Dr. Jan Hajek (biography and disclosures)
What I did before
Most of us recognize that the world is increasingly connected and that infectious diseases know no borders. We are aware that returning travellers, refugees and immigrants can present with illness related to a tropical disease or parasitic infection acquired outside of Canada. However, we are not always pro-active in adequately screening our patients for these infections.
Although an elevated eosinophil count has long been recognized as a key diagnostic clue of a parasitic infection, it is often overlooked.
What changed my practice
A recent case of eosinophilia and Strongyloides hyperinfection and new screening guidelines from both Canadian1 and US2 expert groups have influenced my practice.
The case
Mr. L. is 46 years old, immigrated to Canada from Vietnam in 1992, and was previously in very good health. This past September, progressively worsening headaches led him to seek medical attention at the emergency department where a CT scan was done and showed evidence of brain metastases from a lung primary. He was started on high dose dexamethasone and referred for bronchoscopy and further oncological management. His routine blood work was normal apart from an elevated eosinophil count – which was overlooked.
Over the next few days to weeks, on steroids, his headaches improved, but he began to feel itchy. His first bronchoscopy was non-diagnostic. His repeat bronchoscopy confirmed lung cancer, and the microbiology technician observed an unusual pattern in the normal respiratory bacteria growing on the petri dish – some of the bacterial colonies were spread out in linear tracks. This was an incidental finding, but, to the trained eye, was characteristic of the presence of Strongyloides larvae. Further testing confirmed that Mr. L. had Strongyloides hyperinfection, a potentially fatal disease if not treated early.
Strongyloides stercoralis larva tracks on a blood agar plate from the bronchoalveolar lavage of a patient with disseminated strongyloidiasis (taken from Sue Lim et al.3)
Strongyloides is endemic throughout most of the world, especially tropical, sub-tropical, and developing countries. Asymptomatic strongyloidiasis can persist for decades after immigration. Eosinophilia, a useful indicator, is not always present. If left untreated, in the setting of immunosuppression with even relatively short courses of steroids, it can result in severe illness or death through disseminated disease.
Mr L. had acquired Strongyloides infection years ago in Vietnam. Other than his elevated eosinophil count he was entirely asymptomatic. Only when he was given steroids did the infection become symptomatic as the larvae began to replicate in very high numbers unchecked by his suppressed immune system. Fortunately, he was diagnosed in time and did well following treatment with ivermectin.
The guidelines
The Canadian Collaboration for Immigrant and Refugee Health (CCIRH) recommends screening all refugees arriving from countries in Africa or South East Asia for strongyloidiasis using serology.1 Additional serology for schistosomiasis is recommended for those from Africa.
The US Centre for Disease Control (CDC) and the Division of Global Migration and Quarantine recommend serological screening for strongyloidiasis for all refugees regardless of region of origin.2 In addition, they recommend that all refugees are screened with a CBC (looking for eosinophilia) and stool O&P examination. Schistosomiasis serology is also recommended for refugees from Sub Saharan Africa.
What I do now
In view of the prevalence of parasitic infections among refugees, and the extremely high mortality rate of disseminated strongyloidiasis, I support comprehensive screening for eosinophilia, stool O&P examination, and Strongyloides serology for all refugees, especially those from Africa or South East Asia.
I consider serologic screening for Strongyloides mandatory for all patients who have a history of residence in a tropical or sub-tropical country and require immunosuppressive therapy (corticosteroids, transplant, or chemotherapy).
I interpret an elevated eosinophil count as a parasitic infection until proven otherwise and I pursue comprehensive investigations, tailored to the patient’s epidemiological history, in my diagnostic approach.4
Serology for Strongyloides can be drawn at any outpatient laboratory and will be forwarded to the national reference laboratory in Montreal for testing. Unlike stool examination, serology has excellent sensitivity for the detection of Strongyloides infection.
Ivermectin is the treatment of choice for strongyloidiasis. However, along with albendazole, it is not available in pharmacies and must be obtained through the Special Access Programme. Instructions on how to obtain these medications can be found at Health Canada’s website.5
Providing care for immigrants and refugees requires attention to their previous experiences with the health care system, the potential lack of prior access to preventive care and exposures to infectious diseases. The CCIRH guidelines provide evidence-based recommendations to help guide our practice.1
Not all parasitic infections require international travel or visits to tropical countries. Important, not to be missed, parasitic infections can be acquired right here in BC. For example, raccoon roundworm (Baylisascaris procyonis), a cause of potentially fatal encephalitis is common in raccoons and a potential, albeit very rare, risk to children throughout most of Canada.6
Patients with unexplained eosinophilia or parasitic infection can be referred for consultation to the tropical medicine clinic at the Diamond Centre, Vancouver General Hospital. Our fax number is (604) 874-4013.
