Only one human infectious disease has been fully eradicated worldwide: smallpox, declared gone by the World Health Organization in 1980. But dozens of diseases that were once death sentences are now curable with modern medicine, and several more are on the brink of disappearing entirely. The answer to “what diseases have been cured” depends on whether you mean wiped off the planet, curable in an individual patient, or somewhere in between.
Smallpox: The Only Eradicated Human Disease
Smallpox killed roughly 300 million people in the 20th century alone before a global vaccination campaign brought it to zero. The last natural case occurred in Somalia in 1977, and an independent panel of scientists from 19 nations certified eradication in December 1979. WHO made it official in 1980. No one has caught smallpox from nature since, and routine vaccination stopped worldwide because the virus simply no longer circulates. It remains the only infectious disease in humans to achieve complete global eradication.
On the animal side, rinderpest, a devastating cattle plague that wiped out entire herds across Europe, the Middle East, Asia, and Africa, was declared eradicated by the Food and Agriculture Organization in June 2011. While not a human disease, its elimination removed a major threat to food security for millions of people who depended on livestock.
Diseases Close to Eradication
Polio is the most prominent disease on track to follow smallpox. Wild poliovirus now exists in only two countries, Afghanistan and Pakistan, with 99 confirmed cases in all of 2024. That’s down from an estimated 350,000 cases per year in the late 1980s. The virus has been eliminated from every other country on Earth through vaccination, though the final push has proven stubbornly difficult due to conflict zones and gaps in vaccine coverage.
Guinea worm disease is even closer to zero. This parasitic infection, spread through contaminated drinking water, once affected 3.5 million people a year across Africa and Asia. In 2024, only 15 human cases were reported worldwide, split between Chad and South Sudan. The campaign against Guinea worm is unusual because there’s no vaccine and no drug treatment. Eradication has been achieved almost entirely through behavior change: filtering drinking water and containing infected individuals so larvae can’t re-enter water sources. One complication is that the parasite has been found in dogs and other animals, with 664 animal infections reported in 2024, which could slow final eradication.
Hepatitis C: A Virus You Can Now Cure
For decades, hepatitis C was a chronic infection that slowly destroyed the liver. Older treatments involved months of injections with harsh side effects and modest success rates. That changed dramatically with the arrival of direct-acting antiviral medications starting around 2014. These oral pills target the virus’s own machinery and eliminate it from the body in most people after just 8 to 12 weeks of treatment.
The cure rate is remarkable. Among more than 40,000 patients treated in one large study, 96.8% were cured, meaning the virus became permanently undetectable in their blood. That success rate holds regardless of the viral strain, the patient’s race, HIV status, or even whether they already have significant liver scarring. For people with advanced fibrosis or early cirrhosis, cure rates still exceed 95% with a standard 12-week course. Hepatitis C is one of the clearest examples of a disease that went from chronic and life-threatening to reliably curable within a single generation.
Cancers With High Cure Rates
Cancer as a whole is not “cured,” but specific types now have survival rates so high that doctors use the word cure with real confidence. The transformation in childhood leukemia is one of medicine’s greatest success stories. In the 1960s, a diagnosis of acute lymphoblastic leukemia in a child was almost always fatal. Today, approximately 85% of patients aged 1 to 18 with newly diagnosed ALL are expected to be long-term event-free survivors, and more than 90% are alive at five years. The improvement came not from a single breakthrough but from decades of refining chemotherapy combinations, dosing schedules, and supportive care.
Testicular cancer is another standout. When caught before it spreads beyond the testicle, the five-year survival rate is 99%. Even when the cancer has spread to distant parts of the body, 72% of patients survive at least five years. The high cure rate is largely due to the cancer’s exceptional sensitivity to platinum-based chemotherapy, a vulnerability that most other solid tumors don’t share.
Other cancers with high cure rates when caught early include thyroid cancer, certain skin cancers (particularly basal cell and squamous cell carcinomas), and early-stage Hodgkin lymphoma, where long-term survival exceeds 90% with modern treatment.
