Final answer:
It is difficult to treat viral infections due to a limited understanding of their life cycles, a lack of effective antiviral medications, and the challenge of targeting viruses without harming host cells. Some antiviral drugs exist for specific infections like HIV and influenza, but treatment efficacy varies and prevention through vaccines is often the best approach.
Step-by-step explanation:
Viruses utilize the host cell machinery to replicate, making it a challenge to target them without also damaging the host's cells. While we do have some antiviral drugs effective against specific viruses such as HIV and influenza, their ability to completely cure viral diseases is often limited. Furthermore, viruses with complex life cycles, like HIV, present additional treatment challenges due to mechanisms like integration into the host genome and rapid mutation leading to drug resistance. The best approach for many viral infections remains prevention through vaccines, though not all viral diseases have effective vaccines available.