Approach to child with recurrent infections Flashcards
Normal child
Up to 12 infections/ year
Each up to 2 ws
Onset before age 6 months suggests a T-cell defect because maternal antibodies are usually protective for the first 6 to 9 months.
Ty pes of organisms
• Involvement of specific sites is likely
more common with specific types of
immunodeficiency than others. • Examples:
- Recurrent Sinopulmonary infections:
B-cell defects.
- Recurrent Meningitis: complement
defects or B-cell defect
Recurrent viral, fungal, mycobacterial,
or opportunistic infections suggest T-
cell defects. • Recurrent infections with invasive
encapsulated bacteria (e.g:
pneumococcus) suggest B-cell defects. • Recurrent infections with bacteria of
low virulence (e.g: staph) suggest a
neutrophil abnormality. • Recurrent Nisseria infections suggest
terminal complement defect.
Fa mily History:
• Very important! • Consanguinity is a risk factor • The presence of family members with
similar diseases, recurrent infections,
unexplained death, or autoimmune
disease suggests the possibility of a
genetic illness. Inheritance patterns are
variable.
History summary
History summary
• Infections ü Number, frequency, location, age of
onset üSeverity, life-threatening üPathogen (unusual?) üTreatment required, ühospitalization, IV antimicrobials • Autoimmunity: üCytopenias üColitis üArthritis • Malignancy
10 warning sings
Cl ues on Physical Examination
Absent tonsils can be seen in B cell
defect. • Absent lymph nodes can be seen in T/B
cell defect.
La boratory investigations:
CBC & differential: - Lymphocytes Reduced typically in many primary & secondary immune deficiencies - Neutrophils Increased in some phagocytic diseases or absent in congenital neutropenia - Platelets Reduced in autoimmunity & Wiskott Aldrich Syndrome
Humoral assessment:
Ce llular Assessment
Quantitative: • Lymphocyte subsets to evaluate T cell
numbers Qualitative: • In vitro lymphocyte proliferation in
response to certain antigens.
Pha gocytic Assessment: • Neutrophil count (Quantitative) • Neutrophil Oxidative Burst Index.
(Qualitative) Complement Assessment: • Specific complement level
(Quantitative) • Total Hemolytic complement (CH50)
(Qualitative)
Severe Combined Immunodeficiency (SCID)
T cell defects
• Typical example of T-cell defects. • Persistent, recurrent, severe,
opportunistic infections - Bacterial, fungal & viral - Sinopulmonary - Oral thrush, skin infections • Chronic diarrhea • Failure to thrive • Absent lymph nodes & tonsils
La boratory features of SCID
Lymphopenia • Absent or severely reduced T-cells
numbers. • B and Natural killer cells can be low or
normal. • Low or Absent T cell function • Absent antibodies to vaccine.
Ma nagement of SCID
• Treat and prevent infections: - Aggressive antimicrobial therapy. - Immunoglobulin replacement therapy - Antibiotic/antifungal prophylaxis. • Avoid live vaccines • Hemopoietic stem cell therapy: Most
important step. The earlier the better
chances for succeed.
X-linked (Bruton) agammaglobulinaemia
• X-linked recessive. • Genetic defect causing failure of B cells development and the production of all types of Immunoglobulins. • Male infant, presents after 6 months of age. • Sinopulmonary infections, Enteroviral infection, Giardia lamblia. • Lab findings: Absent B cells, absent Immunoglobulins, No antibodies response to vaccines. • Require Immunoglobulin G replacement therapy for life. • Avoid live vaccines
Common Variable Immunodeficiency (CVID)
• Molecular defect unknown. • Infections similar to XLA. • Can present later in life. • Associated with autoimmunity in 20-
25% of patients: arthritis, Pernicious
anemia, thyroiditis.. • Higher risk for hematological and
gastric malignancies • Presence of lymphatic tissues, tonsils
and splenomegaly differentiate it from
XLA.
• Lab findings: Decreased IgG (Hypogammaglobulinemia), normal or decreased IgA and IgM, normal or low B-cells, decreased/absent response to vaccines. • Management: Similar to XLA
Selective IGA dif صورة
MC primary immunodeficiency
At axia Telangiectasia (AT)
• Autosomal recessive, Gene defect causing
abnormal DNA repair • Ataxia: o Starts around 18 months of age o Wheelchair-bound by teenage years o Progressive neurodegeneration • Telangiectasia: o Prominent on face, conjunctiva, ear lobes o Appears at 2-4 years of age • Immune deficiency: o Not as clinically significant o Can have recurrent sinopulmonary infections &
bronchiectasis
Lab findings: • Increased alpha fetoprotein • Decreased T cells number and function,
Absent IgA Management: • Supportive.
