Malaria

Key Personnel
Sabah A. Omar, BSc, MSc, PhD, Molecular Parasitologist, Senior Research Officer
Centre for Biotechnology Research and Development (CBRD)
Kenya Medical Research Institute (KEMRI)
P.O. Box 54840-00200 Nairobi, Kenya
Telephone: 254-20-722541 ext. 3312; Fax: 254-20-715105
E-mail: OSabah@kemri.org

Research Interest
Assessment of therapeutic efficacy to the antifolates, artemisinin and non-artemisinin based combinations against falciparum malaria. Molecular characterization and application of radionuclide techniques for the detection of drug-resistant malaria parasites. Monitoring of antimalarial drug efficacy using quantitative assays, eg., nucleic acid sequence-based amplification (QT-NASBA). Transmission dynamics studies post-artemisinin-based intervention. Parasite population studies determining origin and dispersal mechanisms of resistant parasites. Human population studies investigating protection to malaria disease and prevalence of some human immune genes and other phenotypic markers. Diagnostic malaria parasite assays. In vitro screening of traditional medicines for antimalarial activity, towards bioprospecting for antimalarial agents.

Publications

1. Khan B, Omar S, Kanyara J N, Warren‑Perry M, Nyalwidhe J, Peterson D S, Wellems T, Kaniaru S, Mulaa F, Gitonga J and Koech D K. Antifolate Drug Resistance and Point Mutations in Plasmodium falciparum in Kenya. Transactions of the Royal Society of Tropical Medicine & Hygiene, 1997;91; 456-460.
2. Rapuoda B A, Ouma J H, Njagi K, Otieno J A, Khan B and Omar S. Ministry of Health- 1997. Status of Anti-malaria drug sensitivity in Kenya.
3. Omar SA, Adagu SI, Gump D, Ndaru NP and Warhurst DC. High prevalence of drug resistance-associated alleles in hospital admissions in an epidemic malaria zone of Kenya. Transactions of the Royal Society Tropical Medicine & Hygiene, 1999;92: 122-123.
4. Schoone GJ, Oskam L, Kroon NCM, Schallig HDFH and Omar SA. Detection and quantification of Plasmodium falciparum in blood samples using quantitative nucleic acid sequence-based amplification (QT-NASBA). Journal of Clinical Microbiology, 2000; 4072-4075.
5. Omar SA, Adagu IS and Warhurst DC. Can pretreatment screening for dhps and dhfr point mutations in Plasmodium falciparum infections be used to predict sulfadoxine-pyrimethamine treatment failure? Transactions of the Royal Society of Tropical Medicine & Hygiene, 2001; 95:315-9.
6. Schallig HDFH, Schoone GJ, Kroon CCM, Omar SA, de Vries PJ and van Gool. Quantification of sub-microscopical levels of Plasmodium falciparum in clinical and field samples by Nucleic acid sequence-based amplification (NASBA). Journal of Microbiological Methods, 2001; 47:83-134.
7. Omar SA, Adagu IS, Gump D, Ndaru NP and Warhurst DC. Plasmodium falciparum in Kenya: High prevalence of drug-resistance-associated polymorphisms in hospital admissions with severe malaria in an epidemic area. Annals of Tropical Medicine and Parasitology, 2001; 95, No. 7, 661-669.
8. Omar SA, Owiti O, Bakari A, Adagu IS and Warhurst DC. Cotrimoxazole compared with sulfadoxine-pyrimethamine in the treatment of uncomplicated malaria in Kenyan children Transactions of the Royal Society of Tropical Medicine and Hygiene, 2001; 95:657-660.
9. Schallig, H.D.F.H., Schoone, G.J., Kroon, C.C.M., Omar, S.A., Vries, P.J. de & Gool, T. van. Quantification of sub-microscopical levels of Plasmodium falciparum in clinical and field samples by nucleic acid sequence-based amplification (NASBA). Journal of Microbiological Methods,  2001; 47: 115.
