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.

Proteomic study of activated Taenia solium oncospheres

Taenia solium cysticerci are a major cause of human seizures and epilepsy in the world. In the gastrointestinal tract of infected individuals, taeniid eggs release the oncospheres, which are then activated by intestinal stimuli, getting ready to penetrate the gut wall and reach distant locations where they transform in cysticerci. Information about oncospheral molecules is scarce, and elucidation of the oncosphere proteome could help understanding the host-parasite relationship during the first steps of infection. In this study, using liquid chromatography and tandem mass spectrometry (LC-MS/MS) analysis, we could identify a set of oncospheral proteins involved in adhesion, protein folding, detoxification and proteolysis, among others. In addition, we have characterized one of the identified molecules, the parasite 14-3-3, by immunoblot and immunolocalization. The identification of these oncospheral proteins represents the first step to elucidate their specific roles in the biology of the host-parasite relationship.

Use of ProteinChip technology for identifying biomarkers of parasitic diseases: the example of porcine cysticercosis (Taenia solium)

Taenia solium cysticercosis is a significant public health problem in endemic countries. The current serodiagnostic techniques are not able to differentiate between infections with viable cysts and infections with degenerated cysts. The objectives of this study were to identify specific novel biomarkers of these different disease stages in the serum of experimentally infected pigs using ProteinChip technology (Bio-Rad) and to validate these biomarkers by analyzing serum samples from naturally infected pigs. In the experimental sample set 30 discriminating biomarkers (p<0.05) were found, 13 specific for the viable phenotype, 9 specific for the degenerated phenotype and 8 specific for the infected phenotype (either viable or degenerated cysts). Only 3 of these biomarkers were also significant in the field samples; however, the peak profiles were not consistent among the two sample sets. Five biomarkers discovered in the sera from experimentally infected pigs were identified as clusterin, lecithin-cholesterol acyltransferase, vitronectin, haptoglobin and apolipoprotein A-I.

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.

Antibody responses and epitope specificities to the Taenia solium cysticercosis vaccines TSOL18 and TSOL45-1A

Taenia solium is a cestode parasite that causes cysticercosis in humans and pigs. This study examined the antibody responses in pigs immunized with the TSOL18 and TSOL45-1A recombinant vaccines against T. solium cysticercosis. Immunization with these proteins induced specific, complement-fixing antibodies against the recombinant antigens that are believed to be associated with vaccine-induced protection against T. solium infection. Sera from immunized pigs were used to define the linear B-cell epitopes of TSOL18 and TSOL45-1A. Prominent reactivity was revealed to one linear epitope on TSOL18 and two linear epitopes on TSOL45-1A. These, and oncosphere antigens from other taeniid cestodes, contain a protein sequence motif suggesting that they may show a tertiary structure similar to the fibronectin type III domain (FnIII). Comparison of the location of linear antigenic epitopes in TSOL18 and TSOL45-1A within the proposed FnIII structure to those within related cestode vaccine antigens reveals conservation in the positioning of the epitopes between oncosphere antigens from different taeniid species.

Combined human and porcine mass chemotherapy for the control of T. solium

A combined (human and porcine) mass chemotherapy program was tested in a controlled design in 12 village hamlets in the Peruvian highlands. A single dose of 5 mg of praziquantel was given to eliminate intestinal taeniasis in humans, and two rounds of oxfendazole (30 mg/kg) were administered to all pigs. The total population in the study villages was 5,658 resident individuals, and the porcine population at the beginning of the study was 716 pigs. Human treatment coverage was 75%, ranging from 69% to 80%. There were only a few refusals of owners for porcine treatment of their animals. The effect of the intervention was measured by comparing incidence rates (seroconversion in pigs who were seronegative 4 months before) in treatment versus control villages, before and up to 18 months after treatment. There was a clear effect in decreasing prevalence (odds ratio, 0.51; P < 0.001) and incidence (odds ratio, 0.39; P < 0.013) in the treatment area after the intervention, which did not leave to extinction of the parasite but stabilized in slightly decreased rates persisting along the follow-up period. Mass chemotherapy was effective in decreasing infection pressure in this hyperendemic area. However, the magnitude of the effect was small and did not attain the goal of eliminating transmission.

Neurocysticercosis: association between seizures, serology, and brain CT in rural Peru

BACKGROUND

Neurocysticercosis (NCC) is the commonest helminthic CNS infection and the main cause of adult-onset seizures in developing countries, also frequent in industrialized countries because of immigration from endemic zones. Although NCC is commonly seen in individuals with seizures in endemic areas, its role as a cause of epilepsy has been questioned on the basis of the poor methodology of published studies.

OBJECTIVE

To determine, in a cysticercosis-endemic area of the northern Peruvian coast, the frequency of 1) epileptic seizures, 2) serum antibodies to Taenia solium, 3) NCC-compatible findings on brain CT, and 4) the associations between these variables.

METHODS

A community-wide screening survey for possible seizure cases was performed using a validated questionnaire. Positive respondents were later examined in the field by neurologists. Seizure cases were categorized as single seizure, active epilepsy, or inactive epilepsy. Serology was performed for all consenting individuals using immunoblot. Noncontrast brain CT scans were performed in all individuals with seizures and two groups of control subjects without seizures (seropositive and seronegative).

RESULTS

The screening survey was applied to 903 permanent residents. Most positive respondents (114/137 [83.2%]) were examined by neurologists. The overall prevalence of epilepsy was 32.1 per 1,000 and that of active epilepsy was 16.6 per 1,000. Seroprevalence was 24.2% (200/825). Seroprevalence was associated with seizures (odds ratio 2.14; p = 0.026). Brain CT abnormalities compatible with NCC were more frequent in individuals with seizures and in those seropositive.

