Eosinophilia in Caucasians returning from the tropics

Eosinophilia in Migrant Children: How Should We Proceed?

BACKGROUND

The diagnostic approach to eosinophilia is complex, given the numerous reported etiologies. Intestinal parasites (especially helminths) are a concern in children from high-burden settings. We describe the diagnostic approach and clinical management of eosinophilia in a cohort of migrant children.

METHODS

We conducted a retrospective observational study that included children diagnosed with eosinophilia at a reference center for pediatric tropical diseases from 2014 to 2018. All patients were screened according to a unified protocol, including direct microbiologic and serologic tests.

RESULTS

A total of 163 children presented with eosinophilia during the study period [median age, 7.7 years (4.1-12.2); 57.1% boys], mostly from Asia (27.6%) and South America (22.1%). Most were internationally adopted children (43.6%) or migrants (26.4%). Only 34.4% of the children were symptomatic, and the main etiology for eosinophilia was helminths (56.4%). After a sequential diagnostic approach, no etiology was found for 40.5% of the patients. The independent risk factors for an unexplained etiology were younger age (≤2 years: odds ratio, 3.6; 95% CI, 1.3-10.2; P = 0.015), absence of symptoms (odds ratio, 4.8; 95% CI, 1.8-12.5; P = 0.001) and mild eosinophilia (<1000/µL: odds ratio, 4.2; 95% CI, 4.5-11.7; P = 0.005). Only 6 children were treated empirically. In those children with an identified cause and in those treated empirically, the eosinophilia resolved in 52% in a median of 7 months (5-9).

CONCLUSIONS

Helminths are the main cause of eosinophilia in migrant children and need to be hunted, especially in older children with eosinophil counts >1000 eosinophils/µL.

Eosinophilie bei pulmonalen Infektionen

Neben Allergien, Autoimmunerkrankungen, Vaskulitiden, Dermatosen, Malignomen und Medikamentennebenwirkungen können sowohl parasitäre als auch nichtparasitäre Infektionen Ursachen für eine Eosinophilie sein. Bei Tropenrückkehrern stellen parasitäre Infektionen die häufigste Ursache für eine Eosinophilie dar. Dabei kann das jeweilige Ausmaß der Eosinophilie Rückschlüsse auf die Art des Erregers liefern. Zur Abklärung der Eosinophilie nach Tropenaufenthalt sollten primär dreimalige Stuhluntersuchungen auf Wurmeier und zusätzlich ggf. Serologien bezüglich Helminthen veranlasst werden. Komplettiert wird die Diagnostik durch eine Thorax-Röntgenaufnahme, eine Sonographie des Oberbauchs und ein Elektrokardiogramm (EKG). In den letzten Jahren werden in spezialisierten Laboren molekulare Techniken (Multiplex-Polymerasekettenreaktion, PCR) für die Diagnostik von Wurmeiern und intestinalen Parasiten im Stuhl eingesetzt, die eine deutlich höhere Sensitivität als die klassischen Stuhlnachweismethoden haben. Nichtparasitäre Infektionen, die zu einer relevanten Blut- oder lediglich pulmonalen Eosinophilie (bronchoalveoläre Lavage, BAL) führen, umfassen die Kryptokokkose sowie endemische Systemmykosen (Kokzidioidomykose, sehr selten bei Histoplasmose) und Schimmelpilzinfektionen (Aspergillus fumigatus, Mucor spp.).

Helminthic infections in returning travelers and migrants with eosinophilia: Diagnostic value of medical history, eosinophil count and IgE

OBJECTIVES

Eosinophilia in travelers and migrants returning from the tropics is often associated with invasive helminthic infections. Total IgE is considered a useful additional diagnostic parameter; however, both parameters are also increased in various other non-helminthic diseases.

METHODS

We retrospectively evaluated travelers and migrants seen at our department between September 2007 and May 2014. Patients with an absolute eosinophil count ≥500 cells/μl were considered for further analyses.

