Monkeypox virus • Virus • Public health • Vaccine

Key facts

• Mpox (formerly monkeypox) is a viral illness caused by the monkeypox virus, a species of the genus Orthopoxvirus. Two different clades exist: clade I and clade II
• Common symptoms of mpox are a skin rash or mucosal lesions which can last 2–4 weeks accompanied by fever, headache, muscle aches, back pain, low energy, and swollen lymph nodes.
• Mpox can be transmitted to humans through physical contact with someone who is infectious, with contaminated materials, or with infected animals.
• Laboratory confirmation of mpox is done by testing skin lesion material by PCR.
• Mpox is treated with supportive care. Vaccines and therapeutics developed for smallpox and approved for use in some countries can be used for mpox in some circumstances.
• In 2022–2023 a global outbreak of mpox was caused by a strain known as clade IIb.
• Mpox can be prevented by avoiding physical contact with someone who has mpox. Vaccination can help prevent infection for people at risk.

Introduction

Monkeypox virus (MPXV) is an orthopoxvirus that causes a disease with symptoms similar to but less severe than smallpox. Despite its name, the virus is not exclusive to monkeys but can be found in various animal species, including rodents and humans. First identified in 1958 in monkeys kept for research, the first human case was recorded in 1970 in the Democratic Republic of the Congo (DRC). Monkeypox is primarily found in Central and West African countries but has seen sporadic outbreaks elsewhere.

Transmission

Monkeypox typically begins with fever, headache, muscle aches, and exhaustion, followed by the development of a rash. The rash often starts on the face before spreading to other parts of the body. The illness usually lasts 2 to 4 weeks.

Transmission occurs through:

• Animal-to-human transmission: Direct contact with blood, bodily fluids, or cutaneous/mucosal lesions of infected animals.
• Human-to-human transmission: Close contact with respiratory secretions, skin lesions, or recently contaminated objects. Prolonged face-to-face contact and intimate physical contact can also facilitate transmission.

Signs and symptoms

Mpox causes signs and symptoms which usually begin within a week but can start 1–21 days after exposure. Symptoms typically last 2–4 weeks but may last longer in someone with a weakened immune system.

Common symptoms of mpox are:

• rash
• fever
• sore throat
• headache
• muscle aches
• back pain
• low energy
• swollen lymph nodes.

For some people, the first symptom of mpox is a rash, while others may have different symptoms first.

The rash begins as a flat sore which develops into a blister filled with liquid and may be itchy or painful. As the rash heals, the lesions dry up, crust over and fall off.

Some people may have one or a few skin lesions and others have hundreds or more. These can appear  anywhere on the body such as the:

• palms of hands and soles of feet
• face, mouth and throat
• groin and genital areas
• anus.

Some people also have painful swelling of their rectum or pain and difficulty when peeing.

People with mpox are infectious and can pass the disease on to others until all sores have healed and a new layer of skin has formed.

Children, pregnant people and people with weak immune systems are at risk for complications from mpox.

Typically for mpox, fever, muscle aches and sore throat appear first. The mpox rash begins on the face and spreads over the body, extending to the palms of the hands and soles of the feet and evolves over 2-4 weeks in stages – macules, papules, vesicles, pustules. Lesions dip in the centre before crusting over. Scabs then fall off. Lymphadenopathy (swollen lymph nodes) is a classic feature of mpox. Some people can be infected without developing any symptoms.

In the context of the global outbreak of mpox which began in 2022 (caused mostly by Clade IIb virus), the illness begins differently in some people. In just over a half of cases, a rash may appear before or at the same time as other symptoms and does not always progress over the body. The first lesion can be in the groin, anus, or in or around the mouth.

People with mpox can become very sick. For example, the skin can become infected with bacteria leading to abscesses or serious skin damage. Other complications include pneumonia, corneal infection with loss of vision; pain or difficulty swallowing, vomiting and diarrhoea causing severe dehydration or malnutrition; sepsis (infection of the blood with a widespread inflammatory response in the body), inflammation of the brain (encephalitis), heart (myocarditis), rectum (proctitis), genital organs (balanitis) or urinary passages (urethritis), or death. Persons with immune suppression due to medication or medical conditions are at higher risk of serious illness and death due to mpox. People living with HIV that is not well-controlled or treated more often develop severe disease.

Precautions and Preventive Measures

To mitigate the spread of monkeypox, several precautions and preventive measures should be adopted:

1. Isolation of Infected Individuals: Anyone infected with monkeypox should be isolated from healthy individuals to prevent transmission.
2. Use of Personal Protective Equipment (PPE): Healthcare workers and caregivers should use gloves, masks, and protective clothing when attending to infected individuals.
3. Hygiene Practices: Regular hand washing with soap and water or using an alcohol-based hand sanitizer, especially after contact with infected individuals or animals.
4. Safe Handling of Animals: Avoiding contact with animals that could harbor the virus, particularly in areas where monkeypox is endemic.
5. Disinfection: Regular cleaning and disinfection of contaminated surfaces and items.
6. Avoiding Consumption of Bushmeat: In regions where monkeypox is endemic, avoiding the hunting, handling, and consumption of wild animals.

Vaccines

Vaccination against monkeypox is an effective preventive measure. The vaccines used include:

1. JYNNEOS (Imvamune or Imvanex): This is a newer, non-replicating vaccine approved by the U.S. FDA for the prevention of monkeypox and smallpox. It is considered safe and effective for use in both the general population and specific groups, such as those with compromised immune systems.
2. ACAM2000: An older, live virus vaccine also used for smallpox, which can provide cross-protection against monkeypox. It is administered as a single dose but requires careful handling due to its potential side effects, including risk for individuals with certain health conditions.

Vaccination campaigns are particularly recommended for:

• Healthcare workers and first responders.
• Individuals in regions with high incidence rates.
• People who have had close contact with confirmed cases of monkeypox.

Public Health Awareness and Education

Raising public awareness and educating communities about monkeypox are crucial components of controlling outbreaks:

1. Information Dissemination: Governments and health organizations should provide accurate information about monkeypox symptoms, transmission, and prevention through various media channels.
2. Community Engagement: Working with community leaders and local organizations to ensure the message reaches remote and vulnerable populations.
3. Training Healthcare Providers: Ensuring that healthcare workers are well-trained to identify and manage monkeypox cases promptly and effectively.
4. Surveillance and Reporting: Strengthening surveillance systems to quickly detect and report new cases, enabling swift public health responses.

Conclusion

Monkeypox is a re-emerging zoonotic disease with the potential to cause significant outbreaks. Through vigilant precautions, vaccination, and robust public health education, its spread can be controlled. Continued research and international collaboration are essential to developing better prevention and treatment strategies, ultimately aiming to reduce the impact of monkeypox on global health.