Hi

My 3 yr old red and blackcurrant bushes have started to fruit but most
of the currants have some kind of rot. Here is a photo:

https://ibb.co/eMNUOF

I've looked on a few sites detailing common pests/diseases on currant
bushes but can't seem to find out what this is. I've cut the fruit open
but can't see any bugs so am assuming it's a disease as opposed to a pest.

The bushes had aphids this and last year but last year's fruit was
perfectly OK despite that. It remains to be seen if the whitecurrant
bush is also affected (they are all next to each other).

Does anyone know what this is?

Thanks
Bigus