http://www.clinicalmolecularallergy.com/content/4/1/8
In United States, strongyloidiasis is the most important nematode infection in humans with a tendency towards chronic persistent infection and with special characteristic features of autoinfection, hyperinfection involving pulmonary and gastrointestinal systems, and disseminated infection involving other organs . Strongyloidiasis is caused by a soil dwelling nematode helminth, Strongyloides stercoralis. This helminth resides in the small intestine of the human host. There is another species of same genus, Strongyloides fuelleborni that can also cause human infection but is mostly seen in African countries .
Infection with Strongyloides stercoralis was first reported in the year 1876 in French soldiers working in Vietnam . It took nearly 50 years for the complete elucidation of the complex life cycle after the discovery of the parasite because of the rare and characteristic feature of autoinfection that occurs in the life cycle. Strongyloidiasis was first described by Fulleborn in 1926 . First reports of disseminated infection or hyperinfection date back to 1966 when Cruz et al., and Rogers et al., independently documented the occurrence of fatal strongyloidiasis with immunosuppression .
Though many advances have been made in the diagnosis and treatment of strongyloidiasis, it still prevails as one of the elusive diseases to tackle in the present day world. Strongyloidiasis may have a spectrum of manifestations ranging from the most common asymptomatic disease to potentially life threatening hyperinfection syndrome and disseminated disease. The patients, if symptomatic, present with pulmonary and gastrointestinal symptoms. Most of them are found to have strongyloidiasis after a laboratory work up reveals an incidental finding of eosinophilia. This review article documents a case report with symptoms along with review of the epidemiology, biology of strongyloidiasis, clinical manifestations of the disease including hyperinfection syndrome, effect of systemic corticosteroids on strongyloidiasis, diagnostic aspects of the disease, various pathophysiological mechanisms and host defense pathways regulating strongyloidiasis, and different options available to treat the infection.
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Strongyloidiasis can manifest in a wide spectrum of clinical features ranging from asymptomatic disease, disease with mild initial symptoms, disease with chronic symptoms and acute exacerbation with hyperinfection or dissemination of larvae involving respiratory and gastrointestinal systems or multiple organ systems respectively. Though fatal hyperinfection or dissemination can occur, asymptomatic strongyloidiasis is the most common form of the disease ]. The various clinical manifestations are shown in the Table 2.
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The most important laboratory finding seen in patients with strongyloidiasis is eosinophilia [65]. Eosinophilia is shown to be 93.5% sensitive with a specificity of 93.1% in high risk populations
. But it is also shown that the eosinophil count if used alone is not sufficiently sensitive to screen for strongyloidiasis [18,66] especially in patients with chronic infection who can have low or normal eosinophil counts [65], in people returning from developing countries [66], and in some cases of hyperinfection syndrome and disseminated strongyloidiasis. However, increased peripheral eosinophilia in the case of hyperinfection syndrome could be considered as a good prognostic factor [10]. Eosinophilia is not a cost effective strategy compared to the stool examinations with agar plate culture method and serological testing in detecting strongyloides infection in humans [67].
Diagnosis of strongyloidiasis could be done by serological methods especially in asymptomatic patients with eosinophilia (as in the patient described in this report) or mildly symptomatic patients. These serological tests are also shown to be useful in the diagnosis of strongyloidiasis even in immunocompromised individuals [68]. The serological methods determine the presence of strongyloid antibody in the serum of the human hosts. The antibody could be determined by the following methods: 1) Enzyme-Linked Immuno-Sorbent Assay (ELISA) [69,70], 2) Gelatin Particle Indirect Agglutination (GPIA) [69], and 3) Western Blot Analysis (WBA) [8].
Huaman et al., in their study showed that both ELISA and GPIA are useful in the diagnosis of strongyloidiasis with sensitivities of 74.1% and 98.2%, respectively and specificity of 100% for both studies. As low titers of strongyloid-specific antibodies are noted in hyperinfection along with a low or normal eosinophil count, GPIA is more sensitive than ELISA in detecting the specific immunoglobulin in cases of chronic infection and hyperinfection [69]. New strongyloides-specific antigens are being discovered that may help in the immunodiagnosis of strongyloidiasis in a more sensitive and effective way [71].
The diagnosis of strongyloidiasis can also be made very reliably by observing strongyloid larvae in stool or sputum specimens. But these tests are not accurate as there is fluctuation in the rate of larval excretion especially in stools [8] decreasing the efficacy and accuracy of these tests [72]. Repeated multiple stool specimens should be analyzed to increase the efficacy of the test in the presence of strong suspicion of strongyloidiasis [2,8,73]. Sudharshi et al., in their study have noted stool examinations by formalin-ether concentration method for larvae to be less sensitive in detecting the disease when used alone, especially in non-endemic regions [18].
Microscopic examination of stool specimens is done for strongyloid larvae. This can be done in the following different ways: 1) Simple direct smear with a sensitivity of 0–52% [8], 2) Formalin-ether concentration method with a sensitivity of 13–55% [8], 3) Harada-Mori filter paper culture method with almost equal sensitivity to the above 2 methods [74,75], and 4) Agar plate culture technique with higher sensitivity of 78–100% [8]. Of all the mentioned methods, multiple studies have shown detection of strongyloides larvae in stool specimens is more effective and accurate with agar plate culture technique [4,73-75]. Biopsy with duodenal intubation and Enterotest™ are rarely used, though they have high sensitivity, because they are very cumbersome [76].
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Im gonna be so pissed if I doctor googled my dx. It takes so long to get in to see specialists and get the tests run, then wait for the "results" appointment. Im currently 2 weeks away from my 6 week wait for the "AWESOME" Rheumatologist and 4 weeks from me 8 WEEK WAIT for the Infectious disease guy. Im thinking of going to go see the first ones that come available again with these new things Ive found in hand.Post Edited (PathogenKiller) : 2/9/2013 9:56:42 PM (GMT-7)