Monkeypox is a viral zoonosis ( virus transmitted from animals to humans), which has symptoms similar to those seen in the past in smallpox patients, although clinically less severe.

History

  • Human monkeypox was first identified in 1970 in the democratic republic of Congo. Since then, most cases have been reported from rural rainforest regions across Central and West Africa. In 2003, the first monkeypox outbreak outside of Africa was in the USA, and later on from other countries including UK and Singapore.
  • The ongoing outbreak was confirmed in May 2022, begining with a cluster of cases found in the UK . The first confirmed case was an individual with travel links to Nigeria, and was detected on 6 May, 2022. Since then, it has been spreading across various countries. On 23 July 2022, the WHO has declared the outbreak a Public Health Emergency of International Concern (PHEIC).
  •  In India, a man from Delhi with no history of foreign travel, tested positive for monkeypox on 24 July 2022, taking the tally of cases to 4. Earlier, 3 cases were reported in Kerala.

The Pathogen

  • Monkeypox is an enveloped, double stranded, DNA virus, that belongs to Orthopoxvirus genus of Poxviridae family.

Natural host

  • Various animal species including rope squirrels, tree squirrels, Gambian pouched rats, dormice, non human primates and others have been identified susceptible.

Transmission

  • Animal-to-human transmission can occur from direct contact with blood, body fluids or lesions of infected animals. Eating inadequately cooked meat and other animal products of infected animals is a possible risk factor.
  • Human-to-human transmission can result from close contact with respiratory secretions, skin lesions of an infected person or recently contaminated objects. Transmission via droplet respiratory particles usually requires prolonged face-to-face contact, which puts health workers, household members and other close contacts of active cases at greater risk.
  • Transmission can also occur via the placenta from mother to fetus (which can lead to congenital monkeypox) or during close contact during and after birth. 
  • While close physical contact is a well-known risk factor for transmission, it is unclear at this time if monkeypox can be transmitted specifically through sexual transmission routes. 

Signs and symptoms

The infection can be divided into two periods:

  • the invasion period (lasts between 0–5 days) characterized by fever, intense headache, lymphadenopathy (swelling of the lymph nodes), back pain, myalgia (muscle aches) and intense asthenia (lack of energy).
  •  the skin eruption usually begins within 1–3 days of appearance of fever. The rash tends to be more concentrated on the face and extremities rather than on the trunk. It affects the face (in 95% of cases), and palms of the hands and soles of the feet (in 75% of cases). Also affected are oral mucous membranes (in 70% of cases), genitalia (30%), and conjunctivae (20%), as well as the cornea.
  • The rash evolves sequentially from macules (lesions with a flat base) to papules (slightly raised firm lesions), vesicles (lesions filled with clear fluid), pustules (lesions filled with yellowish fluid), and crusts which dry up and fall off.

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. Underlying immune deficiencies may lead to worse outcomes.

 Diagnosis and Treatment 

  • Confirmation of monkeypox depends on the type and quality of the specimen and the type of laboratory test. Polymerase chain reaction (PCR) is the preferred laboratory test given its accuracy and sensitivity.
  • Clinical care for monkeypox should be fully optimized to treat symptoms, manage complications and prevent long-term sequelae. Patients should be offered fluids and food to maintain adequate nutritional status. Secondary bacterial infections should be treated as indicated.

Vaccination and Prevention

  • Vaccination against smallpox was demonstrated through several observational studies to be about 85% effective in preventing monkeypox. Thus, prior smallpox vaccination may result in milder illness. 
  • 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.