A chronic inflammatory skin condition of the pilosebaceous unit characterized by comedones, papules, pustules, nodules, and cysts. Affects 85% of adolescents but can persist into adulthood. Severe forms include nodulocystic acne and acne conglobata with risk of permanent scarring.

A neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. Begins in childhood and often persists into adulthood. Affects approximately 5-7% of children and 2.5-4% of adults globally. Three subtypes: predominantly inattentive, predominantly hyperactive-impulsive, and combined.

Progressive degenerative disease of the macula causing central vision loss. Leading cause of irreversible blindness in adults over 50 in developed countries. Dry (atrophic) and wet (neovascular) forms.

A chronic inflammatory arthritis primarily affecting the axial skeleton (spine and sacroiliac joints), causing pain, stiffness, and potential fusion. A form of spondyloarthritis. Strong association with HLA-B27. Onset typically in young adulthood.

A group of mental health conditions characterized by excessive fear, worry, and related behavioral disturbances. Generalized Anxiety Disorder (GAD) involves persistent, uncontrollable worry about everyday things. Most common mental health disorder.

Chronic inflammatory airway disease causing reversible bronchospasm, wheezing, dyspnea. Affects 262 million globally. Can be life-threatening during severe attacks.

The most common sustained cardiac arrhythmia, characterized by chaotic electrical activity in the atria leading to irregular ventricular response. Increases risk of stroke five-fold and heart failure. Prevalence increases with age, affecting ~10% of people over 80.

A complex neurodevelopmental condition characterized by challenges with social communication and interaction, and restricted, repetitive patterns of behavior, interests, or activities. Spectrum disorder ranging from mild to severe. Affects approximately 1-2% of population, more common in males.

Carrier state of beta-thalassemia with one normal and one mutated beta-globin gene. Mild microcytic anemia, usually asymptomatic. Important for genetic counseling as carriers can have children with thalassemia major if partner also carrier.

A mental health condition causing extreme mood swings including emotional highs (mania/hypomania) and lows (depression). Formerly called manic depression. Types I and II. Affects approximately 2.8% of adults globally.

A chronic lung condition characterized by permanent abnormal dilation and destruction of bronchial walls, leading to impaired mucus clearance, recurrent infections, and progressive lung damage. Often underdiagnosed. Can be post-infectious or associated with underlying conditions.

A clouding of the normally clear lens of the eye, leading to decreased vision. Most commonly age-related but can be congenital or secondary to other conditions. Leading cause of blindness globally but highly treatable.

Progressive, irreversible loss of kidney function over months to years. Stage 4 (eGFR 15-29 mL/min) and Stage 5/end-stage renal disease (eGFR <15 mL/min or dialysis). Requires renal replacement therapy. Leading causes: diabetes and hypertension.

A progressive inflammatory disease of the pancreas causing permanent structural damage and loss of function. Characterized by chronic abdominal pain, exocrine insufficiency (malabsorption), and endocrine insufficiency (diabetes). Most commonly caused by alcohol.

End-stage liver disease characterized by replacement of normal hepatic architecture with fibrosis and regenerative nodules. Results from chronic liver injury. Irreversible but progression can be halted.

An extremely painful primary headache disorder characterized by severe unilateral orbital, supraorbital, or temporal pain lasting 15-180 minutes, occurring in clusters (periods of frequent attacks). Known as 'suicide headache' due to intensity. More common in men.

Advanced chronic obstructive pulmonary disease (GOLD grades 3-4, FEV1 <50% predicted). Characterized by persistent respiratory symptoms and airflow limitation. Third leading cause of death globally. Severe disease significantly impairs quality of life and increases mortality.

Respiratory illness caused by SARS-CoV-2 virus. Global pandemic 2020-2023. Range from asymptomatic to severe pneumonia, ARDS, death. Long COVID affects millions.

Persistent symptoms following acute COVID-19 infection, lasting weeks to months after initial recovery. Affects multiple organ systems. Estimated 10-30% of COVID-19 survivors develop long COVID. Symptoms can be debilitating and fluctuating.

