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

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. Author summary: Human cystic echinococcosis (CE) is a parasitic zoonotic disease caused by cestode species belonging to Echinococcus granulosus s.l. complex. CE affects mainly pastoral and rural communities in both low-income and upper-middle-income countries, where the life cycle of the parasite is sustained between livestock and dogs. The larval parasite cysts causing human CE develop mainly in the liver and secondarily the lung, but in a smaller number of cases, larvae may develop in any organ or tissue, including the brain. We report here a case of cerebral CE (CCE) in a child living near Rome (Italy), which was attributed to probable household/backyard infection from the family farm by comparative molecular analysis of the patient's and sheep CE cyst specimens obtained from the family farm and another local farm. We also summarized the clinical characteristics of CCE cases retrieved through a literature review. When considering clinical centres reporting all anatomical sites of CE, liver represented 70%, lungs 19%, and unusual localizations 11% of all CE cases. The proportion of CCE among all CE cyst localizations represented 1.5% of all CE cases. These figures are important when calculating the global burden of disease, since CCE and other uncommon CE localizations, although more rare, are clinically more severe. [ABSTRACT FROM AUTHOR]