This can lead to results similar to those seen in patients who have undergone a splenectomy e.g. becoming infected with encapsulated bacteria such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis.

Patients who have some form of asplenia have an increased susceptibility to these encapsulated bacterial infections mainly because they lack IgM memory B cells and their non-adherence to polysaccharide vaccines.

[13] Asplenia is a form of immunodeficiency, increasing the risk of sepsis from polysaccharide encapsulated bacteria,[14] and can result in overwhelming post splenectomy infection (OPSI), often fatal within a few hours.

[16] The risk to asplenic patients has been expressed as equivalent to an adult dying in a road traffic accident (1 to 5 percent of people without spleens would develop a severe infection per decade) (reference UK Splenectomy Trust Advice)—hence sensible precautions are advisable.

[22] Because of the increased risk of infection, physicians administer oral antibiotics as prophylaxis after a surgical splenectomy, or starting at birth for congenital or functional asplenia.

Even with a course of antibiotics and even with a history of relevant vaccination, persons without a functional spleen are at risk for Overwhelming post-splenectomy infection.