Mpox, formerly known as monkeypox, is a viral disease that can cause a painful rash and other symptoms. While generally not severe, its emergence outside of historically endemic regions has led to increased public health awareness.
Understanding Monkeypox
Mpox is a zoonotic disease, meaning it can transmit from animals to humans. It is caused by the monkeypox virus, which belongs to the Orthopoxvirus genus, the same group as the variola virus responsible for smallpox. The virus was first identified in 1958 in monkeys kept for research in Denmark. The first confirmed human case was recorded in 1970 in the Democratic Republic of Congo.
Historically, the virus has been endemic to parts of Central and West Africa, primarily in rural areas. While monkeys were its initial discovery point, African rodents are suspected to be the natural reservoir. Mpox causes a milder illness compared to smallpox.
Transmission and Symptoms
Mpox primarily spreads through close, personal contact with an infected individual or animal. Direct contact with infectious rash, scabs, or body fluids, including saliva and respiratory secretions, is a common route. This can occur through skin-to-skin contact, such as touching or sexual activity, or mouth-to-mouth or mouth-to-skin contact like kissing. While respiratory transmission is possible through prolonged face-to-face interaction, human-to-human spread via this method is generally low.
Indirect contact with contaminated materials, known as fomites, such as bedding, clothing, or towels, can also transmit the virus. The incubation period, the time between exposure and symptom onset, typically ranges from 3 to 17 days, and can extend up to 21 days. During this period, an infected person usually does not show symptoms.
The illness often begins with flu-like symptoms, including fever, headache, muscle aches, exhaustion, and swollen lymph nodes. Swollen lymph nodes are a distinguishing feature of mpox compared to smallpox. A characteristic rash develops, usually within 1 to 4 days after these initial symptoms. The rash progresses through several stages: flat, discolored spots (macules) evolve into raised bumps (papules), then fluid-filled blisters (vesicles), followed by pus-filled lesions (pustules), and finally scabs that crust over and fall off. The rash can appear on various body parts, including the face, mouth, hands, feet, chest, and genital or anal regions.
Detection, Management, and Prevention
Diagnosis of mpox largely relies on clinical suspicion based on symptoms, followed by laboratory confirmation. The primary method for detecting the monkeypox virus is through polymerase chain reaction (PCR) testing. This test is typically performed on samples collected directly from skin lesions, such as fluid from vesicles or pustules, or scabs.
Swabs of the lesion surface or exudate are recommended for optimal collection. While other specimen types like oropharyngeal swabs can be collected, their sensitivity in pre-symptomatic cases may be lower. Samples should be refrigerated or frozen within an hour of collection for accurate testing.
Management for most individuals with healthy immune systems involves supportive care aimed at alleviating symptoms. This includes managing pain with over-the-counter medications like acetaminophen or NSAIDs, controlling fever, and ensuring adequate hydration. Topical steroids and anesthetics, such as lidocaine, may be considered for localized pain relief. For severe cases or in individuals who are immunocompromised, antiviral medications like tecovirimat (TPOXX) may be used. Tecovirimat is approved for treating human smallpox, and its use for mpox is under an investigational new drug protocol. While studies suggest tecovirimat is safe, its effectiveness in reducing the duration of mpox lesions is still being evaluated.
Preventive measures include vaccination and avoiding close contact with infected individuals or animals. Two vaccines are available for mpox prevention: JYNNEOS and ACAM2000. JYNNEOS is a live, attenuated, non-replicating virus vaccine administered as a two-dose series, 28 days apart, and has been the primary vaccine used in recent outbreaks.
ACAM2000 is a live, replicating vaccinia virus vaccine given as a single dose, but it has more known side effects and is not typically used in the current mpox outbreak. Practicing good hand hygiene, such as washing hands with soap and water or using an alcohol-based hand rub, is also important. Avoiding contact with potentially contaminated materials like bedding or clothing used by an infected person also contributes to prevention.
Disease Progression and Public Health
Mpox illness generally lasts for two to four weeks, with most individuals recovering fully without specific treatment. The severity of the illness can vary depending on an individual’s initial health and the route of exposure. While typically self-limiting, complications can arise, especially in vulnerable populations such as young children, pregnant individuals, and those with weakened immune systems, including people with advanced HIV. Potential complications include secondary bacterial infections of skin lesions, pneumonia, encephalitis (inflammation of the brain), and eye infections that could lead to vision loss.
The mortality rate for mpox has varied across outbreaks and populations, ranging from 0.1% to 10%, but can be higher in specific groups. Global surveillance efforts are important in managing mpox outbreaks. Public health agencies work to rapidly identify cases and clusters of infections, trace contacts, and determine sources of infection. This allows for prompt clinical care, isolation of cases to prevent further spread, and the identification of at-risk groups for targeted prevention measures. Public awareness and a coordinated response are crucial in containing the spread of this viral disease.