Shingles is caused by the varicella zoster virus (VZV), of the herpesvidae family of DNA viruses. These viruses all have the ability, through multiple strategies, to evade the immune system, become dormant, then reactivate at a later time. VZV in particular "hides" in three particular nerve root ganglia, which are inaccessible to the immune system. There are other viruses capable of latency and reactivation, but filoviridae (the family Ebola belongs to) are not believed to have this property. However, relapse of a sort may be possible... Ebola (and Marburg) do so much damage to the body, specifically elements of the immune system, that a normal specific immune response may be delayed, so the patient may begin to appear better due to nonspecific immune response, then get worse as the virus continues to reproduce. I believe that this is the sort of thing they are thinking here, although because his immune system is wrecked it is more likely just a more common secondary infection.
It is doubtful anyone here has
enough information to discriminate in this patient
opportunistic infection vs. latent persistent Ebola
infection ... or both.