The virus was also confirmed on five more Texas farms, as investigators find more clues from animal samples and genetic sequences.
The patient's only symptom is conjunctivitis, which has been seen before in avian flu infections.
Some states have already tightened their requirements for importing dairy cattle from affected states.
Experts wonder if the virus is responsible for all of the symptoms, if the virus can spread from cow to cow, and how the findings might shape farm biosecurity.
Dead wild birds were found on the affected farms.
The health ministry says the man had been exposed to wild birds before and after the Lunar New Year holiday.
So far, the virus subtype and how the patient contracted it aren't known.
Minnesota veterinary officials said animals with weakened or immature immune systems, such as goat kids, are at increased risk.
Most H9N2 detections involve children who were exposed to poultry settings.
In cholera developments, Comoros last month reported its first outbreak since 2008.