Buzz
In the midst of a global health crisis, it's easy to overlook the fact that humanity has successfully defeated numerous diseases that once decimated entire populations. Vaccines are now credited with saving an estimated three million lives annually around the world.
Some diseases have even been completely eradicated (vanished for good), while others have been wiped out in entire nations or regions. While there’s still much work to be done, it’s reassuring to reflect on the progress we've made. Here are 10 of the most remarkable victories in modern science against harmful bacteria, viruses, and parasites.
10. Smallpox
Smallpox was a deadly airborne virus that claimed the lives of approximately one-third of those it infected. With no cure available, doctors had no choice but to wait two weeks to see if the patient would survive. Those who did were often left with permanent scars from the characteristic red pustules that gave the disease its name.
In 1796, a British physician named Edward Jenner made an important observation: people who had contracted cowpox as children seemed to be immune to smallpox. To test his hypothesis, he injected an eight-year-old boy, the son of his gardener, with cowpox before exposing him to the smallpox virus. In a surprising twist, it worked, and Jenner unwittingly discovered the world’s first vaccine.
Jenner’s breakthrough significantly reduced the number of fatalities caused by smallpox. By 1959, when the World Health Organization (WHO) launched its mission to eradicate smallpox, the disease was mainly confined to regions of South America, Africa, and Southeast Asia.
The WHO ordered large quantities of vaccines and provided local governments with guidelines on how to distribute them. In 1977, Somalia reported the last known case of smallpox. Consequently, in 1980, the WHO declared that smallpox had become the first disease in history to be eradicated through human intervention.
9. Rinderpest
Rinderpest, also known as 'cattle plague,' didn’t affect humans but was still catastrophic. During an outbreak in the 1890s, 80–90% of all cattle in sub-Saharan Africa were killed. The people who relied on these animals for food, milk, and labor were left to starve. This disaster caused the population in affected regions to shrink by at least a third.
Any animal that survived rinderpest would never contract it again. Furthermore, the high mortality rate meant that wild animals, like buffalo and giraffes, who had rinderpest, died before they could spread the virus to domesticated cattle.
In the 1960s, a British scientist named Walter Plowright created a vaccine for rinderpest. By the 1990s, the United Nations Food and Agriculture Organization began purchasing the vaccine in large quantities. Veterinarians from Europe, Asia, and Africa worked together to vaccinate cattle, and in 2011, their efforts led to the successful eradication of rinderpest. It became the second disease to be wiped out.
8. Polio
Polio, or poliomyelitis, is a viral infection that causes paralysis in its victims. In some cases, the paralysis is temporary, while in others, it results in permanent disability. In the worst cases, the virus attacks the lungs and leads to death.
In 1953, Jonas Salk revealed that he had created a vaccine for polio. He chose not to patent his discovery, aiming to make it available to as many people as possible, ultimately sacrificing billions in potential earnings in today's US dollars.
The March of Dimes supported a large-scale trial of Salk's vaccine before it was mass-produced for the American public. By 1979, just 24 years after the vaccine's introduction, the United States was officially declared free of polio.
In 1988, the WHO launched the Global Polio Eradication Initiative to eliminate polio worldwide. Between 1980 and 2016, polio cases decreased by 99.99 percent. Today, the disease is only present in Afghanistan, Pakistan, and Nigeria.
7. Guinea Worm
When a person consumes stagnant water contaminated with Guinea worm larvae, the worms travel through the intestines to mate. After 10–14 months, the female worm moves to the human foot, creating a painful skin lesion. The discomfort drives the individual to submerge their foot in a body of water, releasing the larvae. The cycle then begins anew.
Though the painful lesions and risk of bacterial infection are unpleasant, Guinea worm is seldom fatal. However, most people understandably prefer not to host worms in their intestines.
The Carter Center is leading the effort to combat Guinea worm through water purification initiatives. This approach has seen remarkable success. According to McGill University, there were million cases in 1986 across South Asia, Yemen, and sub-Saharan Africa. By 2018, only 28 cases were reported globally.
6. Yaws
Yaws, also known as frambesia, is a skin disease caused by direct contact with the bacterium Treponema pallidum pertenue. Within three months of infection, a patient develops raspberry-like lesions, particularly on the face. These lesions eventually fade within six months, but may reappear later, leaving scars. Unfortunately, these scars often lead to bullying and discrimination.
