Magnitude of the disease burden from neurocysticercosis in a developing country

Clinical signs for identification of neurocysticercosis in swine naturally infected with Taenia solium

Taenia solium infection is a zoonotic disease and swine is the natural intermediate host. Till date no literatures have described clinical signs in swine indicative of brain involvement by cysticerci. In the present study we describe such clinical signs of porcine neurocysticercosis (NCC). These signs were excessive salivation, excessive blinking and tearing, and subconjunctival nodule. A total of 30 swine (18 with 2 or all 3 clinical signs and 12 without any sign) underwent magnetic resonance imaging (MRI). All 18 swine with above signs had NCC on MRI along with variable involvement of other organs that were subsequently confirmed by ex vivo MRI, necropsy and histopathology, while none of the 12 animals without any sign had NCC. As development of a porcine NCC model has proved difficult, we propose that naturally infected swine can be identified on the basis of these clinical signs and thus used as a model for further research on NCC.

Prevalence of active epilepsy in a rural area in South Tanzania: a door-to-door survey

OBJECTIVE

A door-to-door survey was carried out to assess the prevalence of active epilepsy in the rural population within the catchment area of the Mnero Diocesan Hospital in Southern Tanzania.

METHODS

A total of 4,905 individuals living in 1,047 households were enrolled in a study, consisting of a screening dialogue with a representative family member followed by a face-to-face interview with the affected subject. The diagnosis of epilepsy followed clinical guidelines proposed by the International League Against Epilepsy (ILAE).

RESULTS

We detected 42 cases (21 males and 21 females) of active epilepsy (8.6/1,000; 95% CI: 6.0/1,000-11.1/1,000; age-adjusted prevalence ratio: 7.4/1,000). Thirty of them met the case definitions of generalized seizures, whereas 12 patients reported partial seizures. The peak prevalence was found in both sexes in the second decade of life (f: 16.9/1,000; m: 15.8/1,000; t: 16.4/1,000), with a second peak in the group aged 30-39 years (f: 10.4/1,000; m: 8.8/1,000; t: 9.7/1,000). Eleven patients (26.2%) were classified as "strongly suspected of symptomatic" epilepsy, the remaining 31 patients (73.8%) as possibly being idiopathic, symptomatic, or cryptogenic epilepsy cases.

DISCUSSION

This study provides baseline data about the active epilepsy prevalence in a rural African population. Compared to western countries, our study confirmed a pattern toward higher prevalence of epilepsy in tropical countries. As shown in previous studies, we observed a higher prevalence of epilepsy in children and adolescents, followed by a steady decline with increasing age. Reasons for this type of frequency could be ascribed to malnutrition, trauma, genetic conditions, antenatal and prenatal care, diseases resulting in febrile convulsions, cerebral infections and may even result in death in specifically diseased individuals.

Progress in diagnosis, treatment and elimination of echinococcosis and cysticercosis

Here I review the current status of geographical occurrence and public health significance of echinococcosis (Echinococcus spp. infections) and cysticercosis (Taenia solium infection) with special emphasis on the remarkable technologic progress achieved in recent decades that has led to greater understanding of the biology and epidemiology of these cestode infections. The greatest remaining challenges are to apply this knowledge and technology to improved medical management and prevention of these infections.

