Malaria (Plasmodium spp.)

• Plasmodium falciparum: Highest mortality, common in sub-Saharan Africa, Southeast Asia, and South America.
  • Rationale: Drug resistance (e.g., to chloroquine, mefloquine) is a major concern in this region.
• Plasmodium vivax: Widespread in Southeast Asia, often relapsing due to hypnozoites.
  • Rationale: Chloroquine resistance is emerging; primaquine is needed for radical cure.
• Plasmodium knowlesi: Zoonotic, transmitted by macaques, common in Malaysia, Indonesia, and Thailand.
  • Rationale: Rapid 24-hour cycle, can cause severe disease; artemisinin-based therapy is first-line.

• Soil-Transmitted Helminths (STHs)
  • Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus
    • Rationale: Poor sanitation; common in rural areas; mass drug administration (albendazole, mebendazole) is key.

• Schistosomiasis (Schistosoma spp.)
  • Schistosoma mekongi: Mekong River basin (Laos, Cambodia)
    • Rationale: Snail intermediate hosts; chronic fibrosis is a concern.

• Foodborne Trematodes
  • Opisthorchis viverrini (liver fluke): Thailand, Laos, Cambodia, Vietnam
    • Rationale: Raw fish consumption; linked to cholangiocarcinoma.
  • Fasciolopsis buski (giant intestinal fluke): Rural areas, poor sanitation
    • Rationale: Watercress transmission; can cause intestinal obstruction.

• Lymphatic Filariasis (Wuchereria bancrofti, Brugia malayi)
  • Rationale: Mosquito vectors; elimination programs (diethylcarbamazine + albendazole) ongoing.

Key Considerations for Southeast Asia:

• Drug resistance: Malaria (artemisinin resistance in the Greater Mekong Subregion).
• Zoonotic potential: Many parasites (e.g., P. knowlesi, O. viverrini) have animal reservoirs.
• Climate change: Altered vector distribution