10. Omar SA and Warhurst DC. Cotrimoxazole compared with sulfadoxine-pyrimethamine in the treatment of uncomplicated malaria in Kenyan children Transactions of the Royal Society of Tropical Medicine and Hygiene, 2002; 96:573.
11. Muregi WF, Njagi ENM, Ndiege IO, Chabbra SC, Langat-Thorwa C, Njue E, Omar SA, Mkoji GM. (2003). In vivo antimalarial activity of some Kenyan plants and their effects in combination with chloroquine. Journal of Ethnopharmacology, 2003; 84:2-3; 237-241.
12. Macintyre K, Sosler S, Letipila F, Lochigan M, Hassig S, Omar S and Githure J. Permethrin-impregnated bed-sheets (Shukas) for semi-nomadic pastoralists results from an area of unstable malaria transmission. International Journal of Epidemiology, 2003; 32(1):157-60.
13. Wanyoike GN, Chabbra SC, Langat-Thorwa C, Omar SA. Brine shrimp toxicity and antiplasmodial activity of five Kenyan medicinal plants. Journal of Ethnopharmacology, 2004 (90): 129-133.
14. Muregi FW, Chaabbra SC, Njagi ENM, Langat-Thoruwa CC, Njue WM, Orago ASS, Ndiege IO and Omar SA. Antiplasmodial activity of some Kenyan Medicinal plants extracts singly and in combination. Phytotherapy Research, 2004; 18(5):379-84.
15. Stivanello E, Cavailler P, Cassano F, Omar S A, Kariuki D, Mwangi J, Piola P, Guthman JP. Efficacy of chloroquine, sulphadoxine-pyrimethamine and amodiaquine for treatment of uncomplicated Plasmodium falciparum malaria in Kajo Keji county, Sudan. Tropical Medicine and International Health, 2004; 9 (9):975-80.
16. Omar S.A., Mens P.F., Schoone G.J., Yusuf A, Mwangi J, Kaniaru S, Omer G.A.A., Schallig H.D.F.H.  Plasmodium falciparum:Evaluation of a quantitative nucleic acid sequence based amplification (QT-NASBA) assay to predict the outcome of sulfadoxine-pyrimethamine treatment of uncomplicated malaria.  Experimental Parasitology, 2005; 110; 73-79.
17. Mwangi, J. Omar, S.A., & Ranford-Cartwright, L.CComparison of microsatellite and antigen-coding loci for differentiating recrudescing Plasmodium falciparum infections from reinfections in Kenya. International Journal for Parasitology, 2006; 36 (3): 329-336.
18. Schneider P, Bousema T, Omar S, Gouagna L, Sawa P, Schallig H, Sauerwein R. Sub)microscopic Plasmodium falciparum gametocytaemia in Kenyan children after treatment with sulphadoxine-pyrimethamine monotherapy or in combination with artesunate. International Journal for Parasitology, 2006; 36(4):403-8.
19. Bousema JT, Schneider P, Gouagna LC, Drakeley CJ, Tostmann A, Houben R, Githure JI, Ord R, Sutherland CJ, Omar SA, Sauerwein RW. Moderate Effect of Artemisinin-Based Combination Therapy on Transmission of Plasmodium falciparum. Journal of Infectious Diseases, 2006; 193(8):1151-9.
20. P.G. Kirira, G.M. Rukunga, A.W. Wanyonyi,  F.M. Muregi, J.W. Gathirwa, C. N. Muthaura, S.A. Omar, F. Tolo, G.M. Mungai, I.O. Ndiege. Journal of Ethnopharmacology, 2006; 106: 403-407.
21. F.A. Reed, A. Froment, M.W. Smith, S.M. Williams, S.A. Omar, M. Ibrahim, M. Kotze, O. Doumbo, M. Thera, C. Wambebe, S.E. Dobrin, J.L. Weber, S.A. Tishkoff. The Genetic Structure of Human Populations in Africa. Nature Genetics. IN PRESS
22. P. Mens, N. Spieker, Omar SA M. Heijnen, H. Schallig, P. Kager. Molecular biology the best alternative for diagnosis of malaria to microscopy? A comparison between microscopy, antigen detection and molecular tests in rural Kenya and urban Tanzania. Tropical Medicine and International Health. IN PRESS

Bousema JT, Schneider P, Gouagna LC, Silas Otieno, Marga van de Vegrte Bolmer, Omar SA, Sauerwein RW. Submicroscopic Plasmodium falciparum gametocyte densities frequently infect mosquitoes.  Americal Journal of Tropical Medicine and Hygiene. (IN PRESS).

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