Primary cerebral cystic echinococcosis in a child from Roman countryside: Source attribution and scoping review of cases from the literature

Abstract

Background: Human cystic echinococcosis (CE) is a zoonotic parasitic infection caused by the larval stage of the species belonging to the Echinococcus granulosus sensu lato (s.l.) complex. Parasitic cysts causing human CE are mainly localized in the liver and in the lungs. In a smaller number of cases, larvae may establish in any organ or tissue, including the central nervous system (CNS). Cerebral CE (CCE) is rare but poses serious clinical challenges.

Methods: This study presents a case of CCE in a child living in the countryside near Rome (Italy), along with a comparative molecular analysis of the isolated cyst specimens from the patient and sheep of local farms. We also systematically searched the literature to summarize the most relevant epidemiological and clinical aspects of this uncommon localization.

Findings: The comparative molecular analysis confirmed that the infection was caused by E. granulosus sensu stricto (s.s.) (G3 genotype), and most likely acquired in the family farm. The literature search identified 2,238 cases of CCE. In 80.51% of cases, brain was the only localization and single CCE cysts were present in 84.07% of cases. Mean patients' age was 20 years and 70.46% were children. Cyst rupture was reported in 12.96% and recurrence of CCE after treatment in 9.61% of cases. Permanent disability was reported in 7.86% of cases, while death occurred in 6.21%. In case series reporting all CE localization, CCE represented 1.5% of all CE cases. In the few reports that identified at molecular level the CCE cyst, E. granulosus s.s. was found in 40% and E. canadensis in 60% of cases.

Conclusions: We report a rare case of CCE and evidenced the probable local origin of infection. The proportions of CE cases with uncommon localizations and with high impact on patients' lives have been globally neglected and should be included in the computation of the global burden of CE.

Fig 1. Computed tomography imaging without contrast obtained at presentation.

Axial (A) and coronal (B) planes are shown. There is evidence of a round-shaped hypodense left frontal-parietal lesion (*) determining significant mass effect and no evidence of perilesional edema (arrowheads).

Fig 2

A) Tridimensional reconstruction of the left frontal-parietal cystic lesion determining massive brain compression. B) T1 weighted Magnetic Resonance imaging, coronal section integrated by diffusion tensor imaging and 3D fiber tract reconstruction. The cystic lesion (C) compression on the left cortical-spinal tract (*) is shown in comparison to the controlateral cortical-spinal tract (**).

Fig 3

T1 (A, C, E) and T2 (B, D, F) weighted Magnetic Resonance imaging one month after stereotactic cyst drainage (A, B) demonstrated collapse of the cystic cavity (+) and perilesional edema (asterix). Follow-up imaging after 4 weeks of corticosteroid treatment (C, D) demonstrated regression of edema and linear contrast enhancement of the surgical cavity (arrowhead). Long term follow-up (E, F), 12 months after surgery, showed complete disappearance of the lesion.

Fig 4. Cerebral echinococcal cyst removed from the patient and used for molecular diagnosis and Echinococcus granulosus sensu lato species identification.

Fig 5. Haplotype network of the concatenated sequence fragments (total 2,368 bp) of the genes COX1, NAD5, NAD2 and NAD1 from 13 samples of Echinococcus granulosus including cyst removed from the child (green), sheep cysts from farm A (orange) and sheep cysts from farm B (pink), and five reference sequences retrieved from E. granulosus reference mitochondrial genomes (blue) from France, Spain, Turkey (G3), Albania and Italy (G1) (GenBank Accession numbers: KY766900, KY766901, KY766903, MG672135, MG672140).