An inherited disorder of renal amino acid transport causing excessive urinary excretion of cystine and other dibasic amino acids. Cystine precipitates forming recurrent kidney stones (cystine calculi), potentially leading to renal damage.

Cognitive decline caused by impaired blood flow to the brain, typically from strokes or small vessel disease. Second most common dementia after Alzheimer's. Often coexists with Alzheimer's (mixed dementia). Stepwise progression correlating with vascular events.

Mosquito-borne viral infection caused by dengue virus (4 serotypes). Transmitted by Aedes aegypti and Aedes albopictus. 100-400 million infections annually. Can progress to severe dengue (dengue hemorrhagic fever/shock syndrome).

A diabetes complication affecting the eyes, caused by damage to blood vessels in the retina. Leading cause of blindness in working-age adults. Can progress from mild non-proliferative to proliferative retinopathy with neovascularization.

A chronic, relapsing inflammatory skin condition characterized by intense itching, dry skin, and eczematous lesions. Part of the 'atopic triad' with asthma and allergic rhinitis. Affects up to 20% of children and 10% of adults. Often begins in infancy.

Chronic neurological disorder characterized by recurrent, unprovoked seizures due to excessive neuronal activity in brain. Affects 50 million people worldwide. Many types: focal, generalized, unknown onset. Often begins in childhood or after age 65.

A chronic disorder characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive difficulties. Central sensitization syndrome where pain signals are amplified. Affects 2-4% of population, predominantly women.

An intestinal infection caused by the parasite Giardia lamblia (also called Giardia intestinalis or duodenalis). Common waterborne disease causing diarrhea, gas, and stomach cramps. Most common intestinal parasitic disease in US.

A group of eye conditions damaging the optic nerve, often due to abnormally high pressure in the eye (intraocular pressure). Leading cause of irreversible blindness worldwide. Primary open-angle glaucoma most common; angle-closure glaucoma is emergency.

The most common enzyme deficiency worldwide, causing hemolytic anemia with oxidative stress. X-linked. Affects 400 million people, most commonly in malaria-endemic regions (protective against malaria). Triggers include fava beans, certain drugs, infections.

A chronic inflammatory arthritis caused by hyperuricemia and deposition of monosodium urate crystals in joints and tissues. Characterized by recurrent acute flares and progressive joint damage. Associated with metabolic syndrome, cardiovascular disease, and chronic kidney disease.

Structural abnormalities of one or more heart valves (aortic, mitral, tricuspid, pulmonic) causing stenosis (narrowing) or regurgitation (leakage). Can be congenital or acquired. Aortic stenosis most common in elderly; rheumatic heart disease prevalent in developing countries.

Rare inherited bleeding disorders caused by deficiency in clotting factor VIII (Hemophilia A) or IX (Hemophilia B/Christmas disease). X-linked recessive inheritance affecting primarily males. Characterized by prolonged bleeding after injury, surgery, or spontaneous bleeding into joints and muscles.

Viral infection causing liver inflammation, transmitted via blood. Often chronic, leading to cirrhosis and liver cancer. Curable with direct-acting antivirals (DAAs). 58 million chronically infected.

A viral infection caused by hepatitis C virus (HCV) that causes liver inflammation, potentially leading to cirrhosis, hepatocellular carcinoma, and liver failure. Chronic infection develops in 75-85% of acute cases. Curable with direct-acting antivirals.

Viral respiratory infection caused by influenza A and B viruses. Annual epidemics causing significant morbidity and mortality. Vaccine composition updated yearly.

A common functional gastrointestinal disorder affecting the large intestine, characterized by abdominal pain and altered bowel habits (diarrhea, constipation, or both). Brain-gut interaction disorder without structural abnormalities. Affects 10-15% of global population.

Recurrent formation of solid mineral deposits in the kidneys, causing severe pain and potential kidney damage. Affects 1 in 10 people; 50% recurrence rate within 5-10 years without preventive measures. Most common type: calcium oxalate.

A myeloproliferative neoplasm characterized by the Philadelphia chromosome (t(9;22)) creating the BCR-ABL fusion gene, leading to constitutively active tyrosine kinase. Chronic phase is indolent; without treatment progresses to accelerated phase and blast crisis.