RESULTS

Among 6618 returned travelers and migrants, 154 (2.3%) had a total eosinophil count ≥500 cells/μL. Of these, 71 patients (46%) were diagnosed with helminthic infection. In an additional 62 patients (40%) with eosinophilia a final diagnosis was found, including non-helminthic infections in 34 patients and non-infectious causes in 28 patients, while in 21 patients (14%) no diagnosis was made. Patients with helminthic infections had higher eosinophil counts than travelers and migrants with other diagnoses (median 981 vs. 710 cells/μl; p = 0.001), while total IgE levels (n = 70; 172 vs. 152 kU/l; p = 0.731) were similar in both groups.

CONCLUSION

Eosinophil count but not total IgE levels are associated with helminthic infections in returning travelers and migrants with eosinophilia. Our results do not support the use of total IgE to differentiate helminthic infections from other causes of eosinophilia in this population.

[Clinical approach to imported eosinophilia]

Eosinophilia is a common finding in international travelers and immigrants, being an helmintic infection its main etiology. The positive predictive value of eosinophilia for an helmintosis is low in travellers. Eosinophilia may be an incidental finding, or symptomatic, and it represents a clinical challenge due to the low sensitivity and specificity of direct and indirect parasitological diagnostic tests, respectively. It requires a structured approach based on geographical areas, environmental exposures and behavioral risks, and associated symptoms. The initial assessment should include a comprehensive and tailored anamnesis and physical examination, basic laboratory tests, a complete parasitological examination of stool samples and a Strongyloides stercoralis serology, supplemented with other explorations guided by epidemiological and clinical suspicion. Empiric treatment with albendazole and/or ivermectin (plus praziquantel if risk of schistosomiasis) is an option for unidentified persistent eosinophilia after study, and in persons in whom a proper assessment or follow-up can not be assured. In patients at risk for estrongiloidosis who are candidates for immunosuppressive therapies, it is indicated a prior screening and treatment to prevent a future hyperinfestation syndrome.

Eosinophilia in Infectious Diseases

In determining the etiology of eosinophilia, it is necessary to consider the type of patient, including previous travel and exposure history, comorbidities, and symptoms. In this review, we discuss the approach to the patient with eosinophilia from an infectious diseases perspective based on symptom complexes.

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 of eosinophilia in immigrants in Southern Spain using tailored screening and treatment protocols: A prospective study

OBJECTIVE

To determine the etiology of eosinophilia in immigrant patients in Southern Spain.

METHODS

Prospective study of immigrant patients with eosinophilia (> 500 Eo/μL) attended in a reference Tropical Medicine Unit and evaluated through the implementation of a specific protocol structured in different levels meant to be accomplished depending on the findings of each previous level.

RESULTS

Out of the 549 patients included in the study (89.6% from sub-Saharan countries), a diagnosis of helminthiasis was reached in 417 (75.9%), mainly by Strongyloides stercoralis (n = 190), Schistosoma (n = 33) and Hookworms (n = 126). 30 patients (5.5%) had a non-parasitic disorder (asthma, allergic rhinoconjunctivitis, skin conditions and drug-related eosinophilia). Multiple helminthic infections were very common: in 107 patients (19.5%) 2 helminth species were identified, three in 21 patients (3.8%), and four or more in 6 patients (1.1%). Eosinophilia was resolved in 31 of the 33 patients (93.9%) who received empirical treatment with ivermectin, albendazole and praziquantel as an etiological diagnosis was not reached after applying the whole protocol.

CONCLUSIONS

Diagnosis of helminthic infections in immigrant patients with eosinophilia can be improved by using tailored protocols based on geographical exposure. The implementation of these protocols may also save costs by systematizing diagnostic explorations. Empirical treatment with ivermectin, albendazol and praziquantel in sub-Saharan population when an etiologic diagnosis of eosinophilia has not been attained is an effective measure.

The laboratory diagnosis and follow up of strongyloidiasis: a systematic review

BACKGROUND

Strongyloidiasis is frequently under diagnosed since many infections remain asymptomatic and conventional diagnostic tests based on parasitological examination are not sufficiently sensitive. Serology is useful but is still only available in reference laboratories. The need for improved diagnostic tests in terms of sensitivity and specificity is clear, particularly in immunocompromised patients or candidates to immunosuppressive treatments. This review aims to evaluate both conventional and novel techniques for the diagnosis of strongyloidiasis as well as available cure markers for this parasitic infection.

