What is haemophilia?
Haemophilia is a rare inherited blood disease. People with haemophilia have faulty, or too little, blood clotting factor (the part of the blood that makes it thicken or form a scab). This means that they bleed easily – after a small injury or bump, or even spontaneously (without any injury). Haemophiliacs can bleed from broken skin, but they can also bleed inside the body. It takes haemophiliacs longer to stop bleeding, and they are sometimes unable to stop bleeding at all.
How do you get haemophilia?
Almost all people with haemophilia are male. Boys inherit the disease from their mothers. Women “carry” the disease, but do not have symptoms. (Rarely, they have very mild symptoms.) Women can pass on carrier status to their daughters, who may then give the disease to their sons.
There is no cure for haemophilia. However, it can be controlled with special treatment. The usual treatment is to give haemophiliacs blood clotting factor by intravenous infusion (it is put directly into the bloodstream through a drip).
- People with haemophilia A, the most common kind, need clotting factor VIII. People with haemophila B (christmas disease) need factor IX.
- Patients can be infused immediately after they start to bleed. People with severe haemophilia may need regular infusions to prevent bleeding.
- Haemophiliacs don’t need whole blood, just the part of the blood plasma that contains the clotting factor. This is called cryoprecipitate. Units of cryoprecipitate are stored frozen, and are thawed and pooled together before being used.
Haemophilia and HIV
If you are a haemophiliac, you may be worried that the blood you receive is infected with HIV. Unfortunately, this is a real risk with any blood product.
- Because they have infusions so often, and because cryoprecipitate is pooled from several different donors, haemophiliacs are at an increased risk of receiving HIV-infected blood.
- Cryoprecipitate carries as much risk of HIV as whole blood.
- If you receive infected blood by transfusion, you will almost certainly become infected.
- In severe haemophiliacs, AIDS is the most common cause of premature death. However, it is important to remember that almost every case of HIV infection via blood transfusion happened before 1985. That was the year that all donated blood began to be tested for HIV; since then, the safety of donated blood has improved vastly.
- Currently, the risk of HIV infection by blood transfusion in developed countries is extremely low. Blood transfusions in South Africa are very safe, despite our high rates of HIV infection. Sadly, in much of the rest of the developing world, blood transfusions are much more risky.
- Other clotting factors do exist which are less risky for HIV, such as recombinant factor VIII (which is genetically engineered from non-human mammal blood). Synthetic vasopressin (DDAVP) is a clotting product that is not made from blood, and is useful in mild cases. However, these treatments are more expensive than ordinary cryoprecipitate, and most people don’t have access to them.
How is blood made safe?
While there is always some risk of HIV infection, blood banks follow certain steps to make sure that their blood is as safe as possible:
- Donor selection. Blood donors must complete a written questionnaire. The questions deal with the donor’s lifestyle and history, and are designed to find out whether the person is in a risk group for HIV infection. Blood is not accepted from someone who is at high risk, or who shows signs of infection. Of course, this screening depends on the donor answering the questions honestly.
- Testing. All blood that is donated is tested for HIV. Any blood that is infected is destroyed, and the infected donors are informed.
- Careful identification. All blood is carefully labelled, and records of all donors and test results are kept on computer. This ensures that infected blood isn’t mixed up with usable blood.
- Treatment. Using special heating techniques, the blood product is treated to destroy any infection that remains.