In infants, symptoms of listeriosis may be seen in the first few days of life and may include:

• Loss of appetite
• Lethargy
• Jaundice
• Vomiting
• Respiratory distress (usually pneumonia)
• Shock
• Skin rash
• Increased pressure inside the skull (due to meningitis) possibly causing suture separation

Late-appearing infection in the infant (symptoms appear age 5 days or older) and infection in children is often seen as meningitis.

In adults, the disease may take many forms depending on what organ or organ systems are infected. It may occur as meningitis, pneumonia, septicemia, and endocarditis, or in milder form as abscesses, skin lesion, and conjunctivitis.

If a pregnant woman becomes infected, it can lead to:

• Stillbirth
• Death of a newborn within a few hours of birth

Laboratory tests may be done to detect the bacteria in amniotic fluid, blood, feces, and urine. A CSF culture may be performed.

Note: There is no way, without testing, to know if meningitis is due to listeria or another cause.