Role of chemotherapy of taeniasis in prevention of neurocysticercosis

Neurocysticercosis (NC) is a serious public health problem in Taenia solium endemic areas and in some immigrants and international travelers. A key intervention in preventing NC is elimination of taeniasis by chemotherapy. Currently, two safe and effective taenicides, namely niclosamide and praziquantel, are available. Both are on WHO Essential Drug list, but are often inaccessible in T. solium endemic areas. Natural remedies, still widely used in some endemic areas, are frequently carcinogenic or highly toxic and as such should be discontinued. Chemotherapeutic intervention to control T. solium taeniasis/cysticercosis, whilst theoretically feasible, has several practical obstacles. These include poor public awareness, problems with diagnosing Taenia carriers, poor availability of taenicides where needed and low priority afforded to the control of NC. These can be overcome, respectively, by effective health education, wider use of newly developed coproantigen tests, strengthening of health services infrastructure and essential drugs distribution, and increasing the priority given to prevention of NC, as a leading cause of epilepsy in T. solium endemic areas. Information is accumulating on rational approaches to population-based short-term chemotherapeutic control measures. These are: widely available modern diagnostic tools and taenicides, treatment of any case of taeniasis, confirmed or probable, focus-oriented chemotherapy, irrespective of Taenia species implicated, improved sanitation, cooperation of veterinary and medical services, linkage with programs against epilepsy and cooperation of better educated communities. Now, it remains to take an advantage of existing tools and experience.

Evaluation of intrathecal synthesis of IgG in neurocysticercosis

Neurocysticercosis is a world public health problem. An increase in immunoglobulin G (IgG) concentration in the cerebrospinal fluid of patients with neurocysticercosis has been described but the reasons for this finding are unknown. Our hypothesis is that the increase in IgG concentration in cerebrospinal fluid is due to exclusive intrathecal synthesis of IgG and this process is associated with the inflammatory phases of the disease. We studied IgG concentration in cerebrospinal fluid in 16 patients with neurocysticercosis comparing with a control group of 19 patients to verify which pattern of increase in IgG concentration in cerebrospinal fluid occurs in neurocysticercosis. In the neurocysticercosis group, intrathecal synthesis of IgG was detected in 12 (75%) and 5 (31.2%) patients by quantitative and qualitative methods, respectively. When compared with the control group the neurocysticercosis patients had the same pattern of intrathecal synthesis of IgG as multiple sclerosis patients. Intrathecal synthesis of IgG was not associated with any variable indicative of an inflammatory process. We conclude that the increase in IgG concentration in neurocysticercosis is due to intrathecal synthesis, as is also the case for multiple sclerosis, and that this process is not related to the inflammatory stage of NCC.

Control of Taenia solium taeniasis/cysticercosis: From research towards implementation

Theoretically, considering the biology of its transmission and reservoirs, global eradication of Taenia solium taeniasis and cysticercosis is feasible. Recently much progress has been made in research on diagnosis, treatment and prevention of human taeniasis and porcine cysticercosis, although more operational research is still needed. In spite of this, global eradication of T. solium infection is still unlikely in the near future. Major obstacles to practical implementation of control measures include low levels of sanitation and health education amongst endemic populations, ineffective health services infrastructure and inadequate socioeconomic development in these areas. The continued public health impact of neurocysticercosis, especially fatalities and epilepsy, force us to identify improved options for control. In order to implement control measures in highly endemic areas the active involvement of medical services in controlling T. solium infection and more effective collaboration between medical and veterinary services is necessary. A switch is suggested from total reliance on meat inspection to active diagnosis and treatment of human taeniasis, protection of pigs against infection, promotion of health education and improved surveillance preparing chemotherapeutic and/or sanitary interventions. This could be implemented in areas where active transmission causes substantial morbidity and mortality provided there is the political will, social support, better financing and an effective organizational framework.

Therapy for common parasitic diseases in pregnancy in the United States: a review and a survey of obstetrician/gynecologists' level of knowledge about these diseases

