Unexpected false-negative result in a traveller's malaria diagnosis.

A four-year-old traveller returned from Senegal with symptoms compatible with malaria. Plasmodium falciparum HRP-2 antigen detection was negative while panmalarial aldolase was positive. Microscopy confirmed the presence of P. falciparum trophozoites with parasitaemia of 16%. Discarding other causes of false-negative antigen detection, this is a rare case of prozone effect.