Simple categories matching contagious:

• illness,
• disease,
• nature,
• bug,
• agent,
• microbe,
• malady,
• situation,
• condition,
• thing,
• virus,
• affliction,
• substance,
• disorder,
• infection,
• process,
• behavior,
• pathogen,

Members with property contagious:

• dysentery,
• hepatitis,
• flu,
• giardiasis,
• measles,
• fashion,
• infectious_hepatitis,
• bird_flu,
• tuberculosis,
• ebola,
• infectious_mononucleosis,
• mono,
• pertussis,
• mumps,
• cold,
• bacteria,
• mange,
• polio,
• chickenpox,
• diabetes,
• sars_disease,
• vd,
• influenza_flu,
• leptospirosis,
• chicken_pox,
• school_sore,
• pulmonary_tuberculosis,
• dengue,
• diphtheria,
• growth,
• typhoid,
• ear_infection,
• cerebrospinal_meningitis,
• leprosy,
• smallpox,
• gastric_sickness,
• mononucleosis,
• small_pox,
• pest,
• hiv,
• feline_leukemia,
• recent_exposure,
• avian_cholera,
• sars,
• impetigo,
• resistant_tuberculosis,
• infectious_tuberculosis,
• murrain,
• hiv_virus,
• syphilis,
• varicella,
• pandemic_influenza,
• flu_virus,
• electoral_campaign,
• dog_flu,
• active_tuberculosis,
• avian_influenza,
• tuberculosis_tb,
• ringworm,
• strep_pneumonia,
• staph,
• avian_flu,
• brucellosis,
• virus,
• consumption,
• bacterial_meningitis,
• rabies,
• glanders,
• whooping-cough_pertussis,
• pandemic_flu,
• shigellosis,
• aleutian_disease,
• dragon_pox,
• scurvy,
• rubeola,
• rinderpest,
• gastrointestinal_infection,
• mall_pox,
• gastrointestinal_illness,
• fifth_disease,
• distemper,
• genital_herpes,
• chlamydia,
• bladder_infection,
• acute_bronchitis,
• amoebic_dysentery,
• meningitis,
• streptococcus,
• skin_infection,
• measles_virus,
• gonorrhea,
• anthrax,
• venereal_disease,
• yeast_infection,
• viral_meningitis,
• common_cold,
• legionnaire_disease,
• tb,
• wart,
• infectious_leprosy,
• crime,
• scabies,
• typhus,
• mycoplasma,
• horse_flu,
• influenza_virus,
• malaria,
• galloping_consumption,
• verruca,
• cholera,
• fever,
• staphylococcus,
• hiv_disease,
• acute_pneumonia,
• pneumonia,
• isolation,
• fowl_influenza,
• hospital_waste,
• influenza,
• tularemia,
• gonorrhoea,
• infectious_meningitis,
• gastroenteritis,
• rubella,
• hemorrhagic_virus,
• poliomyelitis,
• respiratory_infection,
• lung_disease,
• trachoma,
• respiratory_disease,
• mouth_disease,
• reproduction,
• shingles,
• bronchitis,
• simian_herpes,