Updated Aug 2022
Monkeypox is caused by a virus of the orthopoxvirus group. This group includes viruses causing smallpox (variola) in humans, and animal pox like cowpox, monkeypox, camelpox, horse pox, raccoon pox, and many others.
Pox is a viral disease in humans and other animals, characterized by rash and eruptions of the skin and/or mouth. Smallpox has been eradicated with effective mass vaccination, almost 5 decades back. However, animal pox (zoonotic disease) is occasionally contracted by humans in close contact with animals, thereafter causing its local spread in human community pockets, some particular regions, or rarely across countries (as seen recently with monkeypox). Any age group can be affected when such animal pox spreads in humans.
A viral exanthem refers to a widespread rash and eruptions that accompany a viral infection, and its symptoms of fever, fatigue, and body ache. Pox is different from other viral exanthems (like chickenpox, measles, rubella, hand-foot-mouth disease, etc.) that are caused by other different groups of viruses.
Monkeypox is a zoonotic disease (the primary host is an animal). Man and monkey are both accidental hosts while wild rodents and squirrels seem to be the reservoir of this virus. Monkeypox has been present (endemic) in Africa for several years with 2 prominent viral strains in Western and Central Africa (Congo). The West African strain is currently spreading globally and is less virulent of the two, with a fatality of <3%. Non-endemic countries where monkeypox has been detected in 2022 include USA, UK, Canada, several EU countries, Australia, and some Asian countries including India.
As of Aug 2022, monkeypox has been detected in over 70 countries with around 26,000 cases globally, with over 25,000 cases in countries that have not historically reported monkeypox. WHO has now declared monkeypox a Public Health Emergency of International Concern (PHEIC). Monkeypox is far less severe as compared to smallpox.
There is an initial prodromal phase of up to 5 days with fever (sometimes with chills/sweats), headache, back pain, body ache, muscle pain, fatigue, and flu-like symptoms (sore throat, cough). Swelling of the lymph nodes (lymphadenopathy) is characteristic, and may be generalized (involving many different locations on the body) or localized to certain areas like around the ear (periauricular), under-arm (axillary), neck (cervical) or groin (inguinal).
Rash and Eruptions
The rash and eruptions appear within 1-5 days of the fever.
Monkeypox rash begins on the face (including mouth/tongue) and then spreads to other parts of the body including the palms and soles prominently. The rash starts as red patches (macules), then progresses to raised bumps or eruptions (papules) by the 3rd day. The eruptions are sharply raised, well-demarcated, firm, and round with a flattened top (called umbilication – looks like a dot).
The eruptions can be initially painful, but then become quite itchy. By the 5th day, the papules start to blister by filling with a whitish fluid (vesicles), then by the 7th day with pus (pustules). At about 2 weeks the blisters dry and form scabs or crusts that heal and fall off by 3 weeks. The eruptions in monkeypox develop slowly and look alike and uniform in the same stage of development.
The eruptions last up to 2-3 weeks. The infected patient should be isolated for at least 3 weeks till the scabs have fallen.
The clinical presentation of monkeypox cases associated with the current global outbreak has also been seen to display atypical features in some newly-affected areas as opposed to the classically described clinical picture above. These rarer atypical signs can include few, single or absent skin eruptions, lesions confined to the genital/perianal area, anal pain/bleeding, eruptions appearing before fever and other prodromal symptoms, and the eruptions presenting at different (asynchronous) stages of development.
Differentiating from other viral exanthems
Monkeypox in humans can sometimes be confused with other viral exanthems (chicken pox, measles, etc.), especially in populations not vaccinated or immune to these conditions). Most of these occur in children <10 years, but can sometimes be seen in adults also.
Chickenpox rash appears first on the trunk (chest or back), and then on the face and entire body, usually sparing palms and soles. It lasts for up to a week. The eruptions in chicken pox develop rapidly, are very itchy, and are in different stages so look variable. Fever, headache, and body ache may precede the rash, but flu-like symptoms are rare, and lymphadenopathy is absent.
Measles rash and eruptions first appear on the forehead and then spread to the entire body including hands and feet. The eruptions are diffuse, flatter, and less itchy, lasting up to 2 weeks. Flu-like symptoms of sore throat, runny nose, and cough with lymphadenopathy can be present in measles.
Most populations are now vaccinated against chickenpox, measles, mumps, and rubella, and these are now rarely seen.
Hand-Foot-Mouth Disease (also sometimes called ‘tomato’ fever) is seen in children <5 years. The child has fever, sore throat, loss of appetite, and feels unwell and irritable. The mouth sores are painful and develop within 1-2 days of the fever, followed by the rash which is prominent on hands and feet giving the disease its name.
Monkeypox can be contracted from animals (wild rodents, squirrels, monkeys) by bite or scratch, and prolonged contact with the animals themselves or their meat.
Monkeypox spreads from human to human by close contact through respiratory droplets (shed by coughing/sneezing), sexual contact, and by direct contact with the skin eruptions and recently contaminated objects such as clothing, bedding or utensils. It does not primarily spread via air but if someone is in close contact with an infected person within 2 meters for at least 2-3 hours, one can be infected by large droplets.
Overall monkeypox is less infective than smallpox and chickenpox. After infection, the symptoms appear anytime between 4 days to 3 weeks (incubation period), therefore the observation period for symptoms is regarded as 3 weeks post-exposure. The incubation period is shorter after being bitten by an infected animal.