Sickle Cell Disease and Gene Therapy
Sickle cell disease has historically been manageable but not curable. Patients inherit a genetic mutation that causes red blood cells to become rigid and crescent-shaped, blocking blood flow and triggering episodes of severe pain called vaso-occlusive crises. These episodes can damage organs over time and shorten life expectancy significantly.
In December 2023, the FDA approved the first gene therapies for sickle cell disease, including the first-ever treatment using CRISPR genome editing. The therapy works by collecting a patient’s own blood stem cells, editing them in a lab to boost production of fetal hemoglobin (a form of hemoglobin that prevents red blood cells from sickling), and transplanting them back into the bone marrow. Among 31 patients with enough follow-up time to evaluate, 29 of them (93.5%) went at least 12 consecutive months without a single severe pain crisis. For a disease defined by those crises, that represents something close to a functional cure.
The treatment is intensive. Patients undergo chemotherapy to clear their existing bone marrow before receiving the modified cells, and the process requires weeks of hospitalization. It’s not a simple pill. But for people who previously faced a lifetime of pain episodes and organ damage, the results so far are transformative.
HIV: Functional Cures in a Handful of People
HIV cannot be cured with standard treatment. Antiretroviral therapy keeps the virus suppressed to undetectable levels, but it persists in hidden reservoirs throughout the body and rebounds if medication stops. A true cure, meaning permanent elimination of the virus, has only been achieved in a small number of people under extraordinary circumstances.
The pioneering case was the Berlin patient, Timothy Ray Brown, who received a bone marrow transplant from a donor with a rare genetic mutation that makes cells resistant to HIV. The transplant, done to treat his leukemia, also eliminated his HIV. The London patient later achieved the same result through a similar procedure. More recently, a second Berlin patient (referred to as B2) achieved sustained HIV remission after a stem cell transplant from a donor who did not carry the full protective mutation, suggesting that the transplant process itself may help clear the virus under certain conditions.
These cases are proof that curing HIV is biologically possible, but bone marrow transplants are far too dangerous and complex to use as a general treatment. They carry significant risk of death and are only performed when a patient also has a life-threatening blood cancer that independently requires the procedure. For the roughly 39 million people living with HIV worldwide, a scalable cure remains out of reach.
Common Infections That Are Routinely Cured
Beyond the headline diseases, it’s worth remembering that antibiotics and antivirals cure millions of infections every year that would have been fatal in previous centuries. Bacterial pneumonia, strep throat, urinary tract infections, tuberculosis, syphilis, and many wound infections are all curable with appropriate antibiotic treatment. Tuberculosis requires a longer course, typically six months, but completes with a full cure in the vast majority of cases when patients finish the regimen.
The major threat to these routine cures is antibiotic resistance. Bacteria evolve to survive the drugs designed to kill them, and resistant infections are growing more common worldwide. Diseases that were easily curable 30 years ago can become difficult or even impossible to treat when resistance develops, which is why antibiotic stewardship, using these drugs only when truly needed, matters so much for preserving the cures we already have.
What “Cured” Actually Means
The word “cure” carries different weight depending on context. Eradication means the disease no longer exists anywhere on Earth. A clinical cure means an individual patient’s disease has been completely eliminated, as with hepatitis C or a bacterial infection. A functional cure means the disease process has stopped and symptoms have resolved, even if trace biological evidence might remain, as with the HIV transplant patients. And high survival rates in cancer don’t always mean the underlying risk is gone; they mean the patient is alive and disease-free years after treatment, which for practical purposes feels the same as cured.
The WHO’s 2030 roadmap targets 20 neglected tropical diseases for prevention, control, elimination, or eradication, including diseases like leprosy, sleeping sickness, and lymphatic filariasis. With polio and Guinea worm disease both in single or double digits of annual cases, the list of fully eradicated diseases could grow in the coming decade.