Monkey smallpox: what is the difference between the disease and human smallpox, eradicated 40 years ago

The emergence of several outbreaks of monkeypox in the United States, Canada, Australia and several European countries brought to the memory of humanity the terrible disease that for centuries claimed lives.

Smallpox is one of the deadliest diseases to ever exist, and studies of Egyptian mummies suggest it may have been circulating among us for at least 3,000 years.

In the 20th century alone, it is estimated that smallpox killed around 300 million people.

Fortunately, smallpox became the first disease eradicated in history more than 40 years ago, when the World Health Organization (WHO) certified its end in 1980, following a successful global vaccination campaign.

Now, monkeypox is causing the biggest outbreak of the disease ever seen in Europe. Scientists are investigating what is happening.

At the moment, medical authorities say that the chances of an uncontrolled transmission are low and point out that its lethality is far from that caused by human smallpox.

Experts point out that monkeypox is much milder and less contagious than the human version of the disease.

Next, understand the differences between the two viruses, which belong to the same family of viruses. orthopoxvirus:

Mortality

How deadly is monkeypox?

This is the main question that many ask themselves when hearing about an unknown disease. Especially if she shares her name with one of the deadliest in history.

“Fortunately, monkeypox is much milder than the human version of smallpox,” explains Raúl Rivas González, a professor of microbiology at the University of Salamanca in Spain, to BBC News Mundo (the BBC’s Spanish-language news service).

Smallpox had two versions: smallpox major and smallpox minor. The largest was the deadliest — with a mortality rate of 30% of cases of infection. The smaller one caused milder illness and rarely led to death.

Something similar happens with monkeypox, albeit with lower death rates. There are two versions: West African and Central African.

“West Africa is the mildest, with mortality between 1% and 10%, and it seems to be the one causing the outbreak in Europe,” says Rivas. “Central Africa, on the other hand, is more virulent and dangerous and can kill around 20% of those infected,” she adds.

Jacob Lorenzo Morales, director of the University Institute of Tropical Diseases and Public Health of the Canary Islands, Spain, explains that the highest levels of lethality are concentrated in certain populations.

“Based on the data we’ve seen, most deaths occur in very poor rural areas of Africa and, in general, in many children due to their less developed immune systems,” he told BBC News Mundo.

Streaming

Unlike the coronavirus or even smallpox, where the pathogen is highly transmissible, monkeypox is less contagious.

“It is a virus that transmits very well between animals, but when it passes from animal to human, it does not have a high transmission capacity”, says Lorenzo Morales.

Medical officials note that there is still not much information about possible human-to-human transmission routes in current outbreaks.

As far as is known now, the virus is mainly transmitted through close contacts and exchanges of bodily fluids. Many of the cases in Europe appear to be linked to sexual transmission.

But all possible routes are being studied, such as indirect transmission through contaminated objects and even aerosols.

“Eradicated smallpox was transmitted in a similar way, but the contagion between humans was much easier”, recalls Lorenzo Morales, who does not rule out that in the future smallpox may become more efficient in the way it is transmitted.

Raúl Rivas explains that this monkeypox is a very stable virus that varies very little. But Morales says that “this is a relatively new pathogen, which is getting used to living among us, and which is not yet specialized in multiplying and infecting us.”

Human smallpox could only be transmitted between humans. According to the US Centers for Disease Control and Prevention, there is no scientific evidence that smallpox can be transmitted by insects or other animals.

The origin of smallpox is unknown. In the case of monkeypox, it was so named because it was discovered in monkey colonies held for research in 1958.

Symptoms

In both diseases, the clinical picture begins in a similar way, although it is a little milder in monkeypox.

“As with most infections, they start with a fever and it’s also common to have body discomfort, fatigue, muscle aches and sore throat,” describes Rivas.

In addition, in both diseases, the unmistakable cutaneous pustules (pimples on the skin) also develop, which can leave visible scars on the patients’ skin.

“As days go by, monkeypox tends to swell the lymph nodes, both cervical, maxillary, axillary and in the groin. This did not happen with human smallpox,” says Rivas.

The incubation period for monkeypox is usually 7 to 14 days, but can range from 5 to 21 days.

In the case of smallpox, incubation can last between 7 and 19 days, although the average duration was between 10 and 14 days.

Treatment

Smallpox was eradicated thanks to a historic vaccination campaign that ended thousands of years of deaths caused by the pathogen.

As the monkeypox virus is related to human smallpox, the smallpox vaccine has also been shown to be effective for both diseases.

In that case, people over 55 who were vaccinated against smallpox before its eradication may have considerable immunity against monkeypox.

Available treatments are primarily palliative for symptoms. Lorenzo Morales says there is no specific treatment for the disease.

“Because it is a pathogen that has mainly affected Africa and not developed countries, not enough is invested in the search for treatments”, he says.

However, there is a very big difference between monkeypox and the one that has been eradicated: the advancement of science and knowledge in recent years.

For hundreds of years, smallpox claimed lives without humanity understanding what was happening.

“This monkeypox is a disease that we know well. Perhaps for the general public it is something new, but it was discovered in 1958. It is also well studied because it is very similar to human smallpox,” says Rivas.