A number of food- and waterborne parasitic diseases that are common in the United States can adversely impact women during pregnancy. Therapeutic considerations during pregnancy for these diseases are reviewed. Also, the level of knowledge of obstetrician-gynecologists about diagnosis and treatment of these diseases (toxoplasmosis, cryptosporidiosis, giardiasis, amebiasis, cyclosporiasis, trichinellosis, ascariasis, and taeniasis) was estimated by means of a questionnaire developed by the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG). Of the 1200 obstetrician-gynecologists surveyed, 521 (43%) responded. In general, respondents gave correct answers to questions about toxoplasmosis, but for other illnesses responses, it varied. For example, most (61.4%) respondents gave incorrect answers about treatment of cryptosporidiosis in pregnancy, and many (41.2%) respondents incorrectly identified metronidazole as the safest treatment for giardiasis in the first trimester of pregnancy. Although knowledge among obstetrician-gynecologists about toxoplasmosis is good, there is a wide variation in knowledge about other common food- and waterborne parasitic diseases that are likely to be encountered in the United States. Therapeutic considerations for these diseases during pregnancy are discussed.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to list the various common protozoal diseases, to outline the clinical manifestations as well as route of spread for each of the protozoal diseases, and to outline potential therapies for each of the protozoal diseases.

Epilepsy and neurocysticercosis in rural Bolivia: a population-based survey

PURPOSE

To evaluate the frequency of neurocysticercosis (NCC) in a well-defined prevalent cohort of epilepsy patients in the rural area of the Cordillera province.

METHODS

We carried out a two-phase door-to-door neuroepidemiologic survey in a sample of 10,124 subjects in a rural area of the Cordillera Province, Bolivia, to detect the prevalence of the most common neurologic disorders including epilepsy. A team of health workers administered a standard screening instrument for neurologic diseases; subjects found positive at the screening phase underwent a complete neurologic examination. Epilepsy patients were diagnosed according to the definition proposed by the International League Against Epilepsy (ILAE, 1993). Epilepsy patients identified this way underwent electroencephalographic recording, computed tomography (CT) scan, and serologic evaluation to detect antibodies against Taenia solium by enzyme-linked immunoelectrotransfer blot.

RESULTS

At the end of the survey, we detected 124 defined prevalent epilepsy patients. On the basis of the classification proposed by the ILAE in 1981, partial seizures were the most common type diagnosed (66 patients, 53.3%). Of the 124 patients, 105 underwent CT scan, and a serum sample was taken to detect antibodies against T. solium in 112 patients; for 97 patients, both neuroradiologic and serologic data were available. Considering radiologic, serologic, and clinical features, of these 124 patients, 34 (27.4%) fulfilled the diagnostic criteria for definitive or probable NCC proposed in 2001. Of these 34 patients 24 (70.6%) had partial seizures.

CONCLUSIONS

Our data confirm a high frequency of NCC among a well-defined prevalent cohort of epilepsy patients.

Proteomic analysis of a 120 kDa protein complex in cyst fluid of Taenia solium metacestode and preliminary evaluation of its value for the serodiagnosis of neurocysticercosis

Cyst fluid (CF) of Taenia solium metacestode (TsM) is an important source of serodiagnostic antigens. We have investigated the molecular characteristics of the 120 kDa protein complex in TsM CF purified by fast performance liquid chromatography. The structure of the purified protein was characterized by a variety of proteomic analyses. The protein was found to consist of 2 major components of 42-46 and 22-28 kDa, and shared 3 subunits of 14, 16 and 18 kDa. The 42-46 kDa component was determined to contain 3 additional subunits of 22, 28 and 38 kDa. These 6 subunits were shown to originate from either the 14 or 18 kDa precursor. We assessed the antibody reactivity of the native protein, its individual subunits and the recombinant 14 and 18 kDa proteins, and found that the 120 kDa protein, particularly 14 and 18 kDa subunits revealed high reliability for differentiation of active and mixed stage NC from chronic NC. The subunits of the 120 kDa protein complex identified herein represent some of the low-molecular weight glycoproteins which have been described in several previous studies. Recognizing and understanding the structural and immunological relationship of these proteins will facilitate the development of new serodiagnostic assays.

