Eosinophilia in the returning traveler

Comparison of commercial and in-house real-time PCR platforms for 15 parasites and microsporidia in human stool samples without a gold standard

INTRODUCTION

A test comparison of in-house and commercial real-time PCR (qPCR) kits for the detection of human parasites and microsporidia in stool samples was conducted without a gold standard. Three different commercial kits were included in the comparison, with a range of 3-15 different PCR targets, while 14 targets were covered by in-house testing, so not all 16 target pathogens were covered by all assays.

METHODS

Residual materials from nucleic acid extractions of stool samples with very high likelihood of being colonized or infected by at least one enteric parasite species or microsporidia were tested. In all, 500 DNA samples were analyzed, but due to limited sample volume, only 250 of the 500 samples were tested per assay. Each sample was assessed with the qPCR platforms being compared and cycle threshold (Ct) values were included in a descriptive comparison.

RESULTS

Depending on the assay applied, qPCR detected per 250 tested samples Giardia duodenalis (184-205), Blastocystis spp. (174-183), Trichuris trichiura (118-120), Ascaris lumbricoides (79-96), Necator americanus (78-106), Hymenolepis nana (40-42), Cryptosporidium spp. (27-36), Dientamoeba fragilis (26-28), Schistosoma spp. (13-23), Enterobius vermicularis (8-14), Entamoeba histolytica (7-16), Strongyloides stercoralis (6-38), Cyclospora spp. (6-13), Taenia spp. (1-4), microsporidia (1-5), and Ancylostoma spp. (1-2). Inter-assay agreement kappa was almost perfect (0.81-1) for Dientamoeba fragilis, Hymenolepis nana, Cryptosporidium spp., and Ascaris lumbricoides, substantial (0.61-0.8) for Necator americanus, Blastocystis spp., Ancylostoma spp., Giardia duodenalis, Schistosoma spp., Trichuris trichiura, and Enterobius vermicularis, moderate (0.41-0.6) for Entamoeba histolytica, fair (0.21-0.4) for microsporidia, slight (0-0.2) for Cyclospora spp. and Strongyloides stercoralis, and poor (<0) for Taenia spp.

CONCLUSIONS

Varying inter-assay agreement makes interpretation of microsporidia and parasite PCR in stool samples challenging. Intra-assay agreement had been controlled during the developing of the assays. Future studies, e.g., with optimized nucleic acid procedures and including microscopically characterized samples, are advisable.

Parasitic Hypereosinophilia in Childhood: a Diagnostic Challenge

Severe hypereosinophilia (HE) in children is rare, and its etiological diagnosis is challenging. We describe a case of a 30-month-old boy, living in a rural area, who was admitted to our Clinic with a 7-day history of fever and severe hypereosinophilia. A comprehensive diagnostic workup could not identify the cause of this condition. On day 6, the rapidly increasing eosinophil count (maximum value of 56,000/mm³), the risk of developing hypereosinophilic syndrome, and the patient’s history prompted us to undertake an empiric treatment with albendazole. The eosinophil count progressively decreased following treatment. On day 13, clinical condition and hematological data were satisfactory, therefore the treatment was discontinued, and the patient was discharged. Three months later, anti-nematode IgG antibodies were detected in patient serum, thus establishing the etiological diagnosis. In conclusion, an empiric anthelmintic treatment seems to be justified when parasitic hypereosinophilia is strongly suspected, and other causes have been excluded.

Significance of Diagnosing Parasitic Infestation in Evaluation of Unexplained Eosinophilia

BACKGROUND

The evaluation of unexplained eosinophilia in an asymptomatic individual has always been a diagnostic challenge and requires understanding about a wide range of probable causative agents. Helminthic infestation and schistosomiasis are the main parasitic causes of eosinophilia. Therefore, the availability of simple and accurate diagnostic tests for detection of parasitic infections can prove to be valuable in early diagnosis and solving the mystery of unexplained eosinophilia.

MATERIALS AND METHODS

In the present study we attempt to find an association between relative eosinophilia and parasitic infections and also to find the parasites responsible for eosinophilia in a substantial number of cases. A retrospective study for the presence of eosinophilia was done on 621 cases positive for parasitic infestation.

RESULTS

Among a total of 621 cases of parasitic infestation only 66 (10.6%) cases were found to have relative eosinophilia. The parasites found to be responsible for eosinophilia were Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercoralis, filarial worm and hook worm.

CONCLUSION

From the study it is concluded that eosinophilia is not a universal finding in cases with parasitic infestation. Although presence of eosinophilia can serve as one of the many diagnostic clues to look for the presence of helminthic infestation if other non-infectious causes of eosinophilia are ruled out.