METHODOLOGY/PRINCIPAL FINDINGS

The search strategy was based on the data-base sources MEDLINE, Cochrane Library Register for systematic review, EmBase, Global Health and LILACS and was limited in the search string to articles published from 1960 to August 2012 and to English, Spanish, French, Portuguese and German languages. Case reports, case series and animal studies were excluded. 2003 potentially relevant citations were selected for retrieval, of which 1649 were selected for review of the abstract. 143 were eligible for final inclusion.

CONCLUSIONS

Sensitivity of microscopic-based techniques is not good enough, particularly in chronic infections. Furthermore, techniques such as Baermann or agar plate culture are cumbersome and time-consuming and several specimens should be collected on different days to improve the detection rate. Serology is a useful tool but it might overestimate the prevalence of disease due to cross-reactivity with other nematode infections and its difficulty distinguishing recent from past (and cured) infections. To evaluate treatment efficacy is still a major concern because direct parasitological methods might overestimate it and the serology has not yet been well evaluated; even if there is a decline in antibody titres after treatment, it is slow and it needs to be done at 6 to 12 months after treatment which can cause a substantial loss to follow-up in a clinical trial.

Clinical and epidemiological characteristics of imported infectious diseases in Spanish travelers

INTRODUCTION

Spain could be a potential area in Europe for the development and spread of emerging diseases from the tropics due to its geoclimatic characteristics, but there is little information on infectious diseases imported by travelers. The aim of this article was to analyze clinical-epidemiological characteristics of infectious diseases imported by Spanish travelers from the tropics.

METHODS

A retrospective descriptive study of 2,982 travelers seeking medical advice who return ill from the tropics was conducted. Demographic data, details of travel (destination, type, and duration), preventive measures, clinical syndromes, and diagnoses were analyzed.

RESULTS

Nearly half (46.5%) the travelers had traveled to sub-Saharan Africa; 46.5% reported a stay exceeding 1 month (and almost a quarter more than 6 months). Following pre-travel advice, 69.1% received at least one vaccine and 35.5% took malarial chemoprophylaxis with variations according to geographical area of travel. In all, 58.8% of this took chemoprophylaxis correctly. Most common syndromes were fever 1,028 (34.5%), diarrhea 872 (29.3%), and cutaneous syndrome 684 (22.9%). Most frequent diagnoses were traveler's diarrhea (17.2%), malaria (17%), and intestinal parasites (10.4%). The three main syndromes in travelers to the Caribbean-Central America, Indian subcontinent-Southeast Asia, and other areas were diarrhea, fever, and cutaneous syndrome (p < 0.05); in sub-Saharan Africa were fever, cutaneous syndrome, and diarrhea (p < 0.05); and in South America were cutaneous syndrome, diarrhea, and fever (p < 0.05). Travelers to sub-Saharan Africa showed a higher frequency of malaria, rickettsiosis, filariasis, and schistosomiasis (p < 0.05); those to South America showed cutaneous larva migrants, other ectoparasitosis, and cutaneous/mucocutaneous leishmaniasis; and those to the Indian subcontinent-Southeast Asia showed intestinal parasitosis, arboviriasis, and enteric fever (p < 0.05).

CONCLUSIONS

Increased international travel is a key factor for the development and spread of emerging pathogens. Information on these diseases is essential to establish early warning mechanisms and action plans. Spain represents a unique setting for this.

Eosinophilia in returning travelers and migrants

INTRODUCTION

Eosinophilia in travelers returning from tropical countries is often caused by helminths. The high eosinophil counts arise particularly from tissue migration of invasive larvae.

METHODS

Review of literature selected by means of a Medline search using the MeSH terms "eosinophilia" and "helminth."

RESULTS

The patient's geographic and alimentary history may suggest infection with particular parasitic worms. A targeted diagnostic approach is suggested. The physician should concentrate on the principal signs and be guided by the geographic and alimentary history. Elaborate diagnostic measures are seldom indicated.

DISCUSSION

Although eosinophilia alone has low positive predictive value for a worm infection, it points clearly to helminthosis if the patient has recently returned from the tropics and the eosinophilia is new.

Helminth-related Eosinophilia in African immigrants, Gran Canaria

Of 788 recent African adult immigrants to Las Palmas de Gran Canaria, 213 (27.0%) had eosinophilia. The most frequent causes were filariasis (29.4%), schistosomiasis (17.2%), and hookworm infection (16.8%). Stool microscopy and filarial and schistosomal serologic tests gave the highest diagnostic yield. Country of origin and eosinophil count were associated with specific diagnoses.

