Answer :
Final answer:
A systemic infection occurs when a pathogen distributes itself throughout the body, affecting multiple systems or organs. It can follow a primary infection that compromises the body's defences, leading to more severe secondary infections. Examples include the widespread lesions in chickenpox.
Explanation:
When a pathogen spreads throughout the body rather than remaining confined to a single area or organ, the infection is termed a systemic infection. Unlike local or focal infections, systemic infections indicate a widespread distribution of the pathogen, affecting multiple systems or organs within the body. An example of systemic infection is when the varicella-zoster virus, responsible for chickenpox, enters the body through a mucous membrane of the upper respiratory system and then disseminates throughout the body, evidenced by the widespread, classic red skin lesions.
Systemic infections can arise from a primary infection that weakens the body's defences, making it more susceptible to secondary infections. These can be particularly severe as the immune system is already compromised, allowing opportunistic pathogens to establish infections more easily. Antibiotic treatments for primary infections can also disrupt normal microbiota, paving the way for systemic infections by other pathogens. Recognizing the signs of a systemic infection is crucial for prompt and effective treatment.