Evaluation and Differential Diagnosis of Persistent Marked Eosinophilia

Peripheral blood eosinophilia is commonly encountered in clinical practice. The causes of peripheral blood eosinophilia are varied, ranging from benign eosinophilia to malignancy. A careful history and physical examination along with directed clinical evaluation may help determine the cause. When uncontrolled, peripheral blood eosinophilia may result in end-organ damage and life-threatening complications. This article summarizes the differential diagnosis and evaluation of persistent marked eosinophilia.

Hookworm with hypereosinophilia: atypical presentation of a typical disease

We describe a 55-year-old man returning from the Philippines infected with a hookworm, the novel bacterium Laribacter hongkongensis, and a Blastocystis hominis and presenting with both gastrointestinal and neurological symptoms. The high eosinophilia caused by the hookworm infection resulted in both gastrointestinal and neurological symptoms, resembling a hypereosinophilic syndrome.

Evaluation and differential diagnosis of marked, persistent eosinophilia

High-grade eosinophilia can be a diagnostic dilemma, as the etiologies are extensive and varied. Hypereosinophilic syndromes (HES) are a group of heterogeneous disorders, many of which remain poorly defined. By definition, HES must be distinguished from other disorders with persistently elevated eosinophilia with a defined cause. Although marked eosinophilia worldwide is most commonly caused by helminth (worm) infections, non-infectious causes must be considered, and include drug reactions, malignancies, and immunologic, inflammatory and allergic diseases.

Eosinophilia and thrombosis in parasitic diseases: an overview

It is known that peripheral blood eosinophilia (PBE) is a normal hematopoietic response to several parasitic diseases, but it is less known that PBE promotes a hypercoagulable state that may favor thrombosis. Scope of this article is to explore which parasitic infestations are most likely to be complicated by thrombosis and to highlight the pathogenetic contribution of PBE to vascular occlusions in this setting. A review of the world literature revealed 18 cases in which PBE was associated with vascular occlusion though no specific surveys were dedicated to this topic. The eosinophil exerts its thrombogenic potential by inhibition of the natural anticoagulant pathways and release of tissue factor with enhanced coagulation activation leading to vascular occlusion. It is hoped that this review contributes to the awareness of the link between PBE and thrombosis in parasitic disorders to foster research in this area.

North American paragonimiasis (Caused by Paragonimus kellicotti) in the context of global paragonimiasis

Paragonimus species are highly evolved parasites with a complex life cycle that involves at least three different hosts, i.e., snails, crustaceans, and mammals. The adult forms of Paragonimus species reside and mate in the lungs of a variety of permissive mammalian hosts, including humans. Although human paragonimiasis is uncommonly encountered in North America, both autochthonous and imported disease may be encountered. Paragonimus kellicotti, the species endemic to North America, is a well-known pathogen in wild and domestic animals. Five patients with North American paragonimiasis have been reported in the recent medical literature. The biologic, clinical, radiologic, and laboratory features of paragonimiasis are reviewed, with emphasis on North American paragonimiasis whenever possible.

Evaluation and differential diagnosis of marked, persistent eosinophilia

Hypereosinophilic syndromes (HES) are a group of heterogeneous disorders many of which remain ill-defined. By definition, the HES must be distinguished from other disorders with persistently elevated eosinophilia with a defined cause. Although marked eosinophilia worldwide is most commonly caused by helminth (worm) infections, the diagnostic approach must include noninfectious (nonparasitic) causes of marked eosinophilia as well.

Hematuria in children due to schistosomiasis in a nonendemic setting

Infection with Schistosoma hematobium is common in immigrants from tropical Africa and commonly presents with painless hematuria. Since chronic, heavy infection can lead to significant morbidity, it is imperative for clinicians who serve the immigrant and refugee population to become familiar with this traditionally exotic disease. Increased awareness will allow earlier diagnosis and treatment of infection, avoiding complications and minimizing expensive and invasive diagnostic procedures.

Eosinophilia: Causes and pathobiology in persons with prior exposures in tropical areas with an emphasis on parasitic infections

Eosinophilia in patients exposed to tropical or subtropical environments is caused most commonly by helminth (worm) infections. Besides a detailed exposure history, the diagnostic approach must consider other infections and noninfectious causes of eosinophilia, as treatments for many of these disorders differ.

