Epilepsy and neurocysticercosis in an Andean community

Neurocysticercosis-related Seizures: Imaging Biomarkers

Neurocysticercosis (NCC)-a parasitic CNS infection endemic to developing nations-has been called the leading global cause of acquired epilepsy yet remains understudied. It is currently unknown why a large proportion of patients develop recurrent seizures, often following the presentation of acute seizures. Furthermore, the presentation of NCC is heterogenous and the features that predispose to the development of an epileptogenic state remain uncertain. Perilesional factors (such as oedema and gliosis) have been implicated in NCC-related ictogenesis, but the effects of cystic factors, including lesion load and location, seem not to play a role in the development of habitual epilepsy. In addition, the cytotoxic consequences of the cyst's degenerative stages are varied and the majority of research, relying on retrospective data, lacks the necessary specificity to distinguish between acute symptomatic and unprovoked seizures. Previous research has established that epileptogenesis can be the consequence of abnormal network connectivity, and some imaging studies have suggested that a causative link may exist between NCC and aberrant network organisation. In wider epilepsy research, network approaches have been widely adopted; studies benefiting predominantly from the rich, multimodal data provided by advanced MRI methods are at the forefront of the field. Quantitative MRI approaches have the potential to elucidate the lesser-understood epileptogenic mechanisms of NCC. This review will summarise the current understanding of the relationship between NCC and epilepsy, with a focus on MRI methodologies. In addition, network neuroscience approaches with putative value will be highlighted, drawing from current imaging trends in epilepsy research.

What Causes Seizures in Neurocysticercosis?

Neurocysticercosis (NCC) is the most prevalent parasitic infection of the central nervous system. It is caused by the presence of larvae of the cestode Taenia solium in the brain. The most common symptom of NCC is seizures, and it is widely considered the world’s leading cause of preventable epilepsy. Despite the prevalence and impact of NCC, a thorough, mechanistic understanding of seizure generation is still lacking. In this review, we address the question “What causes seizures in NCC?” by summarizing and discussing the major theories that seek to explain the seizurogenic and epileptogenic processes in this disorder. In addition, we highlight the potential for recent advances in disease modeling to help accelerate progress in this area.

CystiHuman: A model of human neurocysticercosis

INTRODUCTION

The Taenia solium tapeworm is responsible for cysticercosis, a neglected tropical disease presenting as larvae in the body of a host following taenia egg ingestion. Neurocysticercosis (NCC), the name of the disease when it affects the human central nervous system, is a major cause of epilepsy in developing countries, and can also cause intracranial hypertension, hydrocephalus and death. Simulation models can help identify the most cost-effective interventions before their implementation. Modelling NCC should enable the comparison of a broad range of interventions, from treatment of human taeniasis (presence of an adult taenia worm in the human intestine) to NCC mitigation. It also allows a focus on the actual impact of the disease, rather than using proxies as is the case for other models.

METHODS

This agent-based model is the first model that simulates human NCC and associated pathologies. It uses the output of another model, CystiAgent, which simulates the evolution of pig cysticercosis and human taeniasis, adding human and cyst agents, including a model of cyst location and stage, human symptoms, and treatment. CystiHuman also accounts for delays in the appearance of NCC-related symptoms. It comprises three modules detailing cyst development, seizure probability and timing, and intracranial hypertension/hydrocephalus, respectively. It has been implemented in Java MASON and calibrated in three endemic villages in Peru, then applied to another village (Rica Playa) to compare simulation results with field data in that village.

RESULTS AND DISCUSSION

Despite limitations in available field data, parameter values found through calibration are plausible and simulated outcomes in Rica Playa are close to actual values for NCC prevalence and the way it increases with age and cases with single lesions. Initial simulations further suggest that short-term interventions followed by a rapid increase in taeniasis prevalence back to original levels may have limited impacts on NCC prevalence.

Prevalence and incidence of epilepsy in Latin America and the Caribbean: A systematic review and meta-analysis of population-based studies

OBJECTIVE

This study was undertaken to perform an updated systematic review and meta-analysis to estimate the pooled prevalence and incidence of epilepsy in Latin America and the Caribbean (LAC), describing trends over time, and exploring potential clinical and epidemiological factors explaining the heterogeneity in the region.

METHODS

Observational studies assessing the incidence or prevalence of epilepsy in LAC countries up to March 2020 were systematically reviewed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Meta-analyses and cumulative analyses were performed using random-effects models. We assessed between-study heterogeneity with sensitivity, subgroup, and meta-regression analyses. Moreover, the quality of the included studies and the certainty of evidence were evaluated using the GRADE (grading of recommendation, assessment, development, and evaluation) approach.

RESULTS

Overall, 40 studies (from 42 records) were included, 37 for prevalence analyses and six for incidence (312 387 inhabitants; 410 178 person-years). The lifetime prevalence was 14.09 per 1000 inhabitants (95% confidence interval [CI] = 11.72-16.67), for active epilepsy prevalence was 9.06 per 1000 individuals (95% CI = 6.94-11.44), and the incidence rate was 1.11 per 1000 person-years (95% CI = .65-1.70). These high estimates have been constant in the region since 1990. However, substantial statistical heterogeneity between studies and publication bias were found. The overall certainty of evidence was low. Methodological aspects (sample size) and countries' epidemiological characteristics such as access to sanitation services and child and adult mortality rates explained the high heterogeneity. Finally, the prevalence of epilepsy associated with neurocysticercosis (NCC) in the general population was high, and the proportion of NCC diagnosis among people living with epilepsy was 17.37%.

SIGNIFICANCE

The epilepsy prevalence and incidence in LAC are higher than worldwide estimates, being constant since 1990 and strongly influenced by NCC. We identified high between-study heterogeneity and significant methodological limitations (e.g., heterogeneous definitions, lack of longitudinal studies). The region needs upgraded research using standardized definitions and diagnostic methods, and urgent action against preventable causes.

Epilepsy due to Neurocysticercosis: Analysis of a Hospital Cohort

Introduction: Neurocysticercosis (NCC) is a common helminthic infection of the nervous system that occurs when humans become intermediate hosts in the life cycle of the pig tapeworm (Taenia solium) after ingesting its eggs. The objective of this study was to analyze socio-demographic, clinical and paraclinical features of patients with NCC in Lubumbashi, DRC. Methods: This is a cross-sectional study conducted over a period of 2 years within the Neuropsychiatric Center of Lubumbashi. Socio-demographic, clinical, paraclinical and therapeutic features were studied. Results: A total of 18 patients with NCC were listed. Epilepsy was found in 72.2% (13/18) of the cases. The mean age of the patients was 30.2 ± 13.5 years; males accounted for 61.2% of the cases. 84.6% were consumers of pork. Generalized epilepsy was found in 84.6% of the cases and hypereosinophilia in 38% of the cases. On the neuroimaging, the parietal location of lesions represented 92.3%; calcifications were the type of lesion in 53.8% of the cases and 69.2% of the cases presented lesions in the 4th evolutionary stage. Electroencephalogram was normal in 84.4% of the cases. Phenobarbital was the antiepileptic drug used in 69.3%; albendazole and prednisone were used in 53.9% of the cases. Conclusion: This study shows that NCC is one of the causes of epilepsy in Lubumbashi. Generalized tonic-clonic seizures are the most common form of presentation and calcified parenchymal lesions are the most common radiological feature of NCC. So, any patient with acute onset of afebrile seizure should be screened for NCC provided other common causes been ruled out.

