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RDA - Complete PSM Exam Guide (MBBS 2nd Year)

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1. What is RDA? (The One-Line Answer)

RDA (Recommended Dietary Allowance) is the average daily dietary intake of a nutrient that is sufficient to meet the nutritional requirements of nearly all (97-98%) healthy individuals of a specific age, sex, and physiological state.

• Lippincott Biochemistry, 8th ed.

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2. The Big Picture - DRI Family (Must Know!)

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3. How is RDA Calculated? (Impress the Examiner!)

RDA = EAR + 2 SD (standard deviations)

• This is because RDA must cover 97-98% of people, which statistically = mean + 2 SD on a normal distribution curve.
• So RDA is always higher than EAR - it has a built-in safety margin.
• RDA is NOT the minimum requirement. It is an intentionally high value to ensure safety for almost everyone.

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4. When is AI Used Instead of RDA?

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5. ICMR RDA for Indians - The Key Values (Nepal follows ICMR/WHO standards)

Energy (Moderate work - most commonly asked)

Protein

Note: ICMR 2020 changed protein RDA from 1.0 g/kg/day (old 2010 value) to 0.83 g/kg/day based on DIAAS (Digestible Indispensable Amino Acid Score) - this impresses examiners!

Key Minerals (ICMR 2020)

Key Vitamins (ICMR 2020)

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6. Important Concepts to Say Out Loud in the Exam

Who sets RDA?

• In India/Nepal: ICMR-NIN (Indian Council of Medical Research - National Institute of Nutrition), last revised in 2020
• In the USA: Institute of Medicine (IOM) / National Academies
• For international use: WHO/FAO

RDA vs EAR - The Key Difference

• EAR satisfies 50% of people - useful for assessing population groups
• RDA satisfies 97-98% of people - useful for planning diets for individuals
• If someone's intake is at or above RDA → their diet is adequate
• If intake is below EAR → definitely inadequate

RDA is NOT:

• The minimum requirement
• The optimal requirement
• The same for everyone (it varies by age, sex, physiological state like pregnancy/lactation)

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7. Factors that Affect RDA (Determinants)

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8. Uses / Importance of RDA (Common Viva Question)

1. Planning diets for individuals and groups
2. Evaluating nutritional adequacy of existing diets
3. Formulating food and nutrition policies at national level
4. Planning supplementation programs (e.g., iron-folic acid tablets for pregnant women)
5. Food labeling - percent daily values on food packages
6. Research - baseline for nutrition studies
7. Targeted interventions for vulnerable groups (children, pregnant women)

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9. Quick One-Liners to Impress the Examiner

• "RDA = EAR + 2 SD, providing a safety margin for 97-98% of the population"
• "ICMR revised the RDA in 2020, changing protein from 1 g/kg/day to 0.83 g/kg/day based on DIAAS"
• "When EAR cannot be established, AI is used instead of RDA - for example, in infants under 6 months"
• "RDA for iron in women is higher than men (29 vs 19 mg/day) due to menstrual losses"
• "UL is not the same as toxic dose - it is the highest safe average daily intake"

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10. Super-Short Summary to Memorize Tonight

RDA = Average daily intake sufficient for 97-98% healthy people
     = EAR + 2 SD
     = Part of DRI system: EAR → RDA → AI → UL
     = Set by ICMR-NIN for India (latest: 2020)

Key values (adult, moderate work):
  Energy: Man 2710, Woman 2130 kcal/day
  Protein: Man 54g, Woman 46g (0.83 g/kg/day)
  Calcium: 1000 mg/day
  Iron: Man 19 mg, Woman 29 mg/day
  Vitamin D: 600 IU/day

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1. Definition - highlighted box with the one-line answer
2. DRI Family Table - EAR / RDA / AI / UL comparison
3. Energy & Protein - all groups including pregnancy/lactation (ICMR 2020)
4. Key Minerals Table - Ca, Fe, Zn, Iodine, Mg across Man/Woman/Pregnant/Lactating
5. Key Vitamins Table - A, D, C, Folate, B12 and more
6. Who Sets RDA - ICMR-NIN for India/Nepal (2020)
7. Factors affecting RDA - determinants table
8. Uses of RDA - 9 uses in 3 columns
9. Exam Tips (green box) - 6 lines to impress the examiner
10. Rapid Recall Card (orange box) - ultra-short cheat sheet for last-minute review

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RUBELLA & MUMPS — Complete PSM Exam Guide 🎓

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PART 1: RUBELLA (German Measles / जर्मन दादुरा)

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1. What is Rubella?

Rubella is a mild, self-limiting viral illness caused by Rubella virus (RNA virus, Togavirus family) - also called "German Measles" or "3-day measles" (rash lasts only 3 days).

