What are the Monkeypox virus and its symptoms and precautions?

Monkeypox is caused by the monkeypox virus, a member of the Orthopoxvirus genus in the family Poxviridae. Monkeypox is a viral zoonotic disease that occurs primarily in tropical rainforest areas of Central and West Africa and is occasionally exported to other regions. Monkeypox typically presents clinically with fever, rash, and swollen lymph nodes and may lead to a range of medical complications.
The first human case was found in 1970 in the Democratic Republic of Congo.

Signs and symptoms

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. The infection can be divided into two periods:

  • The invasion period (which lasts between 0-5 days) is characterized by fever, intense headache, lymphadenopathy (swelling of the lymph nodes), back pain, myalgia (muscle aches), and intense asthenia (lack of energy). Lymphadenopathy is a distinctive feature of monkeypox compared to other diseases that may initially appear similar (chickenpox, measles, smallpox)
  • The skin eruption usually begins within 1-3 days of the 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), 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%), conjunctivae (20%), as well as 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 that dry up and fall off. The number of lesions varies from a few to several thousand. In severe cases, lesions can coalesce until large sections of skin slough off.
  • Monkeypox is usually a self-limited disease with symptoms lasting from 2 to 4 weeks. Severe cases can occur. In recent times, the case fatality ratio has been around 3-6%.
Mode of Transmission.
  • Monkeypox is transmitted to humans through close contact with an infected person or animal, or with material contaminated with the virus.
  • Monkeypox virus is transmitted from one person to another by close contact with lesions, body fluids, respiratory droplets, and contaminated materials such as bedding.
  • 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. However, the longest documented chain of transmission in a community has risen in recent years from six to nine successive person-to-person infections. This may reflect declining immunity in all communities due to the cessation of smallpox vaccination. 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.
Studies are needed to better understand this risk.

Clinical presentation of Monkeypox
  • The clinical presentation of monkeypox resembles that of smallpox, a related orthopoxvirus infection that was declared eradicated worldwide in 1980.
    Monkeypox is less contagious than smallpox and causes less severe illness.
  • Vaccines used during the smallpox eradication program also provided protection against monkeypox. Newer vaccines have been developed of which one has been approved for the prevention of monkeypox
  • An antiviral agent developed for the treatment of smallpox has also been licensed for the treatment of monkeypox.
  • Monkeypox is usually a self-limited disease with symptoms lasting from 2 to 4 weeks. Severe cases can occur. In recent times, the case fatality ratio has been around 3-6%.
  • Monkeypox is transmitted to humans through close contact with an infected person or animal, or with material contaminated with the virus.
  • Monkeypox virus is transmitted from one person to another by close contact with lesions, body fluids, respiratory droplets, and contaminated materials such as bedding.
  • Clinical Criteria
    • New rash (any of the following)
    • Macular
    • Papular
    • Vesicular
    • Pustular
    • Generalized or localized
    • Discrete or confluent
    • Fever (either of the following)
    • Subjective
    • Measured temperature of ≥100.4° F [>38° C]
    Other signs and symptoms:
    • Chills and/or sweats
    • New lymphadenopathy (periauricular, axillary, cervical, or inguinal)
    • Epidemiologic Criteria
    Within 21 days of illness onset:
    • Report having had contact with a person or people who have a similar-appearing rash or received a diagnosis of confirmed or probable monkeypox OR
    • Is a man who regularly has close or intimate in-person contact with other men, including through an online website, digital application (“app”), or social event (e.g., a bar or party) OR
    • Traveled to a country with confirmed cases of monkeypox AND at least one of the above criteria OR
    • Traveled to the country where MPXV is endemic OR
    • Contact with a dead or live wild animal or exotic pet that is an African endemic species or used a product derived from such animals (e.g., game meat, creams, lotions, powders, etc.)
    Exclusion Criteria

    A case may be excluded as a possible, probable, or confirmed monkeypox case if:

    • An alternative diagnosis* can fully explain the illness OR
    • An individual with symptoms consistent with monkeypox but who does not develop a rash within 5 days of illness onset OR
    • A case where specimens do not demonstrate the presence of orthopoxvirus or monkeypox virus or antibodies to orthopoxvirus as describe in the laboratory criteria
    • Categorization may change as the investigation continues (e.g., a patient may go from PUI to probable)
    • The rash associated with monkeypox can be confused with other diseases that are more commonly encountered in clinical practice (e.g., secondary syphilis, herpes, chancroid, and varicella zoster). Historically, sporadic reports of patients co-infected with monkeypox virus and other infectious agents (e.g., varicella zoster, syphilis).

