Thalassemia is a blood disorder which is common in the Mediterranean, North Africa, and Western and Southern Asia. It is estimated to have killed about 18,000 people in 2010 alone, although this figure may be inaccurate, given that the disease is common in area's of the world where it is difficult to pick up on health issues.
It affects the haemoglobin and red blood cells, which limits the amount of oxygen that can be sent around the body. This can lead to issues such as infection, bone deformities, enlarged spleen, slower growth rates, and heart issues. Because the treatment can involve frequent blood transfusions, this can also lead to increased amounts of iron in the blood (although this can also happen because of the disease itself), which then has to be dealt with through medication.
It has survived as it tends to protect the individual from malaria, which is why it is found in in area's where malaria is, or used to be, an issue. For example, the Tharu people in Nepal and India live in a part of the world that has a very heavy malaria infestation, but have very low infection rates. Genes for thalasseamia have been found in almost all of the individuals in the Tharu population.
How can it be contracted?
Thalassemia is passed genetically, and can only be passed if both parents are affected. If they are both affected, then there is a 25% chance their child will be unaffected, a 50% chance they will have the ability to pass on the disorder, but will be unaffected themselves, and a 25% chance they will be affected.
Is there a treatment?
There are only really two ways of curing Thalassemia. The first is to get a transplant of bone marrow, or (less commonly) blood from an umbilical cord. Both have to be from a sibling to have a large chance of success, and ideally transplanted when the patient is young.
The second is preventative. If people check whether they have the disorder, and know whether they need to check children before they are born, thalassaemia could be eradicated in a generation. This is happening in Cyprus, which has one of the highest rates of the disorder in the world (16%), but through screening and abortion, rarely has a case in the younger generation.