Doctor Zhong had a plan, he had found a rare mushroom8. The spores would have an affect, but they needed to be more potent. In an act of desperation (and not one he was proud to admit), he incubated the spores inside of a lab animal until they were toxic. The challenge was solved9. Once released, it would cause all organic matter to not only die 24 hours after being infected, but also become a carrier of the disease.
Then, he allowed himself to be captured.