Doctors don't know why. Or it could be a natural progression of the disease from mild to severe over several months. When the virus came back, it was more focused. The relapse resulted in epileptic fits, which was different from the coma in the first attack. The virus was also limited to the brain and didn't affect other internal organs.
Relapses are also extremely unusual in viral encephalitis.
Prof Tan says they're unique to Nipah. Doctors are keeping their fingers crossed. We're keeping an open mind. Until they know, Bukit Pelanduk residents will continue to monitor each others' health.