In the 1950s, yaws was widespread in over 70 countries. Due to its easy treatment with a single dose of the antibiotic azithromycin, the World Health Organization (WHO) targeted it for eradication. While yaws was nearly eliminated in the 1960s, the focus shifted to smallpox, and interest in yaws diminished. By 2019, the disease was still present in 15 countries.
5. Hookworm
Hookworms thrive in soil contaminated with sewage. They enter the body through the feet and make their way to the small intestine, where they feed on the host's blood. This leads to symptoms such as fatigue, anemia, bloating, and stunted growth.
Because hookworms live in areas with inadequate sewage systems, the patient often expels them through feces, and the worms return to the soil, where they wait to invade new feet.
In 1910, John D. Rockefeller Sr. contributed $1 million to combat hookworms in the American South. After a five-year initiative, infection rates were greatly reduced, and more children attended school and were able to focus, thanks to the lack of worms draining their energy.
Although hookworms were nearly eradicated, reinfection rates remain high, and the worms can return. To finally defeat them, the Human Hookworm Vaccine Initiative is developing a drug that prevents the worms from feeding. With this breakthrough, they may soon be completely gone.
4. Measles
While measles has made a slight resurgence in recent years due to a decline in vaccinations, globally, the number of measles cases has significantly dropped over the past 50 years.
Before the introduction of the vaccine in 1963, nearly every child in the United States contracted measles by age 15. Major outbreaks occurred every 2–3 years, leading to an average of 2.6 million deaths annually. The virus spreads through coughing and sneezing.
In 1954, Dr. Thomas C. Peebles from Harvard University asked 11-year-old David Edmonston, who was sick with measles, if he wanted “to be of service to mankind.” David agreed, and the doctor swabbed his throat. Dr. John F. Enders was able to isolate the virus from this sample and create the Edmonston-Enders vaccine, which is still in use today.
From 2000 to 2018, measles-related fatalities fell by 73%, saving around 23.2 million lives thanks to widespread vaccination efforts. In the United States, where measles was eradicated in 2000, only 1,282 cases were reported in 2019.
3. Malaria
Malaria is caused by a tiny parasite that infects the blood, transmitted via mosquito bites. Symptoms include fever, chills, headaches, nausea, and body aches. Despite its ongoing global impact, significant progress has been made in combating the disease.
Malaria has been a persistent problem in Europe, Africa, and Asia for centuries. With the European colonization of the Americas, the disease spread further. At its peak, historians estimate that malaria posed a risk to people living across 53% of the world’s landmass.
In the early 1900s, the United States and Europe made significant strides in understanding how malaria spread. They drained or filled in mosquito breeding grounds, particularly wetlands, and began mass spraying insecticides. The Office of Malaria Control in War Areas eventually evolved into the Centers for Disease Control.
The 21st century has seen great progress in malaria control. From 2000 to 2015, the annual number of malaria-related deaths dropped from 840,000 to 440,000, with the majority of the victims being children in Africa.
2. Elephantiasis
Elephantiasis is caused by three types of threadlike worms that infest the lymphatic system. This interference prevents the body from regulating fluids properly, leading to the swelling of limbs or genitals to elephant-like proportions.
While the worms are residing in the lymph nodes, they release larvae into the bloodstream. If a mosquito bites an infected individual, it transmits the disease to others it later bites.
Certain medications can treat the condition, and when combined with protective measures against mosquitoes, the spread of the disease can be halted.
Since 2000, over 7.7 billion treatments have been administered to more than 910 million people. Sixteen countries have successfully eliminated elephantiasis, and seven more are under observation to determine if they can join the list.
1. Tetanus
Tetanus is an infection caused by the bacterium Clostridium tetani, which thrives in soils worldwide. The bacteria enter the body through a wound, where they produce a toxic substance that triggers paralysis and excruciating muscle spasms.
Due to C. tetani's resistance to heat and chemicals, completely eradicating tetanus is improbable. However, mass vaccination can effectively eliminate new cases. Vaccination campaigns have seen remarkable success in reducing the disease.
In 1990, tetanus caused 314,000 deaths worldwide. By 2017, that figure had dropped to just 38,000, representing a dramatic 88% reduction. The highest rates of infection remain in South Sudan and Somalia.
