Viral farming

At present, there are no antiviral compounds approved for use in animals (80MI10805). However, viral diseases of farm animals include such serious complaints as foot-and-mouth disease, and a new agent may very likely surface in the near future. Two possibilities are the following, which have already been approved for human use idoxuridine (53) and vidarabine (54). 

Plants without the virus-resistant transgene contract the viral disease. Consequently, they do not grow as well as the GMO plants. Cucumber beetles feed on both types, but prefer the healthier GMO plants. Cucumber beetle feeding spreads bacterial wilt disease. Hence, plants resistant to viral diseases are those most likely to suffer from bacterial wilt disease. This is an example where solving problems one at a time may not be the most successful approach (Lancaster Farming, 2009). 

SKALL H F, olesen n J and MELLERGAARD s (2005) Viral haemorrhagic septicaemia virus in marine fish and its implications for fish farming - a review. Journal of Fish Diseases, 28,509-529. 

Vehicles coming from a shrimp farm to the hatchery (either owned by the hatchery or by the shrimp farm) to pick up PL are a significant risk of pathogen introduction. Trucks may carry viral particles in mud stuck on the wheels or body of the truck. When driving on shrimp farms, trucks often crush shrimp that have been dropped on the farm roads and may carry the shrimp carcass. 

The realization that selenium (Se) may be an essential micronutrient for human diets has arisen only recently, in the second half of the twentieth century. Selenium deficiency, attributable to low soil selenium levels in farm animals, especially sheep that are afflicted by selenium-responsive white muscle disease, has been recognized for at least half a century. However, the more recent identification of Keshan and Kashin-Beck diseases as endemic selenium-responsive conditions, occurring in a central 4000-1— km-wide belt of central China and in areas of Russia, demonstrated conclusively that not only is selenium an essential element for man but also deficiencies occur naturally and require public health measures to alleviate them. Selenium incorporation into plants is affected by the acidity of the soil and by the concentrations of iron and aluminum present so that selenium content of human diets is modulated by these components of the environment. The very recent discovery that these diseases probably arise through the interaction of selenium deficiency with enhanced viral virulence has added a further layer of complexity, but it does not alter the fact that selenium is an essential dietary component that cannot be substituted by any other element. Another complicating factor is that moderately increased soil selenium concentrations result in the opposite condition of seleno-sis, or selenium overload, with equally debilitating consequences. Of all elements, selenium has a very narrow safe intake range, and unlike some other potentially toxic elements, it is absorbed efficiently by the intestine over a wide range of concentrations and across a variety of different molecular forms. 

LIGHTNER D V, POULOS B T, TANG-NELSON K F, PANTOJA C R, NUNAN L M, NAVARRO S A, REDMAN R M and MOHNEY L L (2006), Application of molecular diagnostic methods to penaeid shrimp diseases advances of the past 10 years for control of viral diseases in farmed shrimp, Dev Biol, 226,117-22. 

FEGAN, D.F., and H.c. CLIFFORD III. 2001. Health management for viral diseases in shrimp farms. Pages 168-198 in C.L. Browdy and D.E. lory (editors) The New Wave, Proceedings of the Special Session on Sustainable Shrimp Culture. Aquaculture 2001. The World Aquaculture Society, Baton Rouge, LA. 

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