This retrospective cohort study was conducted at Vietnam National Children’s Hospital (NCH), Hanoi, Vietnam (a 2300-bed tertiary pediatric hospital), between January 1, 2018, and July 1, 2024. We collected information regarding eligible patients’ characteristics, laboratory results and radiological findings from the medical records system.

In this retrospective cohort of 80 pediatric patients, we identified several key differences between bacterial and parasitic liver abscesses in terms of epidemiology, clinical presentation, laboratory patterns, and imaging characteristics. Liver abscesses occurred across a broad pediatric age range; however, most cases were identified in children older than six months. A marked predominance among males and among children living in rural or mountainous areas was also observed, reflecting the influence of environmental exposures and underlying socioeconomic determinants on infection risk. Clinically, bacterial abscesses are more often associated with high-grade fever, hepatomegaly, and splenomegaly, whereas parasitic abscesses frequently present with more subtle or nonspecific symptoms. The laboratory findings revealed distinct inflammatory profiles, with bacterial etiologies showing marked neutrophilia and elevated CRP levels, whereas parasitic abscesses were characterized by pronounced eosinophilia. Imaging findings further differentiated the two groups, with bacterial infections more likely to manifest as single abscess cavities and parasitic infections presenting with multiple lesions. Together, these results highlight specific clinical and laboratory markers that may support earlier differentiation of liver abscess etiology and guide timely management, particularly in settings where diagnostic resources are limited.

Children across a wide age range were affected in our cohort, but parasitic infections were not observed in infants ≤ 6 months of age. This absence of early-infant parasitic cases is consistent with the limited evidence available in the literature, which consists primarily of isolated neonatal case reports rather than population-level data [12, 22]. The age distribution observed here may reflect differences in exposure pathways, feeding and dietary practices, and immune maturation, which collectively reduce the likelihood of early-life parasitic infection.

A male predominance (60%) was observed, which aligns with findings from previous pediatric studies in Taiwan, Belgium, and China reporting male-to-female ratios ranging from 1.32:1 to 1.92:1 [12, 22, 23]. Although the underlying mechanisms remain uncertain, these consistent patterns across diverse regions suggest potential sex-related differences in exposure behaviors or immunological responses.

Most of the affected children originated from rural and mountainous regions, whereas only a small proportion resided in urban areas. This geographic distribution is consistent with studies showing a greater incidence of liver abscess in areas with poor sanitation, unsafe water sources, and closer contact with livestock or contaminated environments [23–27]. However, reports from Dakar demonstrate that children living in impoverished urban neighborhoods may have similar risks due to crowding, inadequate hygiene, and unstable living conditions [25]. These findings highlight that environmental and socioeconomic factors, rather than the rural–urban distinction alone, play an important role in shaping infection risk.

Although a lack of routine deworming and the consumption of raw or undercooked foods were more frequently reported among children with parasitic abscesses, these associations were not statistically significant. Given the modest sample size and high background prevalence of these exposures in the general population, the absence of statistical significance likely reflects limited power rather than a true lack of etiologic relevance.

In our cohort, parasitic liver abscesses were characterized by a subtler clinical presentation than bacterial infections. Whereas bacterial abscesses frequently manifest with high-grade fever and more overt abdominal signs, including hepatomegaly and splenomegaly, children with parasitic etiologies often display only vague abdominal discomfort, mild anemia, or other nonspecific symptoms, which provides minimal clinical indications of underlying hepatic involvement. This contrast highlights that prominent fever and organomegaly are more suggestive of a bacterial process, whereas parasitic abscesses may remain clinically inconspicuous, posing a diagnostic challenge in endemic settings. As a result, a proportion of cases are detected only incidentally during abdominal ultrasonography performed for unrelated complaints. Despite this recognized clinical contrast, only a few studies have directly compared parasitic and bacterial etiologies in pediatric cohorts. In a detailed etiologic analysis from Pakistan, Devi et al. demonstrated that symptoms such as fatigue or weakness, anorexia, respiratory distress and anemia were disproportionately more common among children with parasitic liver abscess than among those with bacterial disease, underscoring the distinct and sometimes subtle presentation of parasitic infections in this age group [27]. Taken together, these findings emphasize the need for heightened diagnostic vigilance and more systematic etiologic characterization in pediatric liver abscess research.

