Treatment of neurocysticercosis: current status and future research needs

Surgical management of intraventricular neurocysticercosis: Two cases treated through transcallosal interhemispheric approach

Background

Cysticercosis, caused by the larval stage of Taenia solium, is a prevalent parasitic infection affecting the central nervous system, primarily in low-income countries. Surgical intervention becomes necessary when cysticercosis manifests within the ventricular system, with endoscopic techniques increasingly preferred over traditional microsurgical methods due to lower risks and morbidity. However, the microsurgical transcallosal approach, although effective, is infrequently used due to its associated high morbidity.

Case Description

We present two cases of multiple intraventricular neurocysticercosis treated through an open microsurgical technique using a transcallosal interhemispheric approach. Patient 1, a 56-year-old male, presented with severe headaches persisting for 6 months, while Patient 2, a 54-year-old male, experienced a sudden decrease in consciousness. Both patients exhibited typical magnetic resonance imaging characteristics indicative of intraventricular neurocysticercosis, leading to the decision for surgical resection.

Conclusion

Despite the transcallosal approach's decreased popularity due to associated risks, we achieved relatively good outcomes with minimal morbidity in both cases. Our experience highlights the importance of considering microsurgical approaches, particularly in facilities lacking endoscopic instrumentation, for the effective management of intraventricular neurocysticercosis. Compliance with postoperative medical therapy remains crucial to prevent recurrence.

Neurocysticercosis: Isolated Lesion in the Left Middle Frontal Gyrus

OBJECTIVE

Neurocysticercosis (NCC) is one of the most common parasitic infections of the central nervous system. We present a case study of a 21-year-old African man with an isolated NCC lesion to the left middle frontal gyrus, which is also known as the dorsolateral prefrontal cortex (dlPFC).

METHOD

A neuropsychological evaluation was requested by the patient's inpatient psychiatry team regarding worsening attention and depressive symptoms approximately 6 months after NCC diagnosis and treatment.

RESULTS

Neuropsychological findings revealed deficits in the aspects of executive functioning, attention, working memory, and significant depressive symptoms.

CONCLUSION

To our knowledge, this is the first case study of its kind demonstrating deficits in cognitive functioning consistent with the dlPFC lesion location. Sociocultural and linguistic considerations, clinical findings, and limitations are discussed.

Isolated Spinal Cord Neurocysticercosis

The incidence of neurocysticercosis is increasing in the US. The diagnosis is primarily made based on imaging findings, with clinical presentation and epidemiological exposure also playing a role. The differential diagnosis for neurocysticercosis (NCC) is extensive, and being able to differentiate between these conditions on imaging is crucial to making a proper diagnosis. Herein we present a case of a 37-year-old female who presented with lower extremity weakness and was found to have isolated spinal NCC. In this article, we will discuss the symptoms and imaging findings of neurocysticercosis to help guide diagnosis and management.

Update on the diagnosis and management of neurocysticercosis

ABSTRACT Background: Neurocysticercosis (NCC) is a serious public health problem in several developing countries, including those in Latin America, Asia, and Africa. NCC is considered to be the main cause of late-onset epilepsy in endemic areas. Objective: This review summarizes recent advances in diagnosis and therapy of NCC. Methods: Relevant articles and books were reviewed and used as a source of information for this review. Results: The diagnosis of NCC is based upon neuroimaging studies (MRI and computed tomography) and laboratory analysis of the cerebrospinal fluid (CSF). Praziquantel and albendazole are considered parasiticidal drugs against NCC, but there is an intense debate over the value and safety of these drugs. Conclusion: Given the relative scarcity of clinical trials, more comparative interventional studies, especially randomized controlled trials in long-term clinical evolution, are required in order to clarify the controversy over the validity of parasitic therapy in patients with NCC.

Proliferative cells in racemose neurocysticercosis have an active MAPK signalling pathway and respond to metformin treatment

Racemose neurocysticercosis is an aggressive infection caused by the aberrant expansion of the cyst form of Taenia solium within the subarachnoid spaces of the human brain and spinal cord, resulting in the displacement of the surrounding host tissue and chronic inflammation. We previously demonstrated that the continued growth of the racemose bladder wall is associated with the presence of mitotically active cells but the nature and control of these proliferative cells are not well understood. Here, we demonstrated by immunofluorescence that the racemose cyst has an active mitogen-activated protein kinases (MAPK) signalling pathway that is inhibited after treatment with metformin, which reduces racemose cell proliferation in vitro, and reduces parasite growth in the murine model of Taenia crassiceps cysticercosis. Our findings indicate the importance of insulin receptor-mediated activation of the MAPK signalling pathway in the proliferation and growth of the bladder wall of the racemose cyst and its susceptibility to metformin action. The antiproliferative action of metformin may provide a new therapeutic approach against racemose neurocysticercosis.

Cysticidal effect of a pure naphthoquinone on Taenia crassiceps cysticerci

Cysticercosis is a disease caused by the metacestode of the parasite Taenia solium (T. solium). In humans, the most severe complication of the disease is neurocysticercosis. The drug of choice to treat this disease is albendazole; however, the bioavailability and efficacy of the drug are variable. Therefore, new molecules with therapeutic effects against this and other parasitic infections caused by helminths must be developed. Naphthoquinones are naphthalene-derived compounds that possess antibacterial, antifungal, antitumoral, and antiparasitic properties. The aim of this work was to evaluate the in vitro anti-helminthic effect of 2-[(3-chlorophenylamino)phenylmethyl]-3-hydroxy-1,4-naphthoquinone, isolated from a natural source and then synthesized (naphthoquinone 4a), using an experimental model of murine cysticercosis caused by Taenia crassiceps (T. crassiceps). This compound causes paralysis in the cysticerci membrane from day 3 of the in vitro treatment. Additionally, it induces changes in the shape, size, and appearance of the cysticerci and a decrease in the reproduction rate. In conclusion, naphthoquinone 4a has in vitro cysticidal activity on T. crassiceps cysticerci depending on the duration of the treatment and the concentration of the compound. Therefore, it is a promising drug candidate to be used in T. crassiceps and possibly T. solium infections.

Identification and culture of proliferative cells in abnormal Taenia solium larvae: Role in the development of racemose neurocysticercosis

Racemose neurocysticercosis is an aggressive disease caused by the aberrant expansion of the cyst form of Taenia solium within the subarachnoid spaces of the human brain and spinal cord resulting in a mass effect and chronic inflammation. Although expansion is likely caused by the proliferation and growth of the parasite bladder wall, there is little direct evidence of the mechanisms that underlie these processes. Since the development and growth of cysts in related cestodes involves totipotential germinative cells, we hypothesized that the expansive growth of the racemose larvae is organized and maintained by germinative cells. Here, we identified proliferative cells expressing the serine/threonine-protein kinase plk1 by in situ hybridization. Proliferative cells were present within the bladder wall of racemose form and absent from the homologous tissue surrounding the vesicular form. Cyst proliferation in the related model species Taenia crassiceps (ORF strain) occurs normally by budding from the cyst bladder wall and proliferative cells were concentrated within the growth buds. Cells isolated from bladder wall of racemose larvae were established in primary cell culture and insulin stimulated their proliferation in a dose-dependent manner. These findings indicate that the growth of racemose larvae is likely due to abnormal cell proliferation. The different distribution of proliferative cells in the racemose larvae and their sensitivity to insulin may reflect significant changes at the cellular and molecular levels involved in their tumor-like growth. Parasite cell cultures offer a powerful tool to characterize the nature and formation of the racemose form, understand the developmental biology of T. solium, and to identify new effective drugs for treatment.

