Monkeypox

Introduction

Monkeypox (MPX) is a viral zoonotic disease with symptoms like smallpox, with less clinical severity. MPX was first discovered in 1958 in colonies of monkeys kept for research, hence the name ‘monkeypox.’ It is a disease of global public health importance as it not only affects countries in West and Central Africa, but the rest of the world. The true burden of disease is not known.

Historical background

Monkeypox was first identified in humans in 1970 in the Democratic Republic of the Congo in a 9- year-old boy in a region where smallpox had been eliminated in 1968. Since 1970, cases of monkeypox were reported in 11 African countries and in 2003, the first monkeypox outbreak outside of Africa was reported in the United States of America and was linked to contact with infected pet prairie dogs. Since 1st January 2022, Mpox cases have been reported to World Health Organisation (WHO) from 121 Member States across all 6 WHO regions.

During 14th August 2024, World Health Organisation (WHO) determined that the upsurge of mpox in the Democratic Republic of the Congo (DRC) and a growing number of countries in Africa constitutes a public health emergency of international concern (PHEIC) under the International Health Regulations (2005) (IHR). WHO had earlier declared it as a Public Health Emergency of International Concern (PHEIC) first in July 2022.

Epidemiology

Agent

Monkeypox virus (MPXV) is an enveloped double- stranded DNA virus that belongs to the genus Orthopoxvirus and family Poxviridae. There are two distinct genetic clades of the monkeypox virus – the Central African (Congo Basin) clade and the West African clade. The Congo Basin clade has historically caused more severe disease and was thought to be more transmissible. As per the recent literature, the latest strain of monkeypox virus is from West African clade and has about 50 genetic variations compared to related viruses that circulated in 2018-2019. The latest outbreak (during 2024) involves a new variant, called 'clade Ib. It's an offshoot of clade I, which is endemic to African Congo. The virus is continuing to evolve during the current outbreak, including several small changes in the genetic code, minor gene variants and a deleted gene.

Host

Natural reservoir is yet unknown. However, certain rodents (including rope squirrels, tree squirrels, Gambian pouched rats, dormice) and non-human primates are known to be naturally susceptible to infection of monkeypox virus.

Incubation period

The incubation period (interval from infection to onset of symptoms) of monkeypox is usually from 6 to 13 days but can range from 5 to 21 days.

Period of communicability

1-2 days before the rash to until all the scabs fall off/gets subsided.

Mode of transmission: As per reports, clade Ib is spreading primarily through household contacts and frequently infects children. Clade IIb, which had prompted the previous WHO global warning in 2022, spread mainly through sexual contact. While clade Ib causes a similar illness to clade IIb, it is considered capable of spreading faster and killing more people.

Human-to-human transmission is known to occur through large respiratory droplets generally requiring a prolonged close contact. It can also be transmitted through direct contact with body fluids or lesion material, and indirect contact with lesion material, such as through contaminated clothing or linens of an infected person. Transmission between sexual partners, due to intimate contact during sex with infectious skin lesions seems the more likely mode of transmission among men who have sex with men (MSM). The mode of transmission is evolving.

Animal-to-human transmission of MPXV may occur by bite or scratch of infected animals like small mammals including rodents (rats, squirrels) and non-human primates (monkeys, apes) or through bush meat preparation.

Case definition

Suspected case

A person of any age having history of travel to affected countries within last 21 days presenting with an unexplained acute rash AND one or more of the following signs or symptoms

• Swollen lymph nodes
• Fever
• Headache
• Body aches
• Profound weakness

Probable case

A person meeting the case definition for a suspected case, clinically compatible illness and has an epidemiological link (face-to-face exposure, including health care workers without appropriate PPE; direct physical contact with skin or skin lesions, including sexual contact; or contact with contaminated materials such as clothing, bedding or utensils is suggestive of a strong epidemiological link).

Confirmed case

A case which is laboratory confirmed for monkeypox virus (by detection of unique sequences of viral DNA either by polymerase chain reaction (PCR) and/or sequencing).

