There isn't one single "rarest" virus, as rarity depends on discovery and reporting, but contenders include viruses causing extremely rare diseases like Subacute Sclerosing Panencephalitis (SSPE) (from measles), which is devastating but vaccine-preventable, or novel viruses like Yaravirus, a giant amoeba virus with unknown genes, while viruses like Marburg are rare but cause outbreaks. The rarest viruses often cause syndromes with few documented cases, like those linked to rare cancers or neurological conditions, or are simply hard to find.

What is the rarest virus to get?

Marburg virus disease (Marburg) is a rare but severe hemorrhagic fever that can cause serious illness and death. Symptoms can be similar to other tropical diseases, making diagnosis challenging. There is no treatment or vaccine for Marburg. The disease spreads through contact with infected animals or people.

Is the Marburg virus 100% fatal?

Marburg virus disease (MVD), formerly known as Marburg haemorrhagic fever, is a severe, often fatal illness in humans. The average MVD case fatality rate is around 50%. Case fatality rates have varied from 24% to 88% in past outbreaks. Early supportive care with rehydration, and symptomatic treatment improves survival.

What is the deadliest virus on Earth?

Using the “case fatality rate” metric to determine what virus is the deadliest, rabies would likely come out on top. That's because, if an infection becomes symptomatic, rabies is fatal to humans in more than 99 percent of cases. Globally, approximately 59,000 people die from rabies every year.

What is a rare virus?

In the United States, a rare disease is one that fewer than 200,000 people live with. (In other words, 60 per 100,000 individuals.) Around the world, rare diseases are identified and addressed differently. The European Union considers a disease rare if it affects no more than 50 per 100,000 people.

The diseases that changed humanity forever - Dan Kwartler

Is 1 in 100,000 rare?

While some rare diseases are quite close to a prevalence of 1 in 2000, most of them are actually much rarer, affecting only 1 in 100000, 1 in 1 million or even 1 in 1 billion people. Over 6000 different rare diseases have been identified. Each month there are about 5 new rare diseases documented in medical journals.

Which viruses never go away?

Cytomegalovirus (CMV)

Once a person is infected with CMV, they have it for life. In healthy people, CMV mainly stays dormant. The most common cause of a CMV reactivation is a weakened immune system.

Are giant viruses alive?

Indeed, viruses can be viewed as not belonging to the category of living beings because they are incapable of autonomous reproduction and extracellular virions are in a dormant (inert) state.

What virus is 100 fatal?

Rabies virus has a characteristic bullet-shaped virion structure. Rabies virus infection in mammals is nearly 100% fatal if left untreated.

What is the outbreak in Africa 2025?

On November 14, 2025, the Ethiopia Ministry of Health reported the country's first Marburg outbreak. As of December 22, 2025, Ethiopia has reported laboratory-confirmed Marburg among 14 people, nine of whom have died.

What's worse, Ebola or Marburg?

The average fatality rate for both Marburg virus and Ebola virus infections is around 50%. Fatality rates have varied from 24% to 88% in past outbreaks of Marburg virus infection depending on virus strain and case management. Case fatality rates of Ebola virus infection have varied from 25% to 90% in past outbreaks.

What is the sister virus to Ebola?

Marburg virus disease. Marburg hemorrhagic fever is a severe and highly fatal disease caused by a virus from the same family as the one that causes Ebola hemorrhagic fever. Both diseases are rare, but can cause dramatic outbreaks with high fatality. There is currently no specific treatment or vaccine.

Which was worse, the plague or COVID?

COVID-19 already ranks among the world's deadliest epidemics, each of which can claim credit for epochal – not just generational – shifts. Granted, absolute figures tell you only so much: COVID-19 arrived on a far more populous planet than the one which was devastated by the Black Death.

What is the most famous virus?

The title of the most famous computer virus arguably goes to the infamous ILOVEYOU virus. Released in the year 2000, it wreaked havoc on the digital landscape and set new precedents for the damage caused by cyberattacks.

Why isn't a virus life?

Some scientists consider viruses to be microbes made of genetic material enclosed in a protein coat. They are unable to replicate on their own and hijack the machinery of other cells to make copies of themselves. Because they don't have many features of living cells, they are not technically alive.

Are humans a virus on Earth?

So then, scientifically speaking, humans being viruses is indeed a myth.

Which virus is spreading now in 2025?

As of 20 September 2025, CHIKV disease transmission continues across the Americas in line with expected seasonal patterns. A total of 228 591 suspected cases have been reported from 14 countries, including 100 329 confirmed cases and 115 deaths.

Do viruses edit DNA?

How Viruses Change DNA. Viruses cannot make their own proteins. Instead retroviruses, like HIV, Covid-19, and others, inject their RNA with the codes to make viral proteins into the cells they infect. That RNA can be converted into DNA and inserted into the host's DNA.

What is the chandipura virus?

Chandipura virus (CHPV) causes recurrent outbreaks of fatal encephalitis. Identified in 1965, CHPV remains a serious health concern in South Asia. CHPV is transmitted by sandflies and no vaccine or antiviral currently exists. The infection disproportionately affects children aged 15 years old.

Is a virus forever?

Viruses come and go – most of the time, at least. Some, however, stay around forever.

Do good viruses exist?

Although viruses are most often studied as pathogens, many are beneficial to their hosts, providing essential functions in some cases and conditionally beneficial functions in others. Beneficial viruses have been discovered in many different hosts, including bacteria, insects, plants, fungi and animals.

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