Are these plants in pots or in the ground?

If in pots, make sure they are large enough to support a tomato plant's requirements for room. Pots should be at least 5 gallons; better to have 15 gallon containers for most varieties of tomatoes. Also for pots, make sure the soil is a potting mix, not garden soil or topsoil.

Also, if in pots, feed them every 2 or 3 weeks with a weak dilution of fertilizer. You want the instant-acting type of fertilizer such as MiracleGro or Peters. Dilute to the strength for indoor plants. Fertilizer that's too strong will damage the plants. One sign of over-fertilizing is when the edges of the leaves get crispy.

Make sure they are not sitting in soggy soil, whether they are in pots or in the ground.

I don't see an immediate sign of disease. Let us know if the situation gets worse.

The plants are in ground, planted one to a hill. The ground - even up the hills - is wet, though. We've had such a deluge that the soil hasn't been able to dry out. And it's supposed to storm again tomorrow. I don't suppose there's anything I can do except wait for sunny weather, then. I am happy to hear it's likely not a virus, though. Thanks!