Posterior Fossa Craniotomy for Adherent Fourth Ventricle Neurocysticercosis

BACKGROUND AND IMPORTANCE

Neurocysticercosis (NCC) is an infectious helminthic disease often presenting in patients who have immigration or travel history from areas where NCC is endemic. Fourth ventricle cysts from NCC pose a unique treatment challenge, as there is little consensus on the best treatment. This case study describes the treatment of a patient with fourth ventricle neurocysticercosis (FVNCC), examines the therapeutic decision-making, and provides a video of a posterior fossa craniotomy (PFC) resection of a degenerative cyst.

CLINICAL PRESENTATION

The patient presented with headache, dizziness, nausea, and memory difficulties. A fourth ventricle cyst consistent with NCC was found on magnetic resonance imaging, and serum enzyme-linked immunosorbent assay (ELISA) confirmed the diagnosis. The cyst was removed utilizing an open PFC followed by antihelminthic therapy and corticosteroids. There was resolution of symptoms at 9 mo postoperatively.

CONCLUSION

Several treatment modalities have been proposed for isolated cysts in the fourth ventricle, including medication, ventriculoperitoneal shunt, endoscopic removal, and PFC. The treatment decision is complex, and there is little guidance on the best treatment choices. In this article, we describe treatment via PFC for an adherent FVNCC cyst.

Diffuse Parenchymal Neurocysticercosis: A Case Report and Review of Literature

Neurocysticercosis is the commonest parasitic disease of the central nervous system and the leading cause of seizure in the developing world. Human cysticercosis is caused by the dissemination of the embryo of Taenia solium in the intestine via the hepatoportal system to the tissues and organs of the body. The organs most commonly affected are the subcutaneous tissues, skeletal muscles, lung, brain, eye, liver, and occasionally the heart, thyroid, and pancreas. Widespread dissemination of the cysticerci can result in the involvement of almost any organ in the body. We report a case of 60 years old male presented with head injury due to fall, which was diagnosed as diffuse parenchymal neurocysticercosis on computed tomography scan of brain. We discuss the radiological feature, diagnostic criteria, management plan, and literature review of such reported cases.

Taenia solium insulin receptors: promising candidates for cysticercosis treatment and prevention

Insulin signaling pathway is an ancient and highly conserved pathway known to play critical roles in cell growth, control and metabolic regulation. In this study, we identified and characterized two insulin receptor genes (TsIR-1316 and TsIR-4810) from Taenia solium. TsIR-1316 was grouped with E. multilocularis insulin receptor (EmIR-1) and TsIR-4810 was closer to Taenia pisiformis insulin-like growth factor receptor (TpIR) on the same branch with a very high bootstrap value. TsIR-1316 was located on the integument of larvae and adult worms, as well as the ovary of adults and eggs. Alternatively, TsIR-4810 was located in the parenchyma and reproductive organs of the adult worms. By using in vitro cultivation systems with Cysticercus pisiformis as a model, we demonstrated that anti-TsIRs-LBD antibodies could effectively block the insulin signaling pathway, resulting in reduced phosphorylation of the insulin receptor as well as lower levels of glucose uptake and glycogen synthesis. The rabbits immunized with TsIR-1316-LBD, TsIR-4810-LBD and TsIR-1316-LBD + TsIR-4810-LBD produced protection against infection of T. pisiformis as demonstrated by a 94.6%, 96% and 80% reduction of establishment of larvae, respectively. These data suggested that TsIR-1316-LBD and TsIR-4810-LBD are promising vaccine candidates or novel drug targets against swine cysticercosis.

A Rat Model of Neurocysticercosis-Induced Hydrocephalus: Chronic Progressive Hydrocephalus with Mild Clinical Impairment

BACKGROUND

Hydrocephalus is the most common complication of extraparenchymal neurocysticercosis, combining obstructive and inflammatory mechanisms that impair cerebrospinal fluid circulation.

METHODS

We studied the long-term progression of neurocysticercosis-induced hydrocephalus in a rat model. We generated an experimental rat model of neurocysticercosis-induced hydrocephalus by cisternal inoculation of cysts or antigens of Taenia crassiceps and compared it with the classic model of kaolin-induced hydrocephalus. We used 52 animals divided into 4 groups: 1) control, 2) neurocysticercosis-induced hydrocephalus by cysts or 3) by antigens, and 4) kaolin-induced hydrocephalus. We studied behavioral, radiologic, and morphologic alterations at 1 and 6 months after inoculation by open field test, magnetic resonance imaging, and immunohistochemical localization of aquaporin-4 (AQP-4).

RESULTS

Behavioral changes were observed later in neurocysticercosis-induced than in kaolin-induced hydrocephalic rats (P = 0.023). The ventricular volume of hydrocephalus induced by experimental neurocysticercosis progressively evolved, with the magnetic resonance imaging changes being similar to those observed in humans. Periventricular inflammatory and astrocytic reactions were also observed. AQP-4 expression was higher in the sixth than in the first month after inoculation (P = 0.016) and also occurred in animals that received antigen inoculation but did not develop hydrocephalus, suggesting that AQP-4 may constitute an alternative route of cerebrospinal fluid absorption under inflammatory conditions.

CONCLUSIONS

Our neurocysticercosis-induced hydrocephalus model allows for the long-term maintenance of hydrocephalic animals, involving mild clinical performance impairments, including body weight and behavioral changes.

Human taeniasis/cysticercosis: a potentially emerging parasitic disease in Europe

Taenia saginata (T. saginata)/Taenia solium (T. solium) taeniasis/cysticercosis disease complexes remain a significant challenge for food safety and public health. Human taeniasis is an infectious disease caused by the ingestion of the metacestode larval stage, the cysticerci of T. saginata in beef or T. solium in pork. Humans can also become infected via the ingestion of T. solium eggs. In this case, the cysticerci can establish in the central nervous system, causing the infection called neurocysticercosis. T. solium is of higher importance than T. saginata because the former species can cause neurocysticercosis in humans, a major cause of neurological morbidity in the world. The taeniasis/cysticercosis complex is included in the list of neglected zoonotic diseases by the World Health Organization and Food and Agriculture Organization, with T. solium being the number one foodborne parasite; it occurs mostly in developing countries, such as regions of Asia, Africa and Latin America, where the disease remains endemic. Long absent in Western Europe and other developed countries, cysticercosis has been recently re-emerged as a result of immigration, travel and commerce. In this review, cysticercosis is presented with special emphasis on some aspects of this neglected disease: the main clinical manifestations, risk factors and epidemiology. In addition, any recent advances in diagnostic approaches and treatment are discussed. Finally, the complexities involved in the control of the disease and the need to revise current management strategies are highlighted.

Galectin-3 in M2 Macrophages Plays a Protective Role in Resolution of Neuropathology in Brain Parasitic Infection by Regulating Neutrophil Turnover

Macrophages/microglia with M2-activation phenotype are thought to play important anti-inflammatory and tissue reparative functions in the brain, yet the molecular bases of their functions in the CNS remain to be clearly defined. In a preclinical model of neurocysticercosis using brain infection with a parasite Mesocestoides corti, we previously reported the presence of large numbers of M2 cells in the CNS. In this study using female mice, we report that M2 macrophages in the parasite-infected brain display abundant galectin-3 expression. Disease severity was increased in Galectin-3^-/- mice correlating with increased neurological defects, augmented cell death and, importantly, massive accumulation of neutrophils and M2 macrophages in the CNS of these mice. Because neutrophil clearance by efferocytosis is an important function of M2 macrophages, we investigated a possible role of galectin-3 in this process. Indeed, galectin-3-deficient M2 macrophages exhibited a defect in efferocytic clearance of neutrophils in vitro Furthermore, adoptive transfer of M2 macrophages from galectin-3-sufficient WT mice reduced neutrophilia in the CNS and ameliorated disease severity in parasite-infected Galectin-3^-/- mice. Together, these results demonstrate, for the first time, a novel role of galectin-3 in M2 macrophage function in neutrophil turnover and resolution of inflammatory pathology in the CNS. This likely will have implications in neurocysticercosis and neuroinflammatory diseases.SIGNIFICANCE STATEMENT Macrophages/microglia with M1-activation phenotype are thought to promote CNS pathology, whereas M2-anti-inflammatory phenotype promote CNS repair. However, the mechanisms regulating M2 cell-protective functions in the CNS microenvironment are undefined. The current study reports that helminth infection of the brain induces an increased expression of galectin-3 in M2 macrophages accumulated in the CNS. Using multiple experimental models in vivo and in vitro, they show that galectin-3 in M2 macrophages functions to clear neutrophils accumulated in the CNS. Importantly, galectin-3 in M2 macrophages plays a central role in the containment of neuropathology and disease severity. These results provide a direct mechanistic evidence of the protective function of M2 macrophages in the CNS.

