So if i have pinworms or bacterial vaginitis can i still have long nails? ive read i should cut it to prevent transmission

Low grade myth: The eggs of pinworms germs of a vaginitis could conceivably get under your nails if you itch the area. PW eggs are laid by the pregnant female at your anus & contaminate bed linen or underwear. Touching contaminated fingers to your mouth can return the eggs to re-infest you. I doubt the length of your nails has anything to do with such a process & might decrease the risk.

CDC recommends it: Per CDC: "hand hygiene includes diligently cleaning & trimming fingernails, which may harbor dirt & germs & can contribute to the spread of some infections, such as pinworms. Fingernails should be kept short, & the undersides should be cleaned frequently with soap & water. Because of their length, longer fingernails can harbor more dirt & bacteria than short nails"