Monkeypox is self-limiting and runs its course. Treatment is mainly supportive. Complications are rare but can include secondary infections, pneumonia, sepsis, encephalitis, and eye cornea involvement (can lead to loss of vision). One should be alert for evidence of complications in very young children, and those with high-risk factors.
The diagnosis is usually clinical, based on the symptoms, characteristics and onset of the rash and eruptions, as well as the epidemiology of prevalence and spread of viral infections in that particular area. However, lab diagnostic tests are important and should be performed as monkeypox is a disease of global concern, being actively tracked, monitored, and analyzed.
Swabs are taken from the eruptions from multiple sites and the sample includes scrapings from the roof and base of the eruptions, as well as the blister fluid. These swab samples are subjected to polymerase chain reaction (PCR) tests for viral antigen detection, followed by viral gene sequencing. Serological testing (blood test to check for specific antibodies to the suspected virus) and urine test may also be performed during the recovery phase.
Isolation of the patient in a separate room of the home/healthcare center with independent ventilation is highly recommended, till all scabs have fallen off (usually by 3 weeks).
Rest, a healthy nutritious diet, and plenty of water and fluids (like herbal tea, buttermilk, and coconut water) to maintain hydration, are the three cornerstones of treatment. Paracetamol is given for fever, headache or body ache.
Painful eruptions (lesions) may be cleaned with simple antiseptic and covered by a light dressing. To soothe the itching, the doctor may prescribe calamine lotion. Other soothing agents include neem leaves, aloe vera, natural oils like coconut, lavender, or tea tree oil, honey, chamomile compresses, and oatmeal preparations. Cool baths with baking soda added, or applying a cool, wet cloth on the skin for 15 to 30 minutes several times a day, can also help soothe irritation and relieve itching. In severe itching, an oral antihistamine, or a cream with a mild-moderate corticosteroid may be given, but only under medical advice.
Warm saline gargles or an oral anti-inflammatory gel may be given for mouth lesions.
Antiviral medicines are not needed routinely and are given to those with severe disease and those at risk for severe disease (<8 years of age, pregnant or breastfeeding women, patients who develop complications, immunocompromised patients, and elderly with comorbid medical conditions) only under the doctors advise. Currently, tecovirimat alone or as dual therapy as tecovirimat and cidofovir is the antiviral recommended in patients with severe disease or risk.
Antibiotics are given only when a secondary bacterial skin infection or other systemic bacterial infection is diagnosed by the doctor. These may be ointment/creams for the eruptions, or oral tablets.
Red Flag Signs
One should be aware of alert signs for complications, especially in very young children, and adults at risk. In case any of the signs below occur, one should consult a doctor immediately, and consider hospitalization:
- Severe headache or stiff neck
- Confusion, dizziness, unconsciousness (or fainting)
- Severe cough, chest pain, or breathlessness
- Severe abdominal pain
- Severe lethargy or fatigue
- Decreased oral food and water intake
- Decreased urination
- Red eyes, eye pain or blurring of vision
If any viral exanthem is spreading in your area then take care of cleanliness and hygiene, and stay away from anyone who is unwell. Avoid touching your eyes, nose, and mouth, and wash and sanitize your hands often, especially just before you eat or touch your face.
If there is an infected person in the household, the following precautions should be taken –
- Patients should be isolated in a room or area separate from other family members. Healthy household members should limit contact with the patient. Patients should not leave the home except for medical care. No visitors should be allowed at home.
- Patients, especially those who have respiratory symptoms (e.g., cough, sore throat, sneezing) should wear a surgical 3 layered mask. Other household members should consider wearing a surgical mask when in the presence of the patient.
- Disposable gloves should be worn for direct contact with lesions and disposed of after use.
- Skin eruptions (lesions) should be covered to the best extent possible (by long sleeves, long pants) to minimize the risk of contact with others.
- Contain and dispose of contaminated waste (such as dressings and bandages) in the Biomedical waste disposable bag. Do not dispose of waste in open bins, landfills, or dumps.
- Proper hand washing with soap and water (or use of an alcohol-based hand rub) should be performed by the patient and other household members after touching lesion material, clothing, linens, or environmental surfaces that may have had contact with lesion material.
- Laundry (e.g., bedding, towels, clothing) may be washed with warm water and detergent. Care should be used when handling soiled laundry to avoid direct contact with contaminated material or disperse infectious particles.
- Dishes and other eating utensils should not be shared. Soiled dishes and eating utensils should be washed with warm water and dishwashing soap.
- Contaminated surfaces should be cleaned and disinfected. Standard household cleaning/disinfectants may be used in accordance with the manufacturer’s instructions.
- Pets and domestic animals should be excluded from the patient’s environment
Those who have received the smallpox vaccine before 1977, may have some degree of immunity to monkeypox. However, as smallpox has been eradicated, the vaccine may not be readily available currently in many countries.
Smallpox vaccination if given within 4 days of exposure can prevent monkeypox disease. Vaccination can be considered for up to 14 days after exposure, as when given between days 4 and 14, vaccination is thought to reduce the symptoms of disease but not prevent the disease.
The smallpox vaccine contains a live weakened vaccinia virus, which is also an orthopoxvirus, that confers protection against smallpox, monkeypox, and cowpox.
There are two available smallpox vaccines that can reduce the risk of developing monkeypox. The modified vaccinia Ankara (MVA) vaccine (JYNNEOS in the United States, IMVANEX in the EU, and IMVAMUNE in Canada) and the ACAM2000 vaccine.