Bacteria, viruses and other microorganisms have wreaked as much havoc on humanity as the most terrible wars, earthquakes and volcanic eruptions.
Major epidemics and pandemics have marked the history of mankind, in all periods, and have taken the lives of countless people.
In this article, we will address some epidemics and pandemics that have affected the health of millions of individuals in classical antiquity, medieval times, and the contemporary period.
The difference between a pandemic and an epidemic
Before you learn more about the epidemics and pandemics that have marked world history, it is important to pay attention to the difference between the concepts of epidemic and pandemic, and it is quite simple, actually.
An epidemic refers to diseases that have spread to a limited geographical region, such as a city.
The term pandemic refers to a disease that has spread over a very large geographic space, such as a continent.
1. Black Plague
50 million dead (Europe and Asia) – 1333 to 1351 A.D.
History: The bubonic plague was called the “black plague” because of the worst pandemic that hit Europe in the 14th century.
It was fought as cities improved hygiene and sanitation, decreasing the population of urban rats. It wiped out at least 1/3 of the European population.
Infection: Bubonic plague is caused by the bacterium Yersinia pestis, common in rodents like the rat. It is transmitted to humans when a person is bitten by the flea of these contaminated animals.
Symptoms: Inflammation of the lymph nodes, followed by tremors, localized pain, apathy, headache and fever.
Treatment: Based on antibiotics. Without treatment, it kills 60% of those infected.
Hundreds of thousands of dead – 1817 to 1824.
History: Known since classical antiquity (8th century BC to 6th century AD), its first global pandemic was in 1817. Since then, the pathogen responsible for the disease, Vibrio cholerae, has undergone several mutations, causing new epidemic cycles from time to time.
Infection: Its transmission occurs from the consumption of contaminated water or food, and is more common in underdeveloped countries.
One of the countries hardest hit by cholera was Haiti in 2010. In Yemen, in 2019, more than 40,000 people died from the disease.
Symptoms: The bacteria multiply in the intestine and release a toxin that causes severe diarrhea, cramps and nausea.
Treatment: Based on antibiotics. The vaccine available is of low efficacy (50% immunization).
1 billion dead – 1850 to 1950.
History: Traces of the disease were found in 7,000-year-old skeletons. The fight against the disease was accelerated in 1882, after the identification of the Koch bacillus (Mycobacterium tuberculosis), which causes tuberculosis.
In recent decades, it has reappeared in poor countries, and as an opportunistic disease in AIDS patients.
Infection: Highly contagious, tuberculosis is transmitted through the airways in almost all cases. The infection occurs by inhaling droplets containing bacilli expelled by coughing, speaking or sneezing from a person with the disease.
Symptoms: The disease mainly attacks the lungs, and the main symptoms are coughing for more than two weeks, increased mucus production, fever, tiredness, chest pain, lack of appetite and coughing up blood in more severe cases.
Treatment: Based on antibiotics, the patient is cured in up to six months.
300 million dead – 1896 to 1980.
History: This disease affected mankind for more than 3,000 years. Even popular historical figures such as the Egyptian pharaoh Ramesses II, Queen Mary II of England and King Louis XV of France had the dreaded disease. The vaccine was discovered in 1796.
Infection: The Orthopoxvirus variolae virus was transmitted from person to person, usually through the airways.
Symptoms: The symptoms were fever, followed by rashes on the throat, mouth and face. Subsequently, pustules that could leave scars on the body.
Treatment: Eradicated from the planet since 1980, after a mass vaccination campaign.
5. Spanish flu
20 million dead – 1918 to 1919.
History: Despite its name, the Spanish flu did not appear in Spain. It is believed to have arisen in China or the United States. The first cases were recorded at a military camp called Fort Riley, in the state of Kansas, USA. The first known patient was soldier Albert Gitchell.
The disease arose in the context of the First World War and took advantage of the large displacement of soldiers and the agglomerations caused by the war to spread throughout the world.
There were three waves of contagion, which extended from 1918 to 1919. The second wave was known as the one with the greatest contamination capacity and was the most deadly.
Spanish flu has spread to every continent on the planet. Early twentieth-century medicine did not know what caused it, because microscopes were not advanced enough to see the virus responsible for the disease.
Infection: The Spanish flu was caused by a mutation of the influenza virus and transmitted through the air, through inhalation of infected droplets from coughing or sneezing.
Symptoms: Severe head and body aches, chills, swelling of the lungs and fever.
Treatment: The virus is constantly changing, so we will never be completely immune. Flu vaccines prevent infection with known strains of the virus.
3 million dead (Eastern Europe and Russia) – 1918 to 1922.
History: As poverty provides the ideal conditions for proliferation, typhus is linked to Third World countries, refugee and concentration camps, or wars.
Post-World War I conditions in Europe created an environment of poverty ideal for the spread of diseases. A precarious sanitation network ended up spreading rats across the continent, especially in Russia.
Infection: The disease is caused by bacteria of the genus Rickettsia. Epidemic typhus appears when a person scratches the flea’s bite and the contaminated feces of the insect fall into the bloodstream. Endemic typhus is transmitted by the rat flea.
Symptoms: Headache, joint pain, fever, confusion and hemorrhagic rashes.
Treatment: Based on antibiotics.
7. Yellow fever
30,000 dead (Ethiopia) – 1960 to 1962.
History: Genetic studies have shown that the virus responsible for the disease, which belongs to the genus Flavivirus, appeared in Africa, about three thousand years ago. Flavivirus has an urban and a wild version, and has already caused major epidemics in Africa and the Americas.
Infection: The victim is bitten by a mosquito that has previously bitten a person infected with the virus.
Symptoms: Fever, malaise, tiredness, chills, nausea, vomiting and diarrhea. 85% of patients recover in three or four days. Others may have more severe symptoms, which can lead to death.
Treatment: There is a vaccine that can be applied from 12 months of age and renewed every ten years.
6 million dead per year – Until 1963.
History: It was one of the main causes of infant mortality until the discovery of the first vaccine in 1963. Over the years, the vaccine has been improved, and the disease has been eradicated in several countries.
Infection: Highly contagious, measles is caused by the virus Morbillivirus, spread through mucous secretions (such as saliva) by an infected person.
Symptoms: Small rashes or red spots on the skin, fever, headache, malaise and inflammation of the airways.
Treatment: There is a vaccine, and the disease has been eradicated in several countries.
3 million dead per year – Since 1980.
History: In 1880, the protozoan Plasmodium, which causes the disease, was discovered. The WHO considers malaria to be the worst tropical and parasitic disease today, second only to AIDS. The protozoan destroys liver cells, red blood cells and, in some cases, the arteries that carry blood to the brain.
Infection: Contamination occurs when the victim is bitten by the Anopheles mosquito contaminated with the malaria protozoan.
Symptoms: The symptoms of malaria are fever, chills, tremors, sweating and headache.
Treatment: There is no efficient vaccine, only drugs to treat symptoms.
22 million dead – Since 1981.
History: The disease was identified in 1981, in the United States, and has since been considered a global epidemic by the World Health Organization.
AIDS is a sexually transmitted disease that attacks the patient’s immune system and causes a decrease in the body’s natural defenses.
It is an advanced stage of infection by HIV, the human immunodeficiency virus. Therefore, being HIV positive does not mean that a person has AIDS.
Infection: The virus is transmitted through blood, sperm, vaginal discharge and breast milk.
Symptoms: Destroys the immune system, leaving the body fragile to diseases caused by other viruses, bacteria, parasites and cancer cells.
Treatment: There is no cure. HIV-positive people are treated with drug cocktails that inhibit the virus from multiplying, but do not eliminate it from the body.