Comorbidities of epilepsy in low and middle-income countries: systematic review and meta-analysis

Epilepsy is a major public health concern in low and middle-income countries (LMICs) and comorbidities aggravate the burden associated with the disease. The epidemiology of these comorbidities has not been well described, although, identifying the main comorbidities of epilepsy, and their relative importance, is crucial for improving the quality of care. Comorbidities were defined as disorders coexisting with or preceding epilepsy, or else compounded or directly attributed to epilepsy or to its treatment. A meta-analysis of the proportion of main comorbidities by subcontinent as well as overall was also conducted. Out of the 2,300 papers identified, 109 from 39 countries were included in this systematic review. Four groups of comorbidities were identified: parasitic and infectious diseases (44% of comorbid conditions), somatic comorbidities (37%), psychosocial (11%), as well as psychiatric comorbidities (8%). Heterogeneity was statistically significant for most variables then random effect models were used. The most frequently studied comorbidities were: neurocysticercosis (comorbid proportion: 23%, 95% CI: 18-29), head trauma (comorbid proportion: 9%, 95% CI: 5-15) malnutrition (comorbid proportion: 16%, 95% CI: 28-40), stroke (comorbid proportion: 1.3%, 95% CI: 0.2-7.0), and discrimination for education (comorbid proportion: 34%, 95% CI: 28-40). Many comorbidities of epilepsy were identified in LMICs, most of them being infectious.

An estimation of global volume of surgically treatable epilepsy based on a systematic review and meta-analysis of epilepsy

OBJECTIVE

Epilepsy is one of the most common neurological disorders, yet its global surgical burden has yet to be characterized. The authors sought to compile the most current epidemiological data to quantify global prevalence and incidence, and estimate global surgically treatable epilepsy. Understanding regional and global epilepsy trends and potential surgical volume is crucial for future policy efforts and resource allocation.

METHODS

The authors performed a systematic literature review and meta-analysis to determine the global incidence, lifetime prevalence, and active prevalence of epilepsy; to estimate surgically treatable epilepsy volume; and to evaluate regional trends by WHO regions and World Bank income levels. Data were extracted from all population-based studies with prespecified methodological quality across all countries and demographics, performed between 1990 and 2016 and indexed on PubMed, EMBASE, and Cochrane. The current and annual new case volumes for surgically treatable epilepsy were derived from global epilepsy prevalence and incidence.

RESULTS

This systematic review yielded 167 articles, across all WHO regions and income levels. Meta-analysis showed a raw global prevalence of lifetime epilepsy of 1099 per 100,000 people, whereas active epilepsy prevalence is slightly lower at 690 per 100,000 people. Global incidence was found to be 62 cases per 100,000 person-years. The meta-analysis predicted 4.6 million new cases of epilepsy annually worldwide, a prevalence of 51.7 million active epilepsy cases, and 82.3 million people with any lifetime epilepsy diagnosis. Differences across WHO regions and country incomes were significant. The authors estimate that currently 10.1 million patients with epilepsy may be surgical treatment candidates, and 1.4 million new surgically treatable epilepsy cases arise annually. The highest prevalences are found in Africa and Latin America, although the highest incidences are reported in the Middle East and Latin America. These regions are primarily low- and middle-income countries; as expected, the highest disease burden falls disproportionately on regions with the fewest healthcare resources.

CONCLUSIONS

Understanding of the global epilepsy burden has evolved as more regions have been studied. This up-to-date worldwide analysis provides the first estimate of surgical epilepsy volume and an updated comprehensive overview of current epidemiological trends. The disproportionate burden of epilepsy on low- and middle-income countries will require targeted diagnostic and treatment efforts to reduce the global disparities in care and cost. Quantifying global epilepsy provides the first step toward restructuring the allocation of healthcare resources as part of global healthcare system strengthening.

Parasites and epilepsy: Understanding the determinants of epileptogenesis

There is a large body of evidence suggesting that parasites could be a major preventable risk factor for epilepsy in low- and middle-income countries. We review potentially important substrates for epileptogenesis in parasitic diseases. Taenia solium is the most widely known parasite associated with epilepsy, and the risk seems determined mainly by the extent of cortical involvement and the evolution of the primary cortical lesion to gliosis or to a calcified granuloma. For most parasites, however, epileptogenesis is more complex, and other favorable host genetic factors and parasite-specific characteristics may be critical. In situations where cortical involvement by the parasite is either absent or minimal, parasite-induced epileptogenesis through an autoimmune process seems plausible. Further research to identify important markers of epileptogenesis in parasitic diseases will have huge implications for the development of trials to halt or delay onset of epilepsy.

Neurocysticercosis as a probable risk factor for hippocampal sclerosis

ABSTRACT Neurocysticercosis is one of the most common risk factors for epilepsy but its association with drug-resistant epilepsy remains uncertain. Conjectures of an association with drug-resistant epilepsy have been fueled by reports of an association between calcific neurocysticercosis lesions (CNL) and hippocampal sclerosis (HS) from specialized epilepsy centers in Taenia solium-endemic regions. The debate arising from these reports is whether the association is causal. Evidence for the association is not high quality but sufficiently persuasive to merit further investigation with longitudinal imaging studies in population-based samples from geographically-diverse regions. The other controversial point is the choice of a surgical approach for drug-resistant epilepsy associated with CNL-HS. Three approaches have been described: standard anteromesial temporal lobectomy, lesionectomy involving a CNL alone and lesionectomy with anteromesial temporal lobectomy (for dual pathology); reports of the latter two approaches are limited. Presurgical evaluation should consider possibilities of delineating the epileptogenic zone/s in accordance with all three approaches.