Transmission in Children:

It is currently unclear why more children are contracting Mpox. However, it is postulated that in endemic areas, long-term exposure to the virus may have allowed adults to develop immunity over time, making them less vulnerable to the disease. In contrast, children are immunologically naïve and, therefore, more likely to contract the disease compared to adults

Signs and symptoms

Monkeypox is usually a self-limited disease with the symptoms lasting from 2 to 4 weeks. Severe cases occur more commonly among children and are related to the extent of virus exposure, patient health status and nature of complications. The extent to which asymptomatic infection occurs is unknown. Case fatality ratio of monkeypox has historically ranged from 0 to 11% in the general population and has been higher among young children. In recent times, the case fatality ratio has been around 3-6%.

Common symptoms and signs

Prodrome (0-5 days)

• Fever
• Lymphadenopathy
  • Typically occurs with fever onset
  • Periauricular, axillary, cervical or inguinal
  • ➢ Unilateral or bilateral
• Headache, muscle aches, exhaustion
• Chills and/or sweats
• Sore throat and cough

Skin involvement (rash)

• Usually begins within 1-3 days of fever onset, lasting for around 2-4 weeks
• Deep-seated, well-circumscribed and often develop umbilication
• Lesions are often described as painful until the healing phase when they become itchy (in the crust stage)
• Stages of rash (slow evolution)
  • Enanthem- first lesions on tongue and mouth
  • Macules starting from face spreading to arms, legs, palms, and soles (centrifugal distribution), within 24 hours
  • The rash goes through a macular, papular, vesicular and pustular phase. Classic lesion is vesico-pustular.
• Complications of Mpox in children can be severe and may include secondary bacterial infections, severe skin infections, dehydration, pneumonia, encephalitis, ocular complications and even longer sequelae such as scarring of skin lesions.

Management

Treatment of Monkeypox is primarily supportive.

Principles of Management include:

• Patient isolation
  
  • Isolation of the patient in an isolation room of the hospital/ at home in a separate room with separate ventilation
  • Patient to wear a triple layer mask
  • Skin lesions should be covered to the best extent possible (e.g. long sleeves, long pants) to minimize risk of contact with others
  • Isolation to be continued until all lesions have resolved and scabs have completely fallen off
• Protection of compromised skin and mucous membranes
• Rehydration therapy and Nutritional support
• Symptom alleviation
• Monitoring and treatment of complications

Drugs may be considered in special severe cases, strictly as per treating physician and are NOT to be self-administered. These include:

• Tecovirimat
• Vaccinia Immune Globulin Intravenous
• Cidofovir & Brincidofovir - effective against orthopoxviruses in invitro & animal studies

Patient Isolation

• Isolation of the patient in an isolation room of the hospital/ at home in a separate room
• Patient to wear a triple layer mask
• Skin lesions should be covered to the best extent possible (e.g. long sleeves, long pants) to minimize risk of contact with others
• Isolation to be continued until all lesions have resolved and scabs have completely fallen off and a fresh layer of intact skin transformed.

Preventive measures

Raising awareness of risk factors and educating people about the measures they can take to reduce exposure to the virus is the main prevention strategy
for monkeypox. There are number of measures that can be taken to prevent infection with monkeypox virus:

• Avoid contact with any materials, such as bedding, clothing etc. that has been in contact with a sick person.
• Isolate infected patients from others.
• Practice good hand hygiene after contact with infected animals or humans. For example, washing your hands with soap and water or using an alcohol-based hand sanitizer.
• Use appropriate personal protective equipment (PPE) when caring for patients.
• Correct containment and disposal of contaminated waste (e.g., dressings) in accordance with Biomedical Waste Management guidelines for infectious waste.

IPC at home

• Patients who do not require hospitalization may be managed at home taking preventive measures as laid down in MoHFW Guidelines for Management of Monkeypox Disease.

Duration of Isolation Procedures

Affected individuals should avoid close contact with immunocompromised persons and pregnant women until all crusts are gone. Isolation precautions should be continued until all lesions have resolved and a fresh layer of skin has formed.

Vaccination

Vaccination against smallpox was demonstrated through several observational studies to be about 85% effective in preventing monkeypox. Based on currently assessed risks and benefits and regardless of vaccine supply, mass vaccination is not required nor recommended for monkeypox at this time.

Source : CD Alert : MonkeyPox by National Centre for Disease Control, Directorate General of Health Services, Government of India