There’s an epidemic of a viral disease in Florida, although you wouldn’t know it unless you were a vegetable or a farmer:
In recent years, the number of whitefly-transmitted viruses in cucurbit fields, home to crops like cucumbers, squashes, pumpkins, melons and watermelons, has increased to almost epidemic proportions in Florida.
Researchers led by plant pathologists Scott Adkins and Bill Turechek at the ARS Subtropical Plant Pathology Research Unit in Fort Pierce, Fla., are dealing with a “triple threat” to cucurbits: three major viruses, all transmitted by silverleaf whitefly, Bemisia tabaci. The host range is similar–mostly cucurbits–but the symptoms differ. And the researchers have discovered a new host for the whiteflies: green beans. (Science Daily)
The three viruses in the cucumber-squash triple threat are the Cucurbit Leaf Crumple Virus (CuLCrV), a threat to greenbeans; the Squash Vein Yellowing Virus (SqVYV), producing disease in squash and watermelon; and the Cucurbit Yellow Stunting Disorder Virus (CYSDV), a scourge of melons, cucumbers, gourds and squash.
There isn’t a living thing we know of, including tiny bacteria, that aren’t subject to viral infection. We know that viral diseases of animals can infect humans (dare I mention bird flu?), and that viral infections of bacteria can turn a harmless bacterium into a toxin producer (e.g., diphtheria). What is somewhat surprising is that I could find no human diseases caused by plant viruses. In fact I couldn’t find any animal diseases caused by plant viruses.
I have seen statements to the effect that plant viruses must mechanically breach the plant cell wall to gain entrance, a trick they pull with the help of a vector like an insect, but that doesn’t explain why it doesn’t happen in animal host cells. In fact I see references to plant viruses replicating in some insect vectors (e.g., Begomoviruses [Geminiviridae])), although it is not clear if this really does happen.
Any reader know of examples of animal or human infection with plant viruses or a reason why it cannot happen?