Recurrent encephalopathy in milliary neurocysticercosis: An uncommon manifestation of a common infection

Neurocysticercosis is a common parasitic infection in children in developing countries and neurological symptoms such as seizures are the most common manifestations. However, symptoms of encephalopathy are an unusual presentation in children. A 4-year-old boy presented with recurrent episodes of febrile encephalopathy. His magnetic resonance imaging of the brain was suggestive of milliary neurocysticercosis of various stages. Reports on recurrent encephalopathy following neurocysticercosis are scarce in literature. Hence, we report this case who presented with recurrent episodes of encephalopathy.

A novel progesterone receptor membrane component (PGRMC) in the human and swine parasite Taenia solium: implications to the host-parasite relationship

Background

We have previously reported that progesterone (P₄) has a direct in vitro effect on the scolex evagination and growth of Taenia solium cysticerci. Here, we explored the hypothesis that the P₄ direct effect on T. solium might be mediated by a novel steroid-binding parasite protein.

Methods

By way of using immunofluorescent confocal microscopy, flow cytometry analysis, double-dimension electrophoresis analysis, and sequencing the corresponding protein spot, we detected a novel PGRMC in T. solium. Molecular modeling studies accompanied by computer docking using the sequenced protein, together with phylogenetic analysis and sequence alignment clearly demonstrated that T. solium PGRMC is from parasite origin.

Results

Our results show that P₄ in vitro increases parasite evagination and scolex size. Using immunofluorescent confocal microscopy, we detected that parasite cells showed expression of a P₄-binding like protein exclusively located at the cysticercus subtegumental tissue. Presence of the P₄-binding protein in cyst cells was also confirmed by flow cytometry. Double-dimension electrophoresis analysis, followed by sequencing the corresponding protein spot, revealed a protein that was previously reported in the T. solium genome belonging to a membrane-associated progesterone receptor component (PGRMC). Molecular modeling studies accompanied by computer docking using the sequenced protein showed that PGRMC is potentially able to bind steroid hormones such as progesterone, estradiol, testosterone and dihydrodrotestosterone with different affinities. Phylogenetic analysis and sequence alignment clearly demonstrated that T. solium PGRMC is related to a steroid-binding protein of Echinoccocus granulosus, both of them being nested within a cluster including similar proteins present in platyhelminths such as Schistocephalus solidus and Schistosoma haematobium.

Conclusion

Progesterone may directly act upon T. solium cysticerci probably by binding to PGRMC. This research has implications in the field of host-parasite co-evolution as well as the sex-associated susceptibility to this infection. In a more practical matter, present results may contribute to the molecular design of new drugs with anti-parasite actions.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2703-1) contains supplementary material, which is available to authorized users.

Recent advancements and new perspectives in animal models for Neurocysticercosis immunopathogenesis

Neurocysticercosis (NCC), one of the most common parasitic diseases of the central nervous system, is caused by Taenia solium. This parasite involves two hosts, intermediate hosts (pig and human) and a definitive host (human) and has various stages in its complex life cycle (eggs, oncosphere, cysticerci and adult tapeworm). Hence, developing an animal model for T. solium that mimics its natural course of infection is quite challenging. We have reviewed here the animal models frequently used to study immunopathogenesis of cysticercosis and also discussed their usefulness for NCC studies. We found that researchers have used mice, rats, guinea pigs, dogs, cats and pigs as models for this disease with varying degrees of success. Mice and rats models have been utilized extensively for immunopathogenesis studies due to their relative ease of handling and abundance of commercially available reagents to study these small animal models. These models have provided some very exciting results for in-depth understanding of the disease. Of late, the experimentally/naturally infected swine model is turning out to be the best animal model as the disease progression closely resembles human infection in pigs. However, handling large experimental animals has its own challenges and limitations.

Infections of the Central Nervous System in Returning Travelers and Immigrants

PURPOSE OF REVIEW

This review highlights current knowledge in travel-related neuroinfectious diseases, providing insight on approaches to prevention, diagnosis, and treatment of infections of the central nervous system (CNS) in travelers and immigrants.

RECENT FINDINGS

Updates on travel vaccine recommendations including vaccine-specific interactions with immunosuppressive agents, advances in Zika virus and dengue virus vaccine development, new diagnostic criteria for neurocysticercosis, updates on treatment approaches for tuberculosis meningitis. Increasing rates of travel are leading to the spread of known infectious diseases and the emergence of new diseases in travel medicine. Among these infections, neuroinfectious diseases carry significant morbidity and mortality. To reduce the effect of travel-related illness, appropriate pre-travel measures and up-to-date diagnostic and treatment strategies are essential for optimal outcomes. This review highlights important travel information relevant to neuroinfectious diseases for several populations including immunocompetent, immunocompromised, pregnant, and infant/children travelers. It also outlines the travel risk, clinical presentation, diagnosis, and management of a select list of neuroinfectious diseases by region, including neurocysticercosis, Zika virus, tuberculosis meningitis, rabies, and tick-borne encephalitis.

Neurocysticercosis: Diagnostic problems & current therapeutic strategies

Neurocysticercosis (NCC) is the most common single cause of seizures/epilepsy in India and several other endemic countries throughout the world. It is also the most common parasitic disease of the brain caused by the cestode Taenia solium or pork tapeworm. The diagnosis of NCC and the tapeworm carrier (taeniasis) can be relatively inaccessible and expensive for most of the patients. In spite of the introduction of several new immunological tests, neuroimaging remains the main diagnostic test for NCC. The treatment of NCC is also mired in controversy although, there is emerging evidence that albendazole (a cysticidal drug) may be beneficial for patients by reducing the number of seizures and hastening the resolution of live cysts. Currently, there are several diagnostic and management issues which remain unresolved. This review will highlight some of these issues.

Neuropsychiatric Aspects of Infectious Diseases: An Update

Among the critically ill, infectious diseases can play a significant role in the etiology of neuropsychiatric disturbances. All critical care physicians are familiar with delirium as a secondary complication of systemic infection. This article focuses on key infectious diseases that commonly and directly produce neuropsychiatric symptoms, including direct infection of the central nervous system, human immunodeficiency virus infection, and AIDS.

Lumbar spinal intradural neurocysticercosis: A case report

Neurocysticercosis is a parasitic disease that results from the larvae of Taenia solium. While neurocysticercosis is considered as the most common parasitic infection of the nervous system, spinal neurocysticercosis is rare. The present case study investigated a 59-year-old woman, who was admitted to our hospital with pain in the bilateral lower limbs and urinary complaints in the form of straining of micturition with increasing frequency. Magnetic resonance imaging revealed an intradural extramedullary lesion extending from L1/2 to S1 of the spine. Subsequently, a laminectomy from L1 to S1 was performed 3 days post-presentation. Intraoperatively, a thin-walled cyst with clear fluid was identified, extending from L2 to S1. The exposed, white and mucoid cysticerci was removed completely. Which on pathological examination was identified to be cysticercosis.

