I read the journal article, albeit quickly. Although it is very interesting there are a few caveats that show the need for lots more research:
1. The infected group was 3 mice, and these mice were knockout (KO) mice, common in scientific research; this means they are genetically bred a certain way and this leads to a sort of built-in compromised immune system.
2. There are lots of things that can decrease NPC (neural progenitor cell) proliferation (cell division and growth) and cause apoptosis (cell death): not just Zika, but any disease that can lead to any sort of brain inflammation; also drug usage, and aging.
I'm stating this because it can erroneously sound like only Zika is causing these effects and it's not. Just like any other illness, some people have complications and others don't. These types of issues have been noted with Dengue and West Nile both of which have been present in the US far longer than Zika yet seemingly haven't caused the same kind of public fear.
3. Only one time point was examined after infection (presumably due to the small study group) and one type of mice. This is problematic because (a) cells grow and divide rapidly and (b) it has been shown that different types of mice have wide variances in cell proliferation and survival generally.
4. The researchers are looking at two important markers for cell proliferation and differentiation. For lack of a better description these are the markers that make an NPC, an NPC. They state that Zika downregulates the expression of these markers. This means the findings could be in part due to a change stemming from infection that makes it more difficult to detect the cells, not necessarily that the infection is harming the cells completely.