Life and health

Common warts

Common warts (verruca vulgaris) are benign HPV-caused skin growths, rough cauliflower-like papules on hands, knees, elbows; treated with salicylic acid or cryotherapy, often resolving spontaneously.

Common wheat (Triticum aestivum), or bread wheat, is an allohexaploid cereal (AABBDD, 2n=42) formed from emmer and Aegilops tauschii about 8,000-11,000 years ago; the world's leading wheat for bread flour.

Common whitetail

Common whitetail (Plathemis lydia, formerly Libellula lydia), a North American skimmer dragonfly; males chalky white abdomen with one dark wing band, females brown with three wing spots, ponds and slow streams.

Common wood pigeon

Common wood pigeon (Columba palumbus), also woodpigeon, Pigeon ramier: a large European Columbidae pigeon with white neck patches and wing bars; IUCN Least Concern, 51–73 million mature individuals, major UK crop pest.

Common yabby

Common yabby (Cherax destructor), also yabbie or smooth freshwater crayfish, an Australian freshwater crayfish of the Murray-Darling Basin; hardy burrower up to 20 cm, farmed for food, invasive outside its native range.

Commotio cordis

Commotio cordis, also called cardiac concussion, is ventricular fibrillation triggered by a blunt chest blow during a 10-20 ms vulnerable window of the heartbeat, mainly in young male athletes; survival rose from 10-15% to over 60% with rapid CPR and AED use.

Oct 20, 2026

Commotio retinae

Commotio retinae, or Berlin's edema, is transient gray-white outer retinal opacification after blunt closed-globe or blast trauma, seen in about 30% of hospital-treated eye injuries; photoreceptor outer segments are disrupted, and most cases resolve without treatment.

Communicating hydrocephalus

Communicating hydrocephalus (non-obstructive hydrocephalus, ICD-11 8D64.0): impaired CSF reabsorption without ventricular outflow blockage; causes include subarachnoid hemorrhage and meningitis; chronic form is normal pressure hydrocephalus, treated with shunts.

Communication Devices for People with Disabilities

Communication devices for people with disabilities, known as AAC (augmentative and alternative communication), include picture boards, gestures, and speech-generating devices; about 97 million people worldwide may benefit, with no single best system.

Community (ecology)

Community (ecology): an assemblage of interacting species populations in an area, studied via richness, diversity, structure, species interactions, and niche versus neutral assembly theory.

Community health

Community health: a public health field focused on the health of a defined population through community engagement, community health centers (US, since 1965), and community health worker programs, distinct from individual clinical care.

Community Health Centers

Community health centers (CHCs, neighborhood health centers, FQHCs) are US nonprofit clinics founded in 1965 under the War on Poverty, patient-governed, serving low-income Americans regardless of ability to pay.

Community Health Nurses

Community health nurses, also called public health nurses, care for whole populations through health promotion, prevention, and home-based care. Rooted in Lillian Wald's 1893 Henry Street Settlement, the field spans contact tracing, vaccination, and nurse home visiting.

Oct 20, 2026

Community Health Services

Community Health Services: diagnostic, therapeutic, and preventive health services delivered to individuals in the community (MeSH D003153), spanning community nursing, home care, mental health, and preventive care, delivered by mixed professional teams outside hospitals.

Community Health Workers

Community health workers (CHWs), also called lay or close-to-community health workers, are non-professional, paid or volunteer community-based health workers with under two years of training; ILO ISCO 3253; central to primary health care since Alma-Ata 1978.

Community Hospitals

Community hospitals: small, locally serving hospitals. US AHA category of 5,121 nonfederal short-term hospitals (84% of all US hospitals); in England, GP- and nurse-led local hospitals under 100 beds providing intermediate and rehabilitation care, descended from 1859 cottage hospitals.

Oct 20, 2026

Community Mental Health Centers

Community Mental Health Centers (CMHCs) are US facilities created by the 1963 Community Mental Health Act to deliver local psychiatric services, driving deinstitutionalization and later the CCBHC model.

Community Mental Health Services

Community mental health services provide outpatient, team-based, crisis, peer, and supported-living care outside psychiatric institutions; defined by WHO, shaped by the 1963 US Community Mental Health Act, and supported by Cochrane and ACT trial evidence.

Community Participation

Community participation: involvement of community members in community affairs, central to public health since Alma-Ata 1978; typologies include Arnstein's 1969 ladder and Rifkin's mobilization-collaboration-empowerment continuum.

Community reinforcement and family training

Community reinforcement and family training (CRAFT) is a behavioral program that trains families to encourage a loved one's addiction treatment, succeeding about two-thirds of the time.

COMMUNITY study

COMMUNITY (COVID 19 Immunity) study: longitudinal cohort launched April 2020 at Danderyd Hospital, Stockholm, following 2,149 healthcare workers and 118 hospitalized COVID-19 patients with blood and mucosal sampling every 4 months; NCT06784739; known for hybrid immunity and secretory IgA findings.

Community Support

Community support: help from family, friends, neighbors, and community organizations, a social determinant of health linked to lower mortality and hardship, delivered via community health workers, peer support, and social prescribing.

Community trial

A community trial is an epidemiology study design in which whole communities, rather than individuals, are randomized to a health intervention, capturing population-level and herd effects.

Community-acquired pneumonia

Community-acquired pneumonia (CAP) is lung infection acquired outside hospital, caused mainly by Streptococcus pneumoniae and respiratory viruses. Diagnosed clinically plus chest imaging; managed with timely antibiotics, severity scores (CRB65, severe CAP criteria), and, per 2025 ATS guidance, corticosteroids in severe cases.

Comorbidities of rheumatoid arthritis

The comorbidities of rheumatoid arthritis are additional conditions that drive excess deaths in RA, chiefly cardiovascular disease, serious infection, osteoporosis, and roughly doubled lymphoma risk, with 75.7% of patients having at least one other long-term condition.

Comorbidity

Comorbidity: co-occurrence of more than one disease or condition in one person; coined by Alvan Feinstein in 1970; measured with indices such as Charlson and Elixhauser; related to but distinct from multimorbidity.

COMP

COMP (cartilage oligomeric matrix protein, TSP-5, THBS5) is a 524,000-Da pentameric extracellular matrix glycoprotein of cartilage and tendon; mutations cause pseudoachondroplasia and multiple epiphyseal dysplasia, and serum COMP is an osteoarthritis biomarker.

Companion diagnostic

A companion diagnostic is an in vitro test essential for the safe, effective use of a specific drug, identifying patients likely to benefit or suffer serious adverse reactions.

Companion dog

Companion dog: a dog kept primarily for company rather than work. Also called pet dog; distinct from service, emotional support, and therapy dogs. Domesticated 40,000–15,000 years ago; dog ownership linked to 24% lower all-cause mortality (RR 0.76) in meta-analysis.