Immunoglobulin-related immunodeficiencies associated with persistent disease:
(1) common variable immunoglobulinemia
(2) X-linked agammaglobulinemia
(3) other types of hypogammaglobulinemia
Selective IgA deficiency does not appear to predispose a patient to more severe disease.
Gastric disorders (probably reflecting a lower number of cysts to cause infection):
(1) previous gastric resection
(2) reduced gastric acid
Underlying conditions that may be worsened by concurrent intestinal disease:
(1) malnutrition
(2) malabsorption (cystic fibrosis, other)
Other conditions associated with persistent disease:
(1) certain HLA antigens (HLA YB-12, HLA-B5, HLA-B14, HLA-DR3, HLA-DR4, HLA-DR7; haplotype HLA-A9-A5; haplotype HLA-A1-B5)
(2) duodenal diverticulum
The differential diagnosis for frequent relapses includes reinfection.
People with AIDS are more likely to be infected with Giardia lamblia and have an impaired immune response, but these patients do not tend to have more severe symptoms.