Methods for assessing the burden of parasitic zoonoses: echinococcosis and cysticercosis

Cysticercosis and echinococcosis cause illness and productivity losses in human and agricultural animal populations. Recent studies suggest that these diseases have large societal impacts on endemic areas. Estimates of burden provide essential, evidence-based data for conducting cost-benefit and cost-utility analyses that will secure political will, and financial and technical resources. To evaluate the burden, the monetary and non-monetary impacts of these zoonoses on human health, agriculture and society must be considered comprehensively. In this article, we review the framework used to assess the burden of cysticercosis and echinococcosis, and the data needed to estimate the extent of the problem for societies.

Epilepsy and Neurocysticercosis in Atahualpa: A Door-to-Door Survey in Rural Coastal Ecuador

PURPOSE

To determine the prevalence of epilepsy and the role of neurocysticercosis in the occurrence of epilepsy in Atahualpa.

METHODS

We used a door-to-door survey to detect subjects with epileptic seizures, to collect a blood sample for determination of anticysticercal antibodies, and to evaluate social characteristics of the population, including household pig ownership. Neurologists examined suspected cases and a sample of negative individuals. Then patients with epilepsy, as well as age- and sex-matched controls, underwent a head computed tomography (CT) and a scalp EEG.

RESULTS

The questionnaire was answered by 2,415 of 2,548 residents of Atahualpa, and cysticercosis serology was performed in 1,687 consenting individuals. Cysticercosis seroprevalence was 145 (8.6%) per 1,686). Neurologic examination confirmed 24 patients with epilepsy (crude prevalence, 9.9 per 1,000 population, and 10.8 per 1,000 when adjusted to the United States population). After adjustment by age, sex, and pig raising, positive serology was strongly associated with epilepsy (odds ratio (OR), 4.16; 95% confidence interval (CI), 1.6-11.2). CT findings compatible with neurocysticercosis were found in five patients with epilepsy and also were more frequent than in controls, although this did not reach statistical significance (five of 19 vs. one of 19; p = 0.125, McNemar's test). Besides these five cases, three other patients with epilepsy had positive serology (one with a normal CT and two who did not have a CT).

CONCLUSIONS

Neurocysticercosis is associated with one-third of cases of epilepsy in Atahualpa and may be a major contributory factor for the excess fraction of epilepsy seen in this population.

A trial of antiparasitic treatment to reduce the rate of seizures due to cerebral cysticercosis

BACKGROUND

Neurocysticercosis is the main cause of adult-onset seizures in the developing world. Whether therapy with antiparasitic agents results in improved seizure control has been questioned because of the lack of adequate, controlled studies.

METHODS

We conducted a double-blind, placebo-controlled trial in which 120 patients who had living cysticerci in the brain and seizures treated with antiepileptic drugs were randomly assigned to receive either 800 mg of albendazole per day and 6 mg of dexamethasone per day for 10 days (60 patients) or two placebos (60 patients). The patients were followed for 30 months or until they had been seizure-free for 6 months after the doses of the antiepileptic drugs had been tapered. The efficacy of treatment was measured as the decrease in the number of seizures after treatment.

RESULTS

In the albendazole group, there was a 46 percent reduction in the number of seizures (95 percent confidence interval, -74 to 83 percent) during months 2 to 30 after treatment. This reduction, which was not statistically significant, was composed of a nonsignificant reduction of 41 percent in the number of partial seizures (95 percent confidence interval, -124 to 84 percent) and a significant 67 percent reduction in the number of seizures with generalization (95 percent confidence interval, 20 to 86 percent). Most of the difference in the number of partial seizures was attributable to a few patients who had many seizures during follow-up. The proportions of patients who had partial seizures during follow-up were similar in the two groups (19 of 57 in the albendazole group and 16 of 59 in the placebo group), but the patients in the placebo group had a greater tendency to have seizures with generalization (22 of 59, vs. 13 of 57 in the albendazole group; risk ratio, 1.63; 95 percent confidence interval, 0.91 to 2.92). More of the intracranial cystic lesions resolved in the albendazole group than in the placebo group. With the sole exception of abdominal pain, side effects did not differ significantly between the two groups.