Radiological evolution of porcine neurocysticercosis after combined antiparasitic treatment with praziquantel and albendazole

BACKGROUND

The onset of anthelmintic treatment of neurocysticercosis (NCC) provokes an acute immune response of the host, which in human cases is associated with exacerbation of neurological symptoms. This inflammation can occur at the first days of therapy. So, changes in the brain cysts appearance may be detected by medical imaging. We evaluated radiological changes in the appearance of brain cysts (enhancement and size) on days two and five after the onset of antiparasitic treatment using naturally infected pigs as a model for human NCC.

METHODS AND RESULTS

Contrast T1-weighted magnetic resonance imaging with gadolinium was performed before and after antiparasitic treatment. Eight NCC-infected pigs were treated with praziquantel plus albendazole and euthanized two (n = 4) and five (n = 4) days after treatment; another group of four infected pigs served as untreated controls. For each lesion, gadolinium enhancement intensity (GEI) and cyst volume were measured at baseline and after antiparasitic treatment. Volume and GEI quantification ratios (post/pre-treatment measures) were used to appraise the effect of treatment. Cysts from untreated pigs showed little variations between their basal and post treatment measures. At days 2 and 5 there were significant increases in GEI ratio compared with the untreated group (1.32 and 1.47 vs 1.01, p = 0.021 and p = 0.021). Cyst volume ratios were significantly lower at days 2 and 5 compared with the untreated group (0.60 and 0.22 vs 0.95, p = 0.04 and p = 0.02). Cysts with lower cyst volume ratios showed more marked post-treatment inflammation, loss of vesicular fluid and cyst wall wrinkling.

CONCLUSION/SIGNIFICANCE

A significant and drastic reduction of cyst size and increased pericystic enhancement occur in the initial days after antiparasitic treatment as an effect of acute perilesional immune response. These significant changes showed that early anthelmintic efficacy (day two) can be detected using magnetic resonance imaging.

Survey of Obstetrician-Gynecologists in the United States About Taeniasis and Cysticercosis

An estimated 50 million persons worldwide are infected with cysticerci, the larval forms of the Taenia solium tapeworm. Neurocysticercosis can cause seizures, epilepsy, and hydrocephalus, and fatal cases have been reported in the United States in immigrants and in travelers returning from endemic countries. Pregnant women with symptomatic neurocysticercosis present treatment challenges, whereas those with the adult tapeworm infection (i.e., taeniasis) can put their infants and other family members, as well as obstetrician-gynecologists and their staff, at risk for cysticercosis. A questionnaire developed by the American College of Obstetricians and Gynecologists was sent to a representative sample of 1,000 physicians to assess their awareness of T. solium infection and the potential for it to be encountered in an obstetrics and gynecology setting. In total, 31.4% of respondents correctly answered that taeniasis is caused by eating undercooked pork containing T. solium cysts (95% confidence interval [CI] = 26.6-36.5). While only 14.5% (95% CI = 11.0-18.6) of respondents correctly answered that cysticercosis is acquired by ingesting tapeworm eggs shed in human stools, twice that number (30.3%; 95% CI = 25.5-35.3) correctly answered that a mother with taeniasis can cause cysticercosis in her infant. Practicing in a state in which cysticercosis was reportable at the time of the survey was not significantly associated with answering any of the 12 knowledge questions correctly. Overall, knowledge of T. solium infection among U.S. obstetricians-gynecologists is limited. This may result in missed opportunities to diagnose and treat pregnant women with taeniasis, which may put family members and obstetrics clinical staff at risk for cysticercosis.

Taenia crassiceps injection into the subarachnoid space of rats simulates radiological and morphological features of racemose neurocysticercosis

PURPOSE

Neurocysticercosis is a major public health concern. Although its eradication appears feasible, the disease remains endemic in developing countries and has emerged again in Europe and in the USA. Basic studies on neurocysticercosis are needed to better understand the pathophysiologic mechanisms and, consequently, to improve treatment perspectives. Much has been published on experimental parenchymal neurocysticercosis, but there are no experimental models of racemose neurocysticercosis.

METHODS

Cysts of Taenia crassiceps were injected into the subarachnoid space of 11 rats. After 4 months, magnetic resonance imaging (MRI) was performed to verify the occurrence of ventricular dilatation and the distribution of cysts in the cerebrospinal fluid compartments. The histologic assessment was done focusing on changes in the ependyma, choroid plexus, and brain parenchyma.

RESULTS

MRI and histologic assessment confirmed the findings similar to those seen in human racemose neurocysticercosis including enlargement of the basal cisterns, hydrocephalus, and inflammatory infiltration through the ependyma and choroid plexus into cerebrospinal fluid spaces.

CONCLUSIONS

We developed a simple model of racemose neurocysticercosis by injecting cysts of T. crassiceps into the subarachnoid space of rats. This model can help understand the pathophysiologic mechanisms of the disease.

Reduced Leukocyte Infiltration in Absence of Eosinophils Correlates with Decreased Tissue Damage and Disease Susceptibility in ΔdblGATA Mice during Murine Neurocysticercosis

Neurocysticercosis (NCC) is one of the most common helminth parasitic diseases of the central nervous system (CNS) and the leading cause of acquired epilepsy worldwide. NCC is caused by the presence of the metacestode larvae of the tapeworm Taenia solium within brain tissues. NCC patients exhibit a long asymptomatic phase followed by a phase of symptoms including increased intra-cranial pressure and seizures. While the asymptomatic phase is attributed to the immunosuppressive capabilities of viable T. solium parasites, release of antigens by dying organisms induce strong immune responses and associated symptoms. Previous studies in T. solium-infected pigs have shown that the inflammatory response consists of various leukocyte populations including eosinophils, macrophages, and T cells among others. Because the role of eosinophils within the brain has not been investigated during NCC, we examined parasite burden, disease susceptibility and the composition of the inflammatory reaction in the brains of infected wild type (WT) and eosinophil-deficient mice (ΔdblGATA) using a murine model of NCC in which mice were infected intracranially with Mesocestoides corti, a cestode parasite related to T. solium. In WT mice, we observed a time-dependent induction of eosinophil recruitment in infected mice, contrasting with an overall reduced leukocyte infiltration in ΔdblGATA brains. Although, ΔdblGATA mice exhibited an increased parasite burden, reduced tissue damage and less disease susceptibility was observed when compared to infected WT mice. Cellular infiltrates in infected ΔdblGATA mice were comprised of more mast cells, and αβ T cells, which correlated with an abundant CD8⁺ T cell response and reduced CD4⁺ Th1 and Th2 responses. Thus, our data suggest that enhanced inflammatory response in WT mice appears detrimental and associates with increased disease susceptibility, despite the reduced parasite burden in the CNS. Overall reduced leukocyte infiltration due to absence of eosinophils correlates with attenuated tissue damage and longer survival of ΔdblGATA mice. Therefore, our study suggests that approaches to clear NCC will require strategies to tightly control the host immune response while eradicating the parasite with minimal damage to brain tissue.

