The condition of William E. Haast, 78, a snake handler who was bitten at noon Feb. 28 by a saw-scaled viper from the Pakistan area, was upgraded to fair Tuesday morning at University Hospital.

John Dwan, a hospital spokesman, said the condition of Haast, who reported to the hospital at 3:15 p.m. Wednesday, 27 hours after the incident, is slowly improving.He said doctors continue to watch for, but have not detected, any adverse reactions to antivenin serums given him on Thursday and Friday. The serums were flown to Utah from the San Diego Zoo and a Los Angeles laboratory.

Dwan said the "fibrinogen (which aids clotting) level in his blood continues to slowly rise, and there has been no evidence of antivenin reactions, although physicians expect him to develop some symptoms of the antivenin serum sickness. He continues under close observation for that, but the fibrinogen level continues to increase, so the effects of the snake's venom are being decreased."

Typically, reactions appear from five or more days after the antivenin serum is given.

He now faces several weeks of close monitoring.

Haast, director of Miami Serpentarium Laboratories and who has previously been bitten 147 times, has over the past 40 years injected himself once a week with a mixture of about 50 different snake venoms to build up his own immunity to snake bites.

"That is why he has donated his blood in the past to snake-bite victims so he could share his immunity with them. He has not included venom from this kind of snake (the saw-scaled viper) in the mixture with which he has been injecting himself. And that is why he is reacting to the venom now," Dwan said.

Antivenin serum also was transported from Iran, England and the Soviet Union over the weekend, but none of that has yet been used. Doctors are waiting to see if there are adverse reactions from the materials flown from California before risking any other potentially adverse side effects, Dwan said.