Schistosomiasis of the nervous system

Pseudotumoral Encephalic Schistosomiasis: A Literature Review

Pseudotumoral encephalic schistosomiasis (PES) is the chronic form of cerebral neuroschistosomiasis, and is rarely encountered in clinical practice. Clinically, PES closely resembles other intracranial space-occupying lesions including brain tumors. Laboratory investigations are usually inconclusive, and neuroradiologic findings are frequently reported as non-specific. Such diagnostic difficulties may result in delayed diagnosis and treatment. Across the literature, there is a paucity of information about and controversy over many aspects of the disease. Particularly, inconsistent magnetic resonance imaging (MRI) findings, a wide variation of medical treatment protocols, lacking consensus regarding the indications of surgery, and undetermined information regarding the impact of the extent of resection on prognosis. We herein review the pertinent literature with the aim of providing focused information regarding the pathogenesis of PES, its currently identified more distinctive neuroimaging features, and the indications and extent of surgery in light of the state-of-the-art operative neurosurgical practice. A distinctive multinodular arborizing pattern of PES lesions can often be observed on MRI in patients with PES. Praziquantel is considered by many authors to be the drug of choice in all cases, and seems to be effective at variable dose regimens. Although lesion excision utilizing current technology is generally safe, the indications and extent of surgery are still undetermined and should be decided on a case-by-case basis. Multicenter collaborative research is further needed to fill the existing gaps in the current knowledge on PES.

H19/Mir-130b-3p/Cyp4a14 potentiate the effect of praziquantel on liver in the treatment of Schistosoma japonicum infection

BACKGROUND

Schistosomiasis is a prevalent infectious disease caused by the parasitic trematodes of the genus Schistosoma. Praziquantel (PZQ), a safe and affordable drug, is the recommended oral treatment for schistosomiasis. The main pathologic manifestation of schistosomiasis is liver injury. However, the role and interactions of various RNA molecules in the effect of PZQ on the liver after S. japonicum infection have not been elucidated.

RESULTS

In this study, C57BL/6 mice were randomly divided into the control group, infection group, and PZQ treatment group. Total RNA was extracted from the livers of the mice. High-throughput whole transcriptome sequencing was performed to detect the RNA expression profiles in the three groups. A co-expression gene-interaction network was established based on the significant differentially expressed genes in the PZQ treatment group; messenger RNA (mRNA) Cyp4a14 was identified as a critical hub gene. Furthermore, competitive endogenous RNA networks were constructed by predicting the specific binding relations between mRNA and long noncoding (lnc) RNA and between lncRNA and microRNA (miRNA) of Cyp4a14, suggesting the involvement of the H19/miR-130b-3p/Cyp4a14 regulatory axis. Dual luciferase reporter assay result proved the specific binding of miR-130b-3p with Cyp4a14 3'UTR.

CONCLUSIONS

Our findings indicate the involvement of the H19/miR-130b-3p/Cyp4a14 axis in the effect of PZQ on the liver after S. japonicum infection. Moreover, the expression of mRNA Cyp4a14 could be regulated by the bonding of miR-130b-3p with 3'UTR of Cyp4a14. The findings of this study could provide a novel perspective to understand the host response to PZQ against S. japonicum in the future.

Pediatric Spinal Neuroschistosomiasis in Yemen: An Overlooked Dilemma in an Endemic Region

BACKGROUND

Neurological involvement in schistosomiasis presents a significant and serious complication. While the disease is generally considered treatable during the early stages, the rarity of this condition often leads to delays in diagnosis and treatment. This study aims to report the clinical characteristics of pediatric patients with spinal neuroschistosomiasis (NS) in an endemic area to the disease.

METHODS

A retrospective cross-sectional review was conducted at Althora General Hospital in Ibb, Yemen, from January 2016 to January 2021. The study examined confirmed pediatric cases of spinal NS, analyzing their clinical characteristics, laboratory and radiological data, treatment approaches, and complications.

