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MONKEY POX IN DETAIL

Monkeypox is a rare disease caused by infection with the monkeypox virus. Monkeypox virus is part of the same family of viruses as variola virus, the virus that causes smallpox. Monkeypox symptoms are similar to smallpox symptoms, but milder and monkeypox is rarely fatal. Monkeypox is not related to chickenpox.

ETIOLOGY

Monkey pox is caused by monkey pox virus. Monkeypox virus is an enveloped double-stranded DNA virus that belongs to the Orthopox virus genus of the Poxviridae family.

PATHOPHYSIOLOGY

Following viral entry from any route (oropharynx, nasopharynx or intradermal), the monkeypox virus replicates at the inoculation site then spreads to local lymph nodes. 

INCUBATION PERIOD & INFECTION

  • I.P is usually 6 to 13 days but can range from 5 to 21 days.

  • The infection:

  1. It 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).

  2. 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.

  3. 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.

  4. 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.

  5. The number of lesions varies from a few to several thousand. In severe cases, lesions can coalesce until large sections of skin slough off. 

SYMPTOMS

Fever, headache, Myalgia, Lymphadenopathy, chills, exhaustion, respiratory symptoms, rash.

SPREAD

  • Monkeypox can spread to anyone through close, personal, often skin-to-skin contact, including:

    • Direct contact with monkeypox rash, scabs, or body fluids from a person with monkeypox.

    • Touching objects, fabrics (clothing, bedding, or towels), and surfaces that have been used by someone with monkeypox.

    • Contact with respiratory secretions.

  • This direct contact can happen during intimate contact

DIFFERENTIAL DIAGNOSIS

Chickenpox, measles, bacterial skin infections, scabies, syphilis, and medication-associated allergies.

INVESTIGATIONS

  • Polymerase chain reaction (PCR) is the preferred laboratory test given its accuracy and sensitivity. For this, optimal diagnostic samples for monkeypox are from skin lesions – the roof or fluid from vesicles and pustules, and dry crusts. Where feasible, biopsy is an option.

TREATMENT

  • Currently, there are no specific clinically proven treatments for monkeypox infection. As with most viral illnesses, the treatment is supportive symptom management. Patients should be offered fluids and food to maintain adequate nutritional status. Secondary bacterial infections should be treated as indicated. The oral DNA polymerase inhibitor brincidofovir, oral intracellular viral release inhibitor tecovirimat, and intravenous vaccinia immune globulin have unknown efficacy against the monkeypox virus.

  • For individuals exposed to the virus, temperature and symptoms should be monitored twice per day for 21 days because that is the accepted upper limit of the monkeypox incubation period.

  • In some cases, post-exposure vaccination with modified vaccinia, Ankara vaccine (smallpox and monkeypox vaccine, live, non-replicating) is recommended.

  • Contact between broken skin or mucous membranes and an infected patient’s body fluids, respiratory droplets, or scabs is considered a “high risk” exposure that warrants post-exposure vaccination as soon as possible. 

  • According to the CDC, vaccination within four days of exposure may prevent disease onset, and vaccination within 14 days may reduce disease severity.

VACCINATION

  • 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.

  • The replication-defective modified vaccinia Ankara vaccine is a two-shot series, four weeks apart, with a superior safety profile compared to first and second-generation smallpox vaccines.

  • Unlike live vaccinia virus preparations, administering modified vaccinia, Ankara does not create a skin lesion or pose a risk of local or disseminated spread.

PROGNOSIS

  • Two distinct genetic clades of the monkeypox virus:                                                          The central African (Congo Basin) clade and The west African clade.

  • The West African clade has a more favorable prognosis with a case fatality rate below 1%. On the other hand, the Central Basin clade (Central African clade) is more lethal, with a case fatality rate of up to 11% in unvaccinated children.

SOURCE: WHO/CDC/NCBI

© 2022- MEDICALINSIGHT

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