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Monkeypox: what is it and what do we need to know?

07 June 2022 | Story Prof Felicity Burt, Prof Dominique Goedhals and Dr Charles Kotzé

Prof Felicity Burt, Dr Charles Kotze and Prof Dominique Goedhals — From the left; Prof Felicity Burt, Dr Charles Kotzé and Prof Dominique Goedhals.

Opinion article by Prof Felicity Burt , Prof Dominique Goedhals , Division of Virology at the University of the Free State (UFS), and Dr Charles Kotzé, National Health Laboratory Service (NHLS), Universitas Academic Hospital.

The recent COVID-19 pandemic has certainly highlighted the importance of vigilance and awareness of emerging diseases with public health implications. The monkeypox virus has recently made headlines, after the detection of more than 200 cases in geographically distinct regions. On 13 May, the World Health Organisation (WHO) was notified of human cases of the monkeypox disease occurring in the United Kingdom, outside of the known endemic region.

Exported cases have been detected previously and usually occur sporadically. In contrast, within the past two weeks, human cases have been confirmed in at least 21 countries, including various European countries, the United Kingdom, Israel, the Canary Islands, Canada and the United States, and Australia. The initial case appears to have been a traveller from Nigeria. Sequence data may help to determine if there have been multiple exportations from West Africa.

What is monkeypox and what do we know

What is monkeypox and what do we know about the aetiologic agent? Monkeypox is the name given to a disease caused by the monkeypox virus, a zoonotic pathogen endemic in Central and West Africa and responsible for cases of the disease in the endemic region, with occasional exported cases in travellers. The virus was initially identified in 1958 in monkeys housed at a research laboratory in Denmark, and the name monkeypox was derived from the appearance of lesions and the occurrence in monkeys. The first human case was identified 52 years ago in the Democratic Republic of the Congo. Since then, human monkeypox cases have been reported in several other Central and West African countries: Cameroon, the Central African Republic, Ivory Coast, the Democratic Republic of the Congo, Gabon, Liberia, Nigeria, Republic of the Congo, and Sierra Leone. The first monkeypox outbreak outside of Africa was in the United States of America in 2003 and was linked to contact with infected prairie dogs imported as exotic pets. Since then, there have been various small, contained outbreaks outside of Africa that have mostly been linked to the importation of the virus from African countries.

The virus is related to the smallpox virus, which was eradicated in the 1970s by vaccination. Although belonging to the same family of viruses as the smallpox virus, the disease caused by monkeypox is less severe, with fewer fatalities. Unlike smallpox, which carries a case fatality rate of 30%, the case fatality rate in monkeypox is low (estimated at 3-6% in more recent outbreaks). There are two clades of the monkeypox virus: the West African clade and the Congo Basin (Central African) clade. In this outbreak, all of the cases have been linked to the West African clade of the monkeypox virus.

Transmission occurs from animal to human, and from human to human, through close contact with lesions, body fluids, and contaminated materials. The virus enters the body through the respiratory tract, mucous membranes, or broken skin. The disease begins with non-specific symptoms such as fever, headache, muscle pains, and swollen lymph nodes. This is followed by the typical skin rash, which progresses through stages known as macules, then papules, vesicles, pustules, and lastly crusts or scabs. Lesions can also occur on mucous membranes such as the mouth, eye, and genital area. The infectious period lasts through all stages of the rash, until all the scabs have fallen off. There are a number of other infectious and non-infectious conditions that need to be differentiated; therefore, individuals presenting with these symptoms will need to consult their doctor to determine whether a diagnosis of monkeypox needs to be considered. In the current outbreak, a number of the cases in the United Kingdom and Europe have been detected in men who have sex with men, during visits to sexual health clinics. This pattern of spread has not previously been described and it remains to be determined whether the spread has occurred through close person-to-person contact or through sexual transmission.

Vaccination against smallpox virus offers 85% protection against monkeypox

To date, no cases have been detected in South Africa, but the recent global spread of the severe acute respiratory syndrome coronavirus 2 (SARS_CoV-2) highlights the ability of pathogens to spread. The National Institute for Communicable Diseases (NICD) in Johannesburg offers a specialised diagnostic service for the monkeypox virus, using molecular assays and electron microscopy.

