🦠 VARICELLA-ZOSTER VIRUS (VZV) IN PREGNANCY — ZERO-OMISSION MASTER TABLE SET

🟦 TABLE 1: Why Viral Infections (incl. VZV) Are Worse in Pregnancy

🟦 TABLE 2: VZV Basics — Virology, Immunity & Vaccine

🟦 TABLE 3: Clinical Syndromes — Chickenpox vs Zoster

🟦 TABLE 4: Epidemiology — Temperate vs Tropical Regions

🟦 TABLE 5: Fetal Risks by Gestational Age (TIMING TABLE)

🟦 TABLE 6: Congenital Varicella Syndrome (CVS) — Features

🟦 TABLE 7: Maternal Complications of Varicella in Pregnancy

🟦 TABLE 8: Diagnosis — What Test to Use & When

Varicella — Management Around Delivery, Breastfeeding & Post-partum Prevention

A. Delivery Decisions

If ROM occurs DURING the high-risk window (−5 to +2 days)

🚨 This is the MOST DANGEROUS situation

📌 Do NOT attempt to prolong labour just to complete 5 days

→ Risk of chorioamnionitis + sepsis > benefit.

If ROM occurs AFTER ≥5 days from rash onset

Special scenario: PROM + no rash yet (exposed mother)

B. Neonatal Management (CRITICAL / EXAM GOLD)

8️⃣ Breastfeeding

9️⃣ Post-partum Vaccination (Future Prevention)

🔒 One-Line Exam Lock

Varicella −5 to +2 days around delivery → give neonate VZIG ± IV acyclovir; delay delivery if possible; breastfeeding allowed; vaccinate mother postpartum.

🟦 TABLE 9: Management — Aciclovir

🟦 TABLE 10: Management — VZIG (Varicella-Zoster Immunoglobulin)

🟦 TABLE 11: Screening & Prevention Strategy

🟦 TABLE 12: SBA / OSCE Mental Flowchart (EXAM GOLD)

🟩 ONE-LINE EXAM LOCK (FINAL)

Pregnant + chickenpox = think immunity → gestation → pneumonia risk → CVS window → VZIG vs aciclovir.

1️⃣ Why are viral infections (incl. VZV) worse in pregnancy?

• Pregnancy shifts immunity to Th2-dominant (tolerate fetus) → ↓ cell-mediated (Th1) immunity.
• VZV control needs strong T-cell response → so pregnant women get more severe disease (esp. pneumonia) and fetuses are at higher risk.

🧠 Think: “Pregnancy lowers the anti-virus SWAT team → virus gets bolder.”

2️⃣ VZV Basics (Virology + Immunity)

• Family/type: Herpesvirus; enveloped, double-stranded DNA, latency in dorsal root ganglia.
• Serotypes: Only one serotype → natural infection = lifelong immunity.
• Vaccine: Live attenuated Oka strain
• Very good protection
• CONTRAINDICATED in pregnancy (because live)
• Safe postpartum, breastfeeding NOT a contraindication.

🧠 Hooks

• “Herpes hides in nerves” = latency.
• “One virus, one memory” = single serotype.
• Live = danger in pregnancy.

3️⃣ Classic Clinical Pictures (Chickenpox vs Zoster)

Chickenpox (primary varicella)

• Centripetal rash (more on trunk).
• All stages at once: macule → papule → vesicle (“dew drop on rose petal”) → pustule → crust.
• Systemic (generalised rash).

Zoster (shingles)

• Reactivation from dorsal root ganglion.
• One dermatome, doesn’t cross midline.
• All lesions same stage.
• Zoster sine herpete = dermatomal neuropathic pain without rash.

🧠 One-liner:

• Chickenpox = “mixed crop field” 🌾
• Zoster = “one stripe, one stage” ➡️

4️⃣ Epidemiology (Temperate vs Tropics)

• Temperate regions: >95% infected by childhood → most reproductive-age women already immune.
• Tropics: more intense UV → less virus survival in environment → 30–50% adults remain susceptible.

👉 Why this matters in exams:

• In tropical countries, pregnant adults are more likely to be non-immune, so varicella in pregnancy is more common + more dangerous.

