What are the symptoms of mpox vs smallpox?

Both diseases begin with fever, headache, back pain, and fatigue, followed by a characteristic rash. The key distinguishing features of mpox are: (1) prominent lymphadenopathy (swollen glands) — absent in smallpox; (2) rash lesions may appear in different stages simultaneously; (3) genital/perianal lesions are common in clade IIb. Smallpox lesions were uniform in stage and deeply embedded in the skin. Mpox lesions evolve through macule, papule, vesicle, pustule, scab, typically over 2-4 weeks. In the 2022 clade IIb outbreak, many cases presented with few lesions limited to the genital area without a classical widespread rash.