Leukocytosis and blood eosinophilia in a polyparasitised population in north-eastern Brazil

It has long been known that leukocytosis and blood eosinophilia are common in the tropical environment, but data derived from population-based studies are scarce. A study was undertaken in a fishing village in north-east Brazil where both intestinal helminthiases and parasitic skin diseases are common. Of 409 individuals studied, 128 (31.3%) were infected with one intestinal helminth or ectoparasite species, 93 (22.7%) with two, 61 (14.9%) with three, 25 (6.1%) with four and 11 (2.7%) with more than four species; no parasites were found in 91 (22.2%) individuals. Leukocyte counts ranged between 3,300 cells/microl and 16,100 cells/microl (median, 7,200 cells/microl) and eosinophil counts between 40 cells/microl and 5,460 cells/microl (median, 455 cells/microl). Eosinophilia (>500/microl) was detected in 44.7% of the individuals, and hypereosinophilia (>1,000/microl) in 12.9%. Thirty-six (8.8%) individuals showed leukocytosis. While 75% of individuals with normal eosinophil counts were considered parasite-free, only 14% with eosinophilia and 11% with hypereosinophilia did not have enteroparasites or ectoparasites. Multivariate regression showed that the probability of eosinophilia and hypereosinophilia, but not of leukocytosis, increased with the number of parasite species present. The data show that eosinophilia occurs in almost one-half of the individuals from a resource-poor setting and that it is significantly associated with the presence of intestinal helminths, but not with the presence of ectoparasites.

Hyperéosinophilie parasitaire

Blood hypereosinophilia (eosinophilia count of more than 500 per microliter, i.e., 0.5.10(9)/L) is a laboratory finding that requires a careful workup. Review of the patient's medical history and clinical examination can usually rule out non-parasitic causes. Parasitic infections must be sought by examination of stool, urine, and blood examinations and by serological tests. These examinations, with special techniques for cosmopolitan and tropical parasites and for digestive or tissular parasites, must be repeated. Improvement of blood eosinophilia and of the serum antibody titers is one criterion of treatment effectiveness.

Larva migrans visceral: relato de caso

Larva migrans visceral é doença infecciosa, adquirida por ingestão de ovos provenientes dos vermes Toxocara canis e/ou Toxocara cati que infestam cães e gatos; as larvas penetram a parede intestinal e migram através dos tecidos levando a alterações diversas, conseqüentes a uma resposta inflamatória imune.¹ Os autores descrevem um caso clínico de larva migrans visceral com apresentação clínica atípica.

Investigation of tropical eosinophilia; assessing a strategy based on geographical area

OBJECTIVES

Patients with eosinophilia are an important clinical problem. This study aimed to assess the most efficient manner of investigating patients with peripheral eosinophilia (eosinophil count >0.5x10(9)ml(-1)) presenting from the tropics.

METHODS

Patients attending the Hospital for Tropical Diseases, London, from October 1997 to March 2002 for investigation of eosinophilia were identified prospectively. Laboratory, clinical and demographic data were recorded from laboratory and clinical records. An investigation set was proposed prospectively and assessed for all geographical areas (stool microscopy, strongyloides culture and serology), all of Africa (additional schistosomal serology, terminal urine microscopy and filarial serology) and West Africa (additional day-bloods for microfilaria).

RESULTS

Data was analysed for 261 patients. At least one helminthic cause for eosinophilia was found in 64% of patients (median eosinophilia 1.2x10(9)ml(-1)). Seventeen per cent of patients had more than one helminth species found. Median eosinophilia increased with number of diagnoses per patient. The proposed investigation sets were validated, with high yield for all proposed tests apart from filarial serology outside West Africa, and good sensitivity.

CONCLUSIONS

Initial investigation of eosinophilia in patients presenting from the tropics may be guided by a simple investigation set depending on broad area of travel which has high sensitivity and yield. Patients frequently have more than one helminthic cause of eosinophilia.

Evaluation of diarrhea in the returned traveler

Diarrhea in the returned traveler is common, but it is generally self-limited. Although the concern is often directed at the presence of an ongoing infection, postinfectious and noninfectious etiologies must be considered [table: see text] also. Answers to the clinical questions posed in this article will guide the clinician toward an appropriate diagnostic and management strategy.

Assessing eosinophil count as a marker of immune activation among human immunodeficiency virus-infected persons in sub-Saharan Africa

In 611 human immunodeficiency virus-infected persons who had not yet begun to receive antiretroviral therapy, we evaluated the linear association between absolute eosinophil count (as a surrogate for immune response to helminthic infection) and CD4+ T cell count, and between absolute eosinophil count and log virus load. Overall, no significant correlations were observed between eosinophil count and CD4+ T cell count, or between eosinophil count and log virus load.