A–Z Health Conditions
Browse our comprehensive library of health conditions from A to Z.
Allergy
Allergies occur when the immune system overreacts to substances that are otherwise harmless — from pollen and pet dander to certain foods, medications, and insect stings. This exaggerated immune response triggers the release of chemicals like histamine, causing symptoms that can range from sneezing, itchy eyes, and skin rashes to more serious reactions like anaphylaxis. Allergies are among the most common chronic health conditions in the United States, affecting more than 100 million Americans across all ages, and their prevalence is rising — driven in part by climate change, which is extending pollen seasons and increasing environmental allergen loads. Whether seasonal, perennial, or food-related, allergies can significantly impact quality of life, sleep, productivity, and — in severe cases — can be life-threatening. The good news: with proper diagnosis, personalized treatment, and in many cases allergen immunotherapy, most people with allergies can achieve meaningful relief and live full, unrestricted lives.
Alzheimer's Disease
Alzheimer's disease is a progressive brain disorder that gradually destroys memory, thinking skills, and eventually the ability to carry out the simplest tasks. It is the most common cause of dementia in older adults.
Asthma
Asthma is a chronic respiratory condition in which the airways become inflamed, narrowed, and blocked by excess mucus — making it difficult to breathe. Affecting more than 25 million Americans, asthma is one of the most common long-term lung diseases in the country, and it touches people of every age, background, and fitness level. Symptoms range from mild wheezing and shortness of breath to severe, potentially life-threatening asthma attacks that can require emergency care. Triggers vary widely from person to person and may include allergens like pollen and pet dander, air pollution, exercise, respiratory infections, stress, and even cold air. Asthma is also closely linked to allergies — a connection so well established that the two conditions are often managed together. While there is no cure, asthma is highly manageable: with the right combination of controller medications, quick-relief inhalers, trigger avoidance, and a personalized asthma action plan, most people with asthma can keep their symptoms well-controlled and lead fully active lives.
Autism Spectrum Disorder
Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition that affects how a person communicates, interacts socially, and processes the world around them — and it looks different in every individual it touches. ASD is not a single condition but a broad spectrum, ranging from individuals who need significant daily support to those who live and work independently with little or no assistance. It affects an estimated 1 in 36 children in the United States — a prevalence that has risen steadily over recent decades, reflecting both improved diagnostic awareness and genuine increases in incidence. Core features often include differences in social communication, repetitive behaviors or routines, and heightened or reduced sensitivity to sensory input, though no two people with autism share the exact same profile of strengths and challenges. ASD is also frequently accompanied by co-occurring conditions including ADHD, anxiety, epilepsy, and gastrointestinal issues. While autism is a lifelong condition, early intervention — including behavioral therapies, speech and occupational therapy, and educational support — can make a profound difference in outcomes, and many autistic individuals go on to build meaningful relationships, pursue careers, and contribute richly to their communities.
Back Pain
Back pain is a broad category of musculoskeletal conditions affecting the spine and surrounding structures. It is the single leading cause of disability worldwide, affecting roughly 80% of adults at some point in their lives. Back pain ranges from acute (sudden, short-term) to chronic (lasting more than 12 weeks) and can involve the muscles, ligaments, discs, nerves, or vertebrae. The vast majority of cases are non-specific — meaning no single structural cause can be identified — and most resolve with conservative care. Back pain is both overtreated (unnecessary surgery, opioids, imaging) and undertreated (insufficient physical therapy and active rehabilitation).
Balance Problems
Balance disorders occur when the systems your body uses to stay upright stop working together properly — involving the inner ear, eyes, and musculoskeletal system. They significantly increase fall risk, especially in older adults.
Breast Cancer
Breast cancer is a disease in which cells in the breast grow out of control. It is the most common cancer diagnosed in women in the United States, after skin cancer. While breast cancer can occur in both men and women, it is far more common in women. Early detection through mammography and self-exams significantly improves survival rates.
Cancer
Cancer is a family of more than 100 conditions in which cells grow out of control. Malignant tumors can invade nearby tissue and spread (metastasize) to distant parts of the body through the bloodstream or lymphatic system. Survival rates have improved dramatically over the past three decades due to earlier detection and better treatments.
Childhood Vaccines
Childhood vaccines are one of the most effective public health tools ever developed. They train the immune system to recognize and fight specific pathogens without the risk of actual infection, protecting children from 14 serious diseases. Vaccination programs have eliminated smallpox, nearly eradicated polio, and dramatically reduced childhood mortality worldwide.
Chronic Bronchitis
What is chronic bronchitis? Chronic bronchitis is a type of COPD (chronic obstructive pulmonary disease). COPD is a group of lung diseases that make it hard to breathe and get worse over time. The other main type of COPD is emphysema. Most people with COPD have both emphysema and chronic bronchitis, but how severe each type is can be different from person to person. Chronic bronchitis is inflammation (swelling) and irritation of the bronchial tubes. These tubes are the airways that carry air to and from the air sacs in your lungs. The irritation of the tubes causes mucus to build up. This mucus and the swelling of the tubes make it harder for your lungs to move oxygen in and carbon dioxide out of your body. What causes chronic bronchitis? The cause of chronic bronchitis is usually long-ter
Chronic Bronchitis
Chronic bronchitis is a form of chronic obstructive pulmonary disease (COPD) in which the bronchi become chronically inflamed and produce excess mucus, narrowing the airways and making breathing progressively harder. It is clinically defined as a productive cough on most days for at least 3 months in each of 2 consecutive years. It is the fourth leading cause of death in the United States, affecting 16 million Americans.
Chronic Kidney Disease
Chronic kidney disease (CKD) is a long-term, largely silent condition in which the kidneys gradually lose their ability to filter waste and excess fluid from the blood. It affects 37 million Americans (1 in 7 adults), 90% of whom are undiagnosed. CKD is defined by kidney damage or reduced eGFR lasting 3+ months and is staged 1–5 by eGFR. It is a leading cause of cardiovascular disease and premature death. Once established, CKD is permanent — but progression can often be significantly slowed with proper management.
