Molecular analysis of archived blood slides reveals an atypical human Trypanosoma infection.

In 2003, a 10-month-old Ghanaian boy recovered from a Trypanosoma brucei infection, although the patient was not treated with antitrypanosomal drugs. Only T. brucei gambiense and T. brucei rhodesiense are able to infect humans, causing human African trypanosomiasis. The disease is considered 100% fatal if left untreated. The identity of the trypanosome was determined by DNA extraction from the archived stained blood slides followed by sequential application of polymerase chain reactions (PCRs) that are specific for the order, subgenus, species and subspecies, followed by genotyping with microsatellite PCR. Molecular analysis indicated that the parasites observed in the patient's blood in 2003 belong to the T. brucei subspecies brucei, which is normally not infectious to humans. Next to the clinical message, this article provides technical information to extract successfully DNA from archived blood slides for subsequent molecular analysis and to identify a trypanosome by taxon-specific PCRs and microsatellite genotyping.