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Infection Risk in Asplenia and Hyposplenism

It is estimated that up to 25,000 Australians are affected by asplenia or hyposplenism.1  Many are unaware of the fact, and its potential consequences.

The spleen plays an important role in immune function, in particular the prevention of infection due to some specific organisms (Table 1).

Infection Risk

Infection is a relatively common occurrence in those without a functioning spleen. Overwhelming post-splenectomy infection (OPSI), occurs in up to 5% of asplenic patients and has a mortality rate of over 50%. The risk is particularly high in children aged under five, and in the first three years post-splenectomy. However, the risk is lifelong.1

Organisms of Concern

Table 1:     Organisms of Concern

Agent Comment
Streptococcus pneumoniae Accounts for >50% of severe infections. Vaccine available and recommended
Neiserria meningitidis Vaccine available and recommended.
Haemophilus influenza type B Vaccine available and recommended.
Capnocytophagia species Oral flora in animals. Risk of acquisition after animal bites.
Bordetella holmesii Newly recognised pathogen.
Plasmodia species (Malaria)
Babesia, Ehrlichia
Potential risk for travellers. Seek pre-travel advice.

 

Causes of Asplenia and Hyposplenism

Asplenia maybe congenital but is more often acquired as a result of trauma or the surgical removal of the spleen due to haematological conditions, or after incidental splenic damage incurred during intra-abdominal surgery.

Functional hyposplenism also confers an increased risk of infection and may occur as a result of a number of medical conditions (Table 2).

 

Table 2:    Medical conditions associated with hyposplenism

Coeliac disease
SLE
Sickle Cell disease
Rheumatoid arthritis
Malignant infiltration e.g. lymphoma
Splenic infarction or radiation
Graft versus host disease

 

Detection of Asplenia and Hyposplenism

The presence of Howell-Jolly bodies in a blood film may be a clue to the presence of unrecognised asplenia or hyposplenism.  Other investigations that may be of assistance in suspected cases are imaging studies such as ultrasound or CT.

Prevention of Infection

Evidence suggests it is possible to significantly decrease the incidence of infection in asplenic and or hyposplenic patients. Spleen Australia has recently demonstrated a 69% reduction in serious infections in patients on their registry.2

The key strategies utilised by Spleen Australia include;

1. Education

2.  Provision of advice regarding appropriate antibiotic therapy (as per Therapeutic Guidelines)

3.  Provision of current, detailed, practical guidelines for vaccination (As per Immunisation Handbook)

Currently, persons resident in Victoria, Queensland and Tasmania are able to register with Spleen Australia and will then receive regular newsletters and reminders when vaccines are due. It is hoped that this service will be extended to other states. See www.spleen.org.au for details.

 

Key Messages

Spleen Australia provides an excellent range of resources and is happy to assist in the management of these patients if required.

 

References

  1. Spleen Australia. Welcome to Spleen Australia: a clinical service and registry for people with a non-functioning spleen. Melbourne VIC: Diabetes Australia. Available from: www.spleen.org.au
  2. Arnott A, Jones P, Franklin LJ, Spelman D, Leder K, Cheng AC. A Registry for Patients With Asplenia/Hyposplenism Reduces the Risk of Infections With Encapsulated Organisms. Clin Infect Dis. 2018 Aug 1; 67(4): 557-61. Available from: https://doi.org/10.1093/cid/ciy141

 

General Practice Pathology is a new regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs.

The authors provide this editorial, free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.