Eosinophils are known to mediate a protective response against several parasitic infections. This is largely accomplished by eosinophil degranulation (direct killing) and modulating effective adaptive immune responses. Consequently, eosinophils can also contribute to host pathology via a bystander effect. However, the outcome of infection varies depending upon the parasite species. In the case of neurocysticercosis (NCC), the role of eosinophils in disease progression has not been investigated despite the known eosinophilic response in patients. NCC is one of the most common parasitic diseases of the brain which is caused by the metacestode (larva) of the tapeworm Taenia solium. To determine the role of eosinophils in NCC disease outcome, we used a murine model of NCC in which wildtype (WT) or eosinophil deficient mice (ΔdblGATA) were infected intracranially with Mesocestoides corti, a cestode parasite related to T. solium. Our data show that murine NCC is characterized by a robust eosinophil response that correlates with lower parasite burden in the brain. Comparison of T cell response reveals a mixed Th1/Th2 in the WT brain, and ΔdblGATA mice showed a significant decrease in both population but in particular in the Th2 response. In addition, the strong eosinophil reaction observed in WT brains correlates with exacerbated pathology and increased morbidity. Thus, our study suggest that eosinophils act as a double-edged sword playing a role in controlling the infection but worsening the disease outcome by contributing to host pathology.

Cysticidal Efficacy of Combined Treatment With Praziquantel and Albendazole for Parenchymal Brain Cysticercosis

BACKGROUND

The efficacy of current antiparasitic treatment for cerebral Taenia solium cysticercosis with either albendazole (ABZ) or praziquantel (PZQ) is suboptimal. A recent study demonstrated that combining these 2 antiparasitic drugs improves antiparasitic efficacy. We present here the parasiticidal efficacy data obtained during a previous phase II pharmacokinetic study that compared combined ABZ plus PZQ with ABZ alone.

METHODS

The study was a randomized, double-blinded, placebo-controlled phase II evaluation of the pharmacokinetics of ABZ (15 mg/k/d, for 10 days) and PZQ (50 mg/k/d, for 10 days) in intraparenchymal brain cysticercosis. Patients received the usual concomitant medications, including an antiepileptic drug (phenytoin or carbamazepine), dexamethasone, and ranitidine. Randomization was stratified by antiepileptic drug. Patients underwent safety laboratory evaluations at days 4, 7, and 11, as well as magnetic resonance (MR) imaging at 6 months to assess parasiticidal efficacy.

RESULTS

Thirty-two patients were included, 16 in each arm. All of them completed antiparasitic treatment and underwent follow-up brain MR imaging. Cysticidal efficacy was strikingly higher in the combined ABZ-plus-PZQ group than in the ABZ-alone group (proportion of cysts resolved, 78 of 82 [95%] vs 23 of 77 [30%] [relative risk {RR}, 3.18; 95% confidence interval {CI}, 2.08-4.88; P < .001]; patients with complete cyst clearance, 12 of 16 [75%] vs 4 of 16 [25%] [RR, 3.00; 95% CI, 1.23-7.34; P = .005]).

CONCLUSIONS

The combination of ABZ plus PZQ is more effective in destroying viable brain cysticercosis cysts than ABZ alone.

CLINICAL TRIALS REGISTRATION

NCT00441285.

Inflammation Caused by Praziquantel Treatment Depends on the Location of the Taenia solium Cysticercus in Porcine Neurocysticercosis

Background

Neurocysticercosis (NCC), infection of the central nervous system by Taenia solium cysticerci, is a pleomorphic disease. Inflammation around cysticerci is the major cause of disease but is variably present. One factor modulating the inflammatory responses may be the location and characteristics of the brain tissue adjacent to cysticerci. We analyzed and compared the inflammatory responses to cysticerci located in the parenchyma to those in the meninges or cysticerci partially in contact with both the parenchyma and the meninges (corticomeningeal).

Methodology/Principal Findings

Histological specimens of brain cysticerci (n = 196) from 11 pigs naturally infected with Taenia solium cysticerci were used. Four pigs were sacrificed after 2 days and four after 5 days of a single dose of praziquantel; 3 pigs did not receive treatment. All pigs were intravenously injected with Evans Blue to assess disruption of the blood-brain barrier. The degree of inflammation was estimated by use of a histological score (ISC) based on the extent of the inflammation in the pericystic areas as assessed in an image composed of several photomicrographs taken at 40X amplification. Parenchymal cysticerci provoked a significantly greater level of pericystic inflammation (higher ISC) after antiparasitic treatment compared to meningeal and corticomeningeal cysticerci. ISC of meningeal cysticerci was not significantly affected by treatment. In corticomeningeal cysticerci, the increase in ISC score was correlated to the extent of the cysticercus adjacent to the brain parenchyma. Disruption of the blood-brain barrier was associated with treatment only in parenchymal tissue.

Significance

Inflammatory response to cysticerci located in the meninges was significantly decreased compared to parenchymal cysticerci. The suboptimal inflammatory response to cysticidal drugs may be the reason subarachnoid NCC is generally refractory to treatment compared to parenchymal NCC.

The cystic larvae of the pork tapeworm Taenia solium may affect the human brain causing neurocysticercosis (NCC), a very frequent cause of neurological symptoms in developing countries. The clinical expression and response to treatment of human NCC are related to the location of cysticerci inside (intraparenchymal) or outside the brain parenchyma (extraparenchymal NCC). We used a naturally infected pig model to assess the characteristics of inflammation around brain cysticerci of parenchymal, meningeal and mixed locations. There were no major differences in inflammation without treatment. After antiparasitic treatment with praziquantel, inflammation around parenchymal brain cysticerci increased in comparison to meningeal located cysticerci. Cysticerci partially surrounded by both brain parenchyma and meninges showed increased inflammation in relation to the extent of the cysticercus in the brain parenchyma. The location of cysticerci within the brain is a factor that determines the extent and degree of the immune response following anticysticidal treatment. Similar changes may occur in treated human infections. Our work could contribute to explain the differences in response to antiparasitic treatment in different forms of human neurocysticercosis.

The endocrine-immune network during taeniosis by Taenia solium: The role of the pituitary gland

It is well known that sex hormones play an important role during Taenia solium infection; however, to our knowledge no studies exist concerning the immune response following complete or lobe-specific removal of the pituitary gland during T. solium infection. Thus, the aim of this work was to analyze in hamsters, the effects of lack of pituitary hormones on the duodenal immune response, and their impact on T. solium establishment and development. Thus, in order to achieve this goal, we perform anterior pituitary lobectomy (AL, n = 9), neurointermediate pituitary lobectomy (NIL, n = 9) and total hypophysectomy (HYPOX, n = 8), and related to the gut establishment and growth of T. solium, hematoxylin-eosin staining of duodenal tissue and immunofluorescence of duodenal cytokine expression and compared these results to the control intact (n = 8) and control infected group (n = 8). Our results indicate that 15 days post-infection, HYPOX reduces the number and size of intestinally recovered T. solium adults. Using semiquantitative immunofluorescent laser confocal microscopy, we observed that the mean intensity of duodenal IFN-γ and IL-12 Th1 cytokines was mildly expressed in the infected controls, in contrast with the high level of expression of these cytokines in the NIL infected hamsters. Likewise, the duodenum of HYPOX animals showed an increase in the expression of Th2 cytokines IL-5 and IL-6, when compared to control hamsters. Histological analysis of duodenal mucosa from HYPOX hamsters revealed an exacerbated inflammatory infiltrate located along the lamina propria and related to the presence of the parasite. We conclude that lobe-specific pituitary hormones affect differentially the T. solium development and the gut immune response.

