Not everyone using helminthic therapy will experience a change in blood pressure.
We measure our blood pressure regularly at home. Did not have any change after inoculations. 
I have always tended to have blood pressure on the low end of normal, but have experienced no worsening of that condition or dizziness since hosting NA. 
However, helminthic therapy can reduce blood pressure in some cases, especially if it had previously been elevated.
Both of my BP numbers dropped ten points VERY quickly after inoculation. 
… the worms dropped my high BP overall by about 15 points… 
I received my first dose of N.A. in early June. I just checked my blood pressure, and I had a lovely surprise. In six weeks, my systolic blood pressure has fallen by almost 30 points, and my diastolic blood pressure has dropped by 10 points. During my last visit, my doctor said that if my blood pressure increases I'll need medication, but I'm well out of range for that now! 
I can think of two or three instances where my BP was lower than normal as i was adjusting to the worms. This only lasted a few days. They (hookworms) drop my BP from 135/85 to 110/75, which was my norm before getting sick. My pulse also drops from resting 77 to around 60.  
The reduction in blood pressure seen by some users of helminthic therapy may be a result of the worms correcting an autoimmune condition.
Lowered blood pressure may not be advantageous for everyone, especially those on the fatigue spectrum, in which case starting helminthic therapy with too high a dose might result in blood pressure dropping too far, causing dizziness or even a brief loss of consciousness.
Mine dropped when i had too high a dose of hookworm, got gastroenteritis, which triggered my dysautonomia and low BP and i kept passing out.