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Chapter 14 Part 6 - Sickle Cell Disease

Sickle cell


Sickle-Cell anemia is a disease that has a short life expectancy, but carriers of this disease are resistant to the sickness Malaria

Sickle-Cell Anemia versus Malaria[]

Sickle-Cell Anemia

-  This disease is caused when two carriers have a child. It is a blood disorder where the persons red blood cells have an abnormal shape to them.  This different shape makes it difficult for the cells to move through the veins - they can clump and stick to each other blocking vein and artery passageways.   This disease is most common in tropical areas where malaria is common as well.


-  It is a disease caused by the mosquito.  The mosquito is infected by a parasite and the saliva from the mosquito has the parasite when it enters the humans blood stream.  The parasitic Protozoa goes to the liver and infects it. Five protists are know to cause Malaria.  Two of them cause the most deaths.  No vaccine exists.

Common link[]

Sickle-Cell Amenia and Malaria share a common link.  If you are a carrier for the sickle-cell trait you are resistant to malaria.  This resistance is why sickle-cell anemia is more prevalent in tropical areas.  it should be a rather rare disease, but due to it's evolutionary advantage over malaria is it more common there due to the high death rates of malaria in the region.  Scientists have studied the causes for sickle-cell preventing malaria in humans. In 2011 they found that the enzyme  heme oxygenase-1 (HO-1) produces carbon dioxide and inhibits cerebral malaria in humans.

UPDATE - It was originally thought that being a carrier for sickle-cell anemia meant that the parasite, Plasmodium which transmits malaria, was inhibited in some way.  But research conducted by Ana Ferreira, sickle hemoglobin makes the host tolerant to the parasite.  As stated previously, heme oxygenase-1 produces carbon monoxide which prevents the host from experienceing cerebral malaria and does not interfere with the parasites lifecycle.

Reference: Ferreira, A., Marguti, I., Bechmann, I., Jeney, V., Chora, A., Palha, N., Rebelo, S., Henri, A., Beuzard, Y., &  Soares, M. (2011). Sickle Hemoglobin Confers Tolerance to Plasmodium Infection. Cell, Volume 145, Issue 3, 398-409.


Ana Ferreira, Ivo Marguti, Ingo Bechmann, Viktória Jeney, Ângelo Chora, Nuno R. Palha, Sofia Rebelo, Annie Henri, Yves Beuzard, Miguel P. Soares. Sickle Hemoglobin Confers Tolerance to Plasmodium Infection. Cell, Volume 145, Issue 3, 398-409, 29

Platt OS, Brambilla DJ, Rosse WF, et al. (June 1994). "Mortality in sickle cell disease. Life expectancy and risk factors for early death". N. Engl. J. Med. 330 (23): 1639–44

Protective Effects of the Sickle Cell Gene Against Malaria Morbidity and Mortality. Aidoo M, Terlouw DJ, Kolczak MS, McElroy PD, ter Kuile FO, Kariuki S, Nahlen BL, Lal AA, Udhayakumar V. Lancet 2002; 359:1311-1312