We humans have been at war with viruses for as long as we have existed. Our caveman ancestors confronted these unseen enemies with myths and superstitions. We face them boldly with microscopes and face masks thanks to the rapid advancements in science and medicine in the past century.
Some of these pathogens have been so brutal, leading to countless deaths, almost threatening to wipe us off the face of the Earth. For the most part, we have managed to keep viruses under control or even eradicate them by developing timely vaccines. Here are the 10 deadliest viruses the world has seen so far.
Unlike other viruses the HIV (Human Immuno-deficiency Virus) attacks and destroys the T-cells, an essential component of the immune system. With time, the body is rid of its natural defense and this opens the door for all other opportunistic infections; a full-blown condition known as Acquired Immuno-deficiency Syndrome (AIDS). This is what makes it particularly deadly.
The HIV can be traced back to non-human primates, these are certain species of chimpanzees and gorillas in Central and West Africa in the 1920s. Early strains of the virus were likely acquired from bush meat practices. The wounds and cuts of the hunters were drenched in the fresh infected blood of their kill and therefore transmission was made possible. Later, HIV mainly spread from humans to humans through the exchange of sexual fluids during unprotected sex, blood transfusion and sharing of syringe needles during drug use.
In the 1980s the Center for Disease Control detected the first cases of HIV among homosexual men living in Los Angeles, in the United States. In 1981 the World Health Organization (WHO) declared it a pandemic and by 1997, there were over 3 million new infections per year. Since then, 75 million people have been infected worldwide and 32 million have died as a result. As of today, about 37.9 million people are living with HIV and surviving on anti-retroviral drugs.
The Antonine plague also known as Plague of Galen swept through ancient Rome and the Mediterranean from 165 to 180 AD. It first appeared during the siege of Seleucia, a major city along river Tigris. It is therefore widely believed that it originated from China and was likely brought in by Roman troops returning from wars in the near east and trading ships moving westwards.
As the Greek physician Galen described it, the disease caused its causalities to suffer high fever, swollen throat, chronic thirst, cough, vomiting, and diarrhea. There were also instances of red and black rash on the skin.
The strange disease would strike again in the period of 251 to 266 AD. These two separate outbreaks with a mortality rate of 25% almost brought the Roman Empire to its knees. By the end of the scourge, it had claimed about 5 million lives.
Mycobacterium tuberculosis, the bacteria that causes tuberculosis, was discovered on March 24, 1982, by Dr. Robert Koch. To date, Tuberculosis is the leading infectious disease in the world and a whopping 1.6 million people die from it every year. The greater risk of people likely to fall ill from the infection and spread it are people with compromised immune systems especially those living with HIV and those suffering adverse effects of malnutrition. This explains its prevalence in low-income countries.
Persons with Active TB exhibit symptoms such as persistent cough, night sweats, high fever, and weight loss. They can infect about 5 to 15 people through close contact within a year. The good news is that TB is curable and can be prevented by administering a TB vaccine.
7. Dengue Fever
Dengue viruses are hosted in species of female Aedes mosquitos. This makes dengue fever a mosquito-borne tropical disease since mosquitos only survive in tropical regions. Its symptoms include high fever, joints, and muscle pains, headache, vomiting and skin rash. It mainly affects children under 15 years of age.
There are 5 types of dengue virus which cause 5 types of dengue fever diseases. When infected, you can take less than a week to fully recover and become immune to the particular type of virus you suffered from. Infection with one type only offers a short-term immunity to the other types of dengue viruses. If not treated, the disease may develop into severe (dengue hemorrhagic fever), that causes bleeding, blood plasma leakage and very low blood pressure that could lead to dengue shock.
The first outbreak of dengue fever was recorded in 1779 and 1780 occurring in Asia, Africa, and North America. Lately, the fever has been common in countries in Southeast Asia and western pacific island regions, South America and the Caribbean. An estimated 390 million dengue infections occur each year resulting in about 25,000 deaths annually. In 2019 a vaccine for dengue fever was approved and is now commercially available.