Prise en charge des hyperéosinophilies sanguines dans une consultation de maladies tropicales

OBJECTIVE

We assessed the frequency of parasitic diseases and the efficacy of presumptive treatment when no cause was found.

MATERIALS AND METHODS

This prospective study took place in the Tropical Disease department of Bicêtre Hospital over a two-year period and included patients with eosinophil counts exceeding 500/mm(3).

RESULTS

The study included 117 patients with blood eosinophilia. A parasitic infection was identified for 48 (41%), and appropriate treatment resulted in a return to normal eosinophil counts for all of them. No parasite was identified in 45 patients (38.5%), but parasitic disease was suspected on the basis of clinical or epidemiologic evidence. These patients received presumptive treatment with antiparasitic drugs (ivermectin, albendazole and praziquantel, alone or in combination). Of the 30 patients in this group not lost to follow-up, eosinophil counts returned to normal for 20. Finally, a cause other than parasitosis was suspected for 15 of the 117 patients (13%): 9 (7.5%) of them were lost to follow-up.

DISCUSSION

Parasites remain the leading cause of blood eosinophilia. Because the sensitivity of additional testing for these parasites is low and these antiparasitic drugs are safe (except for patients with loiasis), presumptive treatment appears appropriate.

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.

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.

Diagnostic significance of blood eosinophilia in returning travelers

This study was conducted to investigate the predictive value of blood eosinophilia (total white blood cell count with > or =8% eosinophils) for the diagnosis of travel-related infections in 14,298 patients who returned from developing countries. The data show that blood eosinophilia in travelers returning from developing countries has only limited predictive value for the presence of travel-related infections. However, the likelihood of the presence of helminth infections increases considerably with the extent of eosinophilia.

Eosinophilia and helminthic infections

Among microbial agents, helminths are the most common cause of eosinophilia. An approach to the evaluation of a patient with eosinophilia is outlined, with particular emphasis on clues in the history, examination and routine laboratory data that can help with the diagnosis. Multiple helminthic infections have been associated with eosinophilia, and the characteristic modes of spread, clinical manifestations, diagnostic tests and therapeutic considerations of these infections are discussed.

Screening returning travelers

Posttravel screening is the clinical and laboratory assessment of an individual aimed at uncovering occult infections, pathology, or health risks, the treatment of which will yield a significant health benefit to the individual. Screening must be tailored to the different risk patterns associated with different travel categories (e.g., missionary, tourist). Screening, predominantly a secondary prevention strategy, is most cost-effective when integrated with primary prevention strategies aimed at preventing future travel related illness (Table 6). The screening process begins with a medical history that allows a definition of risks and a tailored approach to laboratory tests. The screening tests currently available for STDs, tuberculosis, and parasitic infections have been reviewed, and although cost-effectiveness data are not available for most post-travel screening tests, recommended approaches are proposed. Traditionally, screening has been directed at uncovering occult infectious disease (STDs, tuberculosis, and parasitic infections). Important benefits can be gained, however, by including screening questions and tests for those diseases that are the major causes of mortality, both in nontraveling and in traveling North Americans, that is, the atherosclerotic and neoplastic diseases and trauma, especially vehicular.

Eosinophilia in the returning traveler

Eosinophilia is one of the most common laboratory abnormalities seen in the returning traveler. Although elevations in peripheral eosinophil levels can occur in a wide variety of disease processes, worldwide, helminth parasites are the major group of infectious agents responsible for eosinophilia. While often directed at helminth infections in their early stages of clinical evolution, the approach to the evaluation of the returning traveler with eosinophilia must consider the many causes of eosinophilia including those not casually related to travel. This article reviews the major parasitic causes of eosinophilia and provides a systematic approach to the evaluation of eosinophilia following travel.

