Neglected Tropical Diseases

NTDs: Overview - Unseen Scourges

• Diverse group of communicable diseases prevalent in tropical/subtropical climates.
• Affect >1 billion people globally, primarily in low-income populations.
• India bears a significant burden of many NTDs (e.g., Lymphatic Filariasis, Dengue).
• Lead to chronic disability, stigma, and poverty.

⭐ The WHO currently recognizes over 20 diseases/conditions as Neglected Tropical Diseases (NTDs).

Protozoal NTDs: Kala-azar's Curse

• Agent: Leishmania donovani. Vector: Sandfly (P. argentipes).
• Symptoms: Prolonged fever, splenomegaly (massive), hepatomegaly, weight loss, pancytopenia.
• PKDL: Post-Kala-azar Dermal Leishmaniasis; skin lesions after cure.
• Diagnosis: LD bodies (aspirate), rK39 test.
• Treatment: Liposomal Amphotericin B (LAmB), Miltefosine. (📌 LAmB First!)

⭐ Liposomal Amphotericin B is preferred for Kala-azar, especially in pregnancy and HIV co-infection.

Helminthic NTDs: Filarial & Wormy Woes

• Lymphatic Filariasis (LF)
  • Agents: Wuchereria bancrofti (90%), Brugia malayi, B. timori. Vector: Mosquitoes.
  • Features: Asymptomatic microfilaremia, adenolymphangitis (ADL), lymphedema, elephantiasis, hydrocele.
  • Dx: Nocturnal blood smear (📌 Bancrofti by Night), ICT card (W. bancrofti antigen).
  • Rx: Diethylcarbamazine (DEC) 6 mg/kg/day x 12 days.

  • ⭐ India's strategy for Lymphatic Filariasis elimination involves annual Mass Drug Administration (MDA) with Diethylcarbamazine (DEC) and Albendazole.

  • 

%%{init: {'flowchart': {'htmlLabels': true}}}%% flowchart TD

Endemic["🌍 LF Endemic Area
• Lymphatic filariasis• High risk region"] MDA["💊 MDA Strategy
• Mass Drug Admin• Population focus"] Meds["💊 Drug Regimen
• DEC treatment• Albendazole dose"] Interrupt["🛑 Interrupt Path
• Stop transmission• Break cycle"] Eliminate["✅ Elimination Goal
• Disease free status• Public health win"]

Endemic --> MDA MDA -->|Annually| Meds Meds --> Interrupt Interrupt --> Eliminate

style Endemic fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8 style MDA fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style Meds fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style Interrupt fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E style Eliminate fill:#F6F5F5, stroke:#E7E6E6, stroke-width:1.5px, rx:12, ry:12, color:#525252

*   **Soil-Transmitted Helminthiases (STH)**
    *   Agents: *Ascaris lumbricoides* (roundworm), *Trichuris trichiura* (whipworm), Hookworms (*Ancylostoma*, *Necator*).
    *   Features: Malnutrition, anemia (hookworm), abdominal pain.
    *   Rx: Albendazole **400 mg** (single), Mebendazole **500 mg** (single) or **100 mg** BD x **3 days**.
    *   Prevention: National Deworming Day (Feb 10, Aug 10), WASH (Water, Sanitation, Hygiene).

## Key NTDs: Leprosy & Rabies Rampage

**Leprosy (Hansen's Disease):**
*   Agent: *Mycobacterium leprae*.
*   Cardinal Signs: Anesthetic skin patches (hypopigmented/erythematous), thickened peripheral nerves, positive slit-skin smear for AFB.
*   Multi-Drug Therapy (MDT):
    -   Paucibacillary (PB) (≤5 lesions, smear -ve): Rifampicin + Dapsone for **6 months**.
    -   Multibacillary (MB) (>5 lesions, smear +ve): Rifampicin + Dapsone + Clofazimine for **12 months**.
*   Lepra Reactions: Type 1 (Reversal), Type 2 (Erythema Nodosum Leprosum - ENL).

> ⭐ The duration of Multi-Drug Therapy (MDT) for Paucibacillary (PB) leprosy is **6 months**.

