This is just my take on it but she's been kinda acting like a mad scientist from around 50-ish? First distilling professional grade alcohol, then building a centrifuge using the chainsaw motor, and there's at least two food keep-warm devices she converted into incubators for her petri dishes. The author doesn't explain Hino's background but it's definitely not normal and she's at least an advanced hobbyist when it comes to the DIY lab equipment. Keeping in mind that there's no internet, she'd need to be somewhat familiar with the equipment already in order to cobble together something similar.
I assume the author is hinting that Hino's curiosity lead to her creating the zombie virus but, since she never seems to think "this looks familiar", there's a good change that wasn't her original goal. Her carelessness probably comes from not containing the virus properly, or someone else got their hands on her project and that's how the outbreak starts. It's really hard for me to imagine Hino being in charge of some world changing research project when she's leisurely working at a convenience store. ¯\_ (ツ)_/¯ Maybe she got fired from a research lab pre-outbreak?