Mpox, formerly known as monkeypox, is a viral zoonotic disease that has garnered significant attention due to recent outbreaks in various parts of the world. First discovered in laboratory monkeys in the late 1950s, mpox primarily affected animals but has since become a concern for humans, particularly in regions where there is close contact with infected animals. While mpox is less contagious and less severe than diseases like smallpox, its spread and symptoms can still pose a threat, especially in populations with compromised immunity.
This blog aims to provide an in-depth understanding of mpox, its origins, symptoms, transmission methods, treatment options, and the preventive measures necessary to combat its spread.
1. Origins and History of Mpox
Mpox was first identified in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research purposes, hence the original name “monkeypox.” Despite its name, the primary carriers of the virus are rodents and other animals, not monkeys. The first human case was recorded in 1970 in the Democratic Republic of the Congo (DRC), during a time when efforts to eradicate smallpox were intensifying. Mpox was initially thought to be a disease confined to central and western African countries, but sporadic cases have been reported outside these regions.
The World Health Organization (WHO) officially renamed monkeypox to mpox in 2022 to avoid stigmatization and reflect a broader understanding of the virus’s epidemiology, especially in light of the growing global awareness following outbreaks in non-endemic countries.
2. Understanding the Virus
Mpox is caused by the mpox virus, a member of the Orthopoxvirus genus, which also includes the viruses responsible for smallpox and cowpox. The virus has two distinct genetic clades:
- Central African (Congo Basin) clade: Associated with more severe disease and a higher mortality rate.
- West African clade: Causes a milder form of the disease with fewer fatalities.
Both clades are zoonotic, meaning they can jump from animals to humans, and, in some cases, human-to-human transmission is also possible. While mpox is genetically related to smallpox, it is less contagious and generally less severe.
3. Symptoms of Mpox
The incubation period of mpox is typically 7-14 days but can range from 5-21 days. Once symptoms begin, they usually unfold in two stages:
a. Invasion Stage (Lasts 0-5 Days)
- Fever: One of the first and most common symptoms.
- Headache: Often severe and persistent.
- Muscle Aches: Generalized myalgia.
- Back Pain: Another frequent symptom.
- Lymphadenopathy: Swelling of the lymph nodes, distinguishing mpox from diseases like chickenpox or smallpox.
b. Eruptive Stage (Develops 1-3 Days After Fever Onset)
- A rash typically begins on the face and then spreads to other parts of the body. The rash evolves in stages, starting as macules (flat lesions), then progressing to papules (raised lesions), vesicles (fluid-filled blisters), and pustules (filled with pus), before finally scabbing over.
- Location: The rash is often concentrated on the face, hands, feet, and in severe cases, the palms and soles.
- Duration: The entire rash progression can last between 2-4 weeks.
- Other Symptoms: Patients may also experience respiratory symptoms like cough and sore throat.
4. Transmission of Mpox
Mpox is primarily a zoonotic disease, meaning it is transmitted from animals to humans. However, human-to-human transmission can occur, particularly through direct contact with the lesions, body fluids, or respiratory droplets of an infected person. Key transmission routes include:
a. Animal-to-Human Transmission
- Direct contact with blood, bodily fluids, or lesions of infected animals (particularly rodents and non-human primates).
- Consumption of undercooked meat from infected animals.
b. Human-to-Human Transmission
- Direct Contact: Touching lesions or body fluids of an infected person.
- Respiratory Droplets: Close and prolonged face-to-face contact can result in transmission through large respiratory droplets.
- Fomites: The virus can survive on surfaces, so contact with contaminated objects (like clothing or bedding) can also spread the disease.
- Sexual Contact: Mpox has also been detected in genital fluids, leading to concerns about sexual transmission, though more research is needed to confirm this.
While the virus is not as easily transmitted as some others, close contact in household settings, healthcare environments, or between intimate partners significantly increases the risk.
5. Mpox in Recent Outbreaks
Until recently, mpox was considered a disease confined to Africa. However, outbreaks have occurred in non-endemic countries in Europe, North America, and Asia, raising concerns about the global spread of the virus. In 2022, multiple clusters of mpox cases were reported outside of Africa, most notably in Europe and the United States. These outbreaks were largely associated with close human contact, particularly in social and sexual networks.