The laboratory parameters clearly differed across etiologies. Bacterial abscesses presented increased neutrophil percentages and elevated CRP levels, reflecting an acute inflammatory response characteristic of pyogenic infections. These findings are consistent with previous pediatric and adult studies in which neutrophil-predominant leukocytosis and high CRP levels were among the most reliable markers of bacterial liver abscess [12, 23]. In contrast, pronounced eosinophilia was strongly associated with parasitic disease in our cohort, which is consistent with evidence from pediatric fascioliasis studies showing that peripheral eosinophilia is both common and often marked in helminth-related hepatobiliary infection [28, 29]. These differences underscore the diagnostic utility of peripheral eosinophil counts in distinguishing parasitic from bacterial liver abscesses, particularly in endemic regions. From a pathophysiological perspective, eosinophilia in parasitic liver abscesses reflects a predominantly Th2-driven immune response, in which IL-5-mediated eosinophil proliferation and activation play a central role. This pattern is well documented across pediatric parasitic infections and provides a biologically plausible explanation for the marked eosinophil elevation observed in these cases. [30, 31]

Liver enzymes and the prothrombin ratio did not differ significantly between etiologic groups, which is consistent with prior findings that these markers lack discriminatory power in hepatic abscess evaluation [12]. Likewise, anemia, as a distinguishing parameter between parasitic and bacterial liver abscess, is only minimally addressed in existing studies, and the available data remain inconsistent [32, 33].

Notably, comparative pediatric data delineating clinical differences between parasitic and bacterial liver abscesses remain scarce, as most studies describe single-etiology cohorts without direct comparisons. Although adult series have reported variably distinct patterns between parasitic and bacterial abscesses, the findings are inconsistent and may not be generalizable to children [14, 32]. Future pediatric research with rigorous etiologic stratification is needed to better define clinically meaningful distinctions and support earlier, more accurate diagnostic decision-making.

All patients in our cohort demonstrated focal hepatic lesions on imaging, underscoring the central role of radiologic evaluation in diagnosing liver abscesses. In a retrospective Italian series of 109 pediatric bacterial cases, ultrasonography was used in 42.4% of diagnoses, while CT and MRI were performed in 51.1% and 3.3% of cases, respectively [34]. A separate case report further emphasized the complementary value of combining abdominal ultrasound with CT to improve diagnostic accuracy [26].

In our cohort, solitary abscesses were more frequently associated with bacterial infections, whereas multiple lesions predominated in parasitic cases. The former finding is consistent with existing pediatric data, in which pyogenic liver abscesses commonly present as solitary right-lobe lesions [25]. In contrast, the predominance of multiple lesions in parasitic infections diverges from classical descriptions of amoebic liver abscess, which is typically solitary in children [35]. However, emerging reports demonstrate that non-amoebic parasitic infections, such as Fasciola hepatica and Toxocara canis, can produce multiple or scattered hepatic lesions on imaging, suggesting a broader imaging spectrum for parasitic disease than traditionally recognized [36, 37]. Recent reviews emphasize that helminthic liver infections, like those caused by Fasciola spp. and Toxocara spp., remain an important and often under-recognized cause of hepatic disease in many endemic regions, although robust epidemiological data confirming a broad etiological shift away from Entamoeba histolytica are still lacking [38]. In this context, the predominance of multiple lesions in our parasitic group may reflect local parasitic epidemiology and supports the possibility that lesion number, while not diagnostic on its own, may provide supportive clues to underlying etiology.

This study highlights several clinically meaningful indicators that may help differentiate bacterial from parasitic liver abscesses in children, including neutrophil and eosinophil profiles, CRP concentrations, and the number of abscess cavities on imaging. These parameters have particular value in resource-limited settings, where delays in microbiological confirmation are common and early clinical decision-making is essential. To our knowledge, this represents the largest Vietnamese pediatric cohort directly comparing bacterial and parasitic liver abscess etiologies. Nevertheless, several limitations should be acknowledged. As a retrospective, single-center analysis, causal inference is limited, and the findings may not be fully generalizable beyond similar epidemiologic contexts. The modest overall sample size—particularly within the parasitic subgroup—likely reduced statistical power for some comparisons. Incomplete laboratory or imaging data may have introduced information bias, and the use of serology and imaging alone for parasitic diagnosis in some cases raises the possibility of misclassification, although this reflects real-world diagnostic constraints in endemic areas. Future prospective, multi-center studies are needed to validate the diagnostic utility of these indicators, especially in low- and middle-income countries where advanced diagnostic resources may be limited.