Monkey pox is a rare viral infection that is similar to smallpox, but unlike smallpox, it is zoonotic. Monkey pox virus is endemic in western and central Africa, where it circulates in unknown animal hosts and emerges periodically to affect humans. It ranges from asymptomatic infections to Mild, severe, and fatal illness. Prompt diagnosis and differentiation from smallpox is essential, to prevent disease spread.
On 4th of October 2017 the first outbreak of monkey pox in Nigeria was reported in Bayelsa State, with over 10 persons quarantined for possible infection. Monkey pox as a disease in humans was first associated with an illness in the Democratic Republic of the Congo (formerly Zaire), in the town of Basankusu, Équateur Province, in 1970. A second outbreak of human illness was identified in DRC between 1996–1997. Between August and October 2016, a monkeypox outbreak in the Central African Republic was contained with 26 cases and two deaths. The only outbreak of human monkey pox reported outside Africa occurred in the United States in 2003 where 71 persons were infected with nil mortality. The virus entered North America in exotic African rodents imported as pets, and spread to pet prairie dogs, which were highly susceptible to infection.
Monkey pox results from infection by the monkeypox virus, a member of the genus Orthopoxvirus in the family Poxviridae (subfamily Chordopoxvirinae). Two clades of monkeypox viruses, the West African and Congo Basin viruses have been identified. The Congo Basin viruses are more virulent. Monkeypox virus is closely related to some other orthopoxviruses such as variola (smallpox) virus, and it cannot be distinguished from these viruses in some laboratory tests. Monkeypox should not be confused with benign epidermal monkeypox (BEMP), a poxviral disease of primates caused by tanapox virus, an antigenically unrelated virus in the genus Yatapoxvirus of the family Poxviridae.
Monkey pox is transmitted by direct contact with the blood, bodily fluids, or cutaneous or mucosal lesions of infected animals. In Africa human infections have been documented through the handling and consumption of infected monkeys, Gambian giant rats and squirrels, with rodents being the major reservoir of the virus. Bites and scratches of these animals is a possible risk factor.
Secondary, or human-to-human, transmission can result from close contact with infected respiratory tract secretions, skin lesions of an infected person or objects recently contaminated by patient fluids or lesion materials. Transmission occurs primarily via droplet respiratory particles usually requiring prolonged face-to-face contact, which puts household members of active cases at greater risk of infection. Transmission can also occur by inoculation or via the placenta (congenital monkeypox). There is no evidence, to date, that person-to-person transmission alone can sustain monkeypox infections in the human population.
The incubation period of monkeypox is usually from 6 to 16 days but can range from 5 to 21 days.
The infection can be divided into two periods:
• the invasion period (0-5 days) characterized by fever, intense headache, lymphadenopathy (swelling of the lymph node), back pain, myalgia (muscle ache) and an intense asthenia (lack of energy);
• The skin eruption period (within 1-3 days after appearance of fever) where the various stages of the rash appear, often beginning on the face and then spreading elsewhere on the body. The face (in 95% of cases), and palms of the hands and soles of the feet (75%) are most affected. Evolution of the rash from maculopapules (lesions with a flat bases) to vesicles (small fluid-filled blisters), pustules, followed by crusts (scabs) occurs in approximately 10 days. Three weeks might be necessary before the complete disappearance of the crusts.
The number of the lesions varies from a few to several thousand, affecting oral mucous membranes (in 70% of cases), genitalia (30%), and conjunctivae (eyelid) (20%), as well as the cornea (eyeball). Some patients develop severe lymphadenopathy (swollen lymph nodes) before the appearance of the rash, which is a distinctive feature of monkeypox compared to other similar diseases.
Monkeypox is usually a self-limited disease with the symptoms lasting from 14 to 21 days. Severe cases occur more commonly among children and are related to the extent of virus exposure, patient health status and severity of complications. The case fatality has varied widely between epidemics but has been less than 10% in documented events, mostly among young children. In general, younger age-groups appear to be more susceptible to monkeypox.
The differential diagnoses that must be considered include other rash illnesses, such as, smallpox, chickenpox, measles, bacterial skin infections, scabies, syphilis, and medication-associated allergies. Lymphadenopathy during the prodromal stage of illness can be a clinical feature to distinguish it from smallpox.
Monkeypox can only be diagnosed definitively in the laboratory where the virus can be identified by a number of different tests:
• enzyme-linked immunosorbent assay (ELISA)
• antigen detection tests
• polymerase chain reaction (PCR) assay
• virus isolation by cell culture
Presently samples are taken to WHO laboratory in Senegal for confirmation.
Presently, there are no specific treatments available for monkeypox infection, but monkeypox outbreaks can be controlled. Smallpox vaccine, cidofovir, ST-246, and vaccinia immune globulin (VIG) can be used to control a monkeypox outbreak. Past data suggests that the smallpox vaccine is at least 85% effective in preventing monkeypox. Vaccination within two weeks of monkeypox exposure may help prevent the disease or make it less severe. Others include symptomatic management as indicated.
The prognosis of monkeypox is good except in immunocompromised patients. An estimated death rate of less than 10% is reported.
Monkeypox can be prevented through the following means:
• Small pox Vaccination
• Avoiding contact with animal reservoirs of the virus
• Avoid consuming animal reservoirs
• Wide range Sensitization campaign
• Prompt isolation and contact tracing
• Health practitioners should observe standard precautionary measures in handling all patients irrespective of the diagnosis.
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