COPD
What is COPD (chronic obstructive pulmonary disease )? COPD (chronic obstructive pulmonary disease ) is a group of lung diseases that make it hard to breathe and get worse over time. Normally, the airways and air sacs in your lungs are elastic or stretchy. When you breathe in, the airways bring air to the air sacs. The air sacs fill up with air, like a small balloon. When you breathe out, the air sacs deflate, and the air goes out. If you have COPD , less air flows in and out of your airways because of one or more problems: The airways and air sacs in your lungs become less elastic The walls between many of the air sacs are destroyed The walls of the airways become thick and inflamed The airways make more mucus than usual and can become clogged What are the types of COPD (chronic obstructi
Crohn 's Disease
What is Crohn 's disease ? Crohn 's disease is a chronic (long-lasting) disease that causes inflammation in your digestive tract. It can affect any part of your digestive tract, which runs from your mouth to your anus. But it usually affects your small intestine and the beginning of your large intestine. Crohn 's disease is an inflammatory bowel disease (IBD). Ulcerative colitis and microscopic colitis are other common types of IBD. What causes Crohn 's disease ? The cause of Crohn 's disease is unknown. Researchers think that an autoimmune reaction may be one cause. An autoimmune reaction happens when your immune system attacks healthy cells in your body. Genetics may also play a role, since Crohn 's disease can run in families. Stress and eating certain foods don't cause the disease , bu
Depression
Depression (major depressive disorder) is one of the most common and debilitating mental health conditions in the United States, characterized by persistent feelings of sadness, hopelessness, loss of interest, fatigue, and difficulty functioning in daily life. The current depression rate stands at 18.3% in 2025, projecting to an estimated 47.8 million Americans — up roughly eight percentage points since 2015, with much of the increase occurring after the onset of the COVID-19 pandemic. CDC data confirms that depression prevalence among adolescents and adults has risen 60% over the past decade, with more than 1 in 10 U.S. adults now taking prescription medication for the condition. Rates are highest among adolescents ages 12–19 and decline with age, and are significantly elevated among those living below the poverty line. Depression is caused by a complex interplay of biological, psychological, and social factors, and is treated through a combination of therapy, medication, and lifestyle interventions — though only about 40% of those living with depression currently receive counseling or therapy, with persistent disparities across gender, age, and socioeconomic lines.
Diabetes
Diabetes is a chronic condition that affects how the body turns food into energy. It occurs when the pancreas doesn't produce enough insulin (Type 1) or when the body can't effectively use the insulin it produces (Type 2). Over time, uncontrolled high blood sugar can cause serious damage to the heart, blood vessels, eyes, kidneys, and nerves. More than 38 million Americans are living with diabetes, and approximately 1 in 5 don't know they have it.
Dizziness and Vertigo
Dizziness and vertigo are among the most common complaints in medicine — affecting millions of Americans each year and ranking as one of the top reasons people visit their doctor. Though often used interchangeably, the two terms describe distinct experiences: dizziness refers broadly to feelings of lightheadedness, unsteadiness, or faintness, while vertigo is the specific, often disorienting sensation that you or your surroundings are spinning or moving when they are not. Both can range from a fleeting annoyance to a debilitating condition that interferes with walking, working, and daily life. The causes are wide-ranging — from inner ear disorders like benign paroxysmal positional vertigo (BPPV), Ménière's disease, and vestibular neuritis, to cardiovascular conditions, migraines, medication side effects, neurological disorders, and anxiety. Because so many different conditions can produce dizziness and vertigo, accurate diagnosis is essential — and often requires collaboration between primary care, neurology, otolaryngology, and other specialists. The good news is that most causes are treatable: simple repositioning maneuvers can resolve BPPV in minutes, vestibular rehabilitation therapy can restore balance in chronic cases, and targeted medical or surgical treatment can address underlying conditions — helping most people reclaim their stability and confidence.
Drug Use and Addiction
What are drugs ? Drugs are chemical substances that can change how your body and mind work. They include prescription medicines, over-the-counter medicines, alcohol, tobacco, and illegal drugs . What is drug use? Drug use, or misuse, includes: Using illegal substances, such as: Anabolic steroids Club drugs Cocaine Heroin Inhalants Marijuana Methamphetamines Misusing prescription medicines, including opioids. This means taking the medicines in a different way than your health care provider prescribed. This includes Taking a medicine that was prescribed for someone else. Taking a larger dose than you are supposed to. Using the medicine in a different way than you are supposed to. For example, instead of swallowing your tablets, you might crush and then snort or inject them. Using the medicin
Eczema
Eczema — most commonly known as atopic dermatitis — is a chronic inflammatory skin condition that causes the skin to become dry, itchy, inflamed, and prone to painful flares that can significantly disrupt sleep, comfort, and quality of life. It affects more than 31 million Americans across all ages, making it the most common inflammatory skin disease in the country, and it is particularly prevalent in children — though many carry it into adulthood, and some develop it for the first time as adults. Eczema is not contagious, but it is closely tied to immune system dysregulation and a compromised skin barrier that allows moisture to escape and irritants and allergens to penetrate — which is why it so frequently travels alongside allergies and asthma in what clinicians call the "atopic march." Triggers vary widely from person to person and can include environmental allergens, harsh soaps and detergents, sweat, stress, certain fabrics, and changes in temperature or humidity. While there is no cure, the treatment landscape has been transformed in recent years: from daily moisturizing and topical corticosteroids to targeted biologic therapies like dupilumab and newer JAK inhibitors that offer meaningful, sustained relief for moderate-to-severe cases. With the right personalized treatment plan and trigger management, most people with eczema can achieve significant control over their condition and protect their skin — and their well-being.
Emphysema
Emphysema is a progressive and irreversible lung disease in which the tiny air sacs of the lungs — the alveoli — are gradually destroyed, reducing the surface area available for oxygen exchange and making every breath increasingly difficult. It is one of the two primary conditions that make up chronic obstructive pulmonary disease (COPD), alongside chronic bronchitis, and the two conditions frequently coexist. Cigarette smoking is by far the leading cause, responsible for approximately 85–90% of cases, though long-term exposure to air pollution, occupational dust and chemical fumes, and a rare genetic condition called alpha-1 antitrypsin deficiency can also trigger the disease. Emphysema develops silently over years — many people dismiss early breathlessness as a normal sign of aging — and by the time symptoms become noticeable, significant and permanent lung damage has already occurred. The hallmark symptom is progressive shortness of breath, initially with exertion and eventually at rest, accompanied by chronic cough, wheezing, and a characteristic barrel-shaped chest in advanced disease. While emphysema cannot be reversed, its progression can be slowed: quitting smoking is the single most important intervention, and a combination of bronchodilators, pulmonary rehabilitation, supplemental oxygen, and in select cases surgical or bronchoscopic lung volume reduction can meaningfully improve breathing, function, and quality of life.
