How are some parasites and viruses able to chronically infect us?

Parasites are actively able to induce the regulatory mechanisms of our immune system, thereby suppressing the inflammatory immune response and increasing reproduction and survival.

Some viruses such as Herpes have developed immune escape mechanisms, making themselves "invisible " to our immune system. As these parasitic and viral infections are often asymptomatic, they can chronically infect us for years without us noticing.