CONCLUSIONS

In patients with seizures due to viable parenchymal cysts, antiparasitic therapy decreases the burden of parasites and is safe and effective, at least in reducing the number of seizures with generalization.

Taenia solium cysticercosis

The larval stage of the pork tapeworm (Taenia solium) infects the human nervous system, causing neurocysticercosis. This disease is one of the main causes of epileptic seizures in many less developed countries and is also increasingly seen in more developed countries because of immigration from endemic areas. Little information is available on the natural evolution of taeniasis or cysticercosis. Available therapeutic measures include steroids, treatments for symptoms, surgery, and, more controversially, antiparasitic drugs to kill brain parasites. Efforts to control and eliminate this disease are underway through antiparasitic treatment of endemic populations, development of pig vaccines, and other measures.

Characterization of the 8-kilodalton antigens of Taenia solium metacestodes and evaluation of their use in an enzyme-linked immunosorbent assay for serodiagnosis

The Western blot for cysticercosis, which uses lentil lectin purified glycoprotein (LLGP) antigens extracted from the metacestode of Taenia solium, has been the "gold standard" serodiagnostic assay since it was first described in 1989. We report that the diagnostic antigens at 14, 18, and 21 kDa, as well as some larger disulfide-bonded antigens, are actually all members of a very closely related family of proteins, the 8-kDa antigens. The genes for 18 unique, mature proteins have been identified. Nine of these were chemically synthesized and tested in an enzyme-linked immunosorbent assay with a battery of defined serum samples, including 32 cysticercosis-positive serum samples reactive with the 8-kDa antigens of LLGP on Western blotting, 34 serum samples from patients with other parasitic infections, and 15 normal human serum samples. One of the 8-kDa antigens, TsRS1, is 100% sensitive and 100% specific. TsRS1 will be one component of a cocktail of three to four synthetic or recombinant antigens, based on the diagnostic bands of the Western blot, which will be used for the serodiagnosis of cysticercosis.

Taenia solium infection in a rural community in the Peruvian Andes

An epidemiological study was conducted in a highland, rural community in Peru, to determine the seroprevalences of human and porcine infection with Taenia solium and the risk factors associated with human infection. The seroprevalences, determined using an assay based on enzyme-linked-immuno-electrotransfer blots (EITB), were 21% (66/316) in the humans and 65% (32/49) in the pigs. The human subjects aged <30 years were more likely to be positive for anti-T. solium antibodies than the older subjects (P < 0.001). The risk factors associated with human seropositivity were lack of education beyond the elementary level [odds ratio (OR)=2.69; 95% confidence interval (CI)=1.09-6.65] and pig-raising (OR=1.68; CI=0.96-2.92). Curiously, sheep-raising was inversely associated with human T. solium infection (OR=0.50; CI=0.28-0.90). The study site appears to be a new endemic focus for T. solium in the central Peruvian Andes. Although, in earlier studies, the seroprevalence of T. solium infection has generally been found to increase with age, the opposite trend was observed in the present study. The results of follow-up studies should help determine if the relatively high seroprevalence in the young subjects of the present study is the result of a transient antibody response.