The primary prevention of epilepsy: A report of the Prevention Task Force of the International League Against Epilepsy

Among the causes of epilepsy are several that are currently preventable. In this review, we summarize the public health burden of epilepsy arising from such causes and suggest priorities for primary epilepsy prevention. We conducted a systematic review of published epidemiologic studies of epilepsy of 4 preventable etiologic categories-perinatal insults, traumatic brain injury (TBI), central nervous system (CNS) infection, and stroke. Applying consistent criteria, we assessed the quality of each study and extracted data on measures of risk from those with adequate quality ratings, summarizing findings across studies as medians and interquartile ranges. Among higher-quality population-based studies, the median prevalence of active epilepsy across all ages was 11.1 per 1000 population in lower- and middle-income countries (LMIC) and 7.0 per 1000 in high-income countries (HIC). Perinatal brain insults were the largest attributable fraction of preventable etiologies in children, with median estimated fractions of 17% in LMIC and 15% in HIC. Stroke was the most common preventable etiology among older adults with epilepsy, both in LMIC and in HIC, accounting for half or more of all new onset cases. TBI was the attributed cause in nearly 5% of epilepsy cases in HIC and LMIC. CNS infections were a more common attributed cause in LMIC, accounting for about 5% of all epilepsy cases. Among some rural LMIC communities, the median proportion of epilepsy cases attributable to endemic neurocysticercosis was 34%. A large proportion of the overall public health burden of epilepsy is attributable to preventable causes. The attributable fraction for perinatal causes, infections, TBI, and stroke in sum reaches nearly 25% in both LMIC and HIC. Public health interventions addressing maternal and child health care, immunizations, public sanitation, brain injury prevention, and stroke prevention have the potential to significantly reduce the burden of epilepsy.

On the relationship between calcified neurocysticercosis and epilepsy in an endemic village: A large-scale, computed tomography-based population study in rural Ecuador

OBJECTIVE

Using a large-scale population-based study, we aimed to assess prevalence and patterns of presentation of neurocysticercosis (NCC) and its relationship with epilepsy in community-dwellers aged ≥20 years living in Atahualpa (rural Ecuador).

METHODS

In a three-phase epidemiological study, individuals with suspected seizures were identified during a door-to-door survey and an interview (phase I). Then, neurologists evaluated suspected cases and randomly selected negative persons to estimate epilepsy prevalence (phase II). In phase III, all participants were offered noncontrast computed tomography (CT) for identifying NCC cases. The independent association between NCC (exposure) and epilepsy (outcome) was assessed by the use of multivariate logistic regression models adjusted for age, sex, level of education, and alcohol intake. CT findings were subsequently compared to archived brain magnetic resonance imaging in a sizable subgroup of participants.

RESULTS

Of 1,604 villagers aged ≥20 years, 1,462 (91%) were enrolled. Forty-one persons with epilepsy (PWE) were identified, for a crude prevalence of epilepsy of 28 per 1,000 population (95% confidence interval [CI] = 20.7-38.2). A head CT was performed in 1,228 (84%) of 1,462 participants, including 39 of 41 PWE. CT showed lesions consistent with calcified parenchymal brain cysticerci in 118 (9.6%) cases (95% CI = 8.1-11.4%). No patient had other forms of NCC. Nine of 39 PWE, as opposed to 109 of 1,189 participants without epilepsy, had NCC (23.1% vs. 9.2%, p = 0.004). This difference persisted in the adjusted logistic regression model (odds ratio = 3.04, 95% CI = 1.35-6.81, p = 0.007).

SIGNIFICANCE

This large CT-based study demonstrates that PWE had three times the odds of having NCC than those without epilepsy, providing robust epidemiological evidence favoring the relationship between NCC and epilepsy.

An integrated study of human and animal infectious disease in the Lake Victoria crescent small-holder crop-livestock production system, Kenya

BACKGROUND

The neglected zoonotic diseases (NZD) are an understudied group that are a major cause of illness throughout the developing world. In general, little is known about the prevalence and burden of NZDs in affected communities, particularly in relation to other infectious diseases with which they are often co-endemic. We describe the design and descriptive epidemiological outputs from an integrated study of human and animal zoonotic and non-zoonotic disease in a rural farming community in western Kenya.

METHODS

This cross-sectional survey involved 2113 people, their cattle (n = 983) and pigs (n = 91). People and animals were tested for infection or exposure to a wide range of zoonotic and non-zoonotic pathogens. Prevalence estimates, with adjustment for the complex study design, were derived. Evidence for spatial clustering in exposure or infection was identified using the spatial scan statistic.

RESULTS

There was a high prevalence of human parasitism in the community, particularly with hookworm (Ancylostoma duodenale or Necator americanus) (36.3% (95% CI 32.8-39.9)), Entamoeba histolytica/dispar (30.1% (95% CI 27.5-32.8)), and Plasmodium falciparum (29.4% (95% CI 26.8-32.0)). Human infection with Taenia spp. was also prevalent (19.7% (95% CI 16.7-22.7)), while exposure to other zoonotic pathogens was comparatively rarer (Brucella spp., 0.6% (95% CI 0.2-0.9); Coxiella burnetii, 2.2% (95% CI 1.5-2.9); Rift Valley fever, 0.5% (95% CI 0.2-0.8)). A low prevalence of exposure to Brucella spp. was observed in cattle (0.26% (95% CI 0-0.56). This was higher for Rift Valley fever virus (1.4% (95% CI 0.5-2.22)) and C. burnetii (10.0% (95% CI 7.7-12.2)). The prevalence of Taenia spp. cysticercosis was 53.5% (95% CI 48.7-58.3) in cattle and 17.2% (95% CI 9.1-25.3) in pigs. Mycobacterium bovis infection was found in 2.2% of cattle (95% CI 1.3-3.2), while the prevalence of infection with Mycobacterium spp. was 8.2% (95% CI 6.8-9.6) in people.

CONCLUSION

Zoonotic infections in people and animals occur in the context of a wide range of co-endemic pathogens in a rural community in western Kenya. The wide diversity of pathogens under study provides a unique opportunity to explore the distribution and determinants of infection in a multi-pathogen, multi-host system.

The causal relationship between neurocysticercosis infection and the development of epilepsy - a systematic review

BACKGROUND

Neurocysticercosis (NCC) is a parasitic infection of the human central nervous system, the most common form of which involves infection of the brain parenchyma with the larval form of the Taenia solium tapeworm. A causal relationship between such an NCC infection and the development of epilepsy in infected individuals is acknowledged, in part supported by high levels of comorbidity in endemic countries worldwide.

METHODS

This study undertook a systematic review and critical analysis of the NCC-epilepsy relationship with the primary objective of quantifying the risk of developing epilepsy following NCC infection. A secondary aim was to analyse the proportions of NCC-associated epilepsy within different populations. Significant emphasis was placed on the importance of neuroimaging (CT or MRI) availability and use of clear guidelines for epilepsy diagnosis, in order to avoid overestimations of prevalence rates of either condition; a limitation identified in several previous studies.

RESULTS

A common odds ratio of 2.76 was identified from meta-analysis of case-control studies, indicating that an individual infected with NCC has almost a three times higher risk of developing epilepsy than an uninfected individual. Furthermore, meta-analysis of studies identified a common proportion of 31.54% of epilepsy cases associated with NCC infection which suggests that amongst epileptic populations in at risk countries, approximately one-third may be associated with NCC infection.

