This can’t possibly be correct. It’s the most commonly diagnosed etiology for viral encephalitis, which definitely occurs more than a single digit per million. It’s also going to be underdiagnosed because the diagnostics are bad (fewer than half of encephalitis cases are assigned an etiology). I see several sources saying in the range of 2-4,000 confirmed HSV encephalitis cases per year in the US (which are usually extremely severe, leading to brain damage or death), compared to 5,500 “HIV-related” deaths per year in the US according to the CDC. So at the very least they seem similar in magnitude.