Mpox (Monkeypox): An Overview
Introduction
Mpox, also known as monkeypox, is a zoonotic viral disease caused by the monkeypox virus, which belongs to the Orthopoxvirus genus in the Poxviridae family. Although the virus was first identified in laboratory monkeys in 1958, the disease is primarily associated with rodents, which are considered its natural hosts. The first human case of mpox was recorded in the Democratic Republic of the Congo (DRC) in 1970. Since then, mpox has been reported in several Central and West African countries, with occasional outbreaks outside Africa, primarily linked to travel or imported animals.
Transmission
Mpox can be transmitted to humans through close contact with infected animals, people, or contaminated materials. Here’s a breakdown of the transmission routes:
- Animal-to-Human Transmission: This can occur through direct contact with the blood, bodily fluids, or skin/mucosal lesions of infected animals. Consuming undercooked meat from infected animals can also be a route of transmission.
- Human-to-Human Transmission: While less common than animal-to-human transmission, human-to-human transmission can occur through respiratory droplets, direct contact with body fluids or lesions of an infected person, or indirect contact via contaminated materials (such as bedding or clothing).
- Environmental Transmission: The virus can survive on surfaces and objects, potentially leading to transmission through contact with contaminated items.
Symptoms
The incubation period for mpox typically ranges from 5 to 21 days. The disease progresses through several stages, and symptoms can be divided into two main phases:
- Invasion Period (0-5 days):
- Fever
- Severe headache
- Swollen lymph nodes (lymphadenopathy)
- Muscle aches (myalgia)
- Back pain
- Intense fatigue
- Skin Eruption Period (1-3 days after fever onset):
- A rash usually appears, starting on the face and then spreading to other parts of the body, including the palms and soles.
- The rash progresses from macules (flat lesions) to papules (raised lesions), vesicles (fluid-filled lesions), pustules (pus-filled lesions), and finally to scabs.
The rash can be painful and itchy, and in severe cases, lesions can become confluent. Lymphadenopathy is a distinctive feature of mpox compared to other pox-like diseases, such as smallpox.
Complications
While mpox is generally a self-limiting disease, complications can occur, particularly in children, pregnant women, and individuals with compromised immune systems. Complications may include:
- Secondary bacterial infections
- Respiratory distress
- Sepsis
- Encephalitis
- Corneal infection, which can lead to vision loss
The case fatality ratio (CFR) for mpox varies by the clade of the virus, ranging from less than 1% for the West African clade to as high as 10% for the Central African (Congo Basin) clade.
Diagnosis
Mpox can be diagnosed through a combination of clinical evaluation, patient history, and laboratory tests. Laboratory confirmation typically involves:
- Polymerase Chain Reaction (PCR): The preferred method for diagnosing mpox, as it is highly specific and can differentiate monkeypox virus from other poxviruses.
- Virus Isolation: Less commonly used, but can be done by culturing the virus from clinical specimens.
- Serology: Detects antibodies, but is not the primary diagnostic tool due to potential cross-reactivity with other orthopoxviruses.
Treatment
There is no specific treatment for mpox, and care is primarily supportive, focusing on relieving symptoms and preventing complications. However, certain antiviral drugs, such as tecovirimat (TPOXX), have shown effectiveness against orthopoxviruses and may be used under certain conditions.
Prevention
Prevention strategies for mpox focus on reducing the risk of transmission. Key measures include:
- Avoiding Contact with Wild Animals: Especially those that are sick or found dead, in areas where mpox is endemic.
- Safe Food Practices: Ensuring that all animal products, including meat, are thoroughly cooked before consumption.
- Personal Protective Equipment (PPE): For healthcare workers and others in contact with infected individuals or animals.
- Vaccination: The smallpox vaccine, which provides cross-protection against mpox, can be used in individuals at high risk, such as healthcare workers or laboratory personnel. A newer vaccine, JYNNEOS (also known as Imvamune or Imvanex), has been developed specifically to protect against both smallpox and mpox.
Global Impact and Recent Outbreaks
In recent years, mpox has gained international attention due to outbreaks occurring outside of Africa, notably in 2003 in the United States (linked to imported African rodents) and more recently in 2022, where cases were reported in multiple countries across different continents, raising concerns about its potential spread.
The 2022 outbreak highlighted the need for global surveillance and better understanding of the virus’s transmission dynamics, especially in non-endemic regions. International cooperation and robust public health responses are crucial in managing and containing mpox outbreaks.
Conclusion
Mpox is a re-emerging zoonotic disease with significant public health implications. While traditionally confined to Central and West Africa, global travel and trade have increased the risk of international spread. Understanding the transmission, symptoms, and preventive measures is essential for controlling outbreaks and protecting public health. As the world continues to navigate the challenges posed by emerging infectious diseases, mpox serves as a reminder of the importance of vigilance, preparedness, and global cooperation in safeguarding health security.
