Communicable Diseases & Infection Control – Core Vocabulary

This set of vocabulary flashcards distills essential communicable-disease, immunization, and infection-control terms drawn from the comprehensive lecture Q&A. Use them to reinforce key definitions, precautions, pathogens, vaccines, therapies, and epidemiologic concepts likely to appear on exams or in clinical practice.

Contact Precautions

Infection-control measures (gloves, gown, hand hygiene) used when touching patients or items contaminated with infectious body fluids or organisms such as MRSA.

Airborne Precautions

Isolation strategy that places a patient in a negative-pressure room and requires fit-tested N95 or particulate respirators to prevent inhalation of droplet nuclei (e.g., tuberculosis, measles, varicella).

Droplet Precautions

Use of surgical mask within 3 ft (1 m) of a patient plus hand hygiene to block large-particle droplets (e.g., meningococcal meningitis, influenza).

Negative-Pressure Room

Hospital room with airflow that draws air into the room and exhausts it outdoors, preventing airborne pathogens from escaping.

Standard Precautions

Minimum infection-control practices (hand hygiene, personal protective equipment) applied to every patient regardless of diagnosis.

Methicillin-Resistant Staphylococcus aureus (MRSA)

Strain of S. aureus resistant to β-lactam antibiotics; spread mainly by hands; requires contact precautions.

Purified Protein Derivative (PPD)

Skin-test antigen used to screen for prior infection with Mycobacterium tuberculosis.

Acid-Fast Bacillus (AFB) Smear

Microscopic examination of sputum for acid-fast organisms; confirms active pulmonary tuberculosis.

Directly Observed Treatment, Short-Course (DOTS)

WHO-recommended TB strategy in which a health worker watches the patient swallow each dose of multidrug therapy.

Isoniazid (INH)

First-line antitubercular drug; prophylaxis for PPD converters; can cause peripheral neuropathy (give pyridoxine).

Rifampicin (Rifampin)

Key TB drug that turns body fluids orange-red; best taken on an empty stomach.

Streptomycin

Injectable aminoglycoside used in TB; ototoxicity manifests as vertigo or hearing loss (‘cinchonism-like’).

Multidrug Therapy (MDT)

Use of two or more antimicrobial agents simultaneously to prevent drug resistance, as in TB or leprosy treatment.

CD4 Cell Count

Measurement of helper T-cells; a count <200 cells/mm³ defines AIDS in an HIV-positive individual.

Opportunistic Infection

Illness (e.g., PCP, CMV, oral thrush) that exploits the weakened immune system of HIV/AIDS patients.

Pneumocystis carinii (jirovecii) Pneumonia

Common AIDS-defining opportunistic pneumonia treated with high-dose trimethoprim-sulfamethoxazole.

Anaphylaxis

Severe, rapid allergic reaction; first-line treatment is intramuscular epinephrine 1 mg/mL (1:1000).

Hepatitis A Virus (HAV)

Fecal-oral transmitted picornavirus; prevent with hand hygiene, safe food/water, and inactivated vaccine.

Hepatitis B Virus (HBV)

Blood-borne hepadnavirus; prevented by three-dose recombinant vaccine and perinatal maternal screening.

Tetanus Toxoid (TT)

Inactivated tetanospasmin given to pregnant women (TT1-TT5) to protect mother and newborn from tetanus.

Diphtheria-Pertussis-Tetanus (DPT/DTaP) Vaccine

Combination immunization given at 6, 10, 14 weeks; contraindicated after severe post-dose encephalopathy.

Measles-Mumps-Rubella (MMR) Vaccine

Live attenuated viral vaccine given at 9 months or later; delay after IVIG or Kawasaki immunoglobulin therapy.

Oral Polio Vaccine (OPV)

Live Sabin vaccine given as two oral drops; heat-sensitive and stored in freezer at −15 °C to −25 °C.

Bacille Calmette-Guérin (BCG)

Live attenuated Mycobacterium bovis vaccine given intradermally at birth to prevent severe childhood TB.

Passive Immunity

Immediate, short-term protection conferred by preformed antibodies (e.g., immune globulin, maternal IgG).

Active Immunity

Long-lasting protection produced by one’s own immune system after infection or vaccination.

Incidence Rate

Number of new cases of a disease in a population during a specific period.

Prevalence

Total number of existing cases (new + old) of a disease in a population at a given time.

Endemic

Disease constantly present in a particular geographic area (e.g., malaria in parts of Africa).

Epidemic

Sudden increase in disease cases above what is normally expected in a population or area.

Pandemic

Worldwide epidemic affecting large numbers across continents (e.g., COVID-19, 1918 influenza).

Nosocomial Infection

Infection acquired during hospitalization or healthcare delivery (e.g., ventilator-associated pneumonia).

Chain of Infection

Six links—agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host—whose interruption prevents disease spread.

Hand Hygiene

Most effective routine practice to prevent transmission of infections in healthcare and home settings.

Salmonella

Gram-negative bacillus causing diarrhea and abdominal cramps; prevent by cooking food and handwashing.

Shigella

Bacillus causing bacillary dysentery; stool culture-positive cases must be reported to public health authorities.

