Symptoms of listeriosis can take up to how many days to develop after exposure?

• A. 2 days
• B. 14 days
• C. 90 days
• D. 70 days

Answer: (D)

Listeriosis has a long and variable incubation period, meaning symptoms may not appear for quite a while after exposure. The maximum time from exposure to symptom onset is about 70 days. So, saying symptoms can take up to 70 days is accurate and reflects the full range clinicians consider when tracing sources and monitoring illness. Shorter timeframes like 2 or 14 days can occur, but they don’t represent the longest possible interval, while 90 days exceeds what's documented for this infection. This long window is important for outbreak investigations and for advising high‑risk groups, such as pregnant people, who may develop illness well after exposure.