6. Spanish Flu
This one was one of the deadliest pandemics in recent history. About 500 million people became infected with the flu virus, this was a third of the world’s population at the time. An estimated 50 million people died from it between 1918 and 1919. It is believed that military personnel were affected and their deaths were not reported and hence the figures could be as high as 100 million.
Though it is not known where the virus began, it was especially hard-hitting on Spain, hence it acquired the name. It was caused by the H1N1 virus with an origin from birds.
5. Ebola Virus
The Ebola Virus Disease otherwise known as Ebola was first recorded in 1976 in 2 outbreaks in the Democratic Republic of Congo and the Southern part of Sudan. A major outbreak would occur between 2013 and 2016 in the Western African country of Guinea and later spread to Liberia and Sierra Leone. In August of 2014, the WHO declared it a Public Health Emergency of International Concern.
Ebola virus can be transmitted simply by touching the body fluids of an infected person and even the dead. Therefore, local burial customs of handling and washing bodies greatly contributed to the spread of the disease. Symptoms of Ebola include body aches, headache, abdominal pain, fatigue, diarrhea, vomiting, hemorrhaging and bruising. The patient may also have red eyes, skin rash, and hiccups. Ebola’s case fatality rate is considerably high at 57% to 59%.
When the epidemic was finally contained, there had been a total of 28,616 cases and a resulting 11,310 deaths in the three countries, additionally, 15 deaths were recorded outside Africa mostly among health workers who had jumped in to help with the plague. The dysfunctional healthcare system in the countries affected led to the failure to bring the epidemic under control.
4. Justinian Plague
The Plague of Justinian began around 541-542 AD and recurred several times until 750 AD mostly afflicting the Eastern Roman Empire. Hence it was named after Emperor Justinian 1 of Byzantine who got infected but survived. It was transmitted through the black rat which traveled on grain ships from North Africa. The boats were a perfect breeding ground for fleas and rats. DNA analysis suggests that the plague originated from China and northeast India and was later carried to Egypt and around the Great Lakes Region of Africa. It was one of the deadliest plagues in history putting to death about 25 to 100 million people.
3. Yellow Fever
The yellow fever virus is hosted by a mosquito species known as the Aedes aegypti. The disease is called ‘yellow fever’ because the skin turns yellow in its advanced stages. It originated in East and Central Africa through primate to human transmission and was carried to the Americas and Europe by slave trade ships during European explorations.
The first outbreaks of the disease occurred in the islands of the Caribbean, Barbados, and Guadeloupe in 1647 and 1648. 25 major outbreaks would follow in North America beginning with Philadelphia in 1793, the town of Mississippi in 1878 and New Orleans in 1905. As of today, the Yellow fever virus is estimated to cause about 30,000 deaths each year, with 90% of the fatalities occurring in Africa.
2. Small Pox
Smallpox, an infectious disease, was spread between people and through contaminated objects. Its initial symptoms are fever and vomiting followed by sores in the mouth and skin rash. It. The origin of the disease is unknown and its first occurrence can be traced back to 3rd-century Egyptian mummies.
Up to 300 million people died of smallpox in the 20th century and an overall 500 million people in 100 years of major outbreaks. The first vaccine was introduced in 1796 and it succeeded in eradicating the disease over a long period in vaccination campaigns. The last naturally occurring case was recorded in 1977 and by 1980 the WHO certified the world to be smallpox free.
1. Black Death
The Black Death, also known as the Great Bubonic plague, was the deadliest plague recorded in history. It claimed 75 to 200 million lives in Europe and Asia with the greatest casualties occurring in 1347 and 1351 AD. The bacterium Yersinia Pestis is believed to have caused it. The disease originated in Central and East Asia and was carried by fleas living on black rats that would later travel on merchant ships. The Black Death devastated Europe doing away with 30% to 60% of its population.