Epilepsy
Epilepsy is a chronic neurological disorder characterized by recurrent, unprovoked seizures caused by abnormal electrical activity in the brain. It ranks as the fourth most common neurological disorder globally, and approximately 1 in 26 people will develop epilepsy during their lifetime. In the United States, nearly 3 million adults and approximately 456,000 children 17 and younger are living with active epilepsy. The condition can occur at any age but is most common in young children and adults over 60. Causes range from genetic factors and brain injuries to infections and stroke, though in many cases no specific cause is identified. With appropriate treatment, 70% of people with epilepsy can achieve seizure freedom — primarily through antiseizure medications, though some patients may benefit from dietary therapies, neurostimulation devices, or surgery. Despite effective treatment options, significant gaps in access to specialized care remain, particularly in lower-income and rural communities.
Eye Care
Eye Care encompasses the full spectrum of conditions, diseases, and preventive practices related to the health of the eyes and vision — one of the most vital and complex sensory systems in the human body. Vision problems affect an estimated 93 million adults in the United States, yet only half report having visited an eye doctor in the past 12 months, making eye care one of the most underpracticed areas of preventive health in the country. The range of conditions managed under eye care is broad: from common refractive errors like nearsightedness, farsightedness, and astigmatism, to chronic diseases like glaucoma, age-related macular degeneration, and diabetic retinopathy — which together represent the leading causes of preventable blindness in adults — to inflammatory conditions, cataracts, dry eye disease, and rare genetic disorders of the retina and optic nerve. Many serious eye conditions develop silently, with no pain or noticeable vision changes until significant and often irreversible damage has occurred, which is why routine comprehensive eye exams are a cornerstone of both eye health and overall systemic health — often revealing early signs of diabetes, hypertension, and neurological disease. With advances in imaging technology, gene therapy, anti-VEGF biologics, and minimally invasive surgical techniques, the ability to detect, treat, and in many cases preserve vision has never been greater — making access to quality eye care more important than ever.
Fatigue
Fatigue is one of the most common and pervasive symptoms in medicine — affecting an estimated 45 million Americans and accounting for millions of primary care visits each year — yet it remains one of the most complex and frequently underaddressed complaints in clinical practice. Unlike ordinary tiredness that resolves with rest, pathological fatigue is a persistent, often debilitating exhaustion that can affect physical energy, cognitive function, emotional resilience, and the ability to carry out even basic daily activities. Fatigue is rarely a condition in its own right — it is most commonly a symptom or consequence of an underlying condition, and its causes span virtually every medical specialty: anemia, thyroid dysfunction, diabetes, heart disease, sleep disorders like obstructive sleep apnea, autoimmune conditions, cancer and its treatments, depression, anxiety, chronic infections, and neurological disorders are all common culprits. Two conditions in which fatigue takes center stage as the defining feature are myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) — a serious, often disabling condition affecting up to 3.3 million Americans — and long COVID-associated fatigue, which has emerged as one of the most widespread and challenging post-infectious syndromes of the modern era. Accurate diagnosis requires a thorough evaluation to identify and address the root cause, and treatment is equally individualized — ranging from managing the underlying condition and optimizing sleep to pacing strategies, nutritional support, physical rehabilitation, and mental health care.
Fibrosis
Fibrosis is a condition characterized by the thickening and scarring of connective tissue, most commonly affecting the lungs (pulmonary fibrosis) but can also occur in other organs such as the liver, heart, and skin. Over time, the scarred tissue replaces healthy tissue, impairing normal organ function.
Fistulas
A fistula is an abnormal connection between two parts inside of the body. Fistulas may develop between different organs, such as between the esophagus and the windpipe or the bowel and the vagina. They can also develop between two blood vessels, such as between an artery and a vein or between two arteries. Some people are born with a fistula. Other common causes of fistulas include: Complications from surgery Injury Infection Diseases , such as Crohn 's disease or ulcerative colitis Treatment depends on the cause of the fistula, where it is, and how bad it is. Some fistulas will close on their own. In some cases, you may need antibiotics and/or surgery.
Food Allergy
A food allergy is an immune system response in which the body mistakenly identifies a specific food protein as harmful, triggering reactions that range from mild hives and digestive discomfort to life-threatening anaphylaxis. Food allergy is a serious immune-mediated disease affecting more than 33 million people in the United States, across all regions and demographic groups. This includes approximately 18 million adults and 4 million children. Prevalence among children has risen dramatically — up 50% between 1997 and 2011, and another 50% between 2007 and 2021 — with increases occurring at faster rates among Black and Hispanic Americans than White Americans. The nine most common allergens — milk, eggs, peanuts, tree nuts, wheat, soy, fish, shellfish, and sesame — account for the vast majority of reactions. Each year, approximately 200,000 people in the United States seek emergency medical care due to food allergic reactions. There is no cure for most food allergies; management centers on strict avoidance, emergency preparedness with epinephrine, and emerging immunotherapy options for certain allergens such as peanut.
Heart Disease
Heart disease refers to a range of conditions that affect the heart, including coronary artery disease, arrhythmias, congenital heart defects, and diseases of the heart muscle and valves. It is the leading cause of death globally, encompassing conditions that narrow or block blood vessels, disrupt electrical signaling, or impair the heart's ability to pump effectively.
Hepatitis
Hepatitis refers to inflammation of the liver, most commonly caused by one of five viral strains — A, B, C, D, and E — each differing in transmission, severity, and treatability. Despite vaccines that can prevent hepatitis A and B, and curative treatments available for hepatitis C, more than 86,000 acute viral hepatitis infections were estimated to have occurred and nearly 13,000 hepatitis-related deaths were reported in the United States in 2023. Hepatitis A spreads primarily through contaminated food and water and is vaccine-preventable; most cases resolve on their own. An estimated 660,000 adults in the U.S. are living with chronic hepatitis B, which is transmitted through blood, sexual contact, or mother to child, and can lead to cirrhosis and liver cancer if untreated. Hepatitis C — the most consequential strain in the U.S. — affects an estimated 2.2 million adults, with approximately 67,400 new infections occurring in 2022 alone, and more than 12,700 hepatitis C-related deaths that year, despite the availability of highly effective curative therapies. Hepatitis D only occurs in those already infected with hepatitis B, while hepatitis E is rare in the U.S. and primarily affects travelers. Across all types, disparities in diagnosis, access to care, and treatment uptake remain significant barriers to elimination.
