This week we discussed the case of a young lady with eosinophilia. She had some vague symptoms to begin with, but after thorough investigation, she was found to have disseminated strongyloidiasis complicated by E. coli bacteraemia. She was immunosuppressed due to a new diagnosis of HIV infection.
Strongyloidiasis is a tropical parasitic disease usually caused by the nematode Strongyloides stercoralis. This can be found in South America, South/Southeast Asia and Africa. It is often asymptomatic, but can cause severe disease in immunosuppressed states. As it often affects the bowel, it can facilitate translocation of gut organisms, and because of this is often associated with E. coli septicaemia. Stool microscopic examination often yields the diagnosis. Treatment is generally with ivermectin and treating any underlying cause – like HIV in our patient’s case.
This case illustrates how – more often than not – referrals to haematology can often result in unexpected non-haematological diagnoses. This is especially the case with non-specific abnormalities e.g. abnormal blood counts. It is important to keep an open mind when approaching these cases to avoid bias and ensure appropriate patient care.
Please see below a summary on eosinophilia, taken from case 41!
Eosinophilia can occur in 1-1.5% of blood counts in the UK. Eosinophils develop in the bone marrow and IL-3, IL-5 and GM-CSF are essential for their differentiation. Sometimes solid tumours can secrete these cytokines causing eosinophilia. Eosinophils are involved with host defence against parasites, as modulators of innate and adaptive immunity, inflammatory responses and tissue repair, and affect mast cell activation and T-cell function.
The causes of eosinophilia are extensive and are highlighted below:
Common infectious/tropical causes include:
- Strongyloidiasis – South/Central America, SE Asia, Africa, India
- Hookworm – South/Central America, SE Asia, Africa, India
- Filariasis – Tropical areas
- Ascariasis – Tropical areas
- Toxocariasis – dogs/cats
- Trichinellosis – under cooked pork
- Schistosomiasis – sub-Saharan Africa, South America, East Asia
- Coccidiodomycosis – desert areas aspecially northern and central America
- Fascioliasis – Somalia
- Aspergillosis/ABPA – history of asthma, cystic fibrosis
It must be remembered that the vast majority of cases of eosinophilia are transient and benign. In one case series these were the most common causes:
- atopy including asthma 79.7%
- parasites 8.2%
- haematological neoplasm 2.4%
- allergic / atopic skin disease 2.1%
There is no concrete evidence base to guide the best way to monitor or investigate patients with eosinophilia. Most bodies make decisions based on opinion. The British Committee for standards in haematology is writing a guideline currently on this topic. However if a patient is found to have eosinophilia it is important to undertake a history and examination. The history should be focused on identifying a cause based on the list above. It is important to ask about any new medications, travel and allergic symptoms. This will reveal most causes. If no symptoms are obvious then a systemic enquiry asking about ‘red flag’ symptoms (weight loss, sweats, blood loss, anorexia etc.) is required. An examination is useful to clarify points from the history and also document any enlargement of spleen and liver which may be asymptommatic. It is also useful to document examination findings to allow for assessment of changes. If the eosinophilia is mild (generally <1.5×109/L) and there is an obvious cause many may not feel the need to repeat, but appropriate safety netting is required. If there is no obvious cause on initial evaluation, or the patient has evidence of end organ damage (heart failure, respiratory symptoms, diarrhoea, rash) or the eosinophil count is >1.5×109/L then further evaluation and repeating is generally required. Generally it would be unusual for an allergic cause for the eosinophil count to be >2×109/L.
- Lombardi C, Giovanni P. Eosinophilia and disease: a clinical revision of 1862 cases. Arch Intern Med 2003 163: 1670-3
- Investigation of an incidental finding of eosinophilia: http://www.bmj.com/content/bmj/342/bmj.d2670.full.pdf
- Drug-induced eosinophilia: http://www.pharmaceutical-journal.com/learning/learning-article/drug-induced-eosinophilia/20000049.article
- Eosinophilic Myeloproliferative Disorders. http://asheducationbook.hematologylibrary.org/content/2011/1/257.full.pdf
- Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864371/pdf/0950696.pdf
- Nordic guidelines: http://www.hematology.dk/index.php/vejledninger/kliniske/diverse-vejledninger/66-nordic-eos-guideline-revised-sept-2012/file