Eight year old with fever, hepatomegaly, and positive thick smear

An 8-year-old girl from the rural eastern Amazon department of Loreto presented to her local health post with a 1-week history of fever, headache, and poorly localized abdominal discomfort. At the health post, the child had a temperature of 39°C. A thick smear was obtained, and the patient was started on chloroquine after parasites were observed on the thick smear. The smear was referred to a regional diagnostic center for further evaluation. There the smear was found to be negative for Plasmodium species but positive for