In 9 days he went from being healthy to having brain death from mosquito-borne viruses

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(CNN) - A Michigan man went from being healthy to having brain death in just nine days after contracting Eastern equine encephalitis, his brother said.

Gregg McChesney, 64, was a "perfectly healthy and happy human being" less than two weeks before his death on August 19 from the rare mosquito-borne virus, Mark McChesney told WOOD, a CNN affiliate.

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"... In a matter of nine days he went from being perfectly healthy to having brain death," said Mark McChesney. "Suddenly he had a seizure and the next thing we knew was that he was in the emergency room and never left."

Mark McChesney said he was working with his brother less than a month before that trip to the emergency room.

"At the end of July, he was here at the farm helping me put springs in the pond," Mark McChesney told the station.

He remembered his brother as a man who loved life, who scared a bear when they were camping and made a 25-minute toast at his younger brother's wedding, although he was a man of few words, the station reported.

"We immediately thought, 'How could this happen? What happened?'" Mark McChesney told the station about his brother's illness. "We just didn't know it and the doctors were just trying their best to try to explain what this or that was, and they just couldn't solve it."

The Michigan Department of Health and Human Services on Tuesday confirmed four additional cases of eastern equine encephalitis in southwest Michigan, including two deaths. The state has confirmed seven cases in total this year, including three deaths, authorities said.

The virus, known as EEE, is a rare but potentially deadly virus transmitted by mosquitoes.

Typically, only five to 10 human cases of EEE are reported each year, with approximately 30% of all cases resulting in death, according to the U.S. Centers for Disease Control and Prevention. (CDC). Signs include sudden onset of headache, high fever, chills and vomiting. The most serious symptoms include disorientation, seizures and coma, the CDC said.

"Michigan is experiencing its worst outbreak of eastern equine encephalitis in more than a decade," Dr. Joneigh Khaldun, medical director and deputy medical director of the department, said in a press release. "The ongoing cases reported in humans and animals and the severity of this disease illustrate the importance of taking precautions against mosquito bites."

CNN's Jamie Gumbrecht contributed to this report.

Mosquitoes