Parasites reproduce around the full moon, but they change their environment - the body's ph levels, etc. during the growth of the full moon phase.
Since immunity is lower during the new moon, newer and stronger parasites enter during this phase.
While Full Moons lead to inflammations and an excess of life force flowing, whether healthy or unhealthy, New Moons are the ones that I truly dread. I have lost many of my animals on or around the new moon. If I see a sick dog deteriorate towards the new moon or a thunderstorm, I give it very few weeks left on earth.
And new moon deaths are horrific. They're painful, since bodily fluids aren't retained usefully. If there's bloat it stagnates to a painful distress. If there's dehydration the cells starve to death. Since energy comes to a standstill, there's muscular stiffness and soreness especially for the bedridden dogs. Any organ or gland inflamed during the full moon will harden at the new moon. And mentally the dog is too depressed to struggle out of the cloud of sickness during the period.