- Raúl Rivas Gonzalez
- The Conversation*
Before we manage to leave behind the covid-19 pandemic, another virus, that of monkeypox, is coming with force in the global context.
Monkeypox is a rare viral disease that is endemic in some African countries. However, within days, dozens of cases of the disease were confirmed in at least 12 countries outside Africa. The first appeared in the UK and was reported on the 7th of May. The patient had recently traveled to Nigeria, where he is believed to have contracted the virus before returning to the UK.
The detection of the virus in an infinity of patients and in populations distant from each other, around the world, in a few days, caused a scientific, sanitary, administrative and social alert. The cases reported so far are not linked to travel to endemic areas, but it is possible that some recent mass event has acted as an amplifying focus.
Epidemiological investigations are ongoing. As surveillance increases in non-endemic countries, it is very likely that more cases of monkeypox will be identified and confirmed.
Undoubtedly, the situation indicates that we are at the beginning of a possible epidemic and that it is important to raise awareness in society, provide technical guidance, strengthen and support surveillance and diagnostic systems, in addition to preventing the development of the outbreak, protecting health workers and inform about the characteristics of the disease.
It is necessary to be on alert and to be cautious. But luckily, it’s not all bad news. Here are some reasons to be optimistic about the disease.
1. It is a known virus
We are not dealing with a new, unknown pathogen. The virus was discovered in 1958, when two outbreaks of a smallpox-like disease occurred in colonies of monkeys kept for research purposes.
The first human case of monkeypox was reported in August 1970 in the Democratic Republic of Congo. Since then, the virus has been studied and the cases and outbreaks it has caused have been monitored.
2. It is a relatively stable virus
Monkeypox is a relatively large DNA virus that mutates at a slower rate than RNA viruses such as coronaviruses or influenza viruses. DNA viruses have better systems for detecting and repairing mutations than RNA viruses, which means that monkeypox virus is unlikely to have mutated suddenly or at a high rate to achieve relevant human transmission or manifest high variability. .
This means that, once the disease is overcome, the individual acquires long-term immunity against the virus. Two genetic groups of monkeypox virus have been identified so far: the West African clade and the Central African clade.
Both are geographically separated and have defined epidemiological and clinical differences. The DNA sequence shows that the virus causing the current outbreak is a mild type that circulates in West Africa and is closely related to monkeypox viruses, detected in the UK, Singapore and Israel in 2018 and 2019.
3. Part of the world population already has some degree of immunity
Monkeypox virus, smallpox virus, and vaccinia virus are closely related orthopoxviruses. The success of the smallpox vaccination campaign led to the disease being declared eradicated in 1980.
Historical data suggest that the smallpox vaccine is 85% effective. So people who have been vaccinated against smallpox, which is a large proportion of those over 45 years of age, are less vulnerable to the virus.
4. We know how the disease is transmitted
Animal-to-human zoonotic transmission can occur through direct contact with blood, body fluids, mucous membranes, or skin lesions from infected animals. Eating raw or undercooked meat from infected animals is a risk factor. Animal-to-human transmission can also occur through a bite or scratch.
Person-to-person transmission can occur through close contact, through droplet particles and respiratory secretions, as well as through lesions on the skin of an infected person or recently contaminated objects. Transmission can also occur through the placenta from mother to fetus or during close contact during and after birth.
Knowing the transmission routes makes it possible to establish effective prevention measures.
5. Human-to-human transmission is considered moderate and inefficient
This is the first time that chains of disease transmission have been reported in Europe, with no known epidemiological links to West or Central Africa. The most likely means of transmission of the disease are through droplets and/or contact with infected lesions.
Most cases reported in Europe have occurred in young men. Many of them say they have sex with men. Transmission between sexual partners is increased due to intimate contact during sexual intercourse with infectious skin lesions. The probability of transmission between individuals without close contact is considered low.
6. The clinical manifestation of monkeypox is usually mild
Monkeypox is usually a self-limiting disease, with symptoms lasting between two to four weeks. Historically, the smallpox case fatality rate in the African context has ranged from zero to 11% in the general population.
Mortality is higher in children, young adults and immunosuppressed people.
The West African clade, the type identified so far in Europe, has a mortality rate of around 3.6% (estimated from studies in African countries).
Severe cases can occur, but most people recover from the condition within a few weeks.
7. The symptoms of the disease are characteristic and evident
The virus is easy to track because, unlike SARS-CoV-2, which can spread asymptomatically, monkeypox does not usually go unnoticed. In large part, due to the skin lesions that the disease causes.
In addition, the symptoms of monkeypox (fever, severe headache, inflammation of the lymph nodes, back pain, muscle pain and weakness) make it easier to diagnose the disease and detect infected people.
From the first to the third day after the onset of fever, a characteristic rash appears. It affects the face (in 95% of cases), the palms of the hands and the soles of the feet (in 75% of the cases). The oral mucosa, genitalia and conjunctiva, as well as the cornea, are also affected.
The rash progresses sequentially from macules (flat-based lesions) to papules (slightly raised), vesicles (filled with clear fluid), pustules (filled with yellowish fluid), and crusts that dry out and fall off. The number of injuries can range from a few to several thousand.
8. There are fast and effective detection methods
The detection of monkeypox virus DNA is done by a real-time polymerase chain reaction from suspicious skin lesions. This process is well established in many laboratories in Europe, America and Africa. Specialists prefer to take samples of wounds, nasal secretions and fluids aspirated from the wound to detect the disease more accurately.
Recent real-time PCR protocols can differentiate not only monkeypox virus from other orthopoxviruses, but also between the two different clades.
9. We have effective vaccines
The original (first generation) smallpox vaccines are no longer available worldwide. But new second- and third-generation vaccines based on the vaccinia virus have been developed.
These immunizers demonstrate activity against both human smallpox and monkeypox.
The Acam2000 and Aventis Pasteur Smallpox Vaccine (APSV) vaccines are based on the attenuated replication vaccinia virus. The Jynneos vaccine, called Imvanex in the European Union and Imvamune in Canada, is a third-generation vaccine that contains a modified Ankara vaccinia virus (MVA-BN), which does not replicate in the human body but is capable of eliciting a powerful response. immune against smallpox and monkeypox.
Jynneos is the only non-replicating monkeypox and smallpox vaccine approved by the FDA for non-military use.
10. There are effective antiviral treatments
Cidofovir and Brincidofovir have shown activity against poxvirus in in vitro and animal studies. Brincidofovir has been shown to be a potent inhibitor of DNA polymerase in a wide variety of double-stranded DNA viruses, such as monkeypox.
Tecovirimat (ST-246) is also effective in treating orthopoxvirus-induced diseases and human clinical trials indicate that the drug is safe and tolerable with only minor side effects. The drug is indicated for the treatment of cowpox, monkeypox and human smallpox in adults and children with body weight from 13 kg.
Despite the good news regarding monkeypox, we must be cautious and remain vigilant because there are still unanswered questions. Some are related to the possibility that the sudden increase in cases is due to a mutation that allows this virus to be transmitted more easily than in the past, that it managed to spread silently and that each of the outbreaks can be traced back to single source or to several simultaneous sources.
Still, it is hoped that the current outbreak will not require containment strategies beyond those involving ring vaccination, which tracks and immunizes all people who have had direct contact with an infected person.
Raúl Rivas González is Professor of Microbiology at the University of Salamanca, Spain.
This article was published in The Conversation. Click here to read the original textin Spanish
Have you watched our new videos on YouTube? Subscribe to our channel!