RESULTS

The study identified 10 cases of spinal NS with a mean age of 10.1± 3.2 years. The majority (90%) were male and from rural areas, all with a history of freshwater exposure, a known risk factor for schistosomiasis. The average time from presentation to treatment was 33.4± 45.6 days (7-150 days). Common symptoms observed in all patients were bladder dysfunction and paresthesia (100%). Intestinal dysfunction was prevalent in 90% of cases, while 80% exhibited limb weakness or inability to walk. The diagnosis was confirmed through cerebrospinal fluid (CSF) serology in 80% of cases, and stool and urine exams yielded positive results in 90% and 30% of cases, respectively. Magnetic Resonance Imaging findings revealed medullary lesions in 50% of cases, cauda equina lesions in 20%, and multiple lesions in 30%. All patients received oral praziquantel and high-dose steroids for at least three days as part of their initial treatment. During the average follow-up period of 5.6±1.7 months, one patient experienced lower extremity paraplegia, while two cases (20%) showed partial improvement with residual deficits including urinary and fecal incontinence. Complete resolution of symptoms was achieved in seven cases (70%).

CONCLUSION

Schistosomiasis should be considered in pediatric patients with myeloradicular manifestations, especially in endemic areas. Early identification can be achieved through history, prompt imaging, and CSF serology. In the absence of immediate test results, expert-guided presumptive therapy should be considered to minimize neurological complications.

Alternate-day fasting, a high-sucrose/caloric diet and praziquantel treatment influence biochemical and behavioral parameters during Schistosoma mansoni infection in male BALB/c mice

Schistosoma mansoni-induced granulomas result in severe damage to the host's liver, as well as neurological and metabolic disorders. We evaluated the biochemical and behavioral changes during schistosomiasis under three diet protocols: ad libitum (AL), alternate-day fasting (ADF) and a high-sucrose/caloric diet (HSD). Healthy male BALB/c mice were divided into noninfected, matched infected and infected/treated [praziquantel (PZQ)] groups. Caloric intake and energy efficiency coefficients associated with diets were measured. Behavioral (exploratory and locomotor) and biochemical (glucose, triglycerides, total cholesterol, AST, ALT, ALP, and γ-GT) tests and histological analysis were performed. Fifteen weeks postinfection, HSD and PZQ promoted weight gain, with higher caloric consumption than ADF (p < 0.05), reflecting serum glucose levels and lipid profiles. HSD and PZQ prevented liver dysfunction (AST and ALT) and significantly prevented increases in granuloma area (p < 0.05). HSD and PZQ also significantly improved mouse physical performance in exploratory and locomotor behavior (p < 0.05), reversing the impaired motivation caused by infection. These findings showed that ADF worsened the course of S. mansoni infection, while HSD and PZQ, even with synergistic effects, prevented and/or attenuated biochemical and behavioral impairment from infection.

Medullary neuroschistosomiasis in adolescence: case report and literature review

INTRODUCTION

Medullary neuroschistosomiasis is a severe complication of gastrointestinal infection by Schistosoma. There are several endemic areas, wherein the only causative species present is Schistosoma mansoni, which is responsible for the clinical manifestations of all cases in those areas.

METHODS

We report the case of a 13-year-old female with lumbar pain and progressive lower limb weakness, with a delayed diagnosis of medullary involvement by the parasite. We also reviewed the literature on the disease.

CONCLUSIONS

Although it is related to the less severe forms of schistosomiasis, one should pay attention to the diagnosis of neuroschistosomiasis in cases of transverse myelitis in patients who traveled to endemic areas. The delay in diagnosis and, consequently, the introduction of treatment may result in irreversible neurological sequelae.

Medical Imaging in the Diagnosis of Schistosomiasis: A Review

Schistosomiasis is one of the most important parasitic diseases and it is endemic in tropical and subtropical areas. Clinical and laboratory data are fundamental for the diagnosis of schistosomiasis, but diagnostic imaging techniques such as x-rays, ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) may be helpful in the evaluation of disease severity and complications. In this context, the aim of this review is to explore the actual role of diagnostic imaging in the diagnosis of schistosomiasis, underlining advantages and drawbacks providing information about the utilization of diagnostic imaging techniques in this context. Furthermore, we aim to provide a useful guide regarding imaging features of schistosomiasis for radiology and nuclear medicine physicians of non-endemic countries: in fact, in the last years non-endemic countries have experienced important flows of migrants from endemic areas, therefore it is not uncommon to face cases of this disease in daily practice.

