Transmission Dynamics

• Vertical transmission represents the primary route of HIV infection in pediatric populations, accounting for >90% of cases.
• Without intervention, vertical transmission rates range from 15% to 45%.
• Transmission occurs during three distinct perinatal phases:
  • Intrauterine (20-30%): Occurs transplacentally, predominantly in late gestation, and is typically suggested by a positive PCR test within 48 hours of birth.
  • Intrapartum (70-80%): Occurs via mucosal exposure to infected maternal blood and secretions during delivery or micro-transfusions during labor, suggested by a negative PCR at birth but positive at 1-2 weeks.
  • Postpartum (15-20%): Occurs through breastfeeding in untreated populations, with risk directly increasing alongside the duration of breastfeeding and the practice of mixed feeding.

Risk Factors For Vertical Transmission

Diagnostic Evaluation In Infants

• Standard antibody tests (ELISA) remain strictly non-diagnostic in infants younger than 18 months secondary to the persistence of passively transferred maternal IgG antibodies.
• Definitive diagnosis strictly relies on virologic assays, specifically HIV DNA PCR (detecting proviral DNA) or HIV RNA PCR (detecting viral load) utilizing dried blood spots or whole blood.

Testing Schedule And Confirmation

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graph TD
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    classDef clinicalNode fill:#FFEADA,stroke:#D97724,stroke-width:2px,color:#7A3B08;
    classDef decisionPos fill:#E8F5E9,stroke:#2E7D32,stroke-width:2px,color:#1B5E20;
    classDef decisionNeg fill:#FFEBEE,stroke:#C62828,stroke-width:2px,color:#B71C1C;
    classDef finalNode fill:#FFF3E0,stroke:#E65100,stroke-width:2px,color:#5D4037;

    A[Baby born to HIV infected mother] --> B[Consider NAT at birth<br>within 2 days]
    A -.->|Prophylaxis| Baseline[Start nevirapine 2 mg/kg/dose OD at birth<br>Both nevirapine and zidovudine if high-risk infant<br>Start cotrimoxazole at 4-6 weeks of age]
    
    B --> B_Pos[Positive]
    B --> B_Neg[Negative]
    
    B_Pos --> C[Start ART and repeat NAT to confirm infection]
    
    B_Neg --> D[HIV 1 DNA PCR DBS at 6 weeks]
    D --> D_Pos[Positive]
    D --> D_Neg[Negative]
    
    D_Pos --> E[Send whole blood sample for HIV-1 DNA PCR<br>Repeat HIV 1 DNA PCR]
    E --> E_Pos[Positive]
    E --> E_Neg[Negative]
    
    E_Pos --> F[Collect and send another blood sample for confirmatory HIV-1 PCR<br>Continue cotrimoxazole; start pediatric ART; continue breastfeeding till 2 years]
    
    D_Neg --> G[Continue cotrimoxazole; stop NVP<br>at 6 or 12 weeks depending upon infant's risk status]
    E_Neg --> G
    
    G --> H[Repeat HIV 1 DNA PCR DBS at 9 months<br>or earlier if child is symptomatic]
    H --> H_Pos[Positive]
    H --> H_Neg[Negative]
    
    H_Pos --> F
    
    H_Neg --> I[Continue cotrimoxazole till HIV is excluded.<br>Continue breastfeeding at least till 2 years,<br>followed by gradual stoppage over 1 month]
    
    I --> J[Establish definitive diagnosis at 18 months or 3 months after cessation of breast feeding,<br>whichever is later, by HIV antibody tests 3 rapid tests]

    %% Class Assignments
    class A,B,C,D,E,F,G,H,I,J,Baseline clinicalNode;
    class B_Pos,D_Pos,E_Pos,H_Pos decisionPos;
    class B_Neg,D_Neg,E_Neg,H_Neg decisionNeg;
    class J finalNode;

Prevention Of Mother-To-Child Transmission

Antenatal And Intrapartum Interventions

• Maternal Antiretroviral Therapy:
  • All HIV-infected pregnant women must immediately initiate lifelong combination antiretroviral therapy (cART) to maintain a suppressed maternal viral load below 1,000 copies/mL.
  • The recommended standard regimen is Tenofovir plus Lamivudine plus Dolutegravir.
• Mode Of Delivery:
  • Vaginal delivery remains safe and recommended if the mother is on effective ART with a suppressed viral load (<1,000 copies/mL).
  • Elective Cesarean section is strictly recommended at 38 weeks for women presenting with a viral load >1,000 copies/mL or an unknown viral load.
• Obstetric Practices:
  • Clinicians must avoid artificial rupture of membranes, fetal scalp monitoring, instrumental delivery, and routine episiotomy to minimize fetal exposure to maternal blood.

Infant Antiretroviral Prophylaxis

Postnatal prophylaxis aims to prevent the establishment of infection and depends entirely on the infant's specific risk categorization.

Standard Risk

• Mother on adequate/regular ART
• viral load less than 1000 copies/mL from 32 weeks to delivery

High Risk

• Mother not on ART, on ART <4 weeks at delivery,
• Unknown/high viral load >1000 copies/mL from 32 weeks to delivery,
• Newly identified during pregnancy/within 6 weeks of delivery

Dosage of Prophylactic Drugs

Infant Feeding And General Care

• Feeding Practices:
  • In resource-rich settings, formula feeding is universally recommended to completely eliminate postnatal transmission.
  • In resource-limited settings, exclusive breastfeeding is recommended for the first 6 months provided the mother remains on effective ART; mixed feeding must be strictly avoided as it drastically increases transmission risk.

• Cotrimoxazole Prophylaxis:
  • Mandatory for all HIV-exposed infants starting at 4 to 6 weeks of age to prevent life-threatening Pneumocystis jirovecii pneumonia.
  • This must continue until HIV infection is definitively excluded.
• Immunization:
  • Administer BCG at birth strictly to asymptomatic HIV-exposed infants
  • It is strongly contraindicated in symptomatic HIV-infected infants due to the risk of disseminated BCG disease. Inactivated vaccines are safe and recommended.