By Doris Obinna
The United Kingdom, on Monday, May 7, 2022, notified the World Health Organisation (WHO) of a comfirmed case of Monkey pox in Nigeria. The confirmed case, according to the UK health authorities, was discovered in a returnee from Nigeria. WHO disclosed that the case travelled to Nigeria in late April, staying in Lagos and Delta states, and developed a rash on April 29.
The source of infection in Nigeria is not known, as it still remains a risk of ongoing transmission in the country. The disease typically presents with fever, rash and swollen lymph nodes. It is a viral disease that occurs primarily in tropical rainforest areas of Central and West Africa. It is occasionally exported to other regions.
Monkey pox, as the name implies, is a viral disease first seen in monkeys, but can also be found in all bush animals such as rats, squirrels and antelopes.
Monkey pox is an infectious disease caused by an orthopox virus. Orthopox viruses are a genus of viruses that include the disease agents that cause human smallpox, cowpox, and camel pox as well as monkey pox.
In Africa, monkey pox infection has been found in many animal species: rope squirrels, tree squirrels, Gambian rats, striped mice, dormice and primates. Doubts persist on the natural history of the virus and further studies are needed to identify the exact reservoir of the monkey pox virus and how it is maintained in nature.
According to WHO, monkey pox was first discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research, hence the name ‘monkey pox.’ The first human case of monkey pox was recorded in 1970 in the Democratic Republic of Congo during a period of intensified effort to eliminate smallpox. Since then, monkey pox has been reported in humans in other central and western African countries.
The disease so far has been classified as a zoonosis, which means that it is a disease of animals that can be transmitted to humans under natural conditions. The first cases of monkey pox reported in humans involved contact between humans and animals in the African rain forest.
The outbreak that made headlines in the United States in June 2003, however, involved animals purchased as pets from pet stores. It is not known as of late 2003 whether other wild or domestic animals can contract monkey pox.
How it can be contacted
Experts say infection of index cases results from direct contact with the blood, bodily fluids, or cutaneous or mucosal lesions of infected animals. One study disclosed that, in Africa, human infections have been documented through the handling of infected monkeys, Gambian giant rats and squirrels, with rodents being the major reservoir of the virus. Eating inadequately cooked meat of infected 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 monkey pox). There is no evidence, to date that person-to-person transmission alone can sustain monkey pox infections in the human population.”
In recent animal studies of the prairie dog-human monkey pox model, two distinct clades of the virus were identified – the Congo Basin and the West African clades – with the former found to be more virulent.
Signs and symptoms
A study, however, noted that the incubation period (interval from infection to onset of symptoms) of monkey pox is usually from six to 16 days but can range from five to 21 days.
“The infection can be divided into two periods, the first is 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).
“While the second, the skin eruption period (within 1-3 days after appearance of fever) where the various stages of the rash appears, often beginning on the face and then spreading elsewhere on the body. The face (in 95 per cent of cases), and palms of the hands and soles of the feet (75 per cent) are most affected. Evolution of the rash from maculopapules (lesions with a flat bases) to vesicles (small fluid-filled blisters), pustules, followed by crusts 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 per cent of cases), genitalia (30 per cent), and conjunctivae/eyelids (20 per cent), 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 monkey pox compared to other similar diseases. Monkey pox 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.
“People living in or near the forested areas may have indirect or low-level exposure to infected animals, possibly leading to subclinical (asymptomatic) infection. The case fatality has varied widely between epidemics but has been less than 10 per cent in documented events, mostly among young children. In general, younger age-groups appear to be more susceptible to monkey pox.”
Nigerians must be alert
In 2017, the first case was reported in Agbura, a rural settlement in Yenagoa, Bayelsa State. It was gathered that the victim had eaten a monkey with members of his household and neighbours who later showed symptoms of the virus.