Immunodiagnostic tools for human and porcine cysticercosis

The development of improved immunodiagnostic tools has contributed to our knowledge on the importance of taeniosis/cysticercosis by enabling sero-epidemiological surveys and community-based studies to be carried out. Immunodiagnostic techniques include detection methods for specific antibodies and for circulating parasite antigen in serum or cerebrospinal fluid. The antigens used in immunoblot and enzyme-linked immunosorbent assay (ELISA) for antibody detection have evolved from crude extracts to highly purified specific fractions and recombinant antigens of the glycoprotein family, increasing both the sensitivity and the specificity of the tests. The application of ELISA for the detection of circulating parasite antigens may present some diagnostic advantages since it demonstrates not only exposure but also active infections. Until now only a few of the current techniques have been standardised and fully validated, making comparisons between studies difficult. The lack of a gold standard is a serious drawback. In surveys on cysticercosis, antibody detection systems have been useful in identifying the risk factors associated with transmission of Taenia solium; a high seroprevalence in a community indicates a "hot spot" where preventive and control measures should be applied. In contrast, the potential use of immunodiagnostic tools to identify cases of neurocysticercosis (NCC) in man is subject to debate. The correlation between a positive serology and neurological symptoms and/or lesions indicative for NCC on neuro-imaging techniques is poor to fair in most studies. This may be explained by the unpredictable clinical outcome of the infection and the variable immunological response of the human host to infection. A major problem is that in many developing countries, neuro-imaging methods are inaccessible and/or too expensive for the rural population at risk. Under these conditions, serology may provide the only tool for diagnosis of the infection.

Seroincidence of porcine T. solium infection in the Peruvian highlands

We performed repeated serological sampling of pigs in an endemic area of the Peruvian highlands (eight villages) to assess the feasibility of detecting incident cases of Taenia solium infection as indicators of ongoing transmission of the parasite. A total of 2245 samples corresponding to 1548 pigs were collected in three sampling rounds (n=716, 926, and 603, respectively). Village-period specific seroprevalences of antibodies by enzyme-linked immunoelectrotransfer blot (EITB) assay varied from 39% (95% CI: 34, 44) to 76% (95% CI: 72, 79). The prevalence of cysticercosis increased with the age of the pigs (similarly for both sexes). Around 40% of pigs were re-sampled at the end of each 4-month period. Crude incidence risks were 48% (57/120, 95% CI: 43-52) and 58% (111/192, 95% CI: 54-61) for each period. A proportion of seropositive animals became seronegative at the end of each period (23 and 15%). Incidence varied by the village, and the exposure period, and was higher in males than females (but did not differ by age).

Control of echinococcosis and cysticercosis: a public health challenge to international cooperation in China

Echinococcosis, both cystic and alveolar, and Taenia solium cysticercosis are the most serious zoonotic cestodoses worldwide. Because of the emerging importance of these diseases in China, several international workshops and meetings were held in this country from 1998 to 2001. Based on round table discussions in Chengdu 2000, the proposal of a strategy to control echinococcosis and cysticercosis has been prepared in China. It includes a comprehensive approach based on a careful analysis of the local situations (particularly concerning the particularities of the cycle, ecology, and ethology of the animal hosts, and behavioral characteristics of the population at risk), the use of newly developed tools both in animals and human (immunology, molecular biology, and imaging), and the association of the traditional control measures (control of slaughtering, antiparasitic treatment and control of the definitive hosts, and health education) with more recent developments such as vaccination of the intermediate hosts. Plans on for the control of echinococcosis and cysticercosis in China are summarized.

Neurocysticercosis--New Millennium, ancient disease and unending debate

A spurt of cases of Neurocysticercosis (NCC) at our department reopened the debate on whether to treat or not and spurred us on to review the available literature for a viable solution. Despite the disease having been around for centuries a cogent treatment plan eludes us even as other ancient scources have been successfully engaged. Neurocysticercosis presents a peculiar problem as it is an end-stage infection, accidental in man, with a benign natural course and would have merited considerably less attention, had it not chosen to infest the brain. These unique and characteristic features are the fundamental reasons why so many different treatment strategies are continuously proffered; many or none seem to work, depending on the viewpoint. And the target organs of this otherwise unglamorous tapeworm cyst--the brain, eye and spinal cord-ensure that there is always pressure, and temptation to treat rather than let it be, even if the weight of evidence is to the contrary. An overview of the history of the disease and the most recent happenings is presented here, in which these issues are reviewed with special attention to the debate on treatment. From the facts that emerge, an attempt has been made to present a workable plan that would help practicing pediatricians in treating most encountered cases till such time we hear the last word on the issue.