High Blood Pressure
High blood pressure, or hypertension, is a condition in which the force of blood against artery walls is consistently too high, silently damaging the heart, blood vessels, kidneys, and brain over time. Nearly half of all U.S. adults — 47.7% — have hypertension, with rates higher in men (50.8%) than women (44.6%) and rising sharply with age, reaching 71.6% in adults 60 and older. In 2022, high blood pressure was a primary or contributing cause of nearly 686,000 deaths in the United States. Despite its prevalence, control remains poor — nearly four out of five U.S. adults with hypertension have blood pressure above the current guideline goal of 130/80 mmHg, with related deaths nearly doubling over the past two decades while treatment rates have stagnated. About 1 in 5 adults with high blood pressure is unaware they have it, earning hypertension its reputation as a "silent killer." Disparities are pronounced — Black adults carry the highest burden at 58.8% prevalence — and management typically involves lifestyle modification alongside antihypertensive medications.
HIV
HIV is a virus that attacks the body's immune system — specifically CD4 cells — and, if left untreated, can progress to AIDS (Acquired Immunodeficiency Syndrome), leaving the body vulnerable to life-threatening infections and cancers. Approximately 1.2 million people in the U.S. are currently living with HIV, and about 1 in 8 do not know it. In 2023, over 39,000 people were newly diagnosed with HIV in the U.S., with Black and Hispanic individuals each accounting for more than a third of diagnoses, and the South representing 51% of all new cases. There is encouraging progress — annual new infections declined 12% from 2018 to 2022, driven largely by a 30% drop among young people aged 13–24, with increases in PrEP use, HIV testing, and viral suppression as key contributors. While there is no cure, antiretroviral therapy (ART) can suppress the virus to undetectable levels, preventing transmission and allowing people with HIV to live long, healthy lives. Prevention tools including PrEP (pre-exposure prophylaxis) and regular testing remain central to the national goal of ending the HIV epidemic in the U.S.
Hyperthyroidism
Hyperthyroidism is a condition in which the thyroid gland produces excess thyroid hormone, accelerating the body's metabolism and affecting the heart, bones, muscles, and nervous system. The prevalence of hyperthyroidism in the United States is approximately 1.2%, with overt hyperthyroidism accounting for 0.5% and subclinical hyperthyroidism — where lab values are abnormal but symptoms may be absent — accounting for 0.7%. Hyperthyroidism is significantly more prevalent in women than men (2% vs. 0.2%), and NHANES data show that thyrotoxicosis is nearly three times more common in non-Hispanic Black individuals than in White individuals. The most common cause is Graves' disease, an autoimmune condition in which the immune system overstimulates the thyroid; other causes include toxic multinodular goiter and thyroid adenomas. Symptoms can include rapid heartbeat, unintended weight loss, anxiety, tremors, and heat sensitivity. Onset most commonly occurs between ages 20 and 50, though the condition is more prevalent overall in adults over 60. Treatment options include antithyroid medications, radioactive iodine therapy, and surgery, with the goal of restoring normal hormone levels and preventing cardiovascular and bone-related complications.
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone, slowing the body's metabolism and affecting nearly every organ system. Symptoms often develop gradually and include fatigue, weight gain, cold intolerance, depression, dry skin, and cognitive difficulties. Prevalence in the U.S. has been rising, growing from 9.6% of the population in 2012 to 11.7% in 2019, with women 5 to 9 times more likely than men to be affected. The most common cause — responsible for more than 70% of cases — is Hashimoto's thyroiditis, an autoimmune condition in which the immune system attacks the thyroid gland. Subclinical hypothyroidism, where TSH levels are elevated but symptoms may be mild or absent, adds significantly to the overall burden. Levothyroxine, the primary treatment for hypothyroidism, was the single most prescribed medication in the United States in 2023, underscoring just how widespread the condition has become. While hypothyroidism is highly manageable with consistent treatment, it requires lifelong medication and monitoring, with undertreated or undiagnosed cases carrying elevated risk for cardiovascular disease, infertility, and complications in pregnancy.
Infant and Newborn Nutrition
Infant and newborn nutrition encompasses the feeding practices, dietary guidelines, and health outcomes associated with nourishing babies from birth through the first year of life, with particular focus on breastfeeding, formula use, and the introduction of solid foods. Current U.S. Dietary Guidelines, along with recommendations from the American Academy of Pediatrics and the World Health Organization, advise exclusive breastfeeding for approximately the first six months, followed by continued breastfeeding alongside complementary foods for one to two years or longer. While initiation rates are relatively high, sustained exclusive breastfeeding remains a challenge — among infants born in 2022, 85.7% were ever breastfed, but only 27.9% were exclusively breastfed through six months, and just 40.8% were still breastfeeding at one year. Low rates of breastfeeding add more than $3 billion a year to U.S. medical costs for mothers and children. Infant formula serves as a safe and important alternative or supplement when breastfeeding is not possible, and solid foods are recommended beginning around six months. Disparities in breastfeeding rates persist across race, income, and geography, with infants in the Southeast United States significantly less likely to be breastfed at six months than those in other regions.
Intestinal Cancer
Your small intestine is part of your digestive system. It is a long tube that connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet or having Crohn's disease, celiac disease, or a history of colonic polyps can increase your risk. Possible signs of small intestine cancer include: Abdominal pain Weight loss for no reason Blood in the stool A lump in the abdomen Imaging tests that create pictures of the small intestine and the area around it can help diagnose intestinal cancer and show whether it has spread. Surgery is the most common treatment. Additional options include chemotherapy, radiation therapy, or a combination.
Iron Deficiency Anemia
Iron deficiency anemia is a common type of anemia — a condition in which the blood lacks adequate healthy red blood cells to carry sufficient oxygen to the body's tissues. It occurs when the body doesn't have enough iron to produce hemoglobin, the protein in red blood cells responsible for transporting oxygen. Iron deficiency can result from inadequate dietary intake, poor absorption, blood loss, or increased demand during pregnancy and growth.
Kidney Cysts
Kidney cysts are fluid-filled sacs that form on or within the kidneys. They fall into two main categories: simple cysts, which are benign and extremely common, and complex or polycystic cysts, which can signal a more serious inherited disorder. The prevalence of simple renal cysts is approximately 7.7% to 11.9% when detected by ultrasound, and as high as 27% to 41% when detected by CT imaging, which captures smaller cysts that ultrasound misses. Prevalence increases sharply with age — ranging from about 2.4% in the second decade of life to more than 35% in the seventh decade and beyond — and is nearly three times more common in men than in women. Most simple cysts cause no symptoms, require no treatment, and are discovered incidentally during imaging for unrelated conditions. The more serious form, autosomal dominant polycystic kidney disease (ADPKD), is a genetic condition involving progressive cyst growth throughout both kidneys. ADPKD affects 1 in 400 to 1,000 people, making it the most common genetic cause of renal failure worldwide, and accounts for 6% to 10% of all patients on dialysis in the United States. Management of simple cysts is typically watchful waiting, while ADPKD requires ongoing monitoring and, in advanced cases, dialysis or kidney transplantation.
