Mpox, a viral illness from the same family as smallpox, is characterized by a distinctive rash and flu-like symptoms. The name was updated from monkeypox in late 2022 by the World Health Organization to reduce stigma. Understanding the initial symptoms is useful for timely identification and care.
Incubation and First Flu-like Symptoms
An mpox infection begins with an incubation period, the time between exposure to the virus and the first appearance of symptoms. This phase lasts from 3 to 17 days, during which a person will not show any outward signs of illness. The length of the incubation period can be influenced by how the virus was transmitted.
Following incubation, the prodrome phase begins and can last for up to five days. This stage is characterized by flu-like symptoms like fever, headache, muscle aches, backache, chills, and profound exhaustion. These initial feelings of being unwell often precede the more identifiable rash.
A distinctive feature during this early stage is the swelling of lymph nodes, a condition called lymphadenopathy. Glands in the neck, armpits, and groin may become noticeably swollen and tender. This symptom helps differentiate mpox from other viral illnesses with similar flu-like discomfort.
The Initial Rash Presentation
The mpox rash emerges one to four days after the fever, though for some it may be the first sign of infection. The initial lesions begin as flat, discolored spots (macules) that evolve into raised, firm bumps (papules).
The location of the initial rash varies. While it can start on the face and spread, recent outbreaks show lesions frequently appearing first in the genital or anal areas, or inside the mouth. The palms of the hands and soles of the feet are also common sites, which is an unusual feature for many rash-producing illnesses.
The extent of the rash differs significantly among individuals, ranging from a single lesion to hundreds of spots. These early lesions are firm, rubbery, and deep-seated in the skin. They may also feature a small depression in the center, a characteristic known as umbilication.
Comparison to Similar Rashes
The early mpox rash can be mistaken for other common skin conditions, making medical assessment necessary for differentiation. One of the most frequent comparisons is to chickenpox. A key difference is that mpox lesions on any given part of the body tend to develop at the same time and progress through stages together. In contrast, chickenpox lesions appear in various stages simultaneously.
Herpes and syphilis can also be confused with mpox, particularly if lesions are in the genital or oral areas. While a primary herpes infection can cause a similar prodrome, its lesions progress to ulcers. Mpox lesions, in contrast, become firm, pus-filled pustules. The rash in secondary syphilis also follows a different developmental pattern.
The location and context of the rash provide further clues. For instance, while both mpox and chickenpox can have facial rashes, the chickenpox rash more commonly starts on the chest and back. A definitive diagnosis requires laboratory testing, as clinical presentation alone can be misleading.
When to Contact a Healthcare Provider
If you develop a new, unexplained rash accompanied by flu-like symptoms, contact a healthcare provider. Medical advice is particularly recommended if you have had close contact with someone who has confirmed mpox or have recently traveled to an area with known cases.
Call the clinic or hospital ahead of your visit. Informing them of your symptoms and potential exposure over the phone allows the facility to implement infection control measures to protect other patients and staff.
While awaiting medical guidance, isolate from others to the best of your ability. Avoiding close physical contact, including intimate contact, helps prevent spreading the virus. Following the advice of healthcare professionals ensures you receive proper care and helps safeguard community health.