Virological Overwiev of Monkeypox Virus

Monkeypox Virus: A Virological Overview

The Mpox virus, formerly known as Monkeypox, is a zoonotic disease, meaning it is transmitted from animals to humans. It was first identified in 1958 in monkey colonies used for research, but the first human case was reported in 1970 in the Democratic Republic of Congo. Mpox belongs to the same viral family as smallpox (Poxviridae) and has gained attention in recent years due to its increasing spread worldwide. While the disease has origins in Africa, globalization and modern travel have transformed it into a global public health concern.

Chronological Overview of Mpox Virus Symptoms

The symptoms of the Mpox virus typically progress through two main phases: the Prodromal Phase and the Skin Lesions Phase.

1. Prodromal Phase (Early Stage)

In the initial stage of the illness, flu-like symptoms are predominant:

- Fever:  High fever (above 38.5°C) is usually the first symptom to appear.

- Headache: Severe headaches are common.

- Muscle and Back Pain: Patients often experience muscle aches (myalgia) and back pain.

- Lymphadenopathy: During this phase, noticeable swelling of the lymph nodes (lymphadenopathy) occurs in the neck, armpits, and groin. This is a distinguishing feature of Mpox, setting it apart from smallpox.

- Chills and Fatigue: Symptoms such as chills, fatigue, and weakness are also present.

2. Emergence of Skin Lesions

1-3 days after the onset of prodromal symptoms, the characteristic skin lesions of the disease begin to appear. These lesions can be found on different parts of the body, progressing through distinct stages.

- Skin Lesions: Lesions usually start on the face and then spread to other parts of the body, including the palms of the hands and the soles of the feet. These lesions resemble those of smallpox but progress through five distinct stages:

1. Macular Stage: Small, flat, red spots appear.

2. Papular Stage: The spots become raised and firm, forming papules.

3. Vesicular Stage: The papules then develop into fluid-filled vesicles.

4. Pustular Stage: The vesicles become filled with pus, forming pustules that often have a depressed center.

5. Crusting Stage: Over time, the pustules dry out, crust over, and eventually fall off. This stage may leave scars where the lesions were present.

This entire process typically lasts 2-4 weeks. The patient remains contagious until all the lesions have crusted over and fallen off. Mpox can be more severe in individuals with weakened immune systems, children, and pregnant women.

Preventing Mpox Virus Infection

Understanding the modes of transmission and implementing preventive measures are crucial to controlling the spread of this virus.

Ways of Transmission

1. Respiratory Droplets:

   - The Mpox virus can be transmitted through respiratory droplets, particularly during prolonged face-to-face contact. This is especially common in close living quarters or healthcare settings where infected individuals are present.

2. Direct Contact:

   - Direct skin-to-skin contact with an infected person, especially with their skin lesions, bodily fluids, or scabs, can lead to transmission. The virus can also enter the body through mucous membranes such as the eyes, nose, or mouth.

3. Indirect Contact:

   - Indirect transmission occurs when a person touches contaminated items, such as clothing, bedding, towels, or other personal belongings that have been in contact with the infected individual's lesions or fluids. This type of transmission highlights the importance of hygiene and careful handling of potentially contaminated items.

Preventive Measures

1. Vaccination:

   - Smallpox Vaccine (ACAM2000) and MVA-BN (Modified Vaccinia Ankara-Bavarian Nordic): 

     These vaccines have shown cross-protection against Mpox due to the similarities between the Mpox and smallpox viruses. Vaccination is highly recommended for those who have been in close contact with confirmed Mpox cases or in high-risk populations, such as healthcare workers and laboratory personnel. 

   - Ring Vaccination Strategy:

     To effectively prevent the spread of the virus, a ring vaccination strategy can be employed. This involves vaccinating close contacts of confirmed cases (including healthcare workers) to create a "ring" of immunity, thereby containing the outbreak. This method has proven effective in controlling other viral outbreaks.

2. Isolation and Quarantine:

   - Infected Individuals:

     Patients diagnosed with Mpox should be isolated from others to prevent further spread. Isolation should continue until all lesions have crusted over and the patient is no longer contagious.

   - Quarantine for Close Contacts: 

     Individuals who have been in close contact with a confirmed Mpox case should be monitored for symptoms and, if necessary, quarantined for the incubation period of the virus (typically 5-21 days).

3. Use of Personal Protective Equipment (PPE):

   - Healthcare Settings:

     Healthcare workers should use appropriate PPE, including masks, gloves, gowns, and eye protection, when treating Mpox patients to minimize the risk of transmission.

   - General Public:

     For those caring for infected family members or those in contact with potentially infected individuals, wearing masks and gloves can provide an additional layer of protection.

4. Hygiene and Disinfection:

   - Hand Hygiene: 

     Regular hand washing with soap and water, or using an alcohol-based hand sanitizer, is essential, especially after contact with infected individuals or contaminated items.

   - Disinfection of Contaminated Items:

     Clothing, bedding, and other personal items that may have come into contact with the virus should be handled with care. These items should be washed in hot water and disinfected to kill the virus. Surfaces in the patient’s environment should be regularly cleaned with appropriate disinfectants.

5. Public Health Measures:

   - Education and Awareness:

     Raising awareness about the modes of transmission and symptoms of Mpox can help individuals recognize the signs early and take appropriate action.

   - Contact Tracing:

     Public health authorities should conduct thorough contact tracing to identify and monitor individuals who may have been exposed to the virus. This helps in quickly containing potential outbreaks.

   - Travel Restrictions and Screening:

     In areas where outbreaks are active, implementing travel restrictions and screening procedures at airports and other points of entry can help prevent the spread of the virus to other regions.

6. Community and Environmental Measures:

   - Avoiding Contact with Wild Animals:

     Since Mpox is a zoonotic virus, avoiding contact with wild animals, particularly rodents and primates that could be carriers of the virus, is important. This is especially relevant in regions where Mpox is endemic.

   - Safe Animal Handling Practices: 

     For those working with animals, such as veterinarians or laboratory workers, it’s crucial to follow safe handling practices and use appropriate protective measures to prevent cross-species transmissions.

Resources

Xiang Y, White A. Monkeypox virus emerges from the shadow of its more infamous cousin: family biology matters. Emerg Microbes Infect. 2022 Dec;11(1):1768-1777. doi: 10.1080/22221751.2022.2095309. PMID: 35751396; PMCID: PMC9278444.

Forni D, Cagliani R, Molteni C, Clerici M, Sironi M. Monkeypox virus: The changing facets of a zoonotic pathogen. Infect Genet Evol. 2022 Nov;105:105372. doi: 10.1016/j.meegid.2022.105372. Epub 2022 Oct 4. PMID: 36202208; PMCID: PMC9534092.