Kidney Diseases
Chronic kidney disease (CKD) is a progressive condition in which the kidneys gradually lose their ability to filter waste and excess fluid from the blood, often leading to kidney failure and serious cardiovascular complications if left unmanaged. CKD affects more than 1 in 7 U.S. adults — an estimated 35.5 million Americans — with diabetes and high blood pressure being the two most common underlying causes. Despite its scale, awareness remains critically low: approximately 90% of people with CKD are not aware they have it, as the disease typically produces no symptoms in its early stages. CKD is most prevalent among adults 65 and older (34%), and disproportionately affects non-Hispanic Black adults, roughly 20% of whom have the condition. About 815,000 Americans are living with kidney failure, with nearly 555,000 currently on dialysis. CKD is the 9th leading cause of death in the U.S., claiming more lives than breast cancer or prostate cancer. Treatment focuses on slowing progression through blood pressure and blood sugar control, dietary changes, and medications, with dialysis or kidney transplantation reserved for end-stage disease.
Legionnaires' Disease
Legionnaires' disease is a severe form of pneumonia caused by inhaling water droplets or aerosols contaminated with Legionella bacteria, which thrive in warm water environments such as cooling towers, hot tubs, large plumbing systems, and decorative fountains. Around 6,000 cases are reported in the United States each year, though the actual burden is believed to be significantly higher — with an estimated 8,000 to 18,000 people hospitalized annually, as the disease is frequently misidentified as other forms of pneumonia. Cases have increased roughly ninefold in the U.S. from 2000 to 2018, with a disproportionately higher burden among socioeconomically vulnerable populations. Contributing factors include climate change, an aging population, aging infrastructure, and improved clinical awareness — though no single driver fully explains the rise. The disease is not transmitted person to person. Those most at risk include adults over 50, smokers, and immunocompromised individuals. With a fatality rate of roughly 10%, prompt antibiotic treatment is critical, and prevention centers on water management programs in buildings and healthcare facilities.
Lupus
Lupus, or systemic lupus erythematosus (SLE), is a chronic autoimmune disease in which the immune system mistakenly attacks healthy tissue throughout the body. It can affect the skin, joints, kidneys, brain, heart, lungs, and blood cells. Lupus is characterized by periods of illness (flares) and periods of remission, and its symptoms can range from mild to life-threatening.
Maternal Health
Maternal health encompasses the physical, mental, and social well-being of women during pregnancy, childbirth, and the postpartum period. Despite being one of the wealthiest nations in the world, the U.S. has the highest maternal mortality rate among comparable developed countries and is one of only seven nations to report a significant increase in pregnancy-related deaths since 2000, according to the World Health Organization. In 2024, 649 women died of maternal causes in the United States, reflecting a rate of 17.9 deaths per 100,000 live births. Racial disparities are severe and persistent — the maternal mortality rate for Black women was 44.8 per 100,000 live births in 2024, more than three times the rate for White women (14.2) and Hispanic women (12.1). Age is also a significant factor, with women aged 40 and older facing a maternal mortality rate five times higher than women under 25. Leading causes of maternal death include hemorrhage, cardiovascular conditions, infection, and mental health-related causes including substance use. Addressing the maternal health crisis requires expanding postpartum Medicaid coverage, growing the obstetric and midwifery workforce, and investing in community-based care models — particularly in states and regions with the highest mortality rates.
Meniere's Disease
Ménière's disease is a chronic disorder of the inner ear caused by abnormal fluid buildup in the labyrinth, producing unpredictable episodes of intense vertigo, fluctuating hearing loss, tinnitus (ringing in the ears), and a feeling of fullness or pressure in the affected ear. Over time, episodes can lead to permanent hearing loss and significant disruption to daily functioning. An estimated 600,000 to 750,000 people in the United States are living with Ménière's disease, with 45,000 to 60,000 new cases diagnosed each year. The peak incidence occurs between ages 40 and 60, with prevalence increasing with age and a notable female predominance. The exact cause remains unknown, though factors such as abnormal immune response, viral infection, genetics, and circulatory issues are believed to play a role. Diagnosis can be challenging due to symptom overlap with other vestibular and neurological conditions. There is no cure, but treatment — including dietary changes (particularly sodium restriction), diuretics, vestibular rehabilitation, and in severe cases injections or surgery — can help reduce the frequency and intensity of episodes and preserve quality of life.
Mental Disorders
Mental disorders encompass a broad range of conditions that affect mood, thinking, behavior, and daily functioning — including anxiety disorders, depression, bipolar disorder, schizophrenia, PTSD, OCD, and many others. Over 57.8 million U.S. adults — approximately 22.8% of the adult population — are affected by some form of mental illness, with 14.1 million (5.5%) living with serious mental illness that severely disrupts daily functioning. Mental disorders are among the most common and costly health conditions in the country, with anxiety disorders alone affecting an estimated 42.5 million adults annually. The lifetime prevalence of any mental disorder among U.S. adolescents aged 13–18 is approximately 49.5%, underscoring how early these conditions often emerge. Despite their prevalence, treatment access remains a persistent gap — 1 in 4 adults with any mental illness reported an unmet need for treatment, and more than 5 million adults with mental illness are uninsured. Disparities in diagnosis and care persist across gender, race, income, and geography, and stigma — while declining — remains a barrier to help-seeking. Effective treatments exist for most mental disorders, including psychotherapy, medication, and integrated care models, but investment in the mental health workforce and system capacity has not kept pace with growing need.