5️⃣ Fetal Risks: Timing is EVERYTHING ⏱️

a) Congenital Varicella Syndrome (CVS / embryopathy)

• Needs maternal primary varicella in early–mid pregnancy, especially <20 weeks.
• Highest risk ~13–20 weeks (~2%). Rare after 28 weeks.
• Classic features:
• Limb hypoplasia
• Cicatricial (“scarred”) skin lesions
• Eye defects: chorioretinitis, cataracts, microphthalmia
• Neuro defects: cortical atrophy, microcephaly/hydrocephalus, seizures

⚠️ Key idea:

• Congenital varicella ≠ always brain damage → can be limbs/skin/eyes only.

6️⃣ Maternal Complications in Pregnancy

Biggest killer = Varicella pneumonia

• Occurs in 1–10% of pregnant women with varicella.
• More severe in 3rd trimester.
• Smoking ↑ risk ×5.
• Can be life-threatening → ICU, ventilatory support.

👉 In MCQs:

“Most serious complication of maternal varicella in pregnancy?” → Varicella pneumonia.

7️⃣ Diagnosis: What to Use, When?

• PCR of vesicle fluid = best early test (acute phase).
• DFA (direct fluorescent antibody) from lesion also used.
• Serology:
• IgM = acute infection but can be tricky
• IgG = immunity (reliable from ~day 4 of rash onward)

Special point:

• PCR of amniotic fluid has low sensitivity (virus favours neural tissue) →
• Negative amniotic PCR ≠ guaranteed uninfected fetus.

🧠 Summary:

• PCR = NOW ⏱️ (vesicle)
• IgG = LATER 🕒
• Amniotic PCR = not very helpful for ruling out CVS.

8️⃣ Management in Pregnancy: Aciclovir + VZIG

Aciclovir

• Not contraindicated in pregnancy.
• Indicated for:
• Severe maternal disease (pneumonia, extensive rash)
• High-risk women (e.g. 3rd trimester, smokers, immunocompromised)
• Clear benefit in maternal outcomes.
• Unclear whether it actually reduces vertical transmission (this is an exam trap line).

🧠 Hook:

• “Aci-lover is safe in pregnancy – but fetal effect is still a mystery.”

VZIG (Varicella-Zoster Immunoglobulin)

• Used for post-exposure prophylaxis in seronegative pregnant women.
• Must be given ASAP, ideally ≤72 h (up to 96 h).
• Reduces severity, does NOT guarantee prevention of infection or fetal complications.

In neonate:

• Given when mum has varicella close to delivery (see above) → with aciclovir.

9️⃣ Screening & Postpartum Strategy

• Routine antenatal VZV IgG screening:
• Not universal (cost-effectiveness debated).
• More valuable in settings where adult susceptibility is high (e.g. tropics).
• Postpartum (mother seronegative):
• Give live attenuated vaccine after delivery.
• Safe in breastfeeding.
• Prevents future pregnancy infections.

🧠 Hook:

• “Screening not routine, but smart in high-risk populations.”
• “Post-birth jab → protect the next pregnancy.”

🔟 How to Think in an SBA Stem (Mental Flowchart)

When you see “pregnant + chickenpox/rash/exposure”:

1. Is she immune?
• If known immune → reassure, no special action.
• If unknown → send VZV IgG, treat as non-immune until proven.
2. Is it exposure or actual disease?
• Exposure, seronegative pregnant woman → VZIG within 96 h.
• Established varicella in pregnancy → assess severity + GA.
3. What’s the gestation?
• <20 weeks: risk = congenital varicella syndrome
• 13–20 weeks highest (~2%)
• Near term (last 4 weeks): danger = severe neonatal varicella if infection within 7 days before or 2 days after delivery → neonatal VZIG + aciclovir
4. How sick is mum?
• If pneumonia/dyspnoea/haemoptysis/severe systemic → IV aciclovir + hospital
• Moderate disease → oral aciclovir often used (especially 2nd/3rd trimester)
5. Any test for fetus?
• Detailed US for CVS markers (limb, brain, eye, growth).
• Remember: Negative amniotic PCR does NOT fully exclude CVS.

🩺 Integrated Clinical Scenario: Varicella in Pregnancy (Exam-Perfect)

Clinical Stem

A 27-year-old primigravida, 18 weeks’ gestation, school teacher, presents with a 2-day history of fever and malaise, followed by a generalised itchy rash.

She reports recent exposure to a child with chickenpox in her class one week ago.

She is not sure about past chickenpox and has never been vaccinated.