The progressive form of non-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis with inflammation and hepatocyte injury, with or without fibrosis. Can progress to cirrhosis and hepatocellular carcinoma. Now called MASH (metabolic dysfunction-associated steatohepatitis).

Malignant tumor arising from lung tissue. Leading cause of cancer death worldwide (1.8 million deaths/year). Two main types: non-small cell (NSCLC, 85%) and small cell (SCLC, 15%). Strongly associated with smoking but affects non-smokers too.

A common but serious mood disorder causing persistent feelings of sadness and loss of interest. Affects approximately 280 million people worldwide, leading cause of disability globally. Can occur at any age.

Parasitic disease transmitted by infected Anopheles mosquitoes. Caused by Plasmodium species (falciparum, vivax, ovale, malariae, knowlesi). Major public health problem in tropical regions, causing ~600,000 deaths annually, mostly children under 5.

A malignant tumor of melanocytes, the pigment-producing cells of the skin. The most serious form of skin cancer with high metastatic potential. Incidence rising globally, particularly in fair-skinned populations. Early detection critical for survival.

A disorder of the inner ear causing episodes of vertigo, fluctuating hearing loss, tinnitus, and aural fullness. Caused by abnormal fluid buildup in the inner ear (endolymphatic hydrops). Affects approximately 12-30 per 100,000 people.

A life-threatening infection of the meninges (membranes surrounding the brain and spinal cord) caused by bacteria. Medical emergency requiring immediate antibiotic treatment. Can cause brain damage, hearing loss, and death. Vaccines available for some types.

A primary headache disorder characterized by recurrent attacks of moderate to severe throbbing pain, usually on one side of the head, often accompanied by nausea, vomiting, and sensitivity to light and sound. Can last 4-72 hours. Second most disabling condition worldwide.

A contagious disease most commonly caused by Epstein-Barr virus (EBV). Characterized by fever, sore throat, swollen lymph nodes, and fatigue. Often called 'mono' or 'kissing disease' due to transmission via saliva. Most common in adolescents and young adults.

Complex chronic disease characterized by excessive adipose tissue accumulation (BMI >=35). Associated with metabolic dysfunction, inflammation, and increased morbidity/mortality. Now recognized as relapsing-remitting disease requiring long-term management.

A chronic mental health disorder characterized by uncontrollable, recurring thoughts (obsessions) and behaviors (compulsions) that the person feels compelled to repeat. Often time-consuming and interferes with daily life.

A systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to increased bone fragility and fracture risk. Often called the 'silent disease' because bone loss occurs without symptoms until fracture occurs.

Infection causing inflammation of lung air sacs (alveoli). Can be bacterial, viral, or fungal. Leading cause of death in children worldwide and serious illness in elderly.

A common hormonal disorder affecting women of reproductive age, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Leading cause of infertility. Associated with metabolic syndrome and increased cardiovascular risk.

A chronic immune-mediated inflammatory skin disease characterized by well-demarcated, erythematous plaques with silvery scale. Affects 2-3% of global population. Associated with psoriatic arthritis, cardiovascular disease, and metabolic syndrome.

A mental health condition triggered by experiencing or witnessing a terrifying event. Characterized by intrusive memories, avoidance, negative changes in thinking and mood, and hyperarousal. Can develop after combat, assault, accidents, or natural disasters.

The most common chronic rheumatic disease in children, characterized by persistent joint inflammation lasting >6 weeks in children <16 years. Multiple subtypes including oligoarticular, polyarticular, and systemic (Still's disease). Can cause permanent joint damage and growth abnormalities.

Severe chronic mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions. Involves positive symptoms (hallucinations, delusions), negative symptoms (apathy, withdrawal), and cognitive impairment.

A life-threatening organ dysfunction caused by a dysregulated host response to infection. Medical emergency with high mortality. Septic shock is a subset with circulatory and cellular/metabolic dysfunction. Leading cause of death in hospitals.

A sleep-related breathing disorder characterized by recurrent episodes of complete or partial upper airway obstruction during sleep, causing apneas or hypopneas. Leads to fragmented sleep, daytime sleepiness, and cardiovascular complications. Often undiagnosed.

