Monkeypox OVERVIEW Gain a deep understanding of Monkeypox diagnostics

Monkeypox, is a viral zoonotic disease caused by the Monkeypox virus, a member of the Orthopoxvirus genus in the Poxviridae family. It is similar to smallpox, although it is generally less severe. The disease was first discovered in 1958 in laboratory monkeys, which is how it got its name. The first human case was recorded in 1970 in the Democratic Republic of Congo.

Virus Characteristics

The Monkeypox virus is a double-stranded DNA virus, relatively large, and belongs to the same family as the variola virus, which causes smallpox. It has two distinct genetic clades: the Central African (Congo Basin) clade, which is more virulent, and the West African clade, which tends to cause milder disease. The virus is mainly transmitted to humans from animals, with rodents being the primary reservoir. Human-to-human transmission occurs through close contact with infected respiratory secretions, skin lesions, or contaminated materials.

Disease Symptoms

Mpox typically begins with an incubation period of 5 to 21 days. The disease progresses through several stages:

1. Prodromal Stage: Initial symptoms are non-specific and include fever, headache, muscle aches, backache, swollen lymph nodes, chills, and exhaustion. The swelling of lymph nodes is a key feature distinguishing Mpox from smallpox.

2. Rash Development: A rash usually appears 1 to 3 days after the onset of fever, starting on the face and spreading to other parts of the body. The rash evolves sequentially from macules (flat, discolored areas) to papules (raised, solid bumps), vesicles (fluid-filled blisters), pustules (pus-filled blisters), and finally crusts that eventually fall off.

3. Lesion Stages: The lesions are typically more concentrated on the face and extremities rather than the trunk, and they may cause discomfort, itching, or pain.

The illness usually lasts 2 to 4 weeks. Although most patients recover without treatment, severe cases can occur, especially in children or immunocompromised individuals.

Infection and Transmission

Mpox can be transmitted through:

Direct contact with the blood, bodily fluids, or skin lesions of infected animals or humans.

Respiratory droplets during prolonged face-to-face contact.

Indirect contact with contaminated materials, such as bedding or clothing.

Human-to-human transmission is less efficient compared to smallpox, and outbreaks are generally self-limiting. However, the potential for transmission has increased in recent years, especially in areas with declining smallpox immunity due to the cessation of vaccination programs.

Diagnosis Techniques

Clinical Diagnosis

The clinical diagnosis of Mpox is primarily based on the recognition of its characteristic rash and associated symptoms, particularly in areas where the virus is endemic or during an outbreak. However, because the symptoms can resemble those of other diseases such as chickenpox, smallpox, or measles, laboratory confirmation is essential.

Molecular Diagnosis

Molecular diagnosis of Mpox is critical for confirming infection, especially since clinical symptoms can overlap with other poxviruses and viral exanthems. The primary molecular diagnostic methods include:

?1. Polymerase Chain Reaction (PCR)

• PCR is the gold standard for the molecular diagnosis of Mpox. It involves the amplification of specific DNA sequences of the Monkeypox virus from clinical samples, such as lesion swabs (vesicular, pustular, or crust), blood, or throat swabs.
• Real-time PCR (qPCR) allows for the quantification of viral DNA, providing insights into the viral load. This technique is highly sensitive and specific, enabling early detection and differentiation between Mpox and other Orthopoxviruses like smallpox.
• Multiplex PCR can simultaneously detect multiple pathogens, including different clades of the Monkeypox virus, which is valuable in outbreak situations where co-infections might occur.

2. Next-Generation Sequencing (NGS)

• NGS can be used to sequence the entire viral genome, providing comprehensive data on the virus's genetic makeup. This is particularly useful for epidemiological studies, tracking virus evolution, and identifying mutations that may affect virulence or transmission.
• Metagenomic sequencing can identify Mpox virus sequences in a sample without prior knowledge of the target, making it useful for detecting emerging or unexpected viral strains.

3. LAMP (Loop-Mediated Isothermal Amplification)

• LAMP is an alternative to PCR that amplifies DNA at a constant temperature. It is simpler and faster than PCR, making it suitable for field settings or resource-limited environments. LAMP has been developed for detecting Orthopoxviruses, including Monkeypox, and can be used as a point-of-care diagnostic tool.

4. CRISPR-based Diagnostics

• CRISPR-Cas systems have been adapted for viral diagnostics, including Monkeypox. The technology uses CRISPR's ability to target specific DNA sequences, combined with a reporter molecule that produces a detectable signal upon successful target recognition. This method can be highly specific and rapid, suitable for point-of-care testing.

?5. Serology and Antigen Detection

• Serological tests can detect antibodies against the Monkeypox virus in a patient’s blood, indicating current or past infection. However, serology is generally less specific than molecular methods and is used more for epidemiological purposes than for early diagnosis.
• Antigen detection assays can identify viral proteins in clinical samples. These are quicker but typically less sensitive than PCR-based methods and are not as widely used for Mpox.

Sample Collection and Handling

• Lesion Material: Swabs from vesicles, pustules, or scabs are the preferred samples for molecular testing because they contain the highest viral load.
• Blood and Throat Swabs: These can be used, particularly in cases where lesions are not accessible, but they may have lower viral DNA concentrations.
• Transport and Storage: Samples must be handled and transported under conditions that preserve viral DNA integrity, typically in viral transport media at low temperatures.

Prevention

Preventing the spread of Mpox involves several strategies:

1.?? Vaccination: The smallpox vaccine provides cross-protection against Mpox due to the genetic similarities between the two viruses. Newer vaccines specifically targeting orthopoxviruses are under development.

2.?? Avoiding Contact with Infected Animals: People should avoid handling wild animals, particularly in endemic areas, and take precautions when dealing with sick animals.

3.?? Personal Protective Equipment (PPE): Healthcare workers and those caring for infected individuals should use appropriate PPE, including gloves, masks, and gowns.

4.?? Hygiene Practices: Regular handwashing and the disinfection of contaminated surfaces can reduce the risk of transmission.

5.?? Quarantine and Isolation: Infected individuals should be isolated from others to prevent the spread of the virus. Contacts of confirmed cases should be monitored for signs of illness.

?Conclusion

Mpox, though less severe than smallpox, remains a public health concern, particularly in regions where the virus is endemic. With the advent of molecular diagnostic techniques, such as PCR, early and accurate diagnosis is possible, aiding in the control of outbreaks. Preventive measures, including vaccination, hygiene practices, and the use of personal protective equipment, are essential in managing the spread of this zoonotic disease.

?References:

1. World Health Organization (WHO): "Monkeypox." [WHO](https://www.who.int/news-room/fact-sheets/detail/monkeypox ). Accessed August 2024.

2. Centers for Disease Control and Prevention (CDC): "Monkeypox - About Monkeypox." [CDC](https://www.cdc.gov/poxvirus/monkeypox/about.html ). Accessed August 2024.

3. European Centre for Disease Prevention and Control (ECDC): "Factsheet about Monkeypox." [ECDC](https://www.ecdc.europa.eu/en/all-topics-z/monkeypox/factsheet-monkeypox ). Accessed August 2024.

4. Reynolds, M. G., et al. (2019). "The Detection of Monkeypox in Humans in the United States." The Journal of Infectious Diseases, 199(7), 1019–1021.

5. Vaughan, A., et al.? (2020). "Human-to-Human Transmission of Monkeypox Virus, United Kingdom, October 2018." Emerging Infectious Diseases, 26(4), 782-785.