Varicella-Zoster Virus (VZV)

Herpesvirus causing chickenpox and shingles; isolate until vesicles crust; airborne plus contact precautions.

Pediculosis Capitis

Infestation with head lice; transmitted by sharing hats/combs; treat with pediculicide and nit combing.

Candida albicans

Yeast that is normal flora but can cause oral/vaginal thrush in immunocompromised hosts.

Antigen

Foreign substance that triggers antibody formation and immune response.

Antibody (Immunoglobulin)

Protein produced by B-cells that binds specific antigen to neutralize or eliminate it.

Epinephrine 1:1000

First-choice intramuscular drug for anaphylaxis; dose 0.3–0.5 mL adult, 0.01 mg/kg child.

Quarantine

Restriction of movement of exposed but healthy persons during incubation period to prevent disease spread.

Leprosy (Hansen Disease)

Chronic Mycobacterium leprae infection affecting skin and nerves; treated with multi-drug therapy (dapsone, rifampicin, clofazimine).

Paucibacillary Leprosy

Type with ≤5 skin lesions and negative skin smears; 6-month MDT regimen of rifampicin + dapsone.

Multibacillary Leprosy

5 lesions or positive smears; 12-month MDT regimen of rifampicin, dapsone, clofazimine.

Schistosomiasis

Helminth infection acquired by skin contact with freshwater cercariae from snail hosts; treated with praziquantel.

Filariasis

Mosquito-borne Wuchereria bancrofti infection causing lymphedema/elephantiasis; treated with diethylcarbamazine (DEC).

Vector

Living carrier (e.g., mosquito, tick) that transmits an infectious agent from host to host.

Aedes aegypti

Mosquito vector for dengue, yellow fever, Zika; bites primarily during daytime.

Anopheles Mosquito

Vector for Plasmodium species causing malaria; feeds dusk to dawn.

Incubation Period

Time between entry of pathogen and appearance of first symptoms.

Carrier

Person who harbors a pathogen without signs of disease but can transmit it to others.

Kernig Sign

Inability to straighten the knee when hip is flexed to 90°; indicates meningeal irritation.

Koplik Spots

Small bluish-white lesions on buccal mucosa pathognomonic for measles (rubeola).

Orchitis

Painful testicular inflammation; potential complication of mumps in post-pubertal males.

Interferon

Cell-produced antiviral proteins that inhibit viral replication and modulate immune response.

IgG

Only immunoglobulin class that crosses the placenta, providing newborns with passive immunity.

IgE

Immunoglobulin mediating allergic responses and anaphylaxis.

DOTS Category I

Six-month TB regimen for newly diagnosed smear-positive cases: 2 HRZE/4 HR (intensive/continuation).

DOTS Category II

Eight-month regimen for relapse or treatment failure cases: 2 HRZES/1 HRZE/5 HRE.

Pyridoxine (Vitamin B₆)

Supplement given with INH to prevent peripheral neuropathy.

Epididymitis & Orchitis

Scrotal complications of mumps; managed with bed rest, scrotal support, analgesia.

Giardia lamblia

Protozoan causing foul, fatty diarrhea; transmitted via contaminated water; treat with metronidazole.

Trichomoniasis

Sexually transmitted infection by Trichomonas vaginalis; causes greenish malodorous discharge; treat both partners with metronidazole, avoid alcohol.

Meningococcal Meningitis

Neisseria meningitidis infection requiring droplet isolation and prophylaxis of contacts with rifampicin.

Pneumococcal Vaccine

Polysaccharide or conjugate vaccine preventing Streptococcus pneumoniae infections, especially in elders and asplenic patients.

Hand-Foot-Mouth Disease

Coxsackievirus infection causing oral ulcers and vesicular rash on hands/feet; supportive care, high contagion.

Vector Control

Public-health measures (insecticide spraying, eliminating breeding sites) to reduce disease transmitted by vectors.

Herd Immunity

Community-level protection achieved when a high percentage of the population is immune, reducing spread to susceptibles.

Erythromycin Prophylaxis (Ocular)

0.5% ophthalmic ointment applied to newborns to prevent gonococcal ophthalmia neonatorum.

Ceftriaxone

Single-dose IM third-generation cephalosporin; drug of choice for uncomplicated gonorrhea.

Chlamydia trachomatis

Most common bacterial STD; often asymptomatic; treat with doxycycline or azithromycin.

Impetigo

Superficial skin infection (Staph/Strep) producing honey-colored crusts; complications include post-streptococcal glomerulonephritis.

Intermittent Preventive Therapy (IPT)

Periodic antimalarial drug administration (e.g., sulfadoxine-pyrimethamine) to high-risk groups such as pregnant women.

Safety-Engineered Devices

Needles or sharps with built-in injury protection to reduce occupational exposures and needlestick-related infections.

Post-Exposure Prophylaxis (PEP)

Immediate medications (e.g., HIV antiretrovirals, HBV vaccine ± HBIG, rabies immunoglobulin) given after potential exposure.

Foodborne Illness

Diarrheal or systemic disease caused by ingestion of contaminated food or water, e.g., Salmonella, Shigella, Vibrio cholerae.

Boil-Water Advisory

Public-health notice instructing residents to boil tap water for at least 1 minute to inactivate pathogens.