Mpox

Mpox, formerly called monkeypox, is an infectious viral disease affecting both humans and animals. The disease typically manifests as a rash that forms blisters and then crusts over, accompanied by fever, swollen lymph nodes, muscle aches, and sore throat. Although most individuals recover within a few weeks without treatment, severe cases can occur, especially in children, pregnant women, and immunocompromised individuals.

Cause and Transmission

Mpox is caused by the monkeypox virus, a double-stranded DNA virus in the genus Orthopoxvirus, which also includes the variola virus responsible for smallpox. The disease is endemic in central and Western Africa, with small mammals suspected as the natural reservoir. Human-to-human transmission occurs through direct contact with infected skin or body fluids, including sexual contact. The virus can also spread from animals to humans via bites, scratches, or handling infected meat. Infected individuals remain contagious until all lesions have scabbed and healed.

Signs and Symptoms

Typical symptoms appear 5-21 days post-exposure and last 2-4 weeks. Initial symptoms include fever, muscle pains, and sore throat, followed by an itchy or painful rash, headache, swollen lymph nodes, and fatigue. The rash comprises many small lesions that progress from flat spots to fluid-filled bumps, which then burst and scab over. Lesions may appear on the palms, soles, face, mouth, genitals, or anus.

Diagnosis

Diagnosing mpox involves considering differential diagnoses such as chickenpox, measles, bacterial skin infections, scabies, syphilis, and medication-associated allergies. Confirmation is achieved through PCR testing of skin lesion samples for viral DNA.

Prevention

Vaccination is a key preventive measure. Although no vaccine is specifically developed for mpox, smallpox vaccines have proven effective. Four vaccines are currently in use: MVA-BN (marketed as Jynneos, Imvamune, or Imvanex), LC16, OrthopoxVac, and ACAM2000. Other preventive measures include hand washing, using personal protective equipment (PPE), covering rashes, and social distancing. Public health authorities also recommend avoiding contact with potentially infected animals and refraining from eating bush meat in endemic regions.

Treatment

Treatment for mpox mainly involves supportive care, as there is no specific cure for the disease. Antiviral drugs like tecovirimat have been approved for treating severe cases, although their effectiveness is not fully established. A 2023 Cochrane review indicated no significant risks from tecovirimat and low-certainty evidence suggesting that brincidofovir might cause mild liver injury. Pain management, fever control, hydration, and maintaining mental health are very important aspects of patient care. Hospitalisation and careful monitoring are recommended for high-risk patients such as children, pregnant women, the elderly, and immunocompromised individuals.

Outcome and Complications

Most patients recover without lasting effects, though complications can include secondary infections, pneumonia, sepsis, encephalitis, and loss of vision. Historical case fatality rates range from 1-10%, with clade I being more severe than clade II. The 2022–2023 global outbreak caused by clade IIb had a low case fatality rate of 0.16%, primarily affecting immunocompromised individuals.

Epidemiology and Public Health Threat

Mpox was first identified in 1958 in laboratory monkeys and then in humans in 1970 in the Democratic Republic of the Congo. Since then, the virus has been endemic in several African countries, escalating in frequency and severity over the years. The 2022–2023 global outbreak marked the first instance of widespread community transmission outside Africa. The WHO declared it a Public Health Emergency of International Concern (PHEIC) in July 2022, a status reverted in May 2023 as the outbreak came under control. However, the disease remains a significant public health threat due to its potential to cause future global epidemics and its evolving transmissibility among humans.

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Self-assessment MCQs (single best answer)

What is the primary cause of Mpox?

How is Mpox mainly transmitted between humans?

Which vaccine is NOT used for preventing Mpox?

What is a common initial symptom of Mpox?

Which method is used to confirm a diagnosis of Mpox?

What is the estimated case fatality rate of the 2022–2023 Mpox outbreak caused by clade IIb?

Which of the following is NOT a typical symptom of Mpox?

What does supportive care for Mpox primarily include?

Which population is at higher risk for severe Mpox?

When did the World Health Organisation declare Mpox a Public Health Emergency of International Concern (PHEIC)?