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2. Epidemiology (Quick Facts)

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3. Clinical Features

In Children (Post-natal rubella):

• Rash - maculopapular, starts on face → trunk → limbs (centrifugal spread)
• Rash lasts only 3 days (hence "3-day measles")
• Mild or no fever (low-grade at most)
• Lymphadenopathy - occipital + post-auricular (behind the ear) lymph nodes enlarged and TENDER - this is the hallmark!
• No koplik spots (unlike measles)
• Rash is usually faint, mild, hard to detect in dark skin

In Adults (especially women):

• Arthralgia and arthritis (very common in adult women - a distinguishing feature!)
• Mild constitutional symptoms

Does rubella always present with rash? NO!

• Up to 50% of cases are subclinical (no rash, no symptoms)
• This makes rubella dangerous - infected women may not know they have it during pregnancy!

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4. Measles vs Rubella (Your slide has this comparison - very commonly asked!)

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5. Congenital Rubella Syndrome (CRS) ⭐ MOST IMPORTANT TOPIC

When does it occur?

• When a pregnant woman gets rubella, the virus crosses the placenta and damages the fetus
• Maximum damage in 1st trimester (especially first 8-12 weeks)
• After 16 weeks of pregnancy: NO major abnormalities (very important MCQ answer!)

Classic Triad of CRS (Gregg's Triad):

"CCC" = Cataract + Cardiac defects + Cochlear deafness

Risk of CRS by trimester:

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6. Diagnosis

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7. Prevention (Your slide: MMR Vaccine)

MMR Vaccine:

• Measles + Mumps + Rubella (live attenuated)
• Given at: 9 months + 15 months (Nepal/India schedule)
• Route: Subcutaneous
• Efficacy: ~95% after single dose

Rubella Vaccination Strategy (MCQ from your slide):

• During a rubella outbreak → vaccinate Women 15-49 years (non-pregnant) on PRIORITY
• Why women? Because the real danger is not rubella itself, but CRS in their future babies
• Pregnant women should NOT get MMR (live virus - theoretical risk)
• Conception should be delayed 1 month after MMR vaccination

Contraindications to MMR:

• Pregnancy (delay conception 1 month after vaccine)
• Severe immunocompromise
• Severe allergy to vaccine components

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8. MCQ Answers from Your Slides

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PART 2: MUMPS

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1. What is Mumps?

Mumps is an acute viral illness caused by Mumps virus (RNA virus, Paramyxovirus family - Rubulavirus genus) characterized by painful swelling of the parotid glands (parotitis).

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2. Epidemiology

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3. Clinical Features

Prodrome (1-2 days before swelling):

• Fever, malaise, headache, anorexia

Main Sign - Parotitis:

• Painful swelling of parotid gland (in front of and below the ear)
• Usually bilateral (but can start unilateral then become bilateral)
• Swelling pushes the earlobe upward and outward
• Tender to touch
• Lasts about 7-10 days
• Stensen's duct opening (opposite upper 2nd molar) appears red and swollen

Clinical clue:

• Angle of the jaw is obliterated by swelling (unlike lymph node enlargement where you can feel the angle)

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4. Complications (⭐ Most asked in exams)

Most Common Complication in CHILDREN = Aseptic Meningitis (MCQ answer from your slide!)

Most Common Complication overall = Orchitis (in post-pubertal males)

Important about Orchitis:

• Occurs in 30% of unvaccinated post-pubertal males (only 6% if vaccinated)
• Develops in the 1st week of parotitis
• Both testes in 10-30% of cases
• 30-50% testicular atrophy but permanent infertility is RARE
• Causes fear but rarely leads to complete sterility

Important about Meningitis:

• Up to 55% have subclinical CSF pleocytosis (but no symptoms)
• Only ~10% unvaccinated patients develop symptomatic meningitis
• Self-limited (recovers fully)

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5. Diagnosis

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6. Management

• No specific antiviral treatment for mumps
• Symptomatic treatment only:
  • Analgesics/antipyretics (paracetamol) for pain and fever
  • Soft diet (chewing is painful)
  • Warm/cold compresses on parotid area
  • Rest and hydration
  • For orchitis: bed rest, scrotal support, analgesics

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7. Prevention

MMR Vaccine:

• Same vaccine as rubella: MMR (live attenuated)
• Given at 9 months + 15 months
• Two-dose MMR reduces mumps incidence by 97-99%
• One-dose MMR reduces incidence by 87-88%
• Vaccine strain used: Jeryl Lynn strain

Other measures:

• Isolation of cases for 9 days after onset of parotitis
• Avoid schools/crowded places during infectious period

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8. MCQ Answers from Your Slides

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QUICK COMPARISON: RUBELLA vs MUMPS

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LINES TO IMPRESS THE EXAMINER 🌟

• "Both rubella and mumps are RNA viruses given via the same MMR live attenuated vaccine at 9 and 15 months."
• "Up to 50% of rubella cases are subclinical - this is why pregnant women can unknowingly infect their fetus."
• "CRS triad = Cataract + Cardiac defect (PDA) + Cochlear deafness (Gregg's triad)."
• "During rubella outbreak, we vaccinate non-pregnant women aged 15-49 years on priority to prevent CRS."
• "Most common complication of mumps in children is aseptic meningitis - NOT orchitis - because orchitis only occurs in post-pubertal males."
• "Mumps orchitis causes testicular atrophy in 30-50% but permanent infertility is rare."
• "IgM cannot cross the placenta - so IgM in a newborn confirms CRS regardless of maternal status."
• "Rubella incubation is 14-21 days (avg 18) - NOT less than 10 days - a common wrong answer in MCQs."