Human and porcine Taenia solium infection in rural north India

72 members of a pig farming community and 50 slaughtered pigs in Uttar Pradesh, India, were examined between November 2000 and June 2001 for Taenia solium infection. 27 of the human subjects (38%) had intestinal taeniasis and 7 (9.7%) had reported seizures. All 3 of the latter who were examined had neurocysticercosis. 13 of the pigs (26%) had cysticercosis. Such high prevalences indicate the need for detailed assessment of the disease burden in this community.

Taenia solium oncosphere antigens induce immunity in pigs against experimental cysticercosis

Immunity to Taenia solium infection was investigated using an experimental intramuscular oncosphere infection assay (IMOA) model in pigs. Three naturally infected pigs with cysticercosis were treated with oxfendazole (OFZ), a drug demonstrated to kill cysts in porcine muscle. These animals were then challenged with oncospheres but did not develop any cysts while three uninfected pigs that were similarly challenged, did develop intramuscular cysts. In another study, two groups of three pigs each were immunized with crude T. solium oncosphere and metacestode antigens, respectively, and tested with the IMOA. Immunization with crude oncosphere antigens (OAs) induced 100% protection, while metacestode antigens provided only partial protection. Immunoblots showed that pigs with complete immune protection to oncosphere intramuscular challenge had antibodies to two OAs at 31.3 and 22.5 kDa, respectively. Antibody to these two antigens was absent in pigs immunized with metacestodes or in uninfected control pigs. This study demonstrated the presence of two antigens that are unique to the oncosphere. Although, antibody to these two antigens is consistently present in pigs that are protected from an oncosphere intramuscular challenge their role in preventing infection by T. solium larval cysts is still hypothetical.

Neurocysticercosis in radiographically imaged seizure patients in U.S. emergency departments

Neurocysticercosis appears to be on the rise in the United States, based on immigration patterns and published cases series, including reports of domestic acquisition. We used a collaborative network of U.S. emergency departments to characterize the epidemiology of neurocysticercosis in seizure patients. Data were collected prospectively at 11 university-affiliated, geographically diverse, urban U.S. emergency departments from July 1996 to September 1998. Patients with a seizure who underwent neuroimaging were included. Of the 1,801 patients enrolled in the study, 38 (2.1%) had seizures attributable to neurocysticercosis. The disease was detected in 9 of the 11 sites and was associated with Hispanic ethnicity, immigrant status, and exposure to areas where neurocysticercosis is endemic. This disease appears to be widely distributed and highly prevalent in certain populations (e.g., Hispanic patients) and areas (e.g., Southwest).

Epilepsy, cysticercosis, and toxocariasis: a population-based case-control study in rural Bolivia

OBJECTIVE

To assess the relationship between epilepsy and infection with Taenia solium and Toxocara canis with a case-control study, in the rural area of the Cordillera Province, Bolivia.

METHODS

A preliminary two-phase door-to-door prevalence survey determined the prevalence of epilepsy and identified cases and control subjects. At least two control subjects per case were selected, matching on sex, age, and community of residence. Cases and control subjects were assessed serologically for antibodies against T. canis by ELISA and against T. solium by enzyme-linked immunoelectrotransfer blot (EITB).

RESULTS

The prevalence survey found 130 confirmed cases of epilepsy, of which 113 were eligible for the case-control study (59 partial seizures and 54 generalized seizures). Two hundred thirty-three control subjects were selected. Multivariable analysis for a matched case-control study was carried out. There was an association between EITB positivity for T. solium and epilepsy with an OR of 1.85 (95% CI 0.99 to 3.4) for all cases. A stronger association was found in those with partial epilepsy with a late onset of disease (15 years and older), where the OR was 3.66 (95% CI 1.10 to 12.10). A positive association was also found with T. canis for all cases with an OR of 2.70 (95% CI 1.41 to 5.19). This increased for those with late-onset partial epilepsy to an OR of 18.22 (95% CI 2.10 to 158.10).

