Sandfly Bites and Leishmaniasis: Transmission, Contagion, and Prevention

Leishmaniasis Is Not Contagious Person-to-Person

Leishmaniasis is caused by Leishmania protozoa transmitted by infected female phlebotomine sandflies.

Transmission Cycle

1. Sandfly bites infected reservoir (human, dog, rodent).
2. Parasite transforms to promastigote in gut → multiplies → migrates to proboscis.
3. Next bite injects promastigotes → taken up by macrophages → become amastigotes → replicate.

Why Not Directly Contagious?

• Parasite requires sandfly vector for development (promastigote stage).
• No evidence of sexual, vertical, or casual contact transmission.
• Rare: blood transfusion, needle sharing, congenital (placental).

Clinical Forms

• Cutaneous (CL): Self-healing ulcers (Old World) or chronic/mucosal (New World).
• Mucocutaneous (MCL): Nasopharyngeal destruction (L. braziliensis).
• Visceral (VL/Kala-azar): Fever, hepatosplenomegaly, pancytopenia – fatal if untreated.

Prevention

• Insecticide-treated nets, screens, repellents (DEET, picaridin).
• Indoor residual spraying.
• Dog collars/culling (zoonotic VL).
• Early diagnosis/treatment reduces reservoir.

Treatment

• Pentavalent antimonials (SSG, meglumine), amphotericin B (liposomal), miltefosine, paromomycin – regimen by species/region.

Travelers to endemic areas (Mediterranean, Middle East, South Asia, Latin America) should use bite avoidance.