Which statement best describes the outcome of schistosome immunity?

Which statement best describes the outcome of schistosome immunity?

• A. Immunity completely prevents reinfection
• B. Immunity can be chronic despite immune response
• C. Immunity always clears infection quickly
• D. Immunity has no effect on disease

Answer: (B)

Immunity to schistosomes is partial and non-sterilizing. The host can develop immune responses that reduce worm burden and egg production and may lessen disease severity, but these responses rarely prevent reinfection entirely. Schistosomes survive for years by evading clearance, coating themselves with host proteins, and releasing molecules that modulate the immune system, so adult worms can persist even in the presence of antibodies and T-cell activity. Because of this, infections can become chronic despite ongoing immune responses.

Immunity to schistosomes is partial and non-sterilizing. The host can develop immune responses that reduce worm burden and egg production and may lessen disease severity, but these responses rarely prevent reinfection entirely. Schistosomes survive for years by evading clearance, coating themselves with host proteins, and releasing molecules that modulate the immune system, so adult worms can persist even in the presence of antibodies and T-cell activity. Because of this, infections can become chronic despite ongoing immune responses.