Prevention and Control of Scrub Typhus in Nepal

Background: Scrub Typhus in Nepal

Measures for Prevention and Control

1. Surveillance and Early Detection

• Notifiable disease status: Scrub typhus is listed as #11 among 52 priority infectious diseases for community-based surveillance under Nepal's Community-Based Disease Surveillance Guideline 2082, mandated under the Public Health Service Act 2075 BS. Cases must be reported through the Early Warning and Reporting System (EWARS).
• EDCD guideline: The Epidemiology and Disease Control Division (EDCD), Ministry of Health and Population (MoHP), Nepal published the Guideline on Prevention and Control of Scrub Typhus in Nepal (2016), which standardized case definitions:
  • Suspected/clinical case: AUFI ≥5 days with or without eschar (or fever <5 days if eschar is present)
  • Probable case: Positive IgM titer >1:32 or 4-fold rise in paired sera
  • Confirmed case: PCR-positive (blood/eschar) or 4-fold rise in IFA titers (gold standard)
• Outbreak response: Systematic outbreak investigation and reporting to EDCD with linkage to WHO frameworks.
• Strengthening diagnostic capacity: PCR and ELISA remain limited to a few tertiary centers. Expanding rapid diagnostic tests (lateral flow/RDTs) to primary care levels is a priority to reduce delays in diagnosis and treatment.

2. Case Management (Treatment to Reduce Mortality)

• First-line: Oral doxycycline 100 mg twice daily for 7-15 days
• Alternatives: Azithromycin 500 mg for 3 days, or chloramphenicol 500 mg four times daily for 7-15 days
• In severe cases: combination of doxycycline + azithromycin is superior to monotherapy
• Nepal's CFR declined from ~6% (2015) to ~1% (2017) following government initiatives including drug distribution, guidelines dissemination, and health worker training - Harrison's Principles of Internal Medicine 22E, p. 1860

3. Vector Control (Environmental Measures)

• Vegetation clearance: Clearing scrub/brush vegetation around homes, agricultural fields, and settlements, since chiggers (larval mites) concentrate in areas of dense low vegetation during the wet season
• Insecticide application: Spraying insecticides (lindane, chlordane, or malathion) on soil and vegetation to kill chigger mites and reduce transmission foci
• Rodent control: Controlling rodent populations (rats, mice, shrews) that serve as hosts for the mite life cycle - rodents do not cause human disease directly but sustain mite populations
• These environmental measures are short-term interventions most useful around outbreak sites - Park's Textbook of Preventive and Social Medicine, p. 346

4. Personal Protective Measures

• Protective clothing: Long sleeves, long pants tucked into socks, closed shoes when working in fields or scrub vegetation
• Insect/mite repellents applied to skin and clothing:
  • Diethyltoluamide (DEET) - most commonly recommended
  • Dibutyl phthalate
  • Benzyl benzoate
• Avoid sitting/lying on bare ground or grass: Use ground sheets or other barriers when resting outdoors
• Permethrin-impregnated clothing: Treating clothes and blankets with miticidal chemicals (benzyl benzoate) provides added protection - Park's Textbook, p. 346
• Post-exposure hygiene: Bathing and changing clothes after potential exposure in endemic areas

5. Chemoprophylaxis (High-Risk Situations)

• Weekly single dose of doxycycline starting before exposure and continued for 6 weeks after
• Alternative: Single oral dose of chloramphenicol or tetracycline every 5 days for a total of 35 days, with 5-day non-treatment intervals
• Note: No licensed vaccine is currently available for scrub typhus

6. Health Education and Community Awareness

• Educating communities about the disease, its symptoms (fever, headache, eschar), and the importance of early health-seeking behavior
• Training and orientation of health workers (all levels) for early clinical suspicion, since many Nepali patients do not present with the classic eschar, and scrub typhus is often not in the initial differential diagnosis
• Creating informative materials (brochures, posters) in local languages for rural communities
• Engaging schools and community organizations in awareness programs

7. Public Health Governance and Coordination

• Distribution of national treatment and control guidelines by MoHP/EDCD to district health facilities
• One Health approach: Integrating human, animal, and environmental health monitoring for sustained long-term control, given the disease's zoonotic nature (mites-rodents-humans cycle)
• Post-calamity preparedness: The 2015 earthquake experience showed that disasters increase scrub typhus risk; surveillance must be intensified after floods, landslides, or earthquakes (Nepal is disaster-prone)
• International coordination through WHO and regional networks given Nepal's location in the Tsutsugamushi triangle

Summary Table

• Park's Textbook of Preventive and Social Medicine, p. 346
• Harrison's Principles of Internal Medicine 22E, p. 1860
• Lamichhane et al. (2023), Annals of Medicine and Surgery - PMID: 37811079 (Systematic review of scrub typhus in Nepal)
• EDCD/MoHP Nepal: Guideline on Prevention and Control of Scrub Typhus in Nepal (2016)
• Nepal Infectious Disease Control Guideline (EWARS framework)
• Nepal Community-Based Disease Surveillance Guideline 2082