CONCLUSION

A significant finding was the lack of good clinical data to enable accurate determination of a causal relationship. Even studies that were included had noticeable limitations, including a general lack of consistency in diagnostics, and lack of accurate epidemiological data. This review highlights a need for consistency in research in this field. In the absence of reliable estimates of its global burden, NCC will remain of low priority in the eyes of funding agencies - a truly neglected disease.

Systematic review and meta-analysis estimating association of cysticercosis and neurocysticercosis with epilepsy

Background

We reviewed studies that analyzed cysticercosis (CC), neurocysticercosis (NCC) and epilepsy across Latin America, Asia and Sub-Saharan Africa, to estimate the odds ratio and etiologic fraction of epilepsy due to CC in tropical regions.

Methodology

We conducted a systematic review of the literature on cysticercosis and epilepsy in the tropics, collecting data from case-control and cross-sectional studies. Exposure criteria for CC included one or more of the following: serum ELISA or EITB positivity, presence of subcutaneous cysts (both not verified and unverified by histology), histology consistent with calcified cysts, and brain CT scan consistent with NCC. A common odds-ratio was then estimated using meta-analysis.

Principal findings

37 studies from 23 countries were included (n = 24,646 subjects, 14,934 with epilepsy and 9,712 without epilepsy). Of these, 29 were case-control (14 matched). The association between CC and epilepsy was significant in 19 scientific articles. Odds ratios ranged from 0.2 to 25.4 (a posteriori power 4.5–100%) and the common odds ratio was 2.7 (95% CI 2.1–3.6, p <0.001). Three subgroup analyses performed gave odds ratios as: 2.2 (EITB-based studies), 3.2 (CT-based studies), 1.9 (neurologist-confirmed epilepsy; door-to-door survey and at least one matched control per case). Etiologic fraction was estimated to be 63% in the exposed group among the population.

Significance

Despite differences in findings, this meta-analysis suggests that cysticercosis is a significant contributor to late-onset epilepsy in tropical regions around the world, and its impact may vary depending on transmission intensity.

Cysticercosis is a helminthic infection of the central nervous system (CNS) and the leading cause of late onset epilepsy in low-and middle-income countries. This neurological disease is a public health problem in Sub-Saharan Africa, Asia and Latin America, affecting impoverished rural and peri-urban populations where sanitation is inadequate. Diagnostic criteria for NCC vary according to regional availability and access to imaging and serological tests. This systematic review highlights the lack of appropriate methodology in most observational studies, with few studies including control groups, a basic epidemiological criteria needed to demonstrate an association. EITB for cysticercosis was widely used to measure exposure, and brain CT scan was a non-invasive alternative used to identify cysts. Neurocysticercosis (NCC) is a preventable neurological condition in the tropics despite resource limitations in LMIC regions. Well-designed studies are needed to provide quality evidence to support control interventions and surveillance systems for this important zoonotic disease.

Disease Centered Around Calcified Taenia solium Granuloma

Taenia solium (the pork tapeworm) is present in most developing countries, where it is a frequent cause of seizures and other neurological disease. Parasitic larvae invade the human brain, establish, and eventually resolve, leaving a calcified scar. While these lesions are common in endemic regions, and most of these are clinically silent, a proportion of individuals with calcified cysticerci develop seizures from these lesions, and 30-65% of these cases are associated with perilesional edema (PE), likely due to host inflammation. This manuscript summarizes the importance, characteristics, natural history, and potential prevention and treatments of symptomatic calcified neurocysticercosis (NCC).

Neurocysticercosis among patients with first time seizure in Northern Namibia

INTRODUCTION

Neurocysticercosis is a common cause of seizures in low resource countries. There is a paucity of data regarding the extent of this infection in Namibia. There are multiple causes of First-time seizure including electrolyte abnormalities, infections, trauma, drugs, alcohol and many times no apparent cause can be found. We sought to describe the burden of Neurocysticercosis among individuals with a first-time seizure in Namibia.

METHODS

We recruited 221 patients with a First-time seizure who presented to the Intermediate Hospital Oshakati between August 2012 and March 2014. Patients with seizures due to identifiable causes like trauma, electrolytes, intoxications and meningitis were excluded. Brain CT scans were done, blood serological testing of Neurocysticercosis antibodies, Physical examination and demographic variables were collected. Data was entered into Epidata version 3.1 and transferred to stata version for analysis.

RESULTS

Ninety-six (96) of the participants had evidence of Neurocysticercosis on Brain CT scan representing a prevalence of 51.41%. Consumption of pork and rearing of pigs in the homestead were significant factors associated with Neurocysticercosis in our study population with odds of 3.48(1.45-8.33) and 2.07(1.11-3.86) respectively. Serological testing for Cyticercosis IgG had a sensitivity of 65.93% and Specificity of 96.51%. The positive and negative predictive values were 95.2% and 72.81% respectively.

CONCLUSION

Neurocysticercosis is a common cause of Index seizures in Northern Namibia, living in a rural area, rearing pigs in homesteads, eating pork and poor sanitary practices are the major risk factors for this illness.

Distribution and Potential Indicators of Hospitalized Cases of Neurocysticercosis and Epilepsy in Ecuador from 1996 to 2008

Background

Epilepsy is one of the most common signs of Neurocysticercosis (NCC). In this study, spatial and temporal variations in the incidence of hospitalized cases (IHC) of epilepsy and NCC in Ecuadorian municipalities were analyzed. Additionally, potential socio-economic and landscape indicators were evaluated in order to understand in part the macro-epidemiology of the Taenia solium taeniasis/cysticercosis complex.

Methodology

Data on the number of hospitalized epilepsy and NCC cases by municipality of residence were obtained from morbidity-hospital systems in Ecuador. SatScan software was used to determine whether variations in the IHC of epilepsy and NCC in space and time. In addition, several socio-economic and landscape variables at municipality level were used to study factors intervening in the macro-epidemiology of these diseases. Negative Binomial regression models through stepwise selection and Bayesian Model Averaging (BMA) were used to explain the variations in the IHC of epilepsy and NCC.

Principal findings

Different clusters were identified through space and time. Traditional endemic zones for NCC and epilepsy, recognized in other studies were confirmed in our study. However, for both disorders more recent clusters were identified. Among municipalities, an increasing tendency for IHC of epilepsy, and a decreasing tendency for the IHC of NCC were observed over time. In contrast, within municipalities a positive linear relationship between both disorders was found. An increase in the implementation of systems for eliminating excrements would help to reduce the IHC of epilepsy by 1.00% (IC_95%; 0.2%–1.8%) and by 5.12% (IC_95%; 3.63%-6.59%) for the IHC of NCC. The presence of pig production was related to IHC of NCC.

Conclusion/Significance

Both disorders were related to the lack of an efficient system for eliminating excrements. Given the appearance of recent epilepsy clusters, these locations should be studied in depth to discriminate epilepsies due to NCC from epilepsies due to other causes. Field studies are needed to evaluate the true prevalence of cysticercosis in humans and pigs in different zones of the country in order to better implement and manage prevention and/or control campaigns.

