Diagnosis of falciparum malaria delayed by long incubation period and misleading presenting symptoms: life-saving role of manual leucocyte differential count.

In countries where malaria is not endemic the diagnosis of the disease is often delayed or overlooked, particularly if the clinical symptoms are atypical and if automated cell analyzers are used instead of blood films for leucocyte differential counts. We report 2 cases of severe Plasmodium falciparum malaria with unusual clinical features: a 46-year-old man with an exceptionally long incubation period and a 22-year-old woman with presenting symptoms suggesting viral hepatitis. In both cases the diagnosis of malaria was unexpectedly made by observant laboratory technicians examining stained blood films for differential counts.