Final answer:
Late-onset listeriosis occurs in infants between 1 week and 3 months old and can have various transmission sources, while early onset listeriosis occurs within the first 7 days of life, usually contracted during childbirth. Both are caused by Listeria monocytogenes and can lead to severe complications.
Step-by-step explanation:
Late-onset listeriosis is a form of listeriosis that occurs in infants between 1 week and 3 months of age, whereas early onset listeriosis is defined as occurring in infants up to 7 days old. Early onset disease is typically contracted by the infant from the mother during childbirth.
In contrast, late-onset disease can be transmitted from various sources, and often the source of infection is unknown. Both conditions are caused by the bacterium Listeria monocytogenes, which can cross the placenta and infect the fetus, potentially leading to miscarriage, stillbirth, or neonatal infection.
Pregnant women are more susceptible to this infection and thus advised to avoid certain high-risk foods. Symptoms of early onset disease may include difficulty feeding and irritability, while late-onset symptoms might manifest as seizures or a stiff neck.