T. solium neurocysticercosis is considered the most important parasitic disease of the central nervous system in humans; it is estimated to be responsible for at least one third of acquired epilepsies in developing countries. In Ecuador, the relationship between acquired epilepsy and neurocysticercosis remains unclear due to different factors such as, the lack of specialized health care personnel, appropriate diagnostic techniques and the fact that acquired epilepsy is characteristic of many other infectious and non-infectious diseases in the endemic zones of the country. In this study, spatio-temporal information and potential socio-economic indicators were studied for the number of hospitalized neurocysticercosis and epileptic cases in the country in order to locate and characterize important clusters in space and time. This study identified traditional endemic clusters in the highlands for both conditions as well as new clusters appearing in recent years in other zones not considered endemic. Also the incidence of hospitalized cases of epilepsy and neurocysticercosis were significantly higher in urban zones, probably due to a better access to health facilities. The presence of systems for excrement disposal was significantly associated with a reduction in the incident cases for both epilepsy and neurocysticercosis. More studies are needed to evaluate the true prevalence of neurocysticercosis associated epilepsy in humans and cysticercosis in pigs around the country in order to better implement and manage control campaigns.

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.

Epidemiology, causes, and treatment of epilepsy in sub-Saharan Africa

SUMMARY

Epilepsy is a common neurological disease in tropical countries, particularly in sub-Saharan Africa. Previous work on epilepsy in sub-Saharan Africa has shown that many cases are severe, partly a result of some specific causes, that it carries a stigma, and that it is not adequately treated in many cases. Many studies on the epidemiology, aetiology, and management of epilepsy in sub-Saharan Africa have been reported in the past 10 years. The prevalence estimated from door-to-door studies is almost double that in Asia, Europe, and North America. The most commonly implicated risk factors are birth trauma, CNS infections, and traumatic brain injury. About 60% of patients with epilepsy receive no antiepileptic treatment, largely for economic and social reasons. Further epidemiological studies should be a priority to improve understanding of possible risk factors and thereby the prevention of epilepsy in Africa, and action should be taken to improve access to treatment.

Ring-screening to control endemic transmission of Taenia solium

BACKGROUND

Taenia solium is a major cause of preventable epilepsy in developing nations. Screening and treatment of human intestinal stage infection (taeniasis) within high-risk foci may reduce transmission and prevent epilepsy by limiting human exposure to infective eggs. We piloted a ring-strategy that involves screening and treatment for taeniasis among households located nearby pigs heavily-infected with the larval stage (cysticercosis). These pigs mark areas of increased transmission and can be identified by tongue examination.

METHODOLOGY

We selected two villages in northern Peru for a controlled prospective interventional cohort pilot study. In the intervention village (1,058 residents) we examined the tongues of all pigs every 4 months for nodules characteristic of cysticercosis. We then screened all residents living within 100-meters of any tongue-positive pig using enzyme-linked immunosorbent assay to detect Taenia antigens in stool. Residents with taeniasis were treated with niclosamide. In both the intervention and control (753 residents) we measured incidence of exposure by sampling the pig population every 4 months for serum antibodies against cysticercosis using enzyme-linked immunoelectrotransfer blot.

PRINCIPAL FINDINGS

Baseline seroincidence among pigs born during the study was 22.6 cases per 100 pigs per-month (95% confidence interval [CI] 17.0-30.0) in the intervention and 18.1 (95% CI 12.7-25.9) in the control. After one year we observed a 41% reduction in seroincidence in the intervention village compared to baseline (incidence rate ratio 0.59, 95% CI 0.41-0.87) while the seroincidence in the control village remained unchanged. At study end, the prevalence of taeniasis was nearly 4 times lower in the intervention than in the control (prevalence ratio 0.28, 95% CI 0.08-0.91).

CONCLUSIONS/SIGNIFICANCE

Ring-screening reduced transmission of T. solium in this pilot study and may provide an effective and practical approach for regions where resources are limited. However, this strategy requires validation in larger populations over a greater period of time.

Epilepsy and neurocysticercosis in Latin America: a systematic review and meta-analysis

Background

The difference in epilepsy burden existing among populations in tropical regions has been attributed to many factors, including the distribution of infectious diseases with neurologic sequels. To define the burden of epilepsy in Latin American Countries (LAC) and to investigate the strength of association with neurocysticercosis (NCC), considered one of the leading causes of epilepsy, we performed a systematic review and meta-analysis of the literature.

Methodology

Studies published until 2012 were selected applying predefined inclusion criteria. Lifetime epilepsy (LTE) prevalence, active epilepsy (AE) prevalence, incidence, mortality, treatment gap (TG) and NCC proportion among people with epilepsy (PWE) were extracted. Median values were obtained for each estimate using random effects meta-analysis. The impact of NCC prevalence on epilepsy estimates was determined using meta-regression models. To assess the association between NCC and epilepsy, a further meta-analysis was performed on case-control studies.

Principal findings

The median LTE prevalence was 15.8/1,000 (95% CI 13.5–18.3), the median AE prevalence was 10.7/1,000 (95% CI 8.4–13.2), the median incidence was 138.2/100,000 (95% CI 83.6–206.4), the overall standardized mortality ratio was 1.4 (95% CI 0.01–6.1) and the overall estimated TG was 60.6% (95% CI 45.3–74.9). The median NCC proportion among PWE was 32.3% (95% CI 26.0–39.0). Higher TG and NCC estimates were associated with higher epilepsy prevalence. The association between NCC and epilepsy was significant (p<0.001) with a common odds ratio of 2.8 (95% CI 1.9–4.0).

Significance

A high burden of epilepsy and of NCC in LAC and a consistent association between these two diseases were pointed out. Furthermore, NCC prevalence and TG were identified as important factors influencing epilepsy prevalence to be considered in prevention and intervention strategies.

Epilepsy affects approximately 70 million people worldwide and at least five million people in Latin America. Many researchers have pointed out a different distribution of epilepsy in Latin American countries, with some regions presenting higher frequencies and others presenting lower frequencies. This difference in epilepsy distribution has been attributed to many factors, mainly related to the allocation of health resources and to the presence of environmental and infectious risk factors. Among the latter stands neurocysticercosis, a parasitic disease that has been recognized as the leading cause of acquired epilepsy in the developing world, with a particularly elevated distribution in rural settings. In this study, we performed a statistical analysis to investigate whether neurocysticercosis distribution affects epilepsy distribution among Latin American countries and the relationship between these two conditions. The combined results of the studies included indicated that neurocysticercosis influences epilepsy frequency in Latin America, as countries with higher epilepsy distribution presented also higher neurocysticercosis frequency. Moreover, another analysis pointed out an association between the two diseases. These results appear very important considering that parasitic infections are modifiable factors and that their reduction may contribute to decrease epilepsy burden worldwide.