Managing neurocysticercosis: challenges and solutions

Taenia solium neurocysticercosis (NCC) is a major cause of neurological morbidity in the world. Variability in the neuropathology and clinical presentation of NCC often make it difficult to diagnose and manage. Diagnosis of NCC can be challenging especially in endemic and resource-limited countries where laboratory and imaging techniques are often lacking. NCC management can also be challenging as current treatment options are limited and involve symptomatic agents, antiparasitic agents, or surgery. Although antiparasitic treatment probably reduces the number of active lesions and long-term seizure frequency, its efficacy is limited and strategies to improve treatment regimens are warranted. Treatment decisions should be individualized in relation to the type of NCC. Initial measures should focus on symptomatic management, with antiparasitic therapy only to be considered later on, when appropriate. Symptomatic treatment remains the cornerstone in NCC management which should not only focuses on epilepsy, but also on other manifestations that cause considerable burden (recurrent headaches, cognitive decline). Accurate patients’ categorization, better antiparasitic regimens, and definition of new clinical outcomes for trials on NCC could improve management quality and prognosis of NCC. Prevention strategies targeting tapeworm carriers and infected pigs are yielding good results in local models. If local elimination of transmission is confirmed and replicated, this will open the door to cysticercosis eradication efforts worldwide.

Intranasal microemulsion for targeted nose to brain delivery in neurocysticercosis: Role of docosahexaenoic acid

Intranasal Microemulsions (MEs) for nose to brain delivery of a novel combination of Albendazole sulfoxide (ABZ-SO) and Curcumin (CUR) for Neurocysticercosis (NCC), a brain infection are reported. MEs prepared by simple solution exhibited a globule size <20nm, negative zeta potential and good stability. The docosahexaenoic acid (DHA) ME revealed high and rapid ex vivo permeation of drugs through sheep nasal mucosa. Intranasal DHA ME resulted in high brain concentrations and 10.76 (ABZ-SO) and 3.24 (CUR) fold enhancement in brain area-under-the-curve (AUC) compared to intravenous DHA MEs at the same dose. Direct nose to brain transport (DTP) of >95% was seen for both drugs. High drug targeting efficiency (DTE) to the brain compared to Capmul ME and drug solution (P<0.05) suggested the role of DHA in aiding nose to brain delivery. Histopathology study confirmed no significant changes. High efficacy of ABZ-SO: CUR (100:10ng/mL) DHA ME in vitro on Taenia solium cysts was confirmed by complete ALP inhibition and disintegration of cysts at 96h. Considering that the brain concentration at 24h was 1400±160.1ng/g (ABZ-SO) and 120±35.2ng/g (CUR), the in vitro efficacy seen at a 10 fold lower concentration of the drugs strongly supports the assumption of clinical efficacy. The intranasal DHA ME is a promising delivery system for targeted nose to brain delivery.

Prevalence of Neurocysticercosis in People with Epilepsy in the Eastern Province of Zambia

Zambia is endemic for Taenia solium taeniosis and cysticercosis. In this single-centered, cross-sectional, community-based study, the role of neurocysticercosis (NCC) as a cause of epilepsy was examined. People with epilepsy (PWE, n = 56) were identified in an endemic area using a screening questionnaire followed by in-depth interviews and neurological examination. Computed tomography (CT) was performed on 49 people with active epilepsy (PWAE) and their sera (specific antibody and antigen detection, n = 56) and stools (copro-antigen detection, n = 54) were analyzed. The CT scan findings were compared to a group of 40 CT scan controls. Of the PWE, 39.3% and 23.2% were positive for cysticercal antibodies and antigens, respectively, and 14.8% for coproantigens (taeniosis). Lesions highly suggestive of NCC were detected in 24.5% and definite NCC lesions in 4.1% of CT scans of PWAE. This compares to 2.5% and 0%, respectively, in the control CT scans. Using the Del Brutto diagnostic criteria, 51.8% of the PWAE were diagnosed with probable or definitive NCC and this rose to 57.1% when the adapted criteria, as proposed by Gabriël et al. (adding the sero-antigen ELISA test as a major criterion), were used. There was no statistically significant relationship between NCC, current age, age at first seizure and gender. This study suggests that NCC is the single most important cause of epilepsy in the study area. Additional large-scale studies, combining a community based prevalence study for epilepsy with neuroimaging and serological analysis in different areas are needed to estimate the true impact of neurocysticercosis in endemic regions and efforts should be instituted to the control of T. solium.

Epigenetic Modulation of Microglial Inflammatory Gene Loci in Helminth-Induced Immune Suppression: Implications for Immune Regulation in Neurocysticercosis

In neurocysticercosis, parasite-induced immune suppressive effects are thought to play an important role in enabling site-specific inhibition of inflammatory responses to infections. It is axiomatic that microglia-mediated (M1 proinflammatory) response causes central nervous system inflammation; however, the mechanisms by which helminth parasites modulate microglia activation remain poorly understood. Here, we show that microglia display a diminished expression of M1-inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide synthase 2 (NOS2) in murine neurocysticercosis. Microglia also exhibited a lack of myeloid cell maturation marker major histocompatibility complex (MHC)-II in these parasite-infected brains. Treatment of microglia with helminth soluble/secreted factors (HSFs) in vitro did not induce expression of M1-inflammatory signature molecule NOS2 as well as MHC-II in primary microglia. However, HSF treatment completely inhibited lipopolysaccharide-induced increase in expression of MHC-II, NOS2 and nitric oxide production in these cells. As epigenetic modulation of chromatin states that regulates recruitment of RNA polymerase II (Pol-II) is a key regulatory step in determining gene expression and functional outcome, we next evaluated whether HSF induced modulation of these phenomenon in microglia in vitro. Indeed, HSF downregulated Pol-II recruitment to the promoter region of TNF-α, IL-6, NOS2, MHC-II, and transcription factor CIITA (a regulator of MHC-II expression), by itself. Moreover, HSF suppressed the lipopolysaccharide-induced increase in Pol-II recruitment as well. In addition, HSF exposure reduced the positive histone marks H3K4Me3 and H3K9/14Ac at the promoter of TNF-α, IL-6, NOS2, MHC-II, and CIITA. These studies provide a novel mechanistic insight into helminth-mediated immune suppression in microglia via modulation of epigenetic processes.

Conservative management of neurocysticercosis in a patient with hematopoietic stem cell transplantation: a case report and review

Neurocysticercosis, an infection of the central nervous system with the larval stage of the cestode Taenia solium, is common in developing countries but its occurrence and management in allogeneic hematopoietic stem cell transplantation (HSCT) has not been reported previously, to our knowledge. We report the case of an immigrant female patient who underwent a matched-related allogeneic HSCT for acute lymphoblastic leukemia and was incidentally found to have a solitary viable neurocysticercosis lesion. However, despite severe immunosuppression, the size of the cyst did not increase. More importantly, restoration of the immune system did not induce significant inflammation or seizures. Subsequent follow-up demonstrated complete resolution of the neurocysticercosis lesion. Thus, in the setting of HSCT, an asymptomatic patient with a single neurocysticercosis lesion was successfully managed without the use of anthelmintics, steroids, or anti-epileptics.

