Fever is not always infectious — Which of the following is a non-infectious cause of fever in clinical practice?

Introduction / Context:
Fever is a regulated elevation of core body temperature driven by pyrogenic cytokines. While infections are the most common triggers, numerous non-infectious inflammatory and autoimmune conditions also cause fever. Distinguishing infectious from non-infectious etiologies guides diagnostic testing, antimicrobial stewardship, and management decisions.

Given Data / Assumptions:

• Options include classical infectious diseases and one inflammatory autoimmune category.
• Non-infectious causes can produce systemic inflammation and pyrexia through cytokine release.
• The question asks specifically for a non-infectious example.

Concept / Approach:
Typhoid, chicken pox, and malaria are established infectious causes of fever due to bacterial, viral, and parasitic pathogens respectively. In contrast, rheumatic diseases (for example, rheumatoid arthritis, systemic lupus erythematosus, vasculitides) can cause fever through sterile inflammation. Recognition depends on clinical context, exposure history, and laboratory markers (autoantibodies, inflammatory markers) rather than cultures or pathogen detection alone.

Step-by-Step Solution:

Verification / Alternative check:
Clinical algorithms for fever of unknown origin always include autoimmune and neoplastic conditions alongside infections and miscellaneous causes, highlighting non-infectious sources.

Why Other Options Are Wrong:

• Typhoid: caused by Salmonella enterica serovar Typhi; infectious.
• Chicken pox: caused by varicella-zoster virus; infectious.
• Malaria: caused by Plasmodium species; infectious.

Common Pitfalls:
Assuming antibiotic therapy is needed for all fevers; in non-infectious etiologies, immunomodulatory therapy may be appropriate after excluding infection.

Final Answer:
Rheumatic disease