Hygiene — Key Concepts and Q&A
Core Concepts
Q: Infection prevention — how diseases spread and how to break the chain.
Diseases spread through the "chain of infection":
1.Infectious agent (pathogen: bacteria, virus, fungus)
2.Reservoir (where it lives: person, animal, environment)
3.Portal of exit (how it leaves: respiratory droplets, faeces, blood, skin)
4.Mode of transmission (how it travels: contact, droplets, airborne, faecal-oral)
5.Portal of entry (how it enters new host: mouth, respiratory tract, skin break)
6.Susceptible host (weakened immunity, unvaccinated)
Break any link → prevent infection. Hand hygiene primarily breaks the contact transmission link.
Q: Hand washing — the single most effective hygiene practice.
Proper handwashing with soap and water: 20 seconds minimum.
WHO 6-step method:
1.Wet hands, apply soap
2.Palm to palm, rub
3.Back of hands
4.Between fingers
5.Backs of fingers (interlocked)
6.Thumbs
7.Tips of fingers, nails
8.Wrists
When to wash:
•Before eating or handling food
•After using toilet
•After coughing, sneezing, blowing nose
•After touching animals
•After handling garbage
•Before and after caring for sick person
Alcohol-based hand sanitiser (60-95% alcohol): Good when hands not visibly dirty and soap unavailable. Does NOT work against: Clostridioides difficile (C.diff) spores, norovirus — need soap and water.
Q: Food safety — temperature and cross-contamination.
Danger zone: 5°C to 60°C (40°F to 140°F). Bacteria multiply rapidly in this range.
•Keep hot food hot: >60°C
•Keep cold food cold: <5°C
•Never leave perishables at room temperature >2 hours (1 hour if >32°C ambient)
Temperature rules:
•Fridge: ≤4°C | Freezer: ≤-18°C
•Cook chicken/poultry: 74°C internal temp
•Ground meat: 71°C | Whole cuts: 63°C | Fish: 63°C
•Leftovers: reheat to 74°C
Cross-contamination prevention:
•Separate raw meat from ready-to-eat foods
•Different cutting boards (colour-coded: red for meat, green for vegetables)
•Wash hands between handling raw and cooked
•Store raw meat on bottom shelf of fridge
Q: Personal hygiene for health.
Dental hygiene (often undervalued):
•Brush twice daily (2 minutes), floss once daily
•Poor oral hygiene linked to: cardiovascular disease (bacteria enter bloodstream), diabetes complications, preterm birth
•Replace toothbrush every 3 months or after illness
Skin hygiene:
•Wash daily, especially areas prone to bacterial growth (underarms, groin, feet)
•Moisturise to maintain skin barrier (skin is first line of immune defence)
•Clean wounds promptly
Sleep hygiene:
•Clean bedding (bacteria accumulate) — wash weekly
•Shower before bed (removes allergens, bacteria)
•Clean environment supports respiratory health
Respiratory hygiene:
•Cover mouth and nose when coughing/sneezing
•Use elbow (not hands) — hands spread droplets
•Dispose tissues immediately, wash hands after
Q: Hygiene in healthcare/food service settings.
Standard Precautions (healthcare): Treat all blood/body fluids as potentially infectious regardless of known diagnosis.
PPE (Personal Protective Equipment): Gloves, mask, goggles, gown — selected based on risk.
Donning (putting on) order: Gown → Mask → Goggles/face shield → Gloves
Doffing (removing) order: Gloves → Goggles → Gown → Mask (most contaminated removed first)
Food handling licence (FSSAI in India): Required for food businesses. Covers: personal hygiene, temperature control, pest control, clean facilities.
Revision Notes
CHAIN OF INFECTION: Agent → Reservoir → Exit → Transmission → Entry → Host
Break any link: hand hygiene breaks contact transmission
HANDWASHING: 20 seconds, soap + water, WHO 6-step technique
When: before food, after toilet, after coughing, after animals
Sanitiser: works except C.diff spores + norovirus → must use soap
FOOD SAFETY:
Danger zone: 5-60°C | Fridge ≤4°C | Freezer ≤-18°C
Cook chicken: 74°C internal | Never leave perishables >2hr at room temp
Cross-contamination: separate boards, raw meat bottom shelf, wash hands between raw/cooked
DENTAL HYGIENE: brush 2x/day + floss. Linked to cardiovascular disease, diabetes.
RESPIRATORY HYGIENE: cover with elbow (not hands) | dispose tissues immediately
HEALTHCARE PPE:
Donning: Gown → Mask → Goggles → Gloves
Doffing: Gloves → Goggles → Gown → Mask (most contaminated removed first)
