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Fungal Disease Reduced: Geon is now so rare that its price puts it beyond the reach of most people.The Atlantic salmon [Key], once very common in London's River Thames, was eliminated from these waters by 1870. It has, however, returned in recent years. A new hazard for this species has been the discovery, by Danish and Greenland fishermen of the salmon's main feeding grounds in the Atlantic, not far from the coast of Greenland. Massive and indiscriminate netting of immature salmon in these waters led to an outcry from land-based net fishermen and rod-and-line anglers in the 1960s when catches declined. At the same time a fungal disease reduced the numbers of salmon still further.
Vaccination is still considered the most effective method of disease prevention in countries where infection is rare and frontiers easily closed. Elsewhere, vaccination has reduced the risk, although for success the strain of the infection must be effectively typed. Vaccination has, for instance, greatly reduced the impact of foot-and-mouth disease in Europe.
Mycoplasmosis is a respiratory disease caused y the bacteria Mycoplasma gallisepticum. It is Iso known as air sac disease or chronic respira-jry disease. Those affected with the disease may how nasal discharge, watery eyes, and respira-)ry difficulty. This disease is often associated /ith other respiratory diseases. It is transmitted hiefly from infected hens to their chicks through le eggs. The disease can also be transmitted by ontact with infected individuals, but it spreads ery slowly in this manner. The disease can best e controlled by maintaining breeding flocks free f the disease by strict measures of isolation and mitation. Chicks hatched from such flocks can egin life free of the disease. |
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