Parasitic Infections of the Nervous System

PURPOSE OF REVIEW

This article reviews how parasites affect the human nervous system, with a focus on four parasitic infections of major public health importance worldwide, two caused by protozoa (malaria and toxoplasmosis) and two by helminths (neurocysticercosis and schistosomiasis).

RECENT FINDINGS

Parasitic infections in humans are common, and many can affect the central nervous system where they may survive unnoticed or may cause significant pathology that can even lead to the death of the host. Neuroparasitoses should be considered in the differential diagnosis of neurologic lesions, particularly in individuals from endemic regions or those with a history of travel to endemic regions.

SUMMARY

Cerebral malaria is a significant cause of mortality, particularly in African children, in whom infected red blood cells affect the cerebral vessels, causing severe encephalopathy. Neurocysticercosis is the most common cause of acquired epilepsy worldwide and has varied clinical presentations, depending on the number, size, and location of the parasites in the nervous system as well as on the host's inflammatory response. Toxoplasmosis is distributed worldwide, affecting a significant proportion of the population, and may reactivate in patients who are immunosuppressed, causing encephalitis and focal abscesses. Schistosomiasis causes granulomatous lesions in the brain or the spinal cord.

Surgical management outcome of cerebral schistosomiasis: a case report and review of the literature

BACKGROUND

Schistosomiasis is a parasitic infection that commonly affects the gastrointestinal and genitourinary tracts. Cerebral schistosomiasis is rare, and few operative cases have been reported in the literature. Diagnosis is usually challenging due to the similarity of the lesion to many other brain conditions. Treatment usually requires surgical resection combined with the use of antiparasitic agents, which often results in good outcomes and excellent prognosis.

CASE PRESENTATION

A 24-year-old, previously healthy Afro-asiatic man presented to our neurosurgical outpatient clinic complaining of headache and an attack of convulsions. On examination, he had bilateral lower limb weakness more on the right side. Laboratory investigations including stool and urine general test results were unremarkable. Magnetic resonance imaging of the brain was performed and showed an intra-axial left parietal mass; a granulomatous lesion was suggested in the differential diagnoses. The patient underwent craniotomy and total resection of the lesion. Histopathology confirmed the presence of active cerebral Schistosoma mansoni infection. Orally administered praziquantel was initiated at a dose of 20 mg/kg twice a day for a total of 3 days along with oral administration of corticosteroids for 2 weeks. The patient improved postoperatively without residual weakness and with no further convulsions.

CONCLUSION

Cerebral schistosomiasis is a rare but important consideration in the list of differential diagnoses of cerebral space-occupying lesions. This is of particular importance in in endemic areas like Sudan. In order to reach a diagnosis, careful social and occupational history need to be obtained and correlated with the clinical, laboratory, and radiological findings. Surgical resection along with the use of proper antiparasitic agents usually provides the best clinical outcomes.

Application of Dendrimers for Treating Parasitic Diseases

Despite advances in medical knowledge, parasitic diseases remain a significant global health burden and their pharmacological treatment is often hampered by drug toxicity. Therefore, drug delivery systems may provide useful advantages when used in combination with conventional therapeutic compounds. Dendrimers are three-dimensional polymeric structures, characterized by a central core, branches and terminal functional groups. These nanostructures are known for their defined structure, great water solubility, biocompatibility and high encapsulation ability against a wide range of molecules. Furthermore, the high ratio between terminal groups and molecular volume render them a hopeful vector for drug delivery. These nanostructures offer several advantages compared to conventional drugs for the treatment of parasitic infection. Dendrimers deliver drugs to target sites with reduced dosage, solving side effects that occur with accepted marketed drugs. In recent years, extensive progress has been made towards the use of dendrimers for therapeutic, prophylactic and diagnostic purposes for the management of parasitic infections. The present review highlights the potential of several dendrimers in the management of parasitic diseases.