Parasite antigen in serum predicts the presence of viable brain parasites in patients with apparently calcified cysticercosis only

BACKGROUND

Computed tomography (CT) remains the standard neuroimaging screening exam for neurocysticercosis, and residual brain calcifications are the commonest finding. Magnetic resonance imaging (MRI) is more sensitive than CT but is rarely available in endemic regions. Enzyme-linked immunoelectrotransfer blot (EITB) assay uses antibody detection for diagnosis confirmation; by contrast, enzyme-linked immunosorbent assay (ELISA) antigen detection (Ag-ELISA) detects circulating parasite antigen. This study evaluated whether these assays predict undetected viable cysts in patients with only calcified lesions on brain CT.

METHODS

Serum samples from 39 patients with calcified neurocysticercosis and no viable parasites on CT were processed by Ag-ELISA and EITB. MRI was performed for each patient within 2 months of serologic testing. Conservatively high ELISA and EITB cutoffs were used to predict the finding of viable brain cysts on MRI.

RESULTS

Using receiver operating characteristic-optimized cutoffs, 7 patients were Ag-ELISA positive, and 8 had strong antibody reactions on EITB. MRI showed viable brain cysts in 7 (18.0%) patients. Patients with positive Ag-ELISA were more likely to have viable cysts than Ag-ELISA negatives (6/7 vs 1/32; odds ratio, 186 [95% confidence interval, 1-34 470.0], P < .001; sensitivity 85.7%, specificity 96.9%, positive likelihood ratio of 27 to detect viable cysts). Similar but weaker associations were also found between a strong antibody reaction on EITB and undetected viable brain cysts.

CONCLUSIONS

Antigen detection, and in a lesser degree strong antibody reactions, can predict viable neurocysticercosis. Serological diagnostic methods could identify viable lesions missed by CT in patients with apparently only calcified cysticercosis and could be considered for diagnosis workup and further therapy.

The seroprevalence ofTaenia soliumcysticercosis among epileptic patients in León, Nicaragua, as evaluated by ELISA and western blotting

The Taenia solium taeniasis/cysticercosis complex is an important public-health problem in several countries, where many epileptic seizures appear to be associated with neurocysticercosis. As few data on this problem in Nicaragua exist, the seroprevalence of antibodies reacting with antigens from T. solium cysticerci was investigated among 88 Nicaraguan epileptics (45 males and 43 females, aged 6-53 years). In questionnaire-based interviews, each adult subject and a caregiver of each child investigated were asked about potential risk factors for taeniasis/cysticercosis. When a serum sample from each subject was then checked for anti-cysticercus antibodies, 8.0% of the subjects were found seropositive by ELISA and 14.8% by western blotting. Five samples (all from individuals who had been epileptic for > 5 years) were positive in both tests. When the level of association between each potential risk factor and seropositivity (in ELISA or by blotting) was evaluated, the only statistically significant association detected was that between a positive ELISA and the subject living in a household where pigs were raised (odds ratio = 5.18; 95% confidence interval = 0.8-41.6; P = 0.05). The bands most frequently recognized in the western blots (of 50, 42-39, 24 and 14 kDa) were those previously reported. The results indicate that, in the city of Léon, cysticercosis may be endemic and the cause of a significant proportion of the epilepsy recorded.

Edema surrounding calcified intracranial cysticerci: clinical manifestations, natural history, and treatment

Calcified granulomas are the most common radiological finding in neurocysticercosis (10-20% of endemic populations). A small proportion serves as foci of seizure activity, which results in large numbers of persons with epilepsy. Calcified granulomas are not all the same. Some demonstrate blood-brain barrier dysfunction (magnetic resonance imaging enhancement) most likely due to the presence of inflammation, visualizable scolices, and/or gliosis. About half the patients with a recent history of seizures, positive serology, and only calcified lesions develop perilesional edema at the time of a seizure recurrence. The natural history, treatment, and pathophysiology of this phenomenon are not well studied. Episodes are usually associated with seizures or other neurological manifestations, resolve by 4-6 weeks, sometimes occur repeatedly, and usually involve a subset of the same calcifications. Treatment is supportive. Histopathological examination of one calcification associated with multiple perilesional edema episodes revealed significant inflammation and supports the concept that perilesional edema is inflammatory in nature. This most likely is due to host responses to released or newly recognized parasite antigen and/or upregulation of the host immune response. Immunosuppressive and anti-inflammatory agents may be useful in prevention and/or treatment of this phenomenon.

Neurocysticercosis in sub-Saharan Africa: a review of prevalence, clinical characteristics, diagnosis, and management

Neurocysticercosis has been recognized as a major cause of secondary epilepsy worldwide. So far, most of the knowledge about the disease comes from Latin America and the Indian subcontinent. Unfortunately, in sub-Saharan Africa the condition was neglected for a long time, mainly owing to the lack of appropriate diagnostic tools. This review therefore focuses on the prevalence of neurocysticercosis in sub-Saharan Africa, the clinical picture with emphasis on epilepsy, as well as the diagnosis and treatment of neurocysticercosis and its related epilepsy/epileptic seizures in African resource-poor settings.

Active epilepsy as indicator of neurocysticercosis in rural northwest India

Objective. To determine the contribution of neurocysticercosis as a cause for active epilepsy and to establish Neurocysticercosis as major definable risk of epilepsy in our setup. Methods. We conducted a door-to-door survey of 2,209 individuals of Bhore Pind and Bhore Kullian villages in Chattah zone of district Jammu (Jumma and Kashmir, Northwest India) to identify patients with symptomatic epilepsy. Patients with active epilepsy were investigated with neuroimaging techniques to establish diagnosis of NCC (neurocysticercosis). Results. Among 25 patients with epilepsy 10(40%) had CT/MR evidence of past or recent NCC infection. This gave us the point prevalence of 4.5/1000 for Neurocysticercosis in our study population. Interpretation. The study shows a high prevalence of NCC accounting for symptomatic epilepsy in our part of India.

Substance P causes seizures in neurocysticercosis

Neurocysticercosis (NCC), a helminth infection of the brain, is a major cause of seizures. The mediators responsible for seizures in NCC are unknown, and their management remains controversial. Substance P (SP) is a neuropeptide produced by neurons, endothelial cells and immunocytes. The current studies examined the hypothesis that SP mediates seizures in NCC. We demonstrated by immunostaining that 5 of 5 brain biopsies from NCC patients contained substance P (SP)-positive (+) cells adjacent to but not distant from degenerating worms; no SP+ cells were detected in uninfected brains. In a rodent model of NCC, seizures were induced after intrahippocampal injection of SP alone or after injection of extracts of cysticercosis granuloma obtained from infected wild type (WT), but not from infected SP precursor-deficient mice. Seizure activity correlated with SP levels within WT granuloma extracts and was prevented by intrahippocampal pre-injection of SP receptor antagonist. Furthermore, extracts of granulomas from WT mice caused seizures when injected into the hippocampus of WT mice, but not when injected into SP receptor (NK1R) deficient mice. These findings indicate that SP causes seizures in NCC, and, suggests that seizures in NCC in humans may be prevented and/or treated with SP-receptor antagonists.