Movement Disorders
Movement disorders are a group of neurological conditions that cause abnormal or involuntary movements, or impair the ability to move normally. The category encompasses a wide spectrum of conditions — most notably Parkinson's disease, essential tremor, restless legs syndrome (RLS), dystonia, Huntington's disease, and ataxia — each with distinct causes, presentations, and progression patterns. Parkinson's disease, the most recognized movement disorder, affects an estimated 0.572% of North Americans aged 45 and older, with annual direct medical expenditures estimated between $7.4 and $8.6 billion. Essential tremor is even more common — a 2025 U.S. claims-based study found a diagnosed prevalence of 0.42% after age standardization, rising to 1.61% among adults 75 and older, with an estimated annual direct medical cost of approximately $9.4 billion. Restless legs syndrome affects millions more, with a global prevalence estimated at over 7%. Movement disorders are strongly age-associated, and projections suggest the number of Americans affected will nearly double between 2010 and 2050 as the population ages. Treatment varies widely by condition and may include medications (particularly dopaminergic therapies), physical therapy, deep brain stimulation, and emerging gene therapies, but most movement disorders remain progressive and without a cure.
Multiple Myeloma
Multiple myeloma is a cancer of plasma cells — a type of white blood cell in the bone marrow responsible for producing antibodies. In multiple myeloma, abnormal plasma cells multiply uncontrollably, crowding out healthy blood-forming cells and producing abnormal proteins (M proteins) that can cause kidney damage, bone destruction, and a weakened immune system. It is the second most common blood cancer after non-Hodgkin lymphoma.
Multiple Sclerosis
Multiple sclerosis is a chronic autoimmune disease in which the immune system attacks the myelin sheath — the protective covering of nerve fibers in the brain and spinal cord — disrupting communication between the brain and the rest of the body. Symptoms vary widely and can include fatigue, vision problems, numbness, weakness, difficulty walking, and cognitive changes, with unpredictable relapses and progressive disability over time. Approximately one million people in the United States are currently living with MS, with more than 450 new cases diagnosed each week — a number that has quadrupled since 1994. MS is significantly more common in women, who represent 74% of all U.S. cases, and the average age of diagnosis in the U.S. is 36. Contrary to long-held assumptions, MS is not exclusive to White populations — prevalence is actually highest among Black women, and racial disparities in both incidence and disease severity are increasingly documented. The most common form, relapsing-remitting MS, affects approximately 85% of all people with the disease. While there is no cure, a growing arsenal of disease-modifying therapies can slow progression and reduce relapse frequency, significantly improving outcomes for many patients.
Mycobacterial Infections
Mycobacteria are a type of germ. There are many different kinds. The most common one causes tuberculosis . Another one causes leprosy. Still others cause infections that are called atypical mycobacterial infections. They aren't "typical" because they don't cause tuberculosis . But they can still harm people, especially people with other problems that affect their immunity, such as AIDS. Sometimes you can have these infections with no symptoms at all. At other times, they can cause lung symptoms similar to tuberculosis : Cough Weight loss Coughing up blood or mucus Weakness or fatigue Fever and chills Night sweats Lack of appetite and weight loss Medicines can treat these infections, but often more than one is needed to cure the infection.
Obesity
Obesity is a chronic, complex disease characterized by excessive accumulation of body fat that impairs health. It is not simply a lifestyle issue but a recognized medical condition involving genetic, hormonal, behavioral, and environmental factors. Obesity increases the risk of numerous serious conditions including type 2 diabetes, heart disease, stroke, certain cancers, and joint problems. Body mass index (BMI) of 30 or higher is commonly used to define obesity, though waist circumference and body composition also matter.
Obsessive - Compulsive Disorder
Obsessive-compulsive disorder (OCD) is a chronic mental health condition characterized by intrusive, unwanted thoughts (obsessions) and repetitive behaviors or mental rituals (compulsions) performed to relieve the distress those thoughts cause. Despite its severity, OCD is frequently misunderstood, trivialized, and undertreated. An estimated 1.2% of U.S. adults had OCD in the past year, with a lifetime prevalence of 2.3% — meaning approximately 1 in 40 Americans will develop OCD at some point in their lives. Past-year prevalence is significantly higher in women (1.8%) than in men (0.5%). OCD is the fourth most common mental disorder globally, yet on average it takes 14 to 17 years from symptom onset for a person to receive a proper diagnosis and treatment — a staggering gap that leads to years of unnecessary suffering. Approximately 60% of patients with OCD experience co-occurring major depression, and anxiety disorders, ADHD, and tic disorders are also common comorbidities. The most effective treatments are cognitive behavioral therapy (specifically exposure and response prevention, or ERP) and serotonin reuptake inhibitor medications, though access to OCD-specialized care remains limited across much of the country.
Optic Nerve Disorders
Optic nerve disorders are a group of conditions affecting the optic nerve — the critical pathway that transmits visual signals from the eye to the brain — and are among the leading causes of vision loss and blindness worldwide. The category includes glaucoma, optic neuritis, ischemic optic neuropathy, and hereditary optic neuropathies such as Leber's hereditary optic neuropathy. Glaucoma is by far the most common optic nerve disorder, affecting approximately 4.22 million U.S. adults, with nearly half unaware of their condition. Optic neuritis — inflammation of the optic nerve most commonly associated with multiple sclerosis — is another significant condition: a 2025 study drawing on electronic health records from over 113 million patients found a U.S. prevalence of 51.6 per 100,000 people in 2023, with females at significantly higher risk than males, and Black individuals showing the highest prevalence among racial groups. Prevalence of optic neuritis increased steadily from 2016 to 2023, with notable rises among younger populations and the Hispanic community. Ischemic optic neuropathy — caused by reduced blood flow to the optic nerve — is the most common cause of sudden optic nerve-related vision loss in adults over 50. Across all types, early detection through comprehensive eye exams is critical, as optic nerve damage is often irreversible.
Personality Disorders
Personality disorders are a group of enduring, inflexible patterns of thinking, feeling, and behaving that deviate significantly from cultural expectations, cause significant distress or impairment, and are stable across many contexts over time. The DSM-5 recognizes ten distinct personality disorders organized into three clusters: Cluster A (odd or eccentric, including paranoid, schizoid, and schizotypal), Cluster B (dramatic or erratic, including borderline, antisocial, histrionic, and narcissistic), and Cluster C (anxious or fearful, including avoidant, dependent, and obsessive-compulsive). The prevalence of any personality disorder among U.S. adults is approximately 9.1%, with borderline personality disorder accounting for 1.4%. Roughly 1 in 11 Americans aged 18 and older meet diagnostic criteria for at least one personality disorder — a rate higher than the global prevalence of 7.8%. Personality disorders are diagnosed in 40–60% of psychiatric patients, making them the most common of all psychiatric diagnoses in clinical settings, and between 65–90% of people treated for a substance use disorder have at least one co-occurring personality disorder. Despite their prevalence and serious impact on functioning and relationships, personality disorders remain among the most undertreated mental health conditions, often requiring long-term, specialized psychotherapy such as dialectical behavior therapy (DBT) or schema therapy.
