State and federal officials have received further indication that over 100 mallard ducks found dead near Salmon, died of an acute fungal infection.
The cause of death is almost certainly acute Aspergillosis, a respiratory tract infection caused by a fungus commonly found in soil, dead leaves, moldy grain, compost piles, or in other decaying vegetation.
Fungal cultures of the lungs of two of three ducks tested resulted in growth of Aspergillus fungi. However, final confirmation is pending according to the most recent update from National Wildlife Health Center in Madison, Wisconsin.
The fungus can cause severe respiratory tract infections in birds that inhale the spores but it cannot be passed from one infected duck to another.
"We are fortunate that the die-off seems to have stopped, likely due to the fungus source no longer being available to the ducks,” said Dennis Newman, Idaho Fish and Game wildlife manager based in Salmon.
While the disease is not contagious to humans who eat the meat, hunters can be exposed by inhalation of spores from contaminated carcasses. Though the risk of exposure is minimal, Fish and Game suggests hunters wear masks when dressing their birds. As with all game, hunters should also wear latex gloves when field dressing, and the meat should be thoroughly cooked before eating.
The first dead ducks were reported by a concerned resident December 7 south of Salmon. Fish and Game responded to the area and found 50 ducks along an irrigation ditch and in nearby sloughs and ponds. Since the initial report, Fish and Game has found a total of 115 dead ducks.
While this is a small proportion of the duck population in Idaho or the United States, the number of dead birds found is unusual for this area. Waterfowl die-offs are common and many happen in the United States every year. Testing for diseases is a routine part of the investigation of waterfowl die-offs.
Tissue samples from the dead birds were not consistent with avian influenza, but as a precaution, samples are continuing to undergo further testing to confirm Aspergillosis and rule out any potential underlying disease. Results from these tests are pending.