Post-treatment vascular leakage and inflammatory responses around brain cysts in porcine neurocysticercosis

Cysticidal treatment of neurocysticercosis, an infection of humans and pig brains with Taenia solium, results in an early inflammatory response directed to cysts causing seizures and focal neurological manifestations. Treatment-induced pericystic inflammation and its association with blood brain barrier (BBB) dysfunction, as determined by Evans blue (EB) extravasation, was studied in infected untreated and anthelmintic-treated pigs. We compared the magnitude and extent of the pericystic inflammation, presence of EB-stained capsules, the level of damage to the parasite, expression of genes for proinflammatory and regulatory cytokines, chemokines, and tissue remodeling by quantitative PCR assays between treated and untreated infected pigs and between EB-stained (blue) and non stained (clear) cysts. Inflammatory scores were higher in pericystic tissues from EB-stained cysts compared to clear cysts from untreated pigs and also from anthelmintic-treated pigs 48 hr and 120 hr after treatment. The degree of inflammation correlated with the severity of cyst wall damage and both increased significantly at 120 hours. Expression levels of the proinflammatory genes for IL-6, IFN-γ, TNF-α were higher in EB-stained cysts compared to clear cysts and unaffected brain tissues, and were generally highest at 120 hr. Additionally, expression of some markers of immunoregulatory activity (IL-10, IL-2Rα) were decreased in EB-stained capsules. An increase in other markers for regulatory T cells (CTLA4, FoxP3) was found, as well as significant increases in expression of two metalloproteases, MMP1 and MMP2 at 48 hr and 120 hr post-treatment. We conclude that the increase in severity of the inflammation caused by treatment is accompanied by both a proinflammatory and a complex regulatory response, largely limited to pericystic tissues with compromised vascular integrity. Because treatment induced inflammation occurs in porcine NCC similar to that in human cases, this model can be used to investigate mechanisms involved in host damaging inflammatory responses and agents or modalities that may control damaging post treatment inflammation.

Neurocysticercosis is caused by infection of the brain with the larval (cyst) stage of the tape worm Taenia solium in humans and pigs. Antiparasitic drug treatment is compromised by worsening of neurological symptoms during therapy due to reactive inflammation triggered by the dying parasite. The immune mechanisms that cause this inflammation are poorly understood. In this study, we investigated the nature of inflammation after treatment in pigs naturally infected with T. solium cysts. Evans blue dye injected into infected pigs marks areas in the brain where the normally impermeable capillaries have become more permeable, allowing damaging cells and molecules to leak out into the brain. By microscopy and measurement of gene expression for inflammation-inducing immune mediators, we show that inflammation in the brain tissues around cysts is more severe with increased vessel leakage. Furthermore, the levels of these mediators increased after antiparasitic drug treatment. A significant implication of these findings is that it may be possible to inhibit the inflammation around parasites using drugs or biologics that inhibit these inflammatory pathways and, thereby, reduce local brain damage during treatment. These observations may also be applicable to other inflammatory conditions that affect the brain.

Inhibition of store-operated calcium entry in microglia by helminth factors: implications for immune suppression in neurocysticercosis

Background

Neurocysticercosis (NCC) is a disease of the central nervous system (CNS) caused by the cestode Taenia solium. The infection exhibits a long asymptomatic phase, typically lasting 3 to 5 years, before the onset of the symptomatic phase. The severity of the symptoms is thought to be associated with the intensity of the inflammatory response elicited by the degenerating parasite. In contrast, the asymptomatic phase shows an absence of brain inflammation, which is presumably due to immunosuppressive effects of the live parasites. However, the host factors and/or pathways involved in inhibiting inflammation remain largely unknown. Recently, using an animal model of NCC in which mice were intracranially inoculated with a related helminth parasite, Mesocestoides corti, we reported that Toll-like receptor (TLR)-associated signaling contributes to the development of the inflammatory response. As microglia shape the initial innate immune response in the CNS, we hypothesized that the negative regulation of a TLR-induced inflammatory pathway in microglia may be a novel helminth-associated immunosuppressive mechanism in NCC.

Methods and results

Here we report that helminth soluble factors (HSFs) from Mesocestoides corti inhibited TLR ligation-induced production of inflammatory cytokines in primary microglia. This was correlated with an inhibition of TLR-initiated upregulation of both phosphorylation and acetylation of the nuclear factor κB (NF-κB) p65 subunit, as well as phosphorylation of JNK and ERK1/2. As Ca²⁺ influx due to store-operated Ca²⁺ entry (SOCE) has been implicated in induction of downstream signaling, we tested the inhibitory effect of HSFs on agonist-induced Ca²⁺ influx and specific Ca²⁺ channel activation. We discovered that HSFs abolished the lipopolysaccharide (LPS)- or thapsigargin (Tg)-induced increase in intracellular Ca²⁺ accumulation by blocking the ER store release and SOCE. Moreover, electrophysiological recordings demonstrated HSF-mediated inhibition of LPS- or Tg-induced SOCE currents through both TRPC1 and ORAI1 Ca²⁺ channels on plasma membrane. This was correlated with a decrease in the TRPC1-STIM1 and ORAI1-STIM1 clustering at the plasma membrane that is essential for sustained Ca²⁺ entry through these channels.

Conclusion

Inhibition of TRPC1 and ORAI1 Ca²⁺ channel-mediated activation of NF-κB and MAPK pathways in microglia is likely a novel helminth-induced immunosuppressive mechanism that controls initiation of inflammatory response in the CNS.

Small calcified lesions suggestive of neurocysticercosis are associated with mesial temporal sclerosis

Recent studies have suggested a possible relationship between temporal lobe epilepsy with mesial temporal sclerosis (MTS) and neurocysticercosis (NC). We performed a case-control study to evaluate the association of NC and MTS.

METHOD

We randomly selected patients with different epilepsy types, including: MTS, primary generalized epilepsy (PGE) and focal symptomatic epilepsy (FSE). Patients underwent a structured interview, followed by head computed tomography (CT). A neuroradiologist evaluated the scan for presence of calcified lesions suggestive of NC. CT results were matched with patients' data.

RESULTS

More patients in the MTS group displayed calcified lesions suggestive of NC than patients in the other groups (p=0.002). On multivariate analysis, MTS was found to be an independent predictor of one or more calcified NC lesions (p=0.033).

CONCLUSION

After controlling for confounding factors, we found an independent association between NC calcified lesions and MTS.

Immunology of Taenia solium taeniasis and human cysticercosis

The life cycle of Taenia solium, the pork tapeworm, is continuously closed in many rural settings in developing countries when free roaming pigs ingest human stools containing T. solium eggs and develop cysticercosis, and humans ingest pork infected with cystic larvae and develop intestinal taeniasis, or may also accidentally acquire cysticercosis by faecal-oral contamination. Cysticercosis of the human nervous system, neurocysticercosis, is a major cause of seizures and other neurological morbidity in most of the world. The dynamics of exposure, infection and disease as well as the location of parasites result in a complex interaction which involves immune evasion mechanisms and involutive or progressive disease along time. Moreover, existing data are limited by the relative lack of animal models. This manuscript revises the available information on the immunology of human taeniasis and cysticercosis.

Efficacy of combined antiparasitic therapy with praziquantel and albendazole for neurocysticercosis: a double-blind, randomised controlled trial

BACKGROUND

Neurocysticercosis causes a substantial burden of seizure disorders worldwide. Treatment with either praziquantel or albendazole has suboptimum efficacy. We aimed to establish whether combination of these drugs would increase cysticidal efficacy and whether complete cyst resolution results in fewer seizures. We added an increased dose albendazole group to establish a potential effect of increased albendazole concentrations.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, patients with viable intraparenchymal neurocysticercosis were randomly assigned to receive 10 days of combined albendazole (15 mg/kg per day) plus praziquantel (50 mg/kg per day), standard albendazole (15 mg/kg per day), or increased dose albendazole (22·5 mg/kg per day). Randomisation was done with a computer generated schedule balanced within four strata based on number of cysts and concomitant antiepileptic drug. Patients and investigators were masked to group assignment. The primary outcome was complete cyst resolution on 6-month MRI. Enrolment was stopped after interim analysis because of parasiticidal superiority of one treatment group. Analysis excluded patients lost to follow-up before the 6-month MRI. This trial is registered with ClinicalTrials.gov, number NCT00441285.