Pneumocystis Infections
Pneumocystis pneumonia (PCP), caused by the fungal organism Pneumocystis jirovecii, is a serious and potentially life-threatening lung infection that occurs almost exclusively in people with weakened immune systems. During the early years of the AIDS epidemic, PCP was the AIDS-defining illness for as many as two-thirds of patients in the United States, and it remains the most common serious opportunistic infection in people living with HIV. The landscape of PCP has shifted significantly with the advent of antiretroviral therapy — rates of PCP among hospitalized HIV patients declined from 6.7% in 2002 to 3.5% in 2014 — but the disease has not disappeared. The prevalence of non-HIV immunocompromising conditions among PCP hospitalizations has increased, with malignancy now the most common underlying condition, followed by organ transplantation, autoimmune diseases, and long-term corticosteroid use. Non-HIV patients with PCP face significantly worse outcomes than HIV patients, including higher rates of intubation, longer hospitalizations, and in-hospital mortality of 16% compared to 5% in HIV patients. Prevention through prophylactic trimethoprim-sulfamethoxazole (TMP-SMX) remains highly effective for high-risk populations, and prompt diagnosis and treatment are critical given the rapid progression of disease.
Pneumonia
Pneumonia is an infection of the lungs — caused by bacteria, viruses, or fungi — that inflames the air sacs and can fill them with fluid or pus, leading to cough, fever, chills, and difficulty breathing. It ranges from mild to life-threatening and is among the most common causes of hospitalization and death in the United States. Pneumonia results in approximately 1.2 million emergency department visits annually and was responsible for 41,627 deaths in 2024, or 12.2 per 100,000 population. Despite this ongoing toll, significant progress has been made — age-adjusted pneumonia mortality declined from 22.9 to 9.9 per 100,000 between 1999 and 2023, with males consistently experiencing higher mortality than females. Those at greatest risk include adults over 65, young children, and individuals with chronic conditions or weakened immune systems. Vaccination remains a primary prevention tool, yet only 25.1% of U.S. adults had ever received a pneumococcal vaccine as of 2024 — a concerning gap given the availability of highly effective vaccines. Community-acquired pneumonia (CAP) is the most common form, while hospital-acquired and ventilator-associated pneumonia carry significantly higher mortality rates. Treatment depends on the causative pathogen and may include antibiotics, antivirals, supportive care, or hospitalization.
Postpartum Depression
Postpartum depression (PPD) is a serious mood disorder that can occur after childbirth, characterized by persistent sadness, anxiety, exhaustion, and difficulty bonding with or caring for a newborn. It goes beyond the typical "baby blues" and can significantly impair a new mother's ability to function. Nationally, about 1 in 8 women experience symptoms of postpartum depression after giving birth, representing over 460,000 mothers each year — with rates as high as 1 in 5 in some U.S. states. The condition is on the rise: diagnosed PPD prevalence doubled from 9.4% in 2010 to 19.3% in 2021, with significant increases across all racial and ethnic groups — and the largest relative increase seen among Asian/Pacific Islander women (280%). Despite its prevalence, PPD remains dramatically underidentified — nearly 50% of mothers with postpartum depression are never diagnosed by a health professional, and less than 20% of women are screened for maternal depression. Risk factors include prior mental health history, low income, young or advanced maternal age, and limited social support. With proper treatment — including therapy, medication, and peer support — up to 80% of individuals with PPD achieve full recovery.
Prescription Drug Misuse
Prescription drug misuse refers to the use of prescription medications in ways other than prescribed — including taking higher doses, using someone else's prescription, or using drugs for non-medical purposes such as getting high. It encompasses misuse of opioids, stimulants, tranquilizers, sedatives, and benzodiazepines. An estimated 13.8 million Americans misuse prescription drugs each year, representing approximately 4.8% of the population aged 12 and older. Opioids remain the most consequential category — approximately 8 million people reported misusing prescription pain relievers in 2024, and the opioid crisis continues to drive devastating overdose rates. Opioid overdose deaths increased 885% from 1999 to 2023, with synthetic opioids — primarily fentanyl — now accounting for nearly 70% of all overdose deaths. Beyond opioids, an estimated 3.7 million people misuse prescription stimulants and 4.9 million misuse prescription tranquilizers or sedatives annually. Young adults are among the most affected, and 7.6 million people — more than half of all who misuse prescriptions — meet criteria for addiction to the drugs they misuse. Addressing prescription drug misuse requires a coordinated approach spanning prescriber education, access to treatment for opioid use disorder, harm reduction strategies, and expanded mental health support.
Prostate Cancer
Prostate cancer is one of the most common cancers in men, developing in the prostate — a small walnut-shaped gland that produces seminal fluid. Most prostate cancers grow slowly and remain confined to the prostate gland, where they may cause little harm. However, some types are aggressive and can spread quickly. Early detection through screening greatly improves outcomes, and many men with prostate cancer live long, healthy lives with appropriate monitoring or treatment.
Psoriatic Arthritis
Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales. You usually get them on your elbows, knees, scalp, back, face, palms and feet, but they can show up on other parts of your body. Some people with psoriasis have psoriatic arthritis. It causes pain, stiffness, and swelling of the joints. It is often mild, but can sometimes be serious and affect many joints. The joint and skin problems don't always happen at the same time. Your doctor will do a physical exam and imaging tests to diagnose psoriatic arthritis. There is no cure, but medicines can help control inflammation and pain. In rare cases, you might need surgery to repair or replace damaged joints.
Pulmonary Hypertension
Pulmonary hypertension (PH) is a serious condition characterized by abnormally high blood pressure in the arteries connecting the heart to the lungs, forcing the right side of the heart to work harder and eventually leading to heart failure. It is classified into five groups based on underlying cause, ranging from pulmonary arterial hypertension (PAH) — the most severe and least common form — to PH caused by left heart disease, lung disease, chronic blood clots, or unclear mechanisms. The prevalence of PAH in the United States and Europe is estimated at 15 to 50 individuals per million, making it a rare but devastating disease. Broader pulmonary hypertension affecting all five groups is significantly more common, as it frequently develops as a complication of heart failure, COPD, sleep apnea, and connective tissue disorders. PH and PAH are often diagnosed late due to nonspecific symptoms such as shortness of breath, fatigue, and dizziness — and late-stage diagnosis portends a poor prognosis. Prevalence rates increase with age and are higher among women. Treatment has advanced considerably and includes targeted vasodilator therapies, anticoagulants, and in select patients, lung transplantation, with the five-year survival rate for PAH improving significantly over the past two decades.
