Rating agency analysts continue to try to forecast what the dreaded H5N1 avian influenza might do to the U.S. insurance industry.

Like analysts at competing rating agencies, analysts in the New York office of Fitch Ratings emphasize the enormous difficulty of gauging the effects of the bird flu.

So far, the analysts write, there is no evidence that the virus has mutated enough to enable human-to-human transmission.

If the virus cannot spread easily from human to human, the global economic impact will be limited, the analysts write.

But the subject is “something that needs to be addressed,” says Lauren Kalinowski, a Fitch associate director.

If the virus does mutate and does cause a pandemic, it could easily cause 400,000 deaths in Europe and 209,000 in the United States, with 81,541 of the U.S. deaths affecting patients age 35 or younger, the Fitch analysts predict.

Death benefits could total $18 billion in the United States and about $20 billion in Europe, the analysts estimate.

The analysts expect the costs to fall most heavily on life reinsurers and health insurers.

The effects on U.S. health insurers could be great, because the pandemic could infect more than 90 million U.S. residents, the analysts write.

New drug treatments could help reduce mortality costs, and life insurers may benefit from a hedging effect if it turns out that many victims who own life insurance policies also own annuities, the analysts write.