Due to injury or necessary surgery (splenectomy), some people are lacking a spleen, the organ that filters the bloodstream and helps the body fight infection. You do not need your spleen to live a normal, healthy life. However, since the spleen performs some important tasks, people who do not have one are urged to take certain precautions.
The spleen is a fist-sized organ that sits under your rib cage on the left side of your abdomen. Unlike the stomach, liver, or kidneys, it is not directly connected to the other organs in your abdomen. Instead, the spleen is connected to your blood vessels, with an artery that brings blood to it and a vein which takes the blood away.
The spleen is composed of two types of tissues: the red pulp, which filters the blood, and the white pulp, which contains white blood cells that regulate inflammation and the body’s response to infection. Both types of tissue play roles in fighting pathogens (bacteria, viruses, fungi, or parasites) that cause infections.
The red pulp removes red blood cells — which carry oxygen — when they are old, damaged, or infected. It harvests the iron from the old red blood cells for recycling into new blood cells. Usually new red blood cells are created by the bone marrow, but when blood counts are low or the bone marrow is not working well, the spleen can also make new red blood cells.
The loss of the spleen’s ability to filter out infected red blood cells increases risks associated with two parasitic infections, malaria and Babesia. Malaria is spread by mosquito bites in many parts of Africa, Asia, and South and Central America. Babesia is spread by tick bites in the Northeastern and upper Midwestern part of the USA (a different species of Babesia is found throughout Europe). People without a spleen should take extra precautions to avoid these infections if they live in or visit a region where malaria or Babesia are common.
An area in the red pulp called the marginal zone contains special white blood cells known as splenic macrophages that filter pathogens out of the blood. This is a particularly important defense against a type of bacteria coated in a capsule that resists many of the body’s other defenses. These bacteria can be tagged by antibodies produced by the white pulp of the spleen, then killed by the splenic macrophages.
Someone without a spleen is at increased risk of severe, or even deadly, infections from these encapsulated bacteria. Fortunately, vaccines significantly decrease the risk of these infections, and are available against the most common types (Streptococcus pneumoniae, Haemophilus influenza,and Neisseria meningitidis). Additionally, it is usually recommended that people without a spleen have antibiotics that they carry with them (often referred to as “pill in pocket”) and can take at the first sign of an infection, such as fevers or chills. For children without a spleen, their doctors may even recommend they be on antibiotics all the time. Talk to your doctor about this.
The white pulp is composed of lymphoid tissue, which contains white blood cells, the body’s primary means of fighting pathogens and regulating inflammation. White blood cells act as the body’s police force — patrolling the bloodstream to find infections or damage to the body, and working together to combat it. There are many types of white blood cells that function in different and often complex ways. Some fight infections directly, by releasing substances that are toxic to pathogens or by “swallowing” them (called phagocytosis). Some fight infections indirectly, by assisting the direct fighters or by producing antibodies that mark pathogens for destruction by other white blood cells.
Fortunately for people who do not have a spleen, the body has other lymphoid tissues containing white blood cells, such as lymph nodes. For many types of infections, the remaining lymphoid tissues are able to mount an adequate response. However, with the loss of the lymphoid tissue in the spleen, the immune system fights infections with a bit of a handicap. That’s why the Centers for Disease Control and Prevention recommend that people without a spleen get vaccinated against preventable diseases, including influenza (flu). Discuss vaccinations with your physician.
At this point, we do not know for sure how lacking a spleen might affect a person’s ability to fight COVID-19. For most viruses, not having a spleen does not seem to be a major risk factor for illness.
So far this seems to be true for COVID-19 as well. New studies are being published constantly, but lack of a spleen has not been identified as a risk factor for acquiring COVID-19 or having worse outcomes. This is likely because the other lymphoid tissues in the body are able to produce an adequate response. However, it is likely that a person’s ability to fight any infection is at least a little diminished compared to what it would be if they did have a spleen. So with an infection like COVID-19 that can be severe and deadly even in healthy individuals, anyone without a spleen should be extra vigilant in following CDC recommendations to protect themselves and others.
If you do not have a spleen, ask your doctor what steps to take to prevent infection or illness. This might include precautions about mosquito bites and tick bites, vaccinations, and whether you should carry antibiotics (“pill in pocket”). If you have a fever of 100.4° F or more, you should take your pill in pocket if you have it, and seek urgent medical attention.
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