A bacterial infection of the throat and tonsils caused by group A Streptococcus (GAS). Common in children but can affect all ages. If untreated, can lead to serious complications including rheumatic fever and post-streptococcal glomerulonephritis.

Acute cerebral infarction caused by interruption of blood supply to the brain, typically from thrombosis or embolism. The most common type of stroke (85% of all strokes). Time-critical emergency requiring rapid intervention. Leading cause of disability worldwide.

A parasitic disease caused by Toxoplasma gondii. Most people experience no symptoms, but can cause serious complications in pregnant women and immunocompromised individuals. Transmitted through undercooked meat, cat feces, and mother-to-child.

Bacterial infection caused by Mycobacterium tuberculosis, primarily affecting lungs but can involve any organ. Leading infectious cause of death worldwide. Latent infection common; active disease in 5-10% of infected.

Autoimmune destruction of pancreatic beta cells causing absolute insulin deficiency. Requires lifelong exogenous insulin. Onset typically in childhood/adolescence but can occur at any age.

Progressive metabolic disorder characterized by insulin resistance and relative insulin deficiency. Accounts for 90-95% of diabetes cases. Strongly associated with obesity and sedentary lifestyle.

An autoimmune disorder characterized by loss of melanocytes resulting in depigmented patches of skin and hair. Affects 0.5-2% of global population. Can be segmental (limited) or non-segmental (generalized). Associated with other autoimmune diseases.

A serious bacterial infection causing thick gray membrane in throat and nose, breathing difficulty, heart damage, and nerve paralysis. Caused by Corynebacterium diphtheriae. Once major childhood killer, now rare in vaccinated populations. Vaccine-preventable.

A life-threatening bacterial infection caused by Salmonella typhi. Spread through contaminated food and water. Causes sustained high fever, abdominal pain, and rose-colored spots. Endemic in areas with poor sanitation. Vaccine-preventable.

An acute diarrheal infection caused by Vibrio cholerae bacteria. Causes severe watery diarrhea and dehydration, can kill within hours if untreated. Spread through contaminated water. Major public health problem in areas with poor sanitation.

A common bacterial infection affecting any part of the urinary system including kidneys, ureters, bladder, and urethra. Most commonly affects the lower urinary tract (bladder and urethra). Women are at greater risk than men. Recurrent UTIs affect 20-30% of women.

The involuntary loss of bladder control, ranging from occasional leakage to complete inability to hold urine. Affects twice as many women as men, especially after pregnancy, childbirth, and menopause. Not a normal part of aging but becomes more common with age.

The consistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. Affects approximately 50% of men aged 40-70. Often an early indicator of cardiovascular disease. Can significantly impact quality of life and relationships.

A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. Part of a spectrum of painful bladder syndromes. More common in women. Symptoms often mimic UTI but urine cultures are negative. Cause is unknown but may involve bladder lining defects.

A connective tissue disorder characterized by the development of fibrous scar tissue (plaque) inside the penis, causing curved, painful erections. Affects 3-9% of men, most commonly between ages 45-60. Can significantly impact sexual function and psychological well-being.

A collection of fluid in the scrotum around the testicle, causing swelling. Common in newborns (usually resolves within first year) and older men. Typically painless but can cause discomfort due to swelling. Two types: communicating (patent processus vaginalis) and non-communicating.

Enlargement of the veins within the loose bag of skin holding the testicles (scrotum), similar to varicose veins in legs. Occurs in 15% of men, most commonly on left side due to venous anatomy. Leading cause of correctable male infertility.

A surgical emergency caused by twisting of the spermatic cord, cutting off blood supply to the testicle. Most common in adolescent males (ages 12-18) but can occur at any age. Requires immediate treatment within 6 hours to save the testicle. Affects 1 in 4,000 males under 25 annually.

Inflammation of the epididymis, the coiled tube at the back of the testicle that stores and carries sperm. Most common cause of acute scrotal pain in adults. Can be caused by bacterial infection (sexually transmitted or urinary pathogens) or non-infectious inflammation.

