Why is diagnosing a parasite infection difficult? What factors make it challenging?

The difficulty in developing vaccines against parasitic diseases is to identify (and produce) appropriate protective antigens because of the lack of complete understanding of the type of immune response required for protection.

Explanation:

I hope this kinda helps.

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies

helicase, i think thats it