I suspect Julia Child is more susceptible to RRD than other roses. I had 3 Julias that succumbed, and the roses next to them did not get the virus. They all came from different nurseries, so that wasn't the cause.
The sad thing is, Julia Child is very resistant to all the other diseases, and holds up very very well to heat and humidity.
It's one of the earliest bloomers in the spring, so I planted yellow and white iris with Butter and Cream in their names in that same bed. Just my own little tribute to Julia the cook.