**Rabies:**
*   Fatal viral zoonotic encephalitis, primarily via dog bites.
*   Key Symptoms: Hydrophobia, aerophobia, paresthesia at bite site. Universally fatal once clinical signs appear.
*   Post-Exposure Prophylaxis (PEP) is life-saving.
    ![Rabies virus structure and replication](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Internal_Medicine_International_and_Global_Health_Neglected_Tropical_Diseases/2b8dc5e5-c96c-4476-b312-3b9b028c87f7.jpg)

```mermaid
%%{init: {'flowchart': {'htmlLabels': true}}}%%
flowchart TD
    Start["<b>🐕 Animal Bite</b><br><span style='display:block; text-align:left; color:#555'>• Exposure assessment</span><span style='display:block; text-align:left; color:#555'>• Risk evaluation</span>"]
    WHO["<b>📋 WHO Category?</b><br><span style='display:block; text-align:left; color:#555'>• Classify severity</span><span style='display:block; text-align:left; color:#555'>• Determine PEP</span>"]
    
    Cat1["<b>🩹 Category I</b><br><span style='display:block; text-align:left; color:#555'>• Licks on intact skin</span><span style='display:block; text-align:left; color:#555'>• No broken barrier</span>"]
    Cat2["<b>🩹 Category II</b><br><span style='display:block; text-align:left; color:#555'>• Minor scratches</span><span style='display:block; text-align:left; color:#555'>• No bleeding seen</span>"]
    Cat3["<b>🚨 Category III</b><br><span style='display:block; text-align:left; color:#555'>• Transdermal bites</span><span style='display:block; text-align:left; color:#555'>• Mucosa contact</span>"]

    NoPEP["<b>✅ No PEP</b><br><span style='display:block; text-align:left; color:#555'>• No vaccine needed</span><span style='display:block; text-align:left; color:#555'>• Standard hygiene</span>"]
    Treat2["<b>💊 Vaccine Only</b><br><span style='display:block; text-align:left; color:#555'>• Wound washing</span><span style='display:block; text-align:left; color:#555'>• Give ARV vaccine</span>"]
    Treat3["<b>⚠️ Full PEP</b><br><span style='display:block; text-align:left; color:#555'>• RIG and ARV given</span><span style='display:block; text-align:left; color:#555'>• Immediate washing</span>"]

    Start --> WHO
    WHO --> Cat1 --> NoPEP
    WHO --> Cat2 --> Treat2
    WHO --> Cat3 --> Treat3

    style Start fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
    style WHO fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
    style Cat1 fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8
    style Cat2 fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8
    style Cat3 fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C
    style NoPEP fill:#F6F5F5, stroke:#E7E6E6, stroke-width:1.5px, rx:12, ry:12, color:#525252
    style Treat2 fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
    style Treat3 fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C

NTD Control: India's Initiatives

• National Vector Borne Disease Control Programme (NVBDCP): Covers Lymphatic Filariasis (LF), Kala-azar (VL).
• National Leprosy Eradication Programme (NLEP): Leprosy elimination.
• Soil-Transmitted Helminthiases (STH) Control:

  ⭐ National Deworming Day in India, observed biannually, administers Albendazole to children aged 1-19 years for STH control.

  • Albendazole dose: 400mg (2-19 yrs), 200mg (1-2 yrs).
• Accelerated Plan for Elimination of LF (APELF): 2018 onwards; Triple Drug Therapy (IDA).
• Kala-azar Elimination Programme: Target: <1 case/10k pop/block_level_target_for_VL_elimination_in_India_is_less_than_1_case_per_10000_population_at_the_block_level

High‑Yield Points - ⚡ Biggest Takeaways

• Lymphatic Filariasis: W. bancrofti, Culex mosquito, night smear, DEC; MDA for control.
• Kala-azar: L. donovani, sandfly, fever, splenomegaly, rK39 test, Amphotericin B.
• Leprosy: M. leprae, nerve damage, skin patches, MDT (Rifampicin, Dapsone, Clofazimine).
• Soil-Transmitted Helminths: Cause anemia, malnutrition; Albendazole for mass deworming.
• Rabies: Fatal viral NTD; Post-Exposure Prophylaxis (PEP) is crucial and life-saving.
• Trachoma: C. trachomatis, causes preventable blindness; SAFE strategy (Surgery, Antibiotics, Facial cleanliness, Environmental).