Clinical and laboratory features of patients with loiasis (Loa loa filariasis) in the U.K

To assess differences between Africans and expatriates, we reviewed records of 100 patients with loiasis presenting to The Hospital for Tropical Diseases, London. Fifty-one were black Africans, and 49 were white expatriates. A history of Calabar swellings was more common amongst expatriates (P = 0.0001, OR 8.1), whilst eyeworm was reported more frequently in Africans (P = 0.0038, OR 4.2). Higher eosinophil levels (P < 0.0001) and filarial antibody levels, whether measured by immunofluorescence (P = 0.047) or ELISA (P < 0.0001) were present in the expatriates. Africans were more likely to have microfilaraemia (P < 0.0025, OR 7.3), and among microfilaraemic patients, Africans had denser microfilaraemia (P = 0.012). The sensitivity of microfilaremia as a screening test for loiasis was 75% in Africans and 29% in expatriates. The sensitivities of filarial antibody tests in Africans and expatriates were 81% and 100% for IFAT, and 28% and 93% for ELISA. Following treatment, 63% of patients were considered cured, 25% were lost to follow-up and 12% had a documented relapse. The differences between the two groups of patients could be caused by differences in the chronicity of loiasis, but other explanations are also discussed.

Eosinophilia caused by parasites

Eosinophilia is defined as an absolute count of > 500 eosinophils per mm3 of peripheral blood. Eosinophilia is associated with many disorders, limiting its usefulness as a diagnostic tool in screening expatriates for parasite infections. In addition, only tissue-invasive helminthic parasites cause eosinophilia, which limits its general application as a screening tool for parasitic infections. Because eosinophilia may resolve spontaneously over time, the life cycle of parasites must be considered when evaluating eosinophilic patients, and repeated stool examinations or appropriate serology may be necessary to make the correct diagnosis. Future work on the risks associated with subclinical parasite infections would be helpful to place eosinophilia and other screening tests in proper perspective. Referral of difficult cases to specialists in travel medicine should be considered because detailed information about the geographic distribution and life cycle of helminthic parasites is often crucial to making the correct diagnosis.

Eosinophilia in travelers

Eosinophilia in travelers may be caused by infections acquired during travels. Infections with helminthic, but not protozoan, parasites are the most likely causes of eosinophilia, although other etiologies may warrant consideration. This article reviews the parasitic and other causes of eosinophilia. Helminthic infections early in their development may elicit the most pronounced eosinophilia yet be difficult to diagnose. Chronic helminthic infections may yield eosinophilia that persists for prolonged periods of time after initial infection.

Diagnostic and clinical aspects of schistosomiasis in 182 patients treated at a Swedish ward for tropical diseases during a 10-year period

Patients treated for schistosomiasis during a 10-year period at a hospital for infectious diseases in Stockholm were investigated by a retrospective analysis in order to evaluate the diagnostic procedures. 80% of the 182 individuals originated from an endemic area and 78% were men. The mean age was 28 years for men and 27 for women. 137 had no other detectable parasites. 127 were asymptomatic. Haematuria was found in 6/15 patients with S. haematobium. 143 patients had infection with S. mansoni. Pathological findings during physical examinations were rare. 61% of the patients had eosinophilia. IgE was a sensitive marker among the patients with a chronic infection (84%). Analysis of antibodies directed against the somatic structure of the adult worm by use of immunofluorescence (IFL) technique had a sensitivity of 80% among the patients with a chronic infection. The detection of antibodies against the gut-associated antigens in IFL indicated an early infection. An enzyme-linked immunosorbent assay (ELISA), using a crude soluble egg antigen, had a sensitivity of 95% and specificity of 96% and is of important diagnostic value.

Schistosomiasis in expatriates returning to Britain from the tropics: a controlled study

Clinical features in 173 white expatriates returning to Britain with the sole diagnosis of schistosomiasis were compared with those in non-infected control subjects, matched for age and sex, returning from similar endemic areas. Infection was, with one exception, acquired in Africa. Schistosoma mansoni was found in 135 patients, S haematobium in 29, and mixed infection in 9. 79% of patients with S haematobium had symptoms, compared with 47% of patients with S mansoni. Tiredness, headache, and gastrointestinal disturbance were no more frequent in symptomatic patients than in control subjects. In over 50% of patients with schistosomiasis the diagnosis was established from snips of rectal mucosa, and this raises the question of how best to look for infection in those who have been exposed. Urine examination and schistosomal serology appear to be the best screening methods; patients with haematuria or seropositivity should be investigated further.