Zoonotic and vector-borne parasites and epilepsy in low-income and middle-income countries

Zoonotic and vector-borne parasites are important preventable risk factors for epilepsy. Three parasitic infections - cerebral malaria, Taenia solium cysticercosis and onchocerciasis - have an established association with epilepsy. Parasitoses are widely prevalent in low-income and middle-income countries, which are home to 80% of the people with epilepsy in the world. Once a parasitic infection has taken hold in the brain, therapeutic measures do not seem to influence the development of epilepsy in the long term. Consequently, strategies to control, eliminate and eradicate parasites represent the most feasible way to reduce the epilepsy burden at present. The elucidation of immune mechanisms underpinning the parasitic infections, some of which are parasite-specific, opens up new therapeutic possibilities. In this Review, we explore the pathophysiological basis of the link between parasitic infections and epilepsy, and we consider preventive and therapeutic approaches to reduce the burden of epilepsy attributable to parasitic disorders. We conclude that a concerted approach involving medical, veterinary, parasitological and ecological experts, backed by robust political support and sustainable funding, is the key to reducing this burden.

Zinc oxide nanoparticles and L-carnitine effects on neuro-schistosomiasis mansoni induced in mice

Neuro-schistosomiasis can induce neurological symptoms and severe disability. Since the resistance against the chemotherapy "praziquantel" was reported, the aim of the present study was investigating the anti-neuro-schistosomal effects of ZnO nanoparticles and/or L-carnitine (as free radicals scavenger) on schistosome-infected mice, where technology of nanoparticles has come to the forefront in the medical diagnosis and therapeutic drug delivery. In the human body, nanoscale-sized particles can move freely and reveal unique biological, mechanical, electrical, and chemical properties. In the present study, mice were divided into five groups. The first group served as the non-infected control group. Groups II, III, IV, and V were infected with cercariae of Schistosoma mansoni. Mice of groups III and IV were treated with ZnO nanoparticles (5.6 mg/kg b. wt.) and L-carnitine (500 mg/kg b. wt.), respectively, after 47 days post-infection. Finally, mice of the fifth group were injected with ZnO nanoparticles and after 1 h, the mice were intraperitoneally injected with L-carnitine once daily for 5 days. On day 52, post-infection mice of all groups were cervically decapitated. The treatment of ZnO nanoparticles and/or L-carnitine to schistosome-infected mice decreased brain oxidative stress parameters, where glutathione level and catalase activity were significantly increased as compared to schistosome-infected group. On the contrary, the treatment decreased nitrite/nitrate, malondialdehyde, and reactive oxygen species levels significantly. In addition, ZnO nanoparticles and/or L-carnitine treatment restored DNA laddering profile and improved the brain histopathological impairments resulting from neuro-schistosomiasis. Finally, the ZnO nanoparticle treatment and the co-treatment of ZnO nanoparticles and L-carnitine revealed anti-neuro-schistosomal effects on the infected mice.

Does physical exercise influence in the development of neuroeschistosomiasis?

Neuroschistosomiasis is a severe form of presentation of schistosomiasis in which Schistosoma spp. affects the central nervous system. This is the first study performed to analyze whether there is any relationship between physical effort and the appearance of neuroschistosomiasis, through clinical, molecular and immunological evaluations. An experimental controlled study using 64 male Balb/c inbred mice divided into four groups according to presence or absence of S. mansoni infection and submitted to physical effort or resting was conducted. Thirteen weeks after exercise training, S. mansoni DNA was detected in the brain or spinal cord in about 30% of the infected animals moreover, only S. mansoni-positive samples showed positive labeling for S. mansoni antigens in the brain or spinal cord, with a striking reaction inside the microglia. However, the behavioral tests did not show any clinical symptoms of neuroschistosomiasis in animals submitted to physical effort or in resting. In animals with S. mansoni-positive DNA, immunohistochemical data revealed astrogliosis and microgliosis, elevated IL-10 levels and decreased TNF-α expression. This study demonstrated that isometric exercise does not promote neuroschistosomiasis, furthermore, ectopic forms of schistosomiasis in the central nervous system were largely asymptomatic and exhibited a Th2 immune response profile. More experimental studies are necessary in order to characterize the pathological process of experimental neuroschistosomiasis.

