Which parasite is transmitted by triatomine bugs and can cause Romaña sign in the acute phase of infection?

• A. Giardia lamblia
• B. Trypanosoma cruzi
• C. Brugia malayi
• D. Plasmodium vivax

Answer: (B)

This question tests recognition of the vector and a classic sign of acute Chagas disease. The parasite transmitted by triatomine bugs (kissing bugs) is Trypanosoma cruzi, a protozoan that causes infection when the bug defecates after feeding and the parasite enters through the conjunctiva or mucous membranes. A hallmark of the acute phase is Romaña sign, unilateral periorbital swelling resulting from parasite entry via the eye. So the described combination—vector by triatomine bugs and the Romaña sign—points to Trypanosoma cruzi.

For context, Giardia lamblia is spread by cysts in contaminated water and causes giardiasis; Brugia malayi is a filarial worm transmitted by mosquitoes that leads to lymphatic filariasis; Plasmodium vivax causes malaria and is transmitted by Anopheles mosquitoes.