Inflammation of the urethra, the tube that carries urine from the bladder out of the body. Most commonly caused by sexually transmitted infections (chlamydia, gonorrhea) but can also be non-infectious. Affects both men and women, though symptoms are more prominent in men.

An anxiety disorder characterized by recurrent unexpected panic attacks—sudden periods of intense fear that reach a peak within minutes. Affects 2-3% of adults annually. Often associated with agoraphobia (fear of situations where escape might be difficult).

A chronic mental health condition characterized by intense, persistent fear of being watched and judged by others. Goes beyond ordinary shyness. Affects approximately 7% of adults. Often begins in childhood or adolescence. Can severely impact social and occupational functioning.

A highly contagious, vaccine-preventable liver infection caused by hepatitis A virus. Transmitted through fecal-oral route, typically via contaminated food/water or close contact. Usually self-limited with full recovery and no chronic infection. Common in areas with poor sanitation.

A liver disease caused by hepatitis E virus, transmitted primarily through contaminated water. Similar to hepatitis A in transmission and course. Most common in South Asia and East Asia. Genotypes 1 and 2 cause large waterborne outbreaks; genotypes 3 and 4 are zoonotic. High mortality in pregnant women (15-25%).

Inability to fully digest lactose, the sugar in milk and dairy products, due to deficiency of lactase enzyme in the small intestine. Very common worldwide, especially in certain ethnic groups. Not dangerous but can cause uncomfortable symptoms.

A parasitic disease caused by the nematode worm Onchocerca volvulus, transmitted through the bites of infected blackflies. Leading cause of infectious blindness worldwide. Affects approximately 20-25 million people, primarily in sub-Saharan Africa. WHO goal is elimination by 2030.

A parasitic disease caused by Leishmania protozoa, transmitted by sandfly bites. Three main forms: cutaneous (skin sores), mucocutaneous (destruction of mucous membranes), and visceral (affects organs, fatal if untreated). Affects 1-2 million people annually, with 350 million at risk in 98 countries.

A viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV). First reported in Saudi Arabia in 2012. Transmitted from camels to humans and person-to-person in close contact. Case fatality rate approximately 35%. Most cases in Arabian Peninsula.

A complex, chronic disorder characterized by extreme fatigue that cannot be explained by any underlying medical condition and does not improve with rest. Associated with post-exertional malaise, cognitive impairment, and orthostatic intolerance.

An infection of the female reproductive organs, usually caused by sexually transmitted bacteria spreading from the vagina to uterus, fallopian tubes, or ovaries. Affects approximately 4.4% of women of reproductive age. Leading preventable cause of infertility and ectopic pregnancy.

Inflammation of the vagina that can result in discharge, itching and pain. The most common types are bacterial vaginosis, yeast infections, and trichomoniasis. Affects millions of women annually and is one of the most common reasons for gynecologic visits.

A chronic pain condition affecting the vulva, characterized by burning, stinging, irritation, or rawness. Affects up to 16% of women. The cause is unknown and diagnosis is often delayed. Significantly impacts quality of life and sexual function.

Abnormally heavy or prolonged menstrual bleeding affecting up to 25% of women. Can cause anemia and significantly impact quality of life. Often caused by hormonal imbalances, uterine fibroids, or bleeding disorders.

A combination of physical and emotional symptoms that occur 1-2 weeks before menstruation. Affects up to 90% of women of reproductive age. Severe form (PMDD) affects 3-8% and causes significant functional impairment.

Persistent or recurrent genital pain that occurs just before, during, or after intercourse. Affects up to 20% of women. Can have physical or psychological causes. Significantly impacts sexual health and relationships.

A neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity. Affects approximately 5-7% of children and 2.5-5% of adults globally. Often persists into adulthood and can significantly impact academic, occupational, and social functioning.

A condition characterized by low levels of vitamin B12, leading to megaloblastic anemia and potential neurological complications. Affects approximately 6% of people under 60 and up to 20% of those over 60. Can cause irreversible nerve damage if untreated.

Liver damage caused by excessive alcohol consumption, ranging from fatty liver to alcoholic hepatitis and cirrhosis. A leading cause of liver disease worldwide. Risk increases with amount and duration of alcohol use. Can be reversible in early stages.