CONCLUSION

This finding suggests that both neurocysticercosis and toxocariasis may in part explain the higher prevalence of epilepsy, particularly partial epilepsy, in developing countries.

Taenia solium: identification of specific antibody binding regions of metacestode 10-kDa protein

Taenia solium neurocysticercosis (NCC) represents one of the major public health problems associated with several neurological manifestations worldwide. We previously identified a recombinant 10-kDa protein of T. solium metacestode (CyDA) specific to active NCC. Immunoblottings with sera from active NCC patients and from animals experimentally infected with larval T. solium (pig), T. saginata (pig), T. asiatica (pig), and T. crassiceps (mouse) strongly recognized CyDA, while sera from patients infected only with adult worms did not. Mapping of antigenic sites using deletion mutants revealed that amino acids (aa) residues 30-34, Asn-Met-Thr-Val-Met (NMTVM), reacted only with sera from active stage T. solium cysticercosis cases. Recognition of CyDA aa 30-34 resided almost exclusively in the IgG4 isotype. Competitive immunoprecipitation with synthetic peptides confirmed the specificity of anti-sera for this penta-peptide. These results demonstrated that aa residues NMTVM in CyDA comprise the core sequence for an active stage NCC-related antigenic determinant. ligand binding protein, HLBP; Cyst fluid, CF; Pooled serum of 10 active NCC patients, serum-pool.

Sequence variation in the cytochrome oxidase I, internal transcribed spacer 1, and Ts14 diagnostic antigen sequences of Taenia solium isolates from South and Central America, India, and Asia

We examined the genetic variability in the pig-human tapeworm, Taenia solium, by sequencing the genes for cytochrome oxidase I, internal transcribed spacer 1, and a diagnostic antigen, Ts14, from individual cysts isolated from Peru, Colombia, Mexico, India, China, and the Philippines. For these genes, the rate of nucleotide variation was minimal. Isolates from these countries can be distinguished based on one to eight nucleotide differences in the 396 nucleotide cytochrome oxidase I (COI) sequence. However, all of the 15 isolates from within Peru had identical COI sequences. The Ts14 sequences from India and China were identical and differed from the Peru sequence by three nucleotides in 333. These data indicate that there is minimal genetic variability within the species T. solium. Minimal variability was also seen in the ITS1 sequence, but this variation was observed within the individual. Twenty-two cloned sequences from six isolates sorted into 13 unique sequences. The variability observed within the sequences from individual cysts was as great as the variability between the isolates.

Malnutrition and childhood epilepsy in developing countries

A high prevalence of epilepsy in children is frequently found in developing countries. Though high rates of acquired brain injury may contribute, the possibility that malnutrition may lower seizure threshold has rarely been examined. This review suggests potential biochemical mechanisms that could adversely affect seizure threshold, particularly the effect of malnutrition on inhibitory neurotransmitters and electrolytes. Supporting evidence from animal research and epidemiological findings in children are discussed.

Serum antigen detection in the diagnosis, treatment, and follow-up of neurocysticercosis patients

The efficacy of albendazole (ABZ) treatment for human neurocysticercosis (NCC) was assessed by using a monoclonal antibody-based parasite antigen detection ELISA which specifically detects the products of living cysticerci in human serum. The assay displayed 85% diagnostic sensitivity, detecting 39 of 46 NCC cases. Only patients with a single viable cyst or only enhancing lesions (degenerating parasites) were seronegative. Specificity of the assay was 92% (23/25) when tested in healthy Peruvian volunteers. In 'cured' patients, in whom all parasites died after ABZ therapy, parasite antigen levels fell sharply by 3 months post treatment. This pattern was not observed in patients refractory to treatment. The sensitivity of the assay with serum samples, and its ability to identify successfully treated patients, make this monoclonal antibody-based ELISA the test of choice for the follow-up of NCC cases.