    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. Scientific studies are now underway to assess the feasibility and appropriateness of vaccination for the prevention and control of monkeypox. Some countries have or are developing, policies to offer vaccines to persons who may be at risks such as laboratory personnel, rapid response teams, and health workers.

    Reducing the risk of human-to-human transmission

    Surveillance and rapid identification of new cases are critical for outbreak containment. During human monkeypox outbreaks, close contact with infected persons is the most significant risk factor for monkeypox virus infection. Health workers and household members are at a greater risk of infection. Health workers caring for patients with suspected or confirmed monkeypox virus infection, or handling specimens from them, should implement standard infection control precautions. If possible, persons previously vaccinated against smallpox should be selected to care for the patient.

    Samples taken from people and animals with suspected monkeypox virus infection should be handled by trained staff working in suitably equipped laboratories. Patient specimens must be safely prepared for transport with triple packaging in accordance with WHO guidance for the transport of infectious substances. The identification in May 2022 of clusters of monkeypox cases in several non-endemic countries with no direct travel links to an endemic area is atypical.
    Further investigations are underway to determine the likely source of infection and limit further onward spread. As the source of this outbreak is being investigated, it is important to look at all possible modes of transmission in order to safeguard public health.

    Reducing the risk of zoonotic transmission

    Over time, most human infections have resulted from a primary, animal-to-human transmission. Unprotected contact with wild animals, especially those that are sick or dead, including their meat, blood, and other parts must be avoided. Additionally, all foods containing animal meat or parts must be thoroughly cooked before eating.

    Preventing monkeypox through restrictions on animal trade

    Some countries have put in place regulations restricting the importation of rodents and non-human primates. Captive animals that are potentially infected with monkeypox should be isolated from other animals and placed into immediate quarantine. Any animals that might have come into contact with an infected animal should be quarantined, handled with standard precautions, and observed for monkeypox symptoms for 30 days.

    How monkeypox relates to smallpox

    The clinical presentation of monkeypox resembles that of smallpox, a related orthopoxvirus infection that has been eradicated. Smallpox was more easily transmitted and more often fatal as about 30% of patients died. The last case of naturally acquired smallpox occurred in 1977, and in 1980 smallpox was declared to have been eradicated worldwide after a global campaign of vaccination and containment. It has been 40 or more years since all countries ceased routine smallpox vaccination with vaccinia-based vaccines. As vaccination also protected against monkeypox in West and Central Africa, unvaccinated populations are now also more susceptible to monkeypox virus infection.

    Whereas smallpox no longer occurs naturally, the global health sector remains vigilant in the event it could reappear through natural mechanisms, laboratory accidents, or deliberate release. To ensure global preparedness in the event of the reemergence of smallpox, newer vaccines, diagnostics, and antiviral agents are being developed. These may also now prove useful for the prevention and control of monkeypox.

    Monkey Pox- An Overall Picture

    Man is susceptible to a range of poxvirus infections, but only two of these, smallpox and human monkeypox, regularly produce an acute systemic infection with a generalized rash. Human monkeypox can be distinguished from smallpox only by the cultivation of the virus or the performance of a virus-specific serological test with convalescent serum, but the epidemiology of the two infections is quite different. Monkeypox was the only pox virus infection other than • smallpox seen during the eradication program that gave rise to serious concern. However, the studies in Zaire described in this chapter provide good evidence that it is a • rare zoonosis that cannot be sustained indefinitely by serial transmission in man. Because vaccination can greatly modify the response of humans to either variola or monkeypox virus, so that if skin lesions do occur, they are very few or perhaps only a solitary one develops, other poxvirus infections sometimes cause problems in the differential diagnosis of smallpox or monkeypox, especially because electron microscopic examination of lesion material might reveal poxvirus particles. The diagnosis of cowpox and vaccinia infections depends on the cultivation of the virus on the chorioallantoic membrane; that of tanapox on the clinical picture, the appearance of the virion in the electron microscope, and its failure to grow on the chorioallantoic membrane. The lack of systemic symptoms and the characteristic chronic nodular skin lesions distinguish molluscum contagiosum from all other poxvirus diseases. The viruses of orf and milker's nodules can readily be distinguished by the characteristic morphology of the virion, as well as by serological tests. When they were first studied in the laboratory, camelpox virus (Baxby, 1972) and taterapox virus (Lourie et al ., 1975) were regarded with considerable suspicion because the pocks they produced on the chorioallantoic membrane very closely resembled those produced by the variola virus. It is possible that similar causes of concern may arise, perhaps with orthopoxviruses of wild animals that have yet to be discovered. Comparison of their DNA with that of variola and monkeypox viruses should allow the proper categorization of any such isolates


    Publisher’s name- Dr. Dangs Lab

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  • Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion.