Unexpected Schistosomiasis Diagnosed After Appendectomy in a Migrant Child

Introduction

Schistosomiasis, caused by blood flukes of the genus Schistosoma, is a neglected tropical disease that primarily affects populations in tropical and subtropical regions of Africa, the Middle East, Asia, and parts of Latin America [1,2]. The World Health Organization estimates that approximately 250 million people are at risk of schistosomiasis and may require preventive treatment, making it the second most important parasitic infection after malaria in terms of public health impact [1,2]. In high-income, non-endemic settings, schistosomiasis is rarely diagnosed incidentally during surgery. This report describes an unexpected intraoperative suspicion that arose during appendectomy in a pediatric migrant, emphasizing a clinically important but underrecognized scenario.

The European Network for Tropical Medicine and Travel Health conducted a sentinel surveillance study that identified 486 (33%) cases among European travelers and 748 (51%) among non-European immigrants [3,4]. Another study revealed that 12.3% of newly arrived African immigrants in Spain were infected with schistosomiasis [4,5]. Furthermore, the estimated prevalence of infection among immigrants from sub-Saharan Africa, particularly Mali and Senegal, was 10% [4]. Epidemiologic data specific to Eritrea are lacking. Regional studies have shown a mean prevalence of 32.8% for S. haematobium and 23.2% for S. mansoni [6], but these figures reflect a broader regional context and may not accurately represent the situation in Eritrea. Data regarding the numbers of individuals affected by S. mansoni- and S. haematobium-induced chronic schistosomiasis remain limited [7]. Collectively, these findings indicate underdiagnosis among migrants in Europe and support the rationale for heightened clinical suspicion in non-endemic hospitals, consistent with the case presented here.

Clinically, the disease can present in acute or chronic forms (Table 1). Acute schistosomiasis may manifest as Katayama fever, characterized by fever, urticaria, cough, and gastrointestinal symptoms, particularly in non-immune travelers [7,8]. Chronic schistosomiasis can remain asymptomatic for many years and, depending on the species involved, may cause hematochezia, hematuria, liver fibrosis, or bladder cancer [7,8].

In endemic settings, diagnosis primarily depends on microscopic detection of schistosome eggs in feces or urine, with the Kato-Katz thick stool smear technique widely used and endorsed by the World Health Organization [9,10]. In high-income settings, serologic tests, lateral-flow assays, and polymerase chain reaction (PCR)-based techniques are also utilized (Table 2). Imaging modalities such as ultrasonography, computed tomography, and magnetic resonance imaging can aid diagnosis in cases of advanced chronic disease, including periportal or bladder fibrosis [3,11]. In non-endemic centers, the combination of histopathology and PCR methods can confirm species identity when morphology is inconclusive, as demonstrated in the present case.

Praziquantel remains the recommended treatment for all forms of schistosomiasis because it is effective, safe, and inexpensive. In some endemic areas, preventive chemotherapy is administered to at-risk populations [12,13]. Against this background, the present case emphasizes the importance of maintaining a high index of suspicion for schistosomiasis in migrants, even when eosinophilia is absent, and of integrating targeted screening pathways for newly arrived migrants within primary care.

Case Report

A 10-year-old Eritrean girl who had arrived in Switzerland 6 months before presentation was admitted to the emergency department with migrating peri-umbilical abdominal pain. Her parents also reported multiple episodes of vomiting. Her medical history was unremarkable, and there were no previous episodes of hematuria or gastrointestinal bleeding. The patient denied stool or urinary abnormalities.

Physical examination revealed pronounced tenderness in the right iliac fossa, with a positive McBurney sign and rebound tenderness. The main differential diagnoses at admission included acute appendicitis, mesenteric adenitis, and gastroenteritis; appendicitis was considered most likely based on clinical findings.

Laboratory results showed a leukocyte count of 10.4 G/L and a C-reactive protein level of 34 mg/L. Hemoglobin was 133 g/L, hematocrit 38%, erythrocytes 4.4 T/L, mean corpuscular volume 86 fL, mean corpuscular hemoglobin 30 pg, mean corpuscular hemoglobin concentration 35 g/dL, and platelets 181 G/L. The differential count revealed neutrophilia (75.9%) with normal eosinophil levels (3.5%), lymphocytes 13.4%, monocytes 7.0%, and basophils 0.2%. Liver function tests were not performed. Ultrasound was selected as the first-line modality because of its high diagnostic accuracy and safety in pediatric appendicitis. Imaging demonstrated an inflamed appendix measuring 0.65 cm in diameter, as well as intra-abdominal fluid consistent with acute appendicitis.

Laparoscopic appendectomy was performed, confirming the diagnosis both macroscopically and histopathologically. The laparoscopic approach also enabled systematic inspection of the abdominal cavity, in accordance with surgical best practices. During intraoperative exploration, multiple hepatic lesions described as “white spots”, measuring 2–5 mm in diameter, were observed (Figure 1). A biopsy specimen of these lesions was collected for laboratory analysis. Given the septic presentation and intraoperative findings of ulcero-phlegmonous appendicitis, a 5-day course of amoxicillin-clavulanate was initiated. The postoperative course was uneventful.

Histopathologic examination revealed acute ulcero-phlegmonous appendicitis with peri-appendicitis and serositis extending to the resection margin; no parasites were identified in the appendix. Granulomatous hepatitis was also observed; 2 hepatic granulomas were evident, and 1 of these contained foreign material morphologically consistent with a Schistosoma species (Figure 2). The morphology appeared ambiguous because the histologic section showed a terminal projection, rather than a distinct lateral spine. This variation can result from sectioning artifacts, in which the 3-dimensional orientation of the egg alters the apparent position of the spine. These findings confirmed granulomatous hepatitis secondary to schistosomiasis. Serologic testing for hepatitis B surface antigen and alpha-1 antitrypsin revealed negative results. PCR analysis of circulating cell-free DNA confirmed S. mansoni infection, clarifying the species when morphology alone was inconclusive. The peripheral blood count showed no eosinophilia, highlighting a diagnostic challenge given that eosinophilia is typically expected in parasitic infections.

The patient received 2 courses of praziquantel at 40 mg/kg, administered 14 days apart to target both adult worms and developing schistosomula, in accordance with international recommendations. The patient’s family was also advised to undergo screening and treatment. Follow-up anamnesis revealed frequent river exposure in Eritrea, representing a plausible source of infection. The child remained asymptomatic; she showed complete resolution of symptoms and normalization of laboratory parameters. The incidental diagnosis of schistosomiasis in this pediatric migrant underscores the clinical importance of intraoperative inspection of the abdominal cavity and targeted biopsy, illustrating how tropical diseases may present unexpectedly in non-endemic settings.

Discussion

The epidemiology of schistosomiasis among European travelers and migrants demonstrates considerable prevalence, particularly in individuals originating from endemic regions. A 14-year surveillance study by the Tropical Network (TropNet), a European surveillance system for tropical diseases, confirmed a high frequency of infection in this population, including a substantial proportion of cases involving non-European immigrants [3]. The prevalence among immigrants from endemic countries in Europe reflects both high transmission rates and limited access to diagnosis and treatment in their countries of origin [3,5]. A similar case was documented in a Canadian immigrant [14], further emphasizing the diagnostic challenges in non-endemic settings. The present case adds to the existing literature by illustrating the incidental diagnosis of schistosomiasis in a pediatric migrant during urgent appendectomy in Switzerland, a non-endemic country. The intraoperative discovery of hepatic granulomas highlights the diagnostic value of systematic laparoscopic inspection of the abdominal cavity.

Migrant screening for schistosomiasis offers both advantages and limitations. Early detection and timely treatment can prevent chronic complications; preemptive therapy may be cost-effective and low risk. However, the use of costly and sometimes nonspecific diagnostic tests in high-income settings might pose a financial burden, require specialized expertise, and lack standardized follow-up protocols. In Switzerland, PCR testing is performed in a limited number of reference laboratories at a cost of 200 to 300 CHF per test, which restricts accessibility compared with serologic testing, which generally has a lower cost (e.g., 50 to 100 CHF per test). Broader implementation may lower costs and improve availability in the future. In the present case, histopathologic findings suggested schistosomiasis, but PCR analysis of circulating cell-free DNA was required to confirm S. mansoni infection after morphological assessment proved inconclusive. This molecular confirmation emphasizes the complementary role of molecular diagnostics when morphology alone cannot establish species identity. Stool and urine microscopy were not initially performed, given that the patient presented with acute appendicitis. The diagnosis was considered only after incidental hepatic lesions were biopsied; by the time histologic results were obtained, the patient had already been discharged. PCR testing was then performed on blood samples in accordance with institutional guidelines. Knowledge gaps persist regarding the natural history of schistosomiasis in long-term migrants. Systematic screening programs are needed to identify asymptomatic cases, and a recent systematic review supports use of integrated screening approaches in primary care [15].

The main rationale for schistosomiasis treatment is prevention of long-term complications such as hepatic fibrosis (caused by S. mansoni) and bladder cancer (caused by S. haematobium) [2,15]. Individuals with frequent exposure to freshwater in endemic areas – such as those engaged in fishing, irrigation, washing, or swimming – exhibit an increased risk of infection [16]. However, precise data regarding the rates of long-term complications remain limited.

Beyond the epidemiologic context, the present case demonstrates several notable features. First, it involved a child, whereas most reported cases occur in adults. Second, infection was confirmed despite the absence of eosinophilia, a classic feature of parasitic diseases – its absence may delay recognition [17]. Third, the exploratory laparoscopic assessment performed at the end of the urgent appendectomy proved decisive, enabling systematic inspection and detection of hepatic granulomas that could have been missed with a conventional open approach. Finally, the apparent discrepancy between morphologic and PCR findings underscores the diagnostic value of molecular methods in resolving ambiguous findings. More robust epidemiologic data are needed to determine species-specific chronic disease prevalences [18–20]. Given the high infection burden and risk of complications, public health strategies in Europe should incorporate screening and treatment protocols for schistosomiasis in migrant populations. Taken together, these findings underscore the need for heightened clinical awareness and integrated screening in primary care as a cost-effective approach to managing schistosomiasis among migrants.

Conclusions

This case illustrates the incidental diagnosis of schistosomiasis during an urgent appendectomy in a pediatric migrant – an exceptionally rare presentation in a non-endemic country. It highlights the importance of maintaining a high index of suspicion for parasitic infections in this population, even in the absence of classical laboratory indicators such as eosinophilia.

Intraoperative exploration during laparoscopy proved decisive because systematic inspection of the abdominal cavity enabled the unexpected detection of hepatic granulomas that likely would have been missed during conventional open appendectomy. This finding underlines the clinical value of the laparoscopic approach, serving not only as a therapeutic intervention but also as a diagnostic tool.

Early recognition and prompt treatment with praziquantel are crucial to prevent long-term complications, including hepatic fibrosis and urinary tract malignancy. Molecular confirmation with PCR was essential in the present case, resolving the discrepancy observed in morphological findings and reinforcing the complementary role of advanced diagnostics when histopathologic findings are ambiguous.

Beyond the individual case context, this report emphasizes the need for systematic screening strategies concerning migrants from schistosomiasis-endemic regions and supports the integration of such screening into primary care as a cost-effective public health measure. However, given the limited availability and high cost of advanced diagnostic methods such as PCR and serology, preemptive treatment may remain a pragmatic, low-risk, and cost-effective strategy to prevent chronic disease in at-risk populations.