Surgical or functional splenectomy increases risk of life-threatening invasive bacterial infection. Although staging laparotomy is no longer standard practice for pediatric Hodgkin lymphoma, patients from earlier time periods have ongoing risks.[2,3] In addition, children may be rendered asplenic by radiation therapy to the spleen in doses greater than 30 Gy.[4,5] Low-dose involved-field radiation (21 Gy) combined with multiagent chemotherapy did not appear to adversely affect splenic function as measured by pitted red blood cell assays. No other studies of immune status after radiation therapy are available. Functional asplenia (with Howell Jolly bodies, reduced splenic size and blood flow) after bone marrow transplantation has been attributed to graft-versus-host disease (GVHD).
Individuals with asplenia, regardless of the reason for the asplenic state, have an increased risk of fulminant bacteremia, especially associated with encapsulated bacteria, which is associated with a high mortality rate. The risk of bacteremia is higher in younger children than in older children, and this risk may be greater during the years immediately after splenectomy. Fulminant septicemia, however, has been reported in adults as long as 25 years after splenectomy. Streptococcus pneumoniae is the most common pathogen that causes bacteremia in children with asplenia. Less common causes of bacteremia include Haemophilus influenzae type b (Hib); Neisseria meningitidis; other streptococci; Escherichia coli; Staphylococcus aureus; and gram-negative bacilli, such as the Salmonella species, the Klebsiella species, and Pseudomonas aeruginosa. Individuals with functional or anatomic asplenia are also at increased risk of fatal malaria and severe babesiosis.
Two primary doses of quadrivalent meningococcal conjugate vaccine should be administered 2 months apart to children with asplenia, from age 2 years through adolescence, and a booster dose should be administered every 5 years. (Refer to the Scheduling Immunizations section of the Red Book for more information.) However, the efficacy of meningococcal vaccines in children with asplenia has not been established. (Refer to the Meningococcal Infections section of the Red Book for more information.) No known contraindication exists to giving these vaccines at the same time as other required vaccines, in separate syringes, at different sites.