Romana's sign is seen in infection due to:

Ans. a (Trypanosoma cruzi). (Ref. Harrison's medicine 16th ed. 1239)CHAGAS'DISEASE# Agent and Vector:- Trypanosoma cruzi (a protozoan) is transmitted through infected insect feces deposited near the bite of blood- sucking insects, especially "reduviid" or "kissing bugs"; and also perinatally, through transfusion, or through parenteral injection.# Incubation:- Incubation is 5-14 days for the initial lesion (if present). The acute stage lasts two-four months and the chronic stage may be life-long.# Acute stage - Signs and Symptoms- About 50% of patients develop either a nodular lesion or furuncle (chagoma) at the site of the bite.- Conjunctival contamination with the vector's feces results in unilateral painless palpebral and periorbital swelling (Romana's sign) and associated lymphadenopathy of nodes draining the lesion. Other symptoms include prolonged fever, tachycardia, fatigue, anemia, weakness, hepatosplenomegaly, lymphadenopathy, and myocarditis.- It lasts 4-8 weeks and in rare cases may include myocarditis or meningoencephalitis.- In severe cases temporary electrocardiogram changes are seen, especially first degree A/V block.# chronic stage - Signs and Symptoms- The parasites have an affinity for smooth, skeletal, and heart muscle; and the nervous system.- The heart is the most commonly effected organ, with manifestations including CHF (often right sided), rhythm disturbances, thromboembolism, and cardiomyopathy.- Megaesophagus may occur, with dysphagia, odynophagia, chest pain, cough, and regurgitation.# Rx:- Nifurtimox