Informed decision-making before changing to RDT: a comparison of microscopy, rapid diagnostic test and molecular techniques for the diagnosis and identification of malaria parasites in Kassala, eastern Sudan Mamoun M. M. Osman 1 , Bakri Y. M. Nour 2 , Mohamed F. Sedig 1 , Laura de Bes 3 , Adil M. Babikir 2 , Ahmed A. Mohamedani 2 and Petra F. Mens 3 1 Faculty of Medicine, Kassala University, Kassala, Sudan 2 The Blue Nile National Institute for Communicable Diseases, University of Gezira, Wad Medani, Sudan 3 Royal Tropical Institute, Biomedical Research, Amsterdam, The Netherlands Summary objectives Rapid diagnostic tests (RDTs) are promoted for the diagnosis of malaria in many countries. The question arises whether laboratories where the current method of diagnosis is microscopy should also switch to RDT. This problem was studied in Kassala, Sudan where the issue of switching to RDT is under discussion. methods Two hundred and three blood samples were collected from febrile patients suspected of having malaria. These were subsequently analysed with microscopy, RDT (SD Bioline P.f ⁄ P.v) and PCR for the detection and identification of Plasmodium parasites. results Malaria parasites were detected in 36 blood samples when examined microscopically, 54 (26.6%) samples were found positive for malaria parasites by RDT, and 44 samples were positive by PCR. Further analysis showed that the RDT used in our study resulted in a relatively high number of false positive samples. When microscopy was compared with PCR, an agreement of 96.1% and k = 0.88 (sensitivity 85.7% and specificity 100%) was found. However, when RDT was compared with PCR, an agreement of only 81.2 and k = 0.48 (sensitivity 69% and specificity 84%) was found. conclusion PCR has proven to be one of the most specific and sensitive diagnostic methods, par- ticularly for malaria cases with low parasitaemia. However, this technique has limitations in its routine use under resource-limited conditions, such as our study location. At present, based on these results, microscopy remains the best option for routine diagnosis of malaria in Kassala, eastern Sudan. keywords malaria, diagnostics, Sudan, microscopy, rapid diagnostic tests Introduction Malaria causes between 7.5 and 10 million clinical cases and 35 000 deaths every year in Sudan (Elamin et al. 2005; Salah et al. 2006). Therefore, in this country just as any other malaria-endemic country, early diagnosis and effec- tive treatment with an appropriate drug are essential and the main components of the World Health Organization’s strategy to reduce malaria-related mortality (WHO 2010). The gold standard for diagnosing malaria is demonstration of Plasmodium parasites in Giemsa-stained smears of peripheral blood. Expert microscopy is highly sensitive and specific and allows differentiation of the four malaria parasite species capable of infecting humans: P. falcipa- rum, P. vivax, P. ovale and P. malariae (Rafael et al. 2006). However, microscopy may also have its limitations. Microscopic diagnosis can lead to a delay in making proper decisions on antimalaria drug treatment, in particular if many slides have to be examined during epidemics or at low parasitaemia. Furthermore, this method can sometimes be misleading in identifying Plasmodium species, especially in cases with low-level parasitaemia and mixed parasite infection. In situations lacking reliable microscopic diagnosis, rapid diagnostic tests (RDTs) may offer a useful alter- native to microscopy (Nour et al. 2009). In general, RDTs are fast, easy to perform and relatively cheap (Lubell et al. 2007). Moreover, RDTs do not rely on Tropical Medicine and International Health doi:10.1111/j.1365-3156.2010.02659.x volume 15 no 12 pp 1442–1448 december 2010 1442 ª 2010 Blackwell Publishing Ltd