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CHICKENPOX & MUMPS — Complete PSM Guide (K. Park)

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PART 1: CHICKENPOX (Varicella)

1. One-Line Definition (Park's)

Chickenpox is an acute, highly infectious disease caused by Varicella-Zoster Virus (VZV), also called Human (alpha) Herpesvirus 3, characterized by a vesicular rash with fever and malaise.

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2. Epidemiological Determinants

• Droplet infection + direct contact with lesions + airborne (highly contagious)

• Most common under 10 years of age
• One attack = lifelong immunity (second attacks rare)
• Maternal antibody protects infants in first few months
• Adults get more severe disease

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3. Clinical Features (Park's exact description)

• Mild fever, malaise
• In children: often no prodrome — rash is the FIRST sign

• Trunk first (abundant) → face, arms, legs (less abundant)
• Axilla affected
• Palms and soles usually NOT affected
• Mucosal surfaces (buccal, pharyngeal) involved

• Macule → Papule → Vesicle → Scab in just 4–7 days
• Vesicles = "dew-drops on skin" — superficial, unilocular, easily ruptured
• Area of inflammation around vesicles (erythematous halo)
• Many lesions abort; some go directly to crust without pustule

• All stages — papules, vesicles, crusts — present simultaneously in the same area
• Because rash appears in successive crops over 4–5 days

• Low-grade; rises with each new crop of rash

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4. Complications

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5. Treatment & Prevention (Park's)

• Acyclovir (drug of choice) — also valacyclovir, famciclovir, foscarnet
• Prevents disseminated disease in immunosuppressed patients
• Acyclovir does NOT prevent post-herpetic neuralgia

• Live attenuated — Oka strain
• 2 doses: 12–15 months + 4–6 years
• Subcutaneous route
• Post-exposure: within 5 days of exposure (>90% efficacy if within 3 days)
• Contraindicated in pregnancy (delay 4 weeks)

• Varicella-Zoster Immunoglobulin within 72 hours of exposure
• For pregnant women, immunocompromised, perinatally exposed neonates

• Notification + Isolation for 6 days after onset of rash
• Disinfect articles soiled by secretions

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PART 2: SMALLPOX (Variola)

1. One-Line Definition (Park's)

Smallpox is an acute infectious disease caused by Variola virus, characterized by sudden fever, headache, backache, vomiting, and on the 3rd day a typical rash appearing in a centrifugal distribution passing through macule → papule → vesicle → pustule → scab with subsequent scarring.

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2. Epidemiology

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3. Clinical Features

• High fever (38.9–40°C)
• Severe headache and BACKACHE (characteristic of smallpox!)
• Malaise, severe prostration — patient is bedridden
• Children: vomiting, convulsions

• Face first → forearms → trunk → legs
• Palms and soles frequently involved
• Axilla usually free
• Rash dense on extensor surfaces and bony prominences

• Macule → Papule → Vesicle → Pustule → Scab
• Each stage lasts 1–2 days
• Scabs form 10–14 days after rash

• NO area of inflammation around lesions

• Ordinary (90% of cases)
• Hemorrhagic (~5%) — CFR ~100%
• Malignant/flat (~5%) — CFR ~95%

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4. Eradication of Smallpox — Park's Key Points ⭐

• No animal reservoir
• No subclinical infectious cases (all cases visible)
• Effective vaccine available
• Stable single serotype
• Visible rash — easy case detection

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PART 3: THE BIG COMPARISON TABLE (From Park's — Most Asked!)

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Lines to Impress the Examiner 🌟

• "Chickenpox rash is pleomorphic because it appears in successive crops — all stages simultaneously. Smallpox is monomorphic — all lesions at the same stage, same time. This is the single most important clinical difference."
• "Chickenpox scabs are NOT infective — the virus dies before the pustular stage. This is different from smallpox where scabs are infective."
• "Aspirin is absolutely contraindicated in childhood chickenpox because it causes Reye's syndrome — a fatal hepatic encephalopathy."
• "Smallpox was eradicated because it had no animal reservoir, no subclinical infectious cases, a visible rash, and an effective vaccine — a unique combination that allowed the surveillance and containment strategy to work."
• "India was declared smallpox-free on 5th July 1975. WHO confirmed global eradication in May 1980 — making smallpox the first and only human disease ever to be eradicated."
• "After chickenpox, VZV lies dormant in dorsal root ganglia. When cell-mediated immunity wanes with age or immunosuppression, it reactivates as Herpes Zoster — a painful vesicular eruption along a dermatome."

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