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CHaPtEr 24 Eosinophils and Eosinophilia 355

TABLE 24.1 Parasitical Diseases Capable invasive pathogen. (ii) Coccidioidomycosis, following primary
of Causing Marked (>3000/µL) or Long- infection, especially in conjunction with erythema nodosum,
Standing Eosinophilia and at times with progressive disseminated disease, can elicit
blood eosinophilia and may cause an eosinophilic meningitis.
Helminth Chronic (iii) Basidiobolomycosis infection can also be associated with
Infection Hypereosinophilia Eosinophilia eosinophilia. 24
Angiostrongyliasis costaricensis
Ascariasis + During early lung Human Immunodeficiency Virus and
migration Retroviral Infections
Hookworm infection + During early lung + Common cause of Eosinophilia can uncommonly accompany human immunode-
migration low-grade ficiency virus (HIV) infections for several reasons. First, leukopenia
eosinophilia may increase eosinophil percentages without reflecting true
Strongyloidiasis Uncommonly + Self-perpetuating,
may last > 50 eosinophilia. Second, adverse reactions to medications may elicit
years eosinophilia. Third, patients with acquired immunodeficiency
Trichinellosis + With heavy infections syndrome (AIDS) who develop adrenal insufficiency as a result
Visceral larva migrans + Principally in children of cytomegalovirus and other infections may exhibit eosinophilia
Gnathostomiasis as a consequence. In addition, modest, and uncommonly marked,
Cysticercosis eosinophilia and eosinophilic pustular folliculitis can be observed
Echinococcosis + May be episodic in some patients with HIV infection. Eosinophilia more com-
24
with cyst fluid 24
leakage monly develops with HTLV-1 infections.
Filariases:
Tropical pulmonary + + ALLERGIC DISEASES ASSOCIATED
eosinophilia WITH EOSINOPHILIA
Loiasis + Especially in +
expatriates Among the noninfectious diseases associated with eosinophilia
Onchocerciasis + +
Flukes: (Table 24.2) are allergic diseases, notably those mediated by
Schistosomiasis + During early infection + IgE-dependent mechanisms. In these diseases, including allergic
in nonimmune rhinitis, conjunctivitis, and asthma, eosinophils are present in
patients involved tissues as well as often being increased in blood.
Fascioliasis + During early infection +
Clonorchiasis + During early infection +
Paragonimiasis + During early infection + MYELOPROLIFERATIVE AND NEOPLASTIC DISEASE
Fasciolopsiasis + During early infection +
Eosinophilia can occur with specific neoplastic diseases, as well
Adapted from Wilson ME, Weller PF. Eosinophilia. In: Guerrant RL, Walker DH, as in some disorders of uncertain etiology, including some
Weller PF, eds. Tropical Infectious Diseases: Principles, Pathogens and Practice, 3rd hypereosinophilic syndromes.
ed. Philadelphia, Penn.: Churchill Livingstone; 2011:943.
Hypereosinophilic Syndromes
A syndrome previously termed idiopathic hypereosinophilic
children, owing to their propensity for geophagous pica and syndrome is not a single entity but rather a constellation of
ingestion of dirt contaminated by dog ascarid eggs, visceral larva leukoproliferative disorders characterized by sustained overpro-
migrans caused by Toxocara canis is a potential etiology for duction of eosinophils. The three original diagnostic criteria for
sustained eosinophilia. ELISA serological testing can evaluate this syndrome were eosinophilia in excess of 1500/µL of blood
this possibility. persisting for longer than 6 months; lack of an identifiable
parasitic, allergic, or other etiology for eosinophilia; and signs
Other Infections: Protozoa and Fungi and symptoms of organ involvement. In contemporary practice,
Infections with single-celled protozoan parasites do not char- if eosinophilia is sustained over a month and the other criteria
acteristically elicit eosinophilia. This is true of all intestinal, are reliably met before the 6-month time frame, a diagnosis can
blood-, and tissue-infecting protozoa, with three exceptions. Two be made and treatment promptly initiated. Moreover, in recent
intestinal protozoans, Dientamoeba fragilis and Isospora belli, years there has been increasing recognition that hypereosinophilic
can at times be associated with low-grade eosinophilia. Hence, syndromes (HES), even at times without evident organ damage,
in patients with symptoms of enteric infection and eosinophilia, encompass a spectrum of disorders, and progress has been made
diagnostic trophozoites of D. fragilis or oocysts of I. belli should in identifying the underlying defects in some of these (Fig. 24.4). 25
be sought in stool examinations. Fecal examinations for I. belli
oocysts must be specifically requested, as they are not usually
detected in routine stool ova and parasite examinations. Other
enteric protozoa do not elicit eosinophilia and, if detected in
stool examinations, should not be accepted as causes of eosino- KEY CoNCEPtS
philia. Sarcocystis, a myositis producing protozoan, can elicit Hypereosinophilic Syndromes
modest eosinophilia.
Three fungal diseases can be associated with eosinophilia. (i) Eosinophilia sustained in excess of 1500/µL.
Aspergillosis is accompanied by eosinophilia only in the form Absence of allergic, parasitic, or other etiologies for eosinophilia.
Usually evidence of organ involvement.
of allergic bronchopulmonary aspergillosis, not when it is an