Cysticercosis control: bringing advances to the field

Progress towards Taenia solium control is evident in the development of new technologies and in increasing regional coordination, yet disease eradication remains unlikely in the near future. In the meantime, translation of research advances into functioning control programs is necessary to address the ongoing disease burden in endemic areas. Multiple screening assays, effective treatments for both human and porcine infection, and vaccines blocking transmission to pigs are currently available. Strategies based on identification and treatment of T. solium adult tapeworms, as well as interventions that block cysticercosis acquisition in pigs have temporarily reduced transmission. Building on these successes with controlled community trials in varying endemic scenarios will drive progress towards regional elimination.

Seroepidemiological study of human cysticercosis with blood samples collected on filter paper, in Lages, State of Santa Catarina, Brazil, 2004-2005

INTRODUCTION

Human serofrequency of antibodies against Taenia solium antigens was determined and risk factors for cysticercosis transmission were identified.

METHODS

Individuals (n=878) from periurban and rural locations of Lages, SC, were interviewed to gather demographic, sanitary and health information. Interviews and blood sample collections by finger prick on Whatman filter paper were performed from August 2004 to May 2005. Observation determined that 850 samples were suitable for analysis and were tested by ELISA using vesicular fluid of Taenia crassiceps heterologous antigen. To ensure the reliability of the results, 77 samples of the dried blood were matched with sera. The reactive samples were submitted to a serum confirmatory immunoblot (IB) test using purified Taenia crassiceps glycoproteins.

RESULTS

The ELISA results for the dried blood and serum samples were statistically consistent. ELISA was positive in 186 (21.9%) out of 850 individuals. A group of 213 individuals were asked to collect vein blood for IB (186 with positive result in ELISA and 27 with inappropriate whole blood samples) and 130 attended the request. The IB was positive in 29 (3.4%) out of 850 individuals. A significant correlation (p = 0.0364) was determined among individuals who tested positive in the IB assay who practiced both pig rearing and kitchen gardening.

CONCLUSIONS

ELISA with dried blood eluted from filter paper was suitable for cysticercosis population surveys. In Lages, human infection was associated with pig rearing and kitchen gardening. The prevalence index was compatible with other Latin American endemic areas.

Anti-Taenia solium larval stage Ig G antibodies in patients with epileptic seizures

Background:

Cysticercosis is the most common differential diagnosis for epilepsy. The present study was carried out to assess the serological response among patients with epileptic seizures visiting JIPMER Hospital Puducherry.

Materials and Methods:

A total of 934 serum samples were collected from patients with epileptic seizures. A standardized questionnaire was designed to obtain information on the demographic, socioeconomic, environmental, and behavioral characteristics related to the transmission of infection. An enzyme-linked immunosorbent assay (ELISA) was used to detect the anti-Taenia solium larval stage IgG antibodies. Samples found reactive and inconclusive by ELISA were further tested by the enzyme immunotransfer blot (EITB).

Results:

The frequency of antibodies in the serum samples of the above-mentioned population was 16.2% by EITB. Anti-Taenia solium larval stage antibodies were detected in serum samples of 163 patients, out of which 27 (16.56%) patients belonged to the 0 – 15-year age group, 82 (50.30%) patients were in the 16 – 40-year age group, and 52 (31.90%) patients were above 41 years, respectively. Although the sera from males had higher OD values than those from females, the difference was not statistically significant. Out of 163 seropositive by ELISA, 152 (93.25%) were found to be positive by EITB. Out of the 152, 61 (40.13%) were farmers and 79 (51.97%) were office or factory workers.

Conclusions:

In conclusion, the results indicate a probable endemic situation and a high prevalence of cysticercosis in patients with epileptic seizures. Living in poor sanitary conditions seems to be an important factor related to human cysticercosis in Puducherry and the neighboring districts of Tamil Nadu.

A systematic review of the frequency of neurocyticercosis with a focus on people with epilepsy

BACKGROUND

The objective of this study is to conduct a systematic review of studies reporting the frequency of neurocysticercosis (NCC) worldwide.

METHODS/PRINCIPAL FINDINGS

PubMed, Commonwealth Agricultural Bureau (CAB) abstracts and 23 international databases were systematically searched for articles published from January 1, 1990 to June 1, 2008. Articles were evaluated for inclusion by at least two researchers focusing on study design and methods. Data were extracted independently using standardized forms. A random-effects binomial model was used to estimate the proportion of NCC among people with epilepsy (PWE). Overall, 565 articles were retrieved and 290 (51%) selected for further analysis. After a second analytic phase, only 4.5% of articles, all of which used neuroimaging for the diagnosis of NCC, were reviewed. Only two studies, both from the US, estimated an incidence rate of NCC using hospital discharge data. The prevalence of NCC in a random sample of village residents was reported from one study where 9.1% of the population harboured brain lesions of NCC. The proportion of NCC among different study populations varied widely. However, the proportion of NCC in PWE was a lot more consistent. The pooled estimate for this population was 29.0% (95%CI: 22.9%-35.5%). These results were not sensitive to the inclusion or exclusion of any particular study.

CONCLUSION/SIGNIFICANCE

Only one study has estimated the prevalence of NCC in a random sample of all residents. Hence, the prevalence of NCC worldwide remains unknown. However, the pooled estimate for the proportion of NCC among PWE was very robust and could be used, in conjunction with estimates of the prevalence and incidence of epilepsy, to estimate this component of the burden of NCC in endemic areas. The previously recommended guidelines for the diagnostic process and for declaring NCC an international reportable disease would improve the knowledge on the global frequency of NCC.

Neurocysticercosis: unraveling the nature of the single cysticercal granuloma

A single enhancing lesion in the brain parenchyma, also called an inflammatory granuloma, is a frequent neurologic diagnosis. One of the commonest causes of this lesion is human neurocysticercosis, the infection by the larvae of the pork tapeworm, Taenia solium. Following the demonstration that viable cysticercosis cysts survive in good conditions for several years in the human brain, single cysticercal granulomas have been consistently interpreted as representing late degeneration of a long-established parasite. On the basis of epidemiologic, clinical, and laboratory evidence detailed in this article, we hypothesize that in most cases these inflammatory lesions correspond to parasites that die in the early steps of infection, likely as the natural result of the host immunity overcoming mild infections.

Do helminths cause epilepsy?

Both helminthiases and epilepsy occur globally, and are particularly prevalent in developing regions of the world. Studies have suggested an association between epilepsy and helminth infection, but a causal relationship is not established in many helminths, except perhaps with neurocysticercosis. We review the available literature on the global burden of helminths, and the epidemiological evidence linking helminths to epilepsy. We discuss possible routes that helminths affect the central nervous system (CNS) of humans and the immunological response to helminth infection in the CNS, looking at possible mechanisms of epileptogenesis. Finally, we discuss the current gaps in knowledge about the interaction between helminths and epilepsy.

