ZIMBABWE made great medical strides containing the COVID-19 pandemic, through a rigid and disciplined vaccination campaign during 2021 and 2022.
Today, however, a new virus, in the form of monkeypox virus, has recently emerged to threaten the world. Is Zimbabwe prepared for it?
With the eradication of smallpox in 1980 and subsequent cessation of smallpox vaccination, monkeypox virus emerged as the most important orthopoxvirus for public health.
This viral zoonosis disease – i.e.: a virus transmitted to humans from animals, has clinical symptoms similar to those seen in smallpox patients although it is clinically less severe.
Smallpox is a related orthopoxvirus infection which has been eradicated.
According to the World Health Organisation (WHO) – “Smallpox was more easily transmitted and more often fatal as about 30 percent 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.
In the past monkeypox occurred primarily in Central and West Africa, often in proximity to tropical rainforests, but increasingly recently has been appearing in urban areas.
The disease is called monkeypox because it was first identified in colonies of monkeys kept for research in 1958.
It was only later detected in humans in 1970.
What emerged as an exclusive tropical disease, In recent times, monkeypox has emerged globally as a lethal viral zoonosis
Monkeypox virus is an enveloped double-stranded DNA virus that belongs to the orthopoxvirus genus of the poxviridae family.
Animal hosts include a range of rodents and non-human primates.
To date however, uncertainty remains on the natural history of monkeypox virus and further studies are needed to identify the exact reservoir(s) and how virus circulation is maintained in nature.
Studies are currently underway to further understand the epidemiology, sources of infection, and transmission patterns.
Human monkeypox was first identified in humans in 1970, in the Democratic Republic of the Congo (DRC), in a nine-month-old boy in a region where smallpox had been eliminated in 1968.
Since then, most cases have been reported from rural, rainforest regions of the Congo Basin, particularly in the DRC and human cases have since been reported increasingly from across Central and West Africa.
The Congo Basin clade in Central Africa has historically caused more severe disease and was thought to be more transmissible. The geographical division between the Central and West Africa clades has so far been in Cameroon, the only country where both virus clades have been found.
Since 1970, human cases of monkeypox have been reported in eleven African countries namely: Benin, Cameroon, the Central African Republic (CAR), DRC, Gabon, Cote d’Ivoire, Liberia, Nigeria, the Republic of the Congo, Sierra Leone and South Sudan.
Some of these countries only had a few cases and others have had persistent or recurrent outbreaks.
Monkeypox is now a disease of global public health importance as it not only affects countries in West and Central Africa, but the rest of the world.
In 2003, the first monkeypox outbreak outside of Africa was in the USA. It was linked to contact with infected pet prairie dogs that had been housed with Gambian pouched rats and dormice imported into that country from Ghana.
This outbreak led to over 70 cases of monkeypox in the United States.
In September 2018, monkeypox was reported in travelers from Nigeria to Israel; travelers to the United Kingdom in September 2018, December 2019, May 2021 and May 2022; travelers to Singapore in May 2019 and to the United States of America in July and November 2021.
In May 2022, multiple cases of monkeypox were identified in several non-endemic countries.
However, the identification in May 2022 of clusters of monkeypox cases in several non-endemic countries with no direct travel links to an endemic area was atypical. The recent outbreak affecting many countries at once was not typical of previous outbreaks .
Further investigations were underway to determine the likely source of infection and limit further onward spread.
Animal-to-human (zoonotic) transmission can occur from direct contact with the blood, bodily fluids, or cutaneous or mucosal lesions of infected animals.
The natural reservoir of monkeypox has not yet been identified, though rodents are the most likely suspects.
Evidence of monkeypox virus infection in Africa, has been found in many animals including rope squirrels, tree squirrels, Gambian pouched rats, dormice, different species of monkeys and others. Eating inadequately cooked meat and other animal products of infected animals is a possible risk factor and should be guarded against.
Just as the devastating COVID-19, 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.
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.
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.
Over time, most human infections have resulted from a primary, animal-to-human transmission.
In order to reduce the risk of zoonotic virus 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.
Some countries have put in place regulations restricting 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.
The incubation period – i.e.: the interval from infection to onset of symptoms of monkeypox is usually from six-13 days but can range from five-21 days with the symptoms lasting from two-to-four weeks; the invasion period lasts between zero–five days. It is characterised by fever, lymphadenopathy (swelling of the lymph nodes), intense headache, back pain, myalgia (muscle aches) and intense asthenia (lack of energy).
Skin eruption usually begins within one– three days of the appearance of fever.
In severe cases, lesions (filled with clear fluid and pustules filled with yellowish fluid), can coalesce until large sections of skin slough off. The rash tends to be more concentrated on the face and extremities rather than on the body.
Also affected are oral mucous membranes, genitalia and conjunctivae (20 percent), as well as the cornea. Complications of monkeypox can include secondary infections, bronchopneumonia, sepsis, encephalitis, and infection of the cornea with ensuing loss of vision. The extent to which asymptomatic infection may occur is unknown.
Severe cases of monkeypox are more common among children and are related to the extent of virus exposure, patient health status and nature of complications.
Underlying immune deficiencies may lead to worse outcomes.
Although vaccination against smallpox was protective in the past, according to the WHO, persons younger than 40 to 50 years of age, depending on the country’s health status, may be more susceptible to monkeypox today due to cessation of smallpox vaccination campaigns after the global eradication of the disease announced in 1980.
Dr Tony M. Monda BSc, DVM, is currently conducting veterinary epidemiology, Agronomy and Food Security and Agro-economic research in Zimbabwe. E-mail: tonym.MONDA@gmail.com