The recent mpox outbreak, which began escalating in 2024, was declared a public health emergency of international concern (PHEIC) by the WHO on August 14, 2024. This declaration came due to a surge in cases in the Democratic Republic of the Congo (DRC) and neighboring countries.
This recent global spread of mpox has highlighted the need for heightened surveillance and prevention measures, as well as an understanding that the virus is no longer confined to specific geographic regions.
6. Complications and Severity
Most cases of mpox are mild, but complications can occur, especially in vulnerable populations such as children, pregnant women, and those with weakened immune systems. Complications include:
- Secondary Infections: Bacterial infections of the skin or respiratory tract.
- Pneumonia: In some cases, mpox can lead to viral or bacterial pneumonia.
- Encephalitis: Though rare, inflammation of the brain can occur.
- Corneal Infections: Eye infections may lead to vision loss.
The case fatality rate (CFR) for the Central African clade has been reported to be as high as 10%, while the West African clade has a much lower CFR, typically around 1%.
7. Diagnosis of Mpox
Diagnosing mpox can be challenging due to its similarity to other rash-causing diseases such as chickenpox, measles, or skin allergies. However, mpox can be definitively diagnosed through laboratory tests, such as:
- PCR (Polymerase Chain Reaction): The most reliable method for detecting mpox DNA in samples collected from skin lesions.
- Serology: While less definitive than PCR, serological tests can detect antibodies, though they may not distinguish between different orthopoxviruses.
- Viral Culture: Though less commonly used due to the time required, viral cultures can confirm the presence of the mpox virus.
8. Treatment for Mpox
Currently, there is no specific treatment for mpox, but the disease is generally self-limiting, with symptoms resolving on their own in 2-4 weeks. Treatment mainly focuses on relieving symptoms and preventing complications.
- Supportive Care: Includes fluids, pain relief, and fever control.
- Antiviral Drugs: In severe cases, antivirals like tecovirimat (approved for treating smallpox) have shown some efficacy against mpox, though their use is not widespread.
- Secondary Infections: If bacterial infections occur, antibiotics may be necessary.
In high-risk individuals, such as those with weakened immune systems, prompt treatment may reduce the severity of symptoms.
9. Vaccines for Mpox
The smallpox vaccine provides some cross-protection against mpox because of the genetic similarities between the two viruses. People who received the smallpox vaccine in childhood may have partial immunity. However, routine smallpox vaccinations were stopped after the disease was eradicated in 1980, meaning younger populations are more vulnerable to mpox.
In response to the 2022 outbreaks, vaccines designed for smallpox, such as JYNNEOS (also known as Imvamune or Imvanex) and ACAM2000, have been repurposed to combat mpox. JYNNEOS, a live, non-replicating vaccine, is currently the preferred option due to its safety profile.
10. Prevention of Mpox
Preventing mpox involves a combination of public health measures, education, and vaccination efforts. Some key prevention strategies include:
- Avoid Contact with Infected Animals: In endemic areas, reducing exposure to wildlife, particularly rodents and primates, is crucial.
- Cook Animal Products Thoroughly: Ensure that all animal products, especially meat, are well-cooked.
- Good Hygiene Practices: Regular handwashing and avoiding close contact with infected individuals can help limit the spread.
- Use of Personal Protective Equipment (PPE): Healthcare workers caring for infected patients should wear appropriate PPE, including gloves and masks.
- Vaccination: Vaccines are available for those at high risk, such as healthcare workers, close contacts of infected individuals, and those in endemic regions.
11. Global Response and Future Outlook
The recent global outbreaks of mpox have prompted increased efforts to enhance surveillance, research, and public health response. The WHO has called for international collaboration to ensure rapid detection, isolation, and management of cases. Vaccination campaigns have been launched in affected areas to curb the spread, particularly among high-risk populations.
Looking ahead, ongoing research into mpox, its transmission, and treatment options will be critical to preventing future outbreaks. Public health education and awareness programs are equally important to ensure that communities understand how to protect themselves and limit the spread of the virus.
Mpox is a zoonotic disease with global implications, especially in light of recent outbreaks in non-endemic regions. While the disease is typically mild, its potential to cause severe complications and spread through close contact underscores the importance of preventive measures, early detection, and effective treatment. Through global cooperation, vaccination efforts, and public education, the spread of mpox can be controlled, ensuring that communities worldwide remain safe and informed.