Schistosomiasis in School Age Children in Sierra Leone After 6 Years of Mass Drug Administration With Praziquantel

Historic data and baseline surveys showed schistosomiasis as highly/moderately endemic in 7 of 14 districts in Sierra Leone, justifying annual/biennial mass drug administration (MDA) with praziquantel. MDA commenced in 2009 and reported treatment coverage had been above the World Health Organization recommended 75% of target population. Assessment in 2012 showed significant reduction in infection. In 2016, another national school-based survey was conducted to evaluate the progress. Two schools from each category (high, moderate or low) of endemic communities in each MDA district and five schools in non-MDA districts were selected. Fifty children (25 boys and 25 girls) aged 9-14 years were randomly selected per school. Parasitological examination of 1,980 stool and 1,382 urine samples were conducted. Overall Schistosoma mansoni prevalence in the seven MDA districts decreased to 20.4% (95% CI: 18.7-22.3%) in 2016 from 42.2% (95% CI: 39.8-44.5%) at baseline (p < 0.0001). Mean overall S. mansoni intensity of infection reduced to 52.8 epg (95% CI: 43.2-62.4 epg) in 2016 from 100.5 epg (95% CI: 88.7-112.3 epg) at baseline (p < 0.001). The prevalence of Schistosoma haematobium in the five MDA districts that had baseline prevalence data decreased to 2.2% (95% CI: 1.5-3.1%) in 2016 from 18.3% (95% CI: 16.3-20.5%) at baseline (p < 0.0001). Mean overall intensity of infection increased to 1.12 e/10 ml (95% CI: 0.55-0.1.70 e/10 ml) in 2016 compared to 0.47 e/10 ml (95% CI: 0.16-0.78 e/10 ml) in 2012 (p < 0.05) (no baseline data). No district was highly endemic in 2016 compared to three at baseline and there was no significant difference in prevalence or intensity of infection by sex for both species. This survey illustrated the significant progress made in controlling schistosomiasis in Sierra Leone. The fact that prevalence and intensity of infection showed an increase from the 2010 level suggested a detrimental effect of missing MDA due to the Ebola toward schistosomiasis control. The national program needs to continue the treatment and adopt a comprehensive approach including water, hygiene, and sanitation measures to achieve control and elimination of schistosomiasis.

Neuroschistosomiasis mimicking lower back pain: case report of a rare differential diagnosis in a pediatric patient

Background

Spinal myelitis is an infrequent manifestation of spinal cord infection. It is caused by the Schistosoma species, which are endemic in South America, part of the Middle East, and Africa.

Case presentation

We report the case of a 13-year-old male adolescent complaining of progressive lower back pain and weakness of the lower extremities for 3 days. Initial magnetic resonance imaging revealed typical transverse myelitis. Subsequently, parasite serology showed a markedly elevated level of Schistosoma antibody titers, and cerebrospinal fluid analysis yielded normal results. Because of our presumptive diagnosis of neuroschistosomiasis, the patient was prescribed an empirical regimen of an anti-parasitic agent, after which his neurological deficit promptly subsided. The patient was followed for 1 year and showed a complete long-term resolution of symptoms.

Conclusions

This case highlights the increasing prevalence of neuroschistosomiasis in recent years, particularly in patients with a history of travel to endemic regions. Moreover, the study reports the clinicoradiological features of this enigmatic disorder. This rare occurrence potentiates further studies to address unanswered questions about neuroschistosomiasis.

Global research priorities for infections that affect the nervous system

Infections that cause significant nervous system morbidity globally include viral (for example, HIV, rabies, Japanese encephalitis virus, herpes simplex virus, varicella zoster virus, cytomegalovirus, dengue virus and chikungunya virus), bacterial (for example, tuberculosis, syphilis, bacterial meningitis and sepsis), fungal (for example, cryptococcal meningitis) and parasitic (for example, malaria, neurocysticercosis, neuroschistosomiasis and soil-transmitted helminths) infections. The neurological, cognitive, behavioural or mental health problems caused by the infections probably affect millions of children and adults in low- and middle-income countries. However, precise estimates of morbidity are lacking for most infections, and there is limited information on the pathogenesis of nervous system injury in these infections. Key research priorities for infection-related nervous system morbidity include accurate estimates of disease burden; point-of-care assays for infection diagnosis; improved tools for the assessment of neurological, cognitive and mental health impairment; vaccines and other interventions for preventing infections; improved understanding of the pathogenesis of nervous system disease in these infections; more effective methods to treat and prevent nervous system sequelae; operations research to implement known effective interventions; and improved methods of rehabilitation. Research in these areas, accompanied by efforts to implement promising technologies and therapies, could substantially decrease the morbidity and mortality of infections affecting the nervous system in low- and middle-income countries.