5 differences with Covid-19

pustules generated by monkey pox

May 24, 2022

The smallpox pathogen coexisted with humans for three thousand years and during the 20th century it is estimated that it killed 300 million people. However, Ali Maow Maalin was the last person to naturally contract smallpox (Variola minor) in 1977. On May 8, 1980, the World Health Organization declared the eradication of smallpox. Four decades later, another smallpox appears to threaten the world and comes after the severe impact caused by the COVID-19 pandemic. However, there are several differences between the spread of monkeypox (Orthopoxvirus) and COVID-19 that allow us to think that we are not facing a potential new pandemic.

1. A virus that is not new

The first difference is that “Unlike Sars-Cov-2, monkey pox is not new. Since 1970 it has caused small outbreaks in humans in Central and West African countries. Occasionally there are cases in non-endemic areas, but always associated with contacts in endemic areas”, says Zulma Cucubuná, expert in infectology at the Center for the Global Analysis of Infectious Diseases at Imperial College London. The term endemic is used to refer to a stationary pathological process in a population or a given space for prolonged periods. This is what happens, for example, with monkey pox in some African countries.

In addition to endemic outbreaks, several countries are already preparing for a possible bioterrorist attack with some type of smallpox. All this led to the existence of vaccines, although not specific for monkey pox, but effective in containing it. The first vaccine created by Edward Jenner was against smallpox, at the end of the 18th century. Today, for example, there is the Ynneostm brand vaccine (Imvamune or Imvanex), with an effectiveness of 85%.

In turn, although there is no specific treatment for monkey pox, there are therapies on the drugstore shelves. An example is the antiviral Tecovirimat.

These bootstrapping advantages were not present at the start of the COVID-19 pandemic.

2. Monkey pox: contagiousness

The most important difference between monkeypox and COVID-19 is the contagiousness of each pathogen. In African countries where this smallpox is endemic, the virus spreads from animals to people (zoonosis). Wildlife is the main reservoir.

“Contagion occurs when a person comes into contact with the virus from a carrier animal, another infected person or through contact with contaminated materials,” explains a document from the Argentine Society of Infectology (Sadi).

Contact with the lesions generated by smallpox and body fluids can also be foci of contagion.

This virus also seems to survive longer on contaminated clothing and material than the coronavirus.

Person-to-person transmission also occurs through respiratory droplets expelled by the infected that reach the eyes, nose or mouth of another person. This is a form of contagion that also happens with COVID-19.

The question is whether simian pox, like the coronavirus and human pox, is spread through the air (in the case of COVID-19 it was clear that it was). In any case, the exposure time necessary to achieve the contagion of the new smallpox seems to be much greater than for Sars-Cov-2, especially when comparing it with the Òmicron variants, which require only minutes.

3. Difference with COVID-19: Clearer symptoms

The symptoms of COVID-19 are similar to those of other respiratory diseases: fever, cough, sore throat and headache, etc. This makes clinical diagnosis difficult.

Monkey pox, on the other hand, has particular symptoms. Although it starts like a flu (fever and intense headache), it is also characterized by inflammation of the lymph nodes.

Between day one and three of the contagion, flat rashes develop on the face, feet and hands that later transform into pustules with a yellowish liquid. They are very painful. Lyour symptoms can last two to four weeks.

4. Incubation period

The incubation period (time that passes between contagion and the manifestation of symptoms) is 7 to 14 days in smallpox, against four days on average in COVID-19.

This can make the contact tracing system for smallpox more effective.

5. Variable severity according to strain

It can be a more severe disease than COVID-19, with a fatality rate of 11%. It is estimated that in the case of the coronavirus it was 1.5% before vaccines.

However, the severity of smallpox varies depending on the strain, as there are completely harmless versions. The current outbreak appears to be generated by the West African strain with a 1% lethality and in countries with precarious health systems.

“In most cases, the disease is not serious and evolves favorably by itself. In Africa, it has presented variable lethality rates between 4% and 22%, with greater virulence in children and young people”, says the Sadi document.

Why monkey pox is a concern now

People and authorities are more sensitive to any foreign pathogen that may cause an outbreak due to the pandemic, and cases of monkeypox are worrying for a number of reasons.

The first is that some of the detected cases have no epidemiological link with the endemic site where the outbreaks are usually generated. “What’s new about the current outbreak is that these cases have been happening in countries without being associated with travel or exposure from endemic countries,” says Cucubuná.

The expert lists some of the hypotheses, in the face of this outbreak outside the endemic area. The first is that it happened an intrinsic change due to virus mutations.

The second is that we are looking at the impact of declining immunity to smallpox in humans. “People have not been vaccinated for 40 years. This is perhaps determining a greater risk of transmission”, he indicates. At the same time, the COVID-19 pandemic could have created fertile ground for it to spread to other regions.

The risk is that it will become endemic outside of Africa

Experts agree that while it does not have the characteristics of a pandemic virus, simian pox could become endemic in territories beyond Africa.

The European Center for Disease Prevention and Control warned about this possibility if the current outbreak is not quickly controlled and the virus manages to spread among some animals (rodents, squirrels and even pets) on this continent which can work as reservoirs.

In fact, European authorities recommend quarantining the pets of people infected with simian pox or suspected of having been infected.

Until May 24 of this year, cases were confirmed in the United Kingdom, Italy, Portugal, Spain and the United States, among other countries. Argentina reported one suspected case and there are dozens more in different countries.

By Lucas Viano @LucasViano
redaccion@pensarsalud.com.ar Write to us!

Tags: animals | antiviral | coronavirus | epidemic | vaccines | vaccines; antivaccination | small pox | monkey pox | simian pox | Virus | zoonosis

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