Perilesional brain oedema and seizure activity in patients with calcified neurocysticercosis: a prospective cohort and nested case-control study

BACKGROUND

Cysticercosis due to Taenia solium is a cause of adult-acquired seizures and epilepsy even in patients with only calcified larval cysts. Transient perilesional brain oedema is seen around the calcified foci but its importance, association with seizures, incidence, and pathophysiology are unknown.

METHODS

110 patients with only calcified lesions and a history of seizures or severe headaches were followed prospectively in a cohort design to assess the incidence of seizure relapse. In a nested case-control substudy, perilesional oedema was assessed by MRI at the time of seizure in symptomatic patients and in matched asymptomatic controls taken from the study population.

FINDINGS

Between November, 1999, and December, 2006, 29 patients had an incident seizure during a median follow up of 32.33 (SD 19.99) months, with an estimated 5-year seizure incidence of 36% (95% CI 25% to 49%). 24 of 29 (83%) patients with seizure relapse had an MRI evaluation within 5 days of the event; perilesional oedema was seen in 12 patients (50%) compared with two (9%) of 23 asymptomatic matched controls.

INTERPRETATION

Perilesional oedema is common and associated with episodic seizure activity in patients with calcified neurocysticercosis. Our findings are probably representative of symptomatic patients in regions where T solium neurocysticercosis is endemic and suggest a unique and possibly preventable cause of seizures in this population.

Human cysticercosis and Indian scenario: a review

Cysticercosis, caused by Taenia solium larva is a major public health problem,especially in the developing world and neurocysticercosis (NCC) is considered to be the most common parasitic infestation of the central nervous system. NCC is identified as the single most common cause of community acquired active epilepsy; 26.3% to 53.8% active epilepsy cases in the developing world including India and Latin America are due to NCC.It is also becoming more common in the developed world because of increased migration of people with the disease or Taenia solium carriers and frequent travel to the endemic countries. It is estimated that three quarters of the estimated 50 million people with active epilepsy live in the poor countries of the world. Recent Indian studies using neuroimaging techniques suggest that the disease burden in India surpasses many other developing countries. Hence it is important to know the epidemiology,pathogenesis and diagnostic criteria so as to assess the disease burden and adopt interventional strategies for its control.Literature search was done for this review with special emphasis on Indian studies to create awareness about the disease in India,since cysticercosis is preventable and potentially eradicable.

Control of Taenia solium cysticercosis/taeniosis

Cysticercosis is emerging as a serious public health and agricultural problem in many poorer countries of Latin America, Africa, and Asia. Caused by the pork tapeworm, Taenia solium, this zoonotic disease forms larval cysts in humans and pigs that can lead to epilepsy and death in humans, reduces the market value of pigs and makes pork unsafe to eat. It occurs where pigs range freely, sanitation is poor, and meat inspection is absent or inadequate, and is thus strongly associated with poverty and smallholder farming. Although theoretically easy to control and declared eradicable cysticercosis remains neglected in most endemic countries due to lack of information and awareness about the extent of the problem, suitable diagnostic and management capacity, and appropriate prevention and control strategies. Human neurocysticercosis occurs when the larval cysts develop in the brain. It is considered to be the most common parasitic infection of the human nervous system and the most frequent preventable cause of epilepsy in the developing world. Thus far the infection has not been eliminated from any region by a specific program, and no national control programs are yet in place. We consider the tools available for combating cysticercosis and suggest simple packages of interventions, which can be conducted utilizing existing services and structures in the endemic countries to provide appropriate and sustainable control of the disease.

Treatment of neurocysticercosis: current status and future research needs

Here we put forward a roadmap that summarizes important questions that need to be answered to determine more effective and safer treatments. A key concept in management of neurocysticercosis is the understanding that infection and disease due to neurocysticercosis are variable and thus different clinical approaches and treatments are required. Despite recent advances, treatments remain either suboptimal or based on poorly controlled or anecdotal experience. A better understanding of basic pathophysiologic mechanisms including parasite survival and evolution, nature of the inflammatory response, and the genesis of seizures, epilepsy, and mechanisms of anthelmintic action should lead to improved therapies.

Prevalence of Epilepsy in a Rural District of Central Lao PDR

PURPOSE

To assess the prevalence of epilepsy in a rural district of Lao PDR and to describe the clinical and epidemiological profile of the disease.

METHODS

Door-to-door screening was performed on the entire population of 8 randomly selected villages in the Hinheub district, using an internationally validated and standardized questionnaire. Additional passive case detection was performed through village key informants. Suspected epilepsy patients identified by the questionnaire were revisited and examined by an experienced neurologist on two follow-up visits. The confirmation of epilepsy was based only on an in-depth clinical examination. Electroencephalograms were performed at the district health care center.

RESULTS

In the 8 villages, 277 suspected cases of epilepsy were identified among 4,310 interviewed subjects; 194 of whom (70%) underwent a clinical examination by a neurologist during the first visit while 65 of 83 remaining suspected cases were seen on the second confirmation visit. Twenty-seven persons with epilepsy were identified. Six additional patients were diagnosed in 219 self-referred subjects. An overall prevalence of 7.7 cases of epilepsy per thousand inhabitants was calculated (95% CI 5.3-10.7). Generalized epilepsy (21 cases, 63.6%) was commoner than partial epilepsy (9 cases, 27.3%). The remaining 3 cases (9.1%) were not-classifiable as either generalized or partial. EEG abnormal findings were found in 12 of the 24 patients (50.0%) who had an EEG registration.

CONCLUSIONS

This is the first study in Lao PDR to estimate the prevalence of epilepsy. Compared to Western countries it shows a pattern towards a higher prevalence.

An epidemiological study of familial neurocysticercosis in an endemic Mexican community

Neurocysticercosis (NC) caused by Taenia solium is a frequent parasitic disease of the central nervous system. It is highly endemic in many developing countries, where many people are exposed but few become infected. Here, the relevance of age, gender, and genetic and exposure factors on NC susceptibility was studied in 649 inhabitants of a rural community of Mexico. Endemicity was confirmed by the high prevalence of pig cysticercosis (32.8%) and human seroprevalence (43.8%). Human NC cases were diagnosed by computerised tomography scans. A questionnaire to evaluate risk factors was applied and familial relationships between participants were registered. An overall NC frequency of 9.1% (59/649) was found. NC frequency increased with age but did not associate with gender. Most NC cases were asymptomatic. None of the evaluated risk factors were associated with NC. No familial aggregation was detected when studying all cases, although a significant relationship between mother and child in cases with multiple parasites was found. These findings point to the fact that human NC in high exposure conditions is not simply related to exposure factors and they do not support the participation of a major gene in single-cyst NC. Rather, our results point to a complex interaction of genetic and environmental factors involved in NC.