On examination:

• Temperature: 38.6°C
• Rash is centripetal, involving trunk more than limbs
• Lesions at different stages: macules, papules, vesicles, crusts
• No respiratory distress at present
• She is a smoker (5 cigarettes/day)

🔹 STEP 1: Identify the Disease (Pattern Recognition)

Key clues

• Pregnant
• Exposure to chickenpox
• Mixed-stage rash
• Centripetal distribution

👉 Diagnosis: Primary varicella (chickenpox) in pregnancy

🧠 Exam lock:

Mixed stages = chickenpox

Single dermatome, same stage = zoster

🔹 STEP 2: Why Is This Dangerous in Pregnancy?

Pregnancy causes a shift to Th2 immunity → ↓ cell-mediated (Th1) immunity.

• VZV needs strong T-cell control
• Hence:
• More severe maternal disease
• Higher risk of pneumonia
• Fetal complications possible

🧠 Think: “Anti-viral SWAT team weakened.”

🔹 STEP 3: Maternal Risk Assessment (Immediate Threat)

She is:

• Pregnant
• Smoker
• Early systemic symptoms

👉 Most serious maternal complication to anticipate?

✅ Varicella pneumonia

📌 Occurs in 1–10%, worse in 3rd trimester, smoking ↑ risk ×5

🔹 STEP 4: Fetal Risk — TIMING IS EVERYTHING

Gestation = 18 weeks

👉 Falls into high-risk window for Congenital Varicella Syndrome (CVS)

Risk facts you must recall:

• Occurs when primary maternal infection <20 weeks
• Peak risk: 13–20 weeks (~2%)
• Rare after 28 weeks

Classic CVS features:

• Limb hypoplasia
• Cicatricial skin scars
• Eye defects (chorioretinitis, cataracts)
• Neuro defects (cortical atrophy, microcephaly)

🧠 Exam trap:

CVS ≠ always brain damage → can be limb/skin/eye only

🔹 STEP 5: Confirming the Diagnosis (What Test, When?)

She has active vesicles.

👉 Best diagnostic test now?

✅ PCR of vesicle fluid

Why not others?

• IgM → unreliable
• IgG → shows immunity, rises later
• Amniotic fluid PCR → low sensitivity

🧠 One-liner:

• PCR = NOW
• IgG = immunity
• Negative amniotic PCR ≠ fetus safe

🔹 STEP 6: Management of the Mother

Is aciclovir safe?

✅ YES — not contraindicated in pregnancy

Indications here:

• Systemic illness
• Smoker
• Pregnancy itself = high risk

👉 Start oral aciclovir (or IV if respiratory symptoms develop)

📌 Exam nuance:

• Aciclovir improves maternal outcomes
• Does NOT reliably prevent fetal infection (classic SBA trap)

🧠 Memory hook:

“Aci-lover is safe — fetal effect uncertain.”

🔹 STEP 7: Fetal Monitoring Strategy

You do NOT rush to invasive testing.

Correct approach:

• Serial detailed ultrasound
• Limbs
• Brain (ventricles, cortex)
• Eyes
• Growth

⚠️ Remember:

• Normal US early does not exclude CVS
• Abnormalities may appear weeks later

🔹 STEP 8: What If This Was Only Exposure (Variation Question)?

If she had:

• No rash
• Unknown immunity
• Recent exposure

👉 Correct step:

• Send VZV IgG
• Treat as non-immune until proven
• Give VZIG within 96 h

📌 VZIG:

• Reduces severity
• Does NOT guarantee prevention

🔹 STEP 9: Postpartum Strategy (Future Prevention)

If she turns out VZV IgG negative after delivery:

✅ Give live attenuated varicella vaccine postpartum

• Contraindicated in pregnancy
• Safe in breastfeeding

🧠 Lock:

“Post-birth jab protects the next pregnancy.”

🔹 STEP 10: Examiner’s One-Page Mental Flow (Final Lock)

When you see “pregnant + chickenpox/exposure”:

1. Immune?
• Yes → reassure
• No/unknown → IgG
2. Exposure or disease?
• Exposure → VZIG ≤96 h
• Disease → assess severity + GA
3. Gestation?
• <20 w → CVS risk
• 13–20 w → highest risk
• Peripartum → neonatal varicella risk
4. Maternal severity?
• Pneumonia → IV aciclovir + ICU
5. Fetal testing?
• US surveillance
• Amniotic PCR ≠ reassurance