FINDINGS

Between March 3, 2010 and Nov 14, 2011, 124 patients were randomly assigned to study groups (41 to receive combined albendazole plus praziquantel [39 analysed], 43 standard albendazole [41 analysed], and 40 increased albendazole [38 analysed]). 25 (64%) of 39 patients in the combined treatment group had complete resolution of brain cysts compared with 15 (37%) of 41 patients in the standard albendazole group (rate ratio [RR] 1·75, 95% CI 1·10-2·79, p=0·014). 20 (53%) of 38 patients in the increased albendazole group had complete cyst resolution at 6-month MRI compared with 15 (37%) of 41 patients in the standard albendazole group (RR 1·44, 95% CI 0·87-2·38, p=0·151). No significant differences in adverse events were reported between treatment groups (18 in combined treatment group, 11 in standard albendazole group, and 19 in increased albendazole group).

INTERPRETATION

Combination of albendazole plus praziquantel increases the parasiticidal effect in patients with multiple brain cysticercosis cysts without increased side-effects. A more efficacious parasiticidal regime without increased treatment-associated side-effects should improve the treatment and long term prognosis of patients with neurocysticercosis.

FUNDING

National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health.

Helminth induced suppression of macrophage activation is correlated with inhibition of calcium channel activity

Helminth parasites cause persistent infections in humans and yet many infected individuals are asymptomatic. Neurocysticercosis (NCC), a disease of the central nervous system (CNS) caused by the cestode Taenia solium, has a long asymptomatic phase correlated with an absence of brain inflammation. However, the mechanisms of immune suppression remain poorly understood. Here we report that murine NCC displays a lack of cell surface maturation markers in infiltrating myeloid cells. Furthermore, soluble parasite ligands (PL) failed to induce maturation of macrophages, and inhibited TLR-induced inflammatory cytokine production. Importantly, PL treatment abolished both LPS and thapsigargin-induced store operated Ca2+ entry (SOCE). Moreover, electrophysiological recordings demonstrated PL-mediated inhibition of LPS or Tg-induced currents that were TRPC1-dependent. Concomitantly STIM1-TRPC1 complex was also impaired that was essential for SOCE and sustained Ca2+ entry. Likewise loss of SOCE due to PL further inhibited NFkB activation. Overall, our results indicate that the negative regulation of agonist induced Ca2+ signaling pathway by parasite ligands may be a novel immune suppressive mechanism to block the initiation of the inflammatory response associated with helminth infections.

Neglected parasitic infections in the United States: cysticercosis

Cysticercosis is a potentially fatal and preventable neglected parasitic infection caused by the larval form of Taenia solium. Patients with symptomatic disease usually have signs and symptoms of neurocysticercosis, which commonly manifest as seizures or increased intracranial pressure. Although there are many persons living in the United States who emigrated from highly disease-endemic countries and there are foci of autochthonous transmission of the parasite in the United States, little is known about burden and epidemiology of the disease in this country. In addition, despite advances in the diagnosis and management of neurocysticercosis, there remain many unanswered questions. Improving our understanding and management of neurocysticercosis in the United States will require improved surveillance or focused prospective studies in appropriate areas and allocation of resources towards answering some of the key questions discussed in this report.

Clinical management of neurocysticercosis

Neurocysticercosis is the most common helminthic disease of the nervous system and a leading cause of acquired epilepsy worldwide. Differences in the number and location of lesions as well as in the severity of the immune response against the parasites, makes neurocysticercosis a complex disease. Therefore, a single therapeutic approach is not expected to be useful in every patient. Introduction of cysticidal drugs - praziquantel and albendazole - have changed the prognosis of thousands of patients with neurocysticercosis. While pioneer trials of therapy were flawed by a poor design, recent studies have shown that cysticidal drugs results in disappearance of lesions and clinical improvement in most cases. Nevertheless, some patients with parenchymal neurocysticercosis may be left with remaining cysts and may develop recurrent seizures after therapy, and many patients with subarachnoid cysts may need repeated courses of therapy. In addition, not all forms of the disease benefit from cysticidal drugs.

Neurocysticercosis

Known as a disease of swine in ancient civilizations, cysticercosis is currently considered the most common helminthic infection of the nervous system, and a leading cause of acquired epilepsy worldwide. The disease occurs when humans become intermediate hosts of the tapeworm Taenia solium by ingesting its eggs from contaminated food or, most often, directly from a Taenia carrier by the fecal-oral route. Once in the human intestine, Taenia eggs evolve to oncospheres that, in turn, cross the intestinal wall and lodge in human tissues - especially the nervous system - where cysticerci develop. The brain is a hostile environment in which parasites attempt to escape the immune surveillance while the host is trying to drive out the infection. In some cases, cysticerci are destroyed by this immunological attack, while in others, parasites may live unchanged for years. Cysticerci may be located in brain parenchyma, subarachnoid space, ventricular system, or spinal cord, causing a myriad of pathologic changes that are the main changes responsible for the clinical pleomorphism of neurocysticercosis. Seizures are the most common clinical manifestation of the disease, but some patients present with focal deficits, intracranial hypertension, or cognitive decline. With the exception of cystic lesions showing the scolex as an eccentric nodule, neuroimaging findings of neurocysticercosis are nonspecific and may be seen in other diseases of the nervous system. Likewise, immune diagnostic tests have been faced with problems related to poor sensitivity or specificity. Accurate diagnosis is possible after interpretation of clinical data together with findings of neuroimaging studies and results of immunologic tests, in a proper epidemiologic scenario. The introduction of cysticidal drugs has changed the prognosis of neurocysticercosis. Praziquantel and albendazole have been shown to reduce the burden of infection in the brain (as seen on neuroimaging studies) and to improve the clinical course of the disease in most patients. Further efforts should be directed towards eradicating this disease through the implementation of control programs for all the interrelated steps in the life cycle of T. solium, including human carriers of the adult tapeworm, infected pigs, and eggs in the environment.

Rickettsiae, protozoa, and opisthokonta/metazoa

Rhizobiales (formerly named Rickettsiales) cause in rare instances meningitis and meningovasculitis, respectively. In case of history of exposure, infection by Rhizobiales needs to be considered since both diagnosis and therapy may be extremely difficult and pathogen-specific. The same applies to protozoa; in this chapter, Babesia species, free-living amoebae and Entamoeba histolytica infection, including severe meningitis and brain abscess, infection by Trypanosoma species (South American and African trypanosomiasis) are discussed with respect to history, epidemiology, clinical signs, and symptoms as well as differential diagnosis and therapy. Parasitic flatworms and roundworms, potentially able to invade the central nervous system, trematodes (flukes), cestodes (in particular, Cysticercus cellulosae), but also nematodes (in particular, Strongyloides spp. in the immunocompromised) are of worldwide importance. In contrast, filarial worms, Toxocara spp., Trichinella spp., Gnathostoma and Angiostrongylus spp. are seen only in certain geographically confined areas. Even more regionally confined are infestations of the central nervous system by metazoa, in particular, tongue worms (=arthropods) or larvae of flies (=maggots). The aim of this chapter is (1) to alert the neurologist to these infections, and (2) to enable the attending emergency neurologist to take a knowledgeable history, with an emphasis on epidemiology, clinical signs, and symptoms as well as therapeutic management possibilities.

Neurocysticercosis

Cysticercosis is one of the most common parasitic diseases of the nervous system in humans, and constitutes a major public health problem for most of the developing world. The clinical manifestations of neurocysticercosis (NCC) largely depend on the the host immune response against the parasite. NCC diagnosis is based upon neuroimaging studies (computerized tomography, magnetic resonance imaging) and antibody/antigen detection in the serum and the cerebrospinal fluid. Anticysticercal therapy has been marked by an intense controversy. Randomized controlled trials evaluating the clinical benefit of treatment have yield conflicting data with some studies indicating a benefit and others failing to show a difference. Prevention strategies must rely on multiple approaches, tailoring each to the special features of the particular endemic area.