Infections in immunocompromised children

A registrar hands you a child on chemotherapy who has spiked a fever at home. The child looks well, is playing on the bed, and the temperature is only 38.1 °C. The trap is to be reassured. The whole principle of this topic is that the missing immune compartment — whether neutrophils, T-cells, antibody, or spleen — removes the early-warning system that tells you a normal host is sick. Height of fever correlates poorly with serious bacterial infection even in immunocompetent children, and the relationship is weaker still when the inflammatory response itself is disabled. [4]

This page owns the approach to infections in immunocompromised children. It sits beside the sister pages on paediatric sepsis, fever by age and immune status, fungal infections, EBV and CMV, and antimicrobial stewardship. Those pages take the organism-specific depth; this page builds the unifying framework a fellowship candidate must defend at viva. [1] [14]

Overview & Definition

An immunocompromised child is one whose immune system cannot mount the response a normal host would mount to the same organism. The compromise may be inherited, as in primary immunodeficiency; acquired, as in chemotherapy-induced neutropenia or HIV; iatrogenic, as in post-transplant immunosuppression; or structural, as in asplenia or the presence of an indwelling central venous catheter. What unites these children is a shared clinical problem: the usual signs of infection — fever, localising pain, pus, an inflammatory wall — are blunted or absent, so the window between treatable infection and overwhelming sepsis narrows. [1]

Fever in the immunocompromised host is defined operationally, not arbitrarily. In the febrile-neutropenia pathway, fever is a single oral or tympanic reading at or above 38.3 °C, or two readings at or above 38.0 °C taken at least an hour apart. Neutropenia — an absolute neutrophil count below 0.5 × 10⁹/L, or below 1.0 × 10⁹/L with an expected fall — is the qualifier that converts a febrile child into a febrile-neutropenic emergency. The definition matters because the threshold triggers an entire pathway that does not wait for proof of infection. [1]

References14Show ledgerHide ledger

1. [1]Lehrnbecher T Guideline for the Management of Fever and Neutropenia in Pediatric Patients With Cancer and Hematopoietic Cell Transplantation Recipients: 2023 Update. Journal of clinical oncology, 2023.PMID 36689694
2. [2]Schlapbach LJ International Consensus Criteria for Pediatric Sepsis and Septic Shock. JAMA, 2024.PMID 38245889
3. [3]Weiss SL Surviving Sepsis Campaign International Guidelines for the Management of Sepsis and Septic Shock in Children 2026. Pediatric critical care medicine, 2026.PMID 41869844
4. [4]De S Lack of Accuracy of Body Temperature for Detecting Serious Bacterial Infection in Febrile Episodes. The Pediatric infectious disease journal, 2015.PMID 26065864
5. [5]Biondi EA Prevalence of Bacteremia and Bacterial Meningitis in Febrile Neonates and Infants in the Second Month of Life: A Systematic Review and Meta-analysis. JAMA network open, 2019.PMID 30901044
6. [6]Groll AH 8th European Conference on Infections in Leukaemia: 2020 guidelines for the diagnosis, prevention, and treatment of invasive fungal diseases in paediatric patients with cancer or post-haematopoietic cell transplantation. The Lancet. Oncology, 2021.PMID 33811813
7. [7]Cornely OA Global guideline for the diagnosis and management of candidiasis: an initiative of the ECMM in cooperation with ISHAM and ASM. The Lancet. Infectious diseases, 2025.PMID 39956121
8. [8]Maertens J ECIL guidelines for preventing Pneumocystis jirovecii pneumonia in patients with haematological malignancies and stem cell transplant recipients. The Journal of antimicrobial chemotherapy, 2016.PMID 27550992
9. [9]Kotton CN The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation. Transplantation, 2018.PMID 29596116
10. [10]Hsu AJ Challenges in the Treatment of Invasive Aspergillosis in Immunocompromised Children. Antimicrobial agents and chemotherapy, 2022.PMID 35766509
11. [11]Bavare AC Central Line-Associated Bloodstream Infections in Pediatrics: A Review. Pediatrics in review, 2025.PMID 40875258
12. [12]Lee GM Preventing infections in children and adults with asplenia. Hematology. American Society of Hematology. Education Program, 2020.PMID 33275684
13. [13]Cesaro S Adenovirus infection in allogeneic hematopoietic cell transplantation. Transplant infectious disease, 2023.PMID 37846850
14. [14]Srinivasan A Timeline, epidemiology, and risk factors for bacterial, fungal, and viral infections in children and adolescents after allogeneic hematopoietic stem cell transplantation. Biology of blood and marrow transplantation, 2013.PMID 22922523