Validation of PCR for detection and characterization of parasitaemia in massive splenomegaly attributed clinically to malaria infection.

In this study, 101 patients with massive splenomegaly (MS) and 41 with moderate splenomegaly (MoS) from Kassala, Eastern Sudan, were included. The patients were recruited during a peak and the end of a malaria season and during a dry season between 2007 and 2008. Based on clinical findings and exclusion of other causes of MS, the former patients were presumed to be infected with malaria parasite; thus, the condition was termed as massive malarial splenomegaly (MMS). Rapid diagnostic test (RDT) and polymerase chain reaction (PCR) were used for malaria parasite detection. In the MMS group, the parasite rate was 50% and 49% as estimated by microscopy and RDT, respectively. However, the PCR showed higher parasite rate (79.3%, P = 0.000), Plasmodium vivax infection, and mixed infections. The PCR-corrected parasite rate in the MoS and control groups was 73.2% and 3.5%, respectively. The parasite rate as estimated by microscopy was highest at the end of the malaria season and lowest in the dry season; however, the parasite rate estimated by PCR was stable in all study periods. There was significant reduction in spleen size following anti-malaria treatment. In conclusion, the use of PCR had revealed significantly higher parasite rate, P. vivax, and mixed infections in MMS as compared to microscopy, while the RDT was found to be comparable to microscopy and is suggested to complement the use of the latter. The study also disclosed a seasonal variation of patent parasitemia with an overall low parasite count and scarce gametocytaemia in MMS.