Sarcoidosis
Sarcoidosis is an inflammatory disease characterized by the formation of granulomas — clusters of immune cells — in various organs throughout the body. Most commonly, it affects the lungs and lymph nodes, but it can involve the skin, eyes, heart, liver, and nervous system. The cause is not fully understood, but it is thought to result from an overactive immune response to an unknown trigger in genetically susceptible individuals. Many cases resolve on their own, while others require treatment to prevent organ damage.
Schizophrenia
Schizophrenia is a severe, chronic mental disorder characterized by hallucinations, delusions, disorganized thinking, and impaired ability to function — profoundly affecting how a person perceives reality and engages with the world. The prevalence of schizophrenia among U.S. adults is estimated at approximately 3.7 million people, or 1.2% of adults between the ages of 18 and 65, and it ranks as the third leading cause of disability worldwide. Onset typically occurs in late adolescence to early adulthood, with males generally diagnosed 3 to 5 years earlier than females. Racial disparities in diagnosis are pronounced — Black individuals in the U.S. are approximately 2.4 to 3 times more likely to receive a schizophrenia diagnosis than White individuals, a pattern increasingly attributed to structural inequities rather than differences in underlying prevalence. The human and economic toll is enormous: the estimated economic burden of schizophrenia in the U.S. was $343.2 billion in 2019, more than doubling in just six years. People with schizophrenia lose an estimated average of 28.5 years of potential life, largely due to preventable physical illness and elevated suicide risk. Antipsychotic medications and coordinated specialty care programs can significantly improve outcomes, but access to consistent, high-quality care remains a major challenge.
Sickle Cell Disease
Sickle cell disease (SCD) is an inherited blood disorder that affects hemoglobin, the protein in red blood cells that carries oxygen. In SCD, abnormal hemoglobin causes red blood cells to become rigid, sticky, and shaped like a crescent or sickle. These sickled cells can block blood flow, causing pain, organ damage, and other complications. SCD is lifelong and requires ongoing medical care, but advances in treatment have significantly improved life expectancy and quality of life for those affected.
Small Intestine Disorders
Your small intestine is the longest part of your digestive system - about twenty feet long! It connects your stomach to your large intestine (or colon) and folds many times to fit inside your abdomen. Your small intestine does most of the digesting of the foods you eat. It has three areas called the duodenum, the ileum, and the jejunum. Problems with the small intestine can include: Bleeding Celiac disease Crohn 's disease Infections Intestinal cancer Intestinal obstruction Irritable bowel syndrome Ulcers, such as peptic ulcer Treatment of disorders of the small intestine depends on the cause.
Throat Cancer
Throat cancer is a broad term referring to malignancies of the pharynx (oropharynx, nasopharynx, hypopharynx) and larynx (voice box) — structures essential to breathing, speaking, and swallowing. Most throat cancers are squamous cell carcinomas arising from the moist mucosal lining of these passages. The American Cancer Society estimates approximately 60,480 new cases of oral cavity and oropharyngeal cancer and about 12,290 new cases of laryngeal cancer in 2026, with a combined total of more than 17,000 deaths. The epidemiology of throat cancer is shifting significantly: while tobacco and alcohol historically drove the majority of cases, rates of HPV-associated oropharyngeal cancer have been rising steadily since the mid-2000s, with death rates for mouth and throat cancers increasing approximately 0.7% per year from 2009 through 2022 — reversing decades of prior decline. Men account for more than 80% of oropharyngeal cancer cases, and the average age at diagnosis is 64. Racial disparities are notable — Black men are more likely than White men to develop laryngeal cancer and more likely to die from it. Treatment typically involves surgery, radiation, chemotherapy, or a combination depending on location and stage, with five-year survival rates varying widely from roughly 30% for distant-stage disease to over 75% for localized cancers.
Thyroid Diseases
Thyroid disease is an umbrella term covering a spectrum of conditions affecting the thyroid gland — a butterfly-shaped gland in the neck that regulates metabolism, energy, heart rate, and hormone balance. The major categories include hypothyroidism (underactive thyroid), hyperthyroidism (overactive thyroid), autoimmune thyroid disease (Hashimoto’s and Graves’ disease), thyroid nodules, goiter, and thyroid cancer. Collectively, thyroid disorders represent one of the most prevalent endocrine conditions in the United States. The age-standardized prevalence of diagnosed thyroid disease among U.S. adults is approximately 5.05%, with the highest rates observed in non-Hispanic Whites (8.1%), adults 60 and older (15.4%), and women. Autoimmune thyroid disease — in which the immune system attacks the thyroid — is the leading cause of both hypothyroidism and hyperthyroidism in the U.S., and a 2025 NHANES-based study found that a substantial proportion of cases remain undiagnosed at the population level. Thyroid cancer adds a growing malignant dimension: an estimated 44,020 new cases of thyroid cancer were projected for 2025 — the ninth most common cancer among women in the United States — with incidence rising steadily over recent decades. Women are disproportionately affected across all thyroid conditions, and levothyroxine — the primary treatment for hypothyroidism — remains the single most prescribed medication in the country, underscoring the enormous and often underappreciated scale of thyroid disease in America.
Tuberculosis
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis that primarily affects the lungs but can spread to other organs, transmitted through airborne droplets when an infected person coughs, speaks, or sneezes. Globally, TB remains the deadliest infectious disease in the world, killing more than 1 million people annually. In the U.S., TB was long considered a disease in decline, but recent years have reversed that trend. After surging to 10,347 cases in 2024 — the highest count since 2011 and an 8% increase over 2023 — provisional CDC data show 10,260 TB cases reported in 2025, a modest 1% decline but still well above pre-pandemic levels. The vast majority of U.S. TB cases (77%) occur in people born outside the country, with a rate of 15.4 per 100,000 among non-U.S.-born individuals compared to just 0.8 per 100,000 among U.S.-born individuals. One-third of all cases involve adults aged 25 to 44. A critical complicating factor is latent TB infection — in which the bacteria remain dormant and non-contagious — which affects an estimated 13 million Americans and can reactivate when the immune system is weakened. Drug-resistant TB strains pose an increasing global concern, and eliminating TB in the U.S. requires a dual strategy of treating active disease while identifying and treating latent infections in high-risk populations.