References (Note: Article requests might require a login ID with CPSBC or UBC)
- Pottie K, Greenaway C, Feightner J, et al; coauthors of the Canadian Collaboration for Immigrant and Refugee Health. Evidence-based clinical guidelines for immigrants and refugees. CMAJ. 2011;183(12):E824-925. http://www.cmaj.ca/content/183/12/E824/suppl/DC1
- United States Division of Global Migration and Quarantine and Centre for Disease Control. Guidelines for Evaluation of Refugees for Intestinal and Tissue-Invasive Parasitic Infections during Domestic Medical Examination. http://www.cdc.gov/immigrantrefugeehealth/guidelines/domestic/intestinal-parasites-domestic.html Accessed November 1, 2012.
- Lim S, Katz K, Krajden S, Fuksa M, Keystone J, Kain K. Complicated and fatal Strongyloides infection in Canadians: risk factors, diagnosis and management. CMAJ. 2004 August 31; 171(5): 479–484.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC514646/pdf/20040831s00030p479.pdf
- Page KR, Zenilman J. Eosinophilia in a patient from South America. JAMA. 2008;299(4):437-44 (View Article with UBC or CPSBC)
- The Health Canada Special Access Program. http://www.hc-sc.gc.ca/dhp-mps/acces/drugs-drogues/index-eng.php Accessed November 1, 2012.
- Hajek J, Yau Y, Kertes P, et al. Baylisascaris Procyonis: A child with raccoon roundworm meningoencephalitis: A pathogen emerging in your own backyard? Can J Infect Dis Med Microbiol. 2009;20(4)177-180.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807255/pdf/idmm20e177.pdf
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It was very refreshing view of looking at elevated eosinophil count. It is certainly very useful in my practice that has high percentage of immigrants from South Asia.
Eosinophil counts are not reported on Interior Health automated differentials. I used to find these counts useful. now, they have to be ordered specifically.
Nice to see this summary of the CCIRH guidelines as well as and a relevant case study.
good info. Any figures re the actual incidence?
Excellent review
Interesting article on a group of illnesses that I feel I do not know much about. I think we often do think of these types of things in people with an obvious travel history, but the problem is that travel is only a risk factor and we all know that risk factors alone don’t pick everyone up with the disease. Just to name 2, I know of cases of Cryptococcous gatii and Typhoid without any risk factors or travel to emdemic areas. I am sure the same holds for many of these parasitic infections. It seems like we need a guideline for workup of eosinophilia for all patients, keeping in mind what would be cost effective. I am not sure how many of our patients have undiagnosed eosinophilia right now…perhaps this could be a lot?
Good to consider in treating travellers and refugees especially when the eos count is high
I, too, appreciated having the guidelines summarized. I don’t believe we should have to ask for an eosinophil count at Interior Health; it should be part of a CBC.
Thank you for this excellent case presentation. I confess I knew nothing about strongyloides infection (I even have a hard time pronouncing it).
I too will change my practise.
I do a fair amount of work at YVR so a fair number of the patients we see are from the endemic areas and this information will I’m sure be useful in the future.
This information is useful. I have a number of immigrant patients and travellers from areas at risk for parasitic infections.
Interesting.One’s education continues. you don’t mention his Ca Lung. How did he get into Canada and would that likely not be a potential life limiting issue?
This is very relevant to my Hospitalist practice in Burnaby as we have patients from all over the world. I will watch for eosinophilia more carefully in future!
Thanks to my background medical degree from Hong Kong, where tropical and parasititc diseases course was manadatory, we have been taught even 45 years ago to use eosinophil counts as “allerts” to parasitic diseases.
Thanks for the informative review. Lots of immigrant patients and I never knew there’s even a Tropical Medicine clinic at VGH which I could refer to… Two years ago I had a returning traveller from South Asia who presented with delirium and a 40+ degree fever 4 months after her return, sent to VGH Emerg specifically for malaria work up, and had a resident call me to argue that this patient would NOT need any malaria blood smears. I think more time and resources was spent to convince me that the workup was redundant, than to actually work up the patient.
Anyways, I digress. Any similar tropical medicine / parasitology referral center that will see children?? I often have cases of perianal itch / failure to thrive etc in toddlers who turn out to have an eosinophil count… but we never find anything on repeated Stool O&P attempts….