What demographic is particularly at risk for severe listeriosis?

The group most at risk for severe listeriosis includes pregnant women and individuals with weakened immune systems. Listeriosis is caused by the bacterium Listeria monocytogenes, which can lead to serious health complications in these populations.

Pregnant women are particularly vulnerable because the infection can lead to severe outcomes such as miscarriage, premature birth, or severe illness in the newborn. The immune system naturally suppresses during pregnancy, making these women less able to fight off infections.

Individuals with weakened immune systems, such as those undergoing chemotherapy, living with HIV/AIDS, or having other chronic illnesses, are also at heightened risk. Their bodies are less capable of effectively combating infections, increasing the likelihood that they will experience severe manifestations of listeriosis.

While young children and older adults (like those over 60 years) are also at risk for foodborne illnesses in general, the most severe forms of listeriosis predominantly affect pregnant women and immunocompromised individuals according to health guidelines and statistical data. Thus, while option D might encompass a broader group, option B correctly identifies the specific demographic that experiences the most severe consequences of the disease.