CONCLUSION

In this hyperendemic area, an important proportion of seizure cases are associated with neurocysticercosis as demonstrated by serology or brain CT.

Calcific neurocysticercosis and epileptogenesis

Neurocysticercosis is responsible for increased rates of seizures and epilepsy in endemic regions. The most common form of the disease, chronic calcific neurocysticercosis, is the end result of the host's inflammatory response to the larval cysticercus of Taenia solium. There is increasing evidence indicating that calcific cysticercosis is not clinically inactive but a cause of seizures or focal symptoms in this population. Perilesional edema is at times also present around implicated calcified foci. A better understanding of the natural history, frequency, epidemiology, and pathophysiology of calcific cysticercosis and associated disease manifestations is needed to define its importance, treatment, and prevention.

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).

Circulating parasite antigen in patients with hydrocephalus secondary to neurocysticercosis

End stages of neurocysticercosis include residual intraparenchymal brain calcifications and hydrocephalus. Although brain calcifications alone have a benign prognosis, hydrocephalus is frequently associated with chronic inflammation and intracranial hypertension, together with a protracted clinical evolution, and may lead to patient deaths. By using a monoclonal-based antigen detection enzyme-linked immunosorbent assay, we measured the levels of circulating parasite antigen in the sera of 56 patients with neurocysticercosis: 27 with calcifications only and 29 with hydrocephalus. The assay gave positive results in 14 of 29 patients with hydrocephalus but was consistently negative in patients with calcifications. Circulating parasite antigen in hydrocephalus secondary to neurocysticercosis indicates the presence of live parasites in these patients and thus a potential benefit from antiparasitic therapy.

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.

Proposed diagnostic criteria for neurocysticercosis

Neurocysticercosis is the most common helminthic infection of the CNS but its diagnosis remains difficult. Clinical manifestations are nonspecific, most neuroimaging findings are not pathognomonic, and some serologic tests have low sensitivity and specificity. The authors provide diagnostic criteria for neurocysticercosis based on objective clinical, imaging, immunologic, and epidemiologic data. These include four categories of criteria stratified on the basis of their diagnostic strength, including the following: 1) absolute--histologic demonstration of the parasite from biopsy of a brain or spinal cord lesion, cystic lesions showing the scolex on CT or MRI, and direct visualization of subretinal parasites by funduscopic examination; 2) major--lesions highly suggestive of neurocysticercosis on neuroimaging studies, positive serum enzyme-linked immunoelectrotransfer blot for the detection of anticysticercal antibodies, resolution of intracranial cystic lesions after therapy with albendazole or praziquantel, and spontaneous resolution of small single enhancing lesions; 3) minor--lesions compatible with neurocysticercosis on neuroimaging studies, clinical manifestations suggestive of neurocysticercosis, positive CSF enzyme-linked immunosorbent assay for detection of anticysticercal antibodies or cysticercal antigens, and cysticercosis outside the CNS; and 4) epidemiologic--evidence of a household contact with Taenia solium infection, individuals coming from or living in an area where cysticercosis is endemic, and history of frequent travel to disease-endemic areas. Interpretation of these criteria permits two degrees of diagnostic certainty: 1) definitive diagnosis, in patients who have one absolute criterion or in those who have two major plus one minor and one epidemiologic criterion; and 2) probable diagnosis, in patients who have one major plus two minor criteria, in those who have one major plus one minor and one epidemiologic criterion, and in those who have three minor plus one epidemiologic criterion.

Protection of pigs with cysticercosis from further infections after treatment with oxfendazole

Cysticercosis, the infection by the larvae of Taenia solium, is a major cause of acquired epilepsy in the world; it also causes significant economic loss because of contaminated pork. This disease is endemic in most developing countries and no control strategy has yet been proven efficient and sustainable. To further evaluate the full potential of single-dose oxfendazole treatment for pigs as a control measure, 20 pigs with cysticercosis were treated with oxfendazole and later matched with 41 naive pigs and exposed to a natural challenge in a hyperendemic area. New infections were found by serologic testing in 15 of the 32 controls (47%), and by the presence of cysts at necropsy in 12 of them (37%). Only minute residual scars were detected in the carcasses of oxfendazole-treated pigs. Pigs with cysticercosis, once treated with oxfendazole, are protected from new infections for at least three months.

Short report: transient antibody response in Taenia solium infection in field conditions-a major contributor to high seroprevalence

The discordance between extremely high seroprevalence of Taenia solium antibodies in disease-endemic populations, relatively few symptomatic cases of neurocysticercosis, and high background levels of putatively inactive brain lesions (mainly calcifications) in seronegative controls have confused researchers, clinicians, and epidemiologists in the last decade. We reviewed longitudinal serologic data from general population serosurveys in 3 different disease-endemic areas of Peru and Colombia and found that approximately 40% of seropositive people were seronegative when resampled after 1 year (3 surveys) or after 3 years (1 survey). Transient antibodies may have significant implications for the epidemiology of and immunity to this disease.

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.

Cluster-cluster aggregation in binary mixtures

The structure and aggregation kinetics of three-dimensional clusters composed of two different monomeric species at three concentrations are thoroughly investigated by means of extensive, large-scale computer simulations. The aggregating monomers have all the same size and occupy the cells of a cubic lattice. Two bonding schemes are considered: (a) the binary diffusion-limited cluster-cluster aggregation (BDLCA) