Symptoms of listeriosis. Symptoms of listeriosis in most healthy adults are mild. They usually develop from 3-70 days after the initial infection. Symptoms are similar to flu and gastroenteritis, and include:1  a high temperature (fever) of 38C (100.4F) or above. 2  muscle ache or pain. 3  chills. 4  feeling or being sick. 5  diarrhoea.ymptoms of listeriosis. Symptoms of listeriosis in most healthy adults are mild. They usually develop from 3-70 days after the initial infection. Symptoms are similar to flu and gastroenteritis, and include: 1  a high temperature (fever) of 38C (100.4F) or above. 2  muscle ache or pain. 3  chills. 4  feeling or being sick.