Vaccination against the smallpox virus is believed to offer 85% protection against monkeypox, hence older persons should have some protection; however, vaccination against smallpox was phased out globally following the eradication of smallpox during the 1970s. A more recently developed vaccine against monkeypox is available but has very limited availability. No specific antivirals are available with proven efficacy in clinical trials.

While the monkeypox virus can be spread via the respiratory route, this occurs in the form of large droplets, rather than aerosol transmission, which is seen with SARS-CoV-2 (causing COVID-19). Aerosols are smaller particles that can remain suspended in the air for prolonged periods, facilitating the transmission of SARS-CoV-2. Monkeypox is therefore less contagious than COVID-19, as close contact is required for longer periods. For this reason, many experts around the world predict that this outbreak will not spread like SARS-CoV-2. The importation of monkeypox to South Africa is a definite possibility, because South Africa is a significant economic and travel hub for Africa. Previous outbreaks of monkeypox in non-endemic areas have been interrupted by contact tracing and isolation, which was very effective in controlling further spread. Heightened vigilance is therefore needed for the early detection of such cases.

News Archive

Fight against Ebola virus requires more research

2014-10-22

Dr Abdon Atangana
Photo: Ifa Tshishonge

Dr Abdon Atangana, a postdoctoral researcher in the Institute for Groundwater Studies at the University of the Free State (UFS), wrote an article related to the Ebola virus: Modelling the Ebola haemorrhagic fever with the beta-derivative: Deathly infection disease in West African countries.

“The filoviruses belong to a virus family named filoviridae. This virus can cause unembellished haemorrhagic fever in humans and nonhuman monkeys. In literature, only two members of this virus family have been mentioned, namely the Marburg virus and the Ebola virus. However, so far only five species of the Ebola virus have been identified, including: Ivory Coast, Sudan, Zaire, Reston and Bundibugyo.

“Among these families, the Ebola virus is the only member of the Zaire Ebola virus species and also the most dangerous, being responsible for the largest number of outbreaks.

“Ebola is an unusual, but fatal virus that causes bleeding inside and outside the body. As the virus spreads through the body, it damages the immune system and organs. Ultimately, it causes the blood-clotting levels in cells to drop. This leads to severe, uncontrollable bleeding.

Since all physical problems can be modelled via mathematical equation, Dr Atangana aimed in his research (the paper was published in BioMed Research International with impact factor 2.701) to analyse the spread of this deadly disease using mathematical equations. We shall propose a model underpinning the spread of this disease in a given Sub-Saharan African country,” he said.

The mathematical equations are used to predict the future behaviour of the disease, especially the spread of the disease among the targeted population. These mathematical equations are called differential equation and are only using the concept of rate of change over time.

However, there is several definitions for derivative, and the choice of the derivative used for such a model is very important, because the more accurate the model, the better results will be obtained. The classical derivative describes the change of rate, but it is an approximation of the real velocity of the object under study. The beta derivative is the modification of the classical derivative that takes into account the time scale and also has a new parameter that can be considered as the fractional order.

“I have used the beta derivative to model the spread of the fatal disease called Ebola, which has killed many people in the West African countries, including Nigeria, Sierra Leone, Guinea and Liberia, since December 2013,” he said.

The constructed mathematical equations were called Atangana’s Beta Ebola System of Equations (ABESE). “We did the investigation of the stable endemic points and presented the Eigen-Values using the Jacobian method. The homotopy decomposition method was used to solve the resulted system of equations. The convergence of the method was presented and some numerical simulations were done for different values of beta.

“The simulations showed that our model is more realistic for all betas less than 0.5. The model revealed that, if there were no recovery precaution for a given population in a West African country, the entire population of that country would all die in a very short period of time, even if the total number of the infected population is very small. In simple terms, the prediction revealed a fast spread of the virus among the targeted population. These results can be used to educate and inform people about the rapid spread of the deadly disease,” he said.

The spread of Ebola among people only occurs through direct contact with the blood or body fluids of a person after symptoms have developed. Body fluid that may contain the Ebola virus includes saliva, mucus, vomit, faeces, sweat, tears, breast milk, urine and semen. Entry points include the nose, mouth, eyes, open wounds, cuts and abrasions. Note should be taken that contact with objects contaminated by the virus, particularly needles and syringes, may also transmit the infection.

“Based on the predictions in this paper, we are calling on more research regarding this disease; in particular, we are calling on researchers to pay attention to finding an efficient cure or more effective prevention, to reduce the risk of contamination,” Dr Atangana said.

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