syndrome (Sars), the 9/11 terrorist attacks in the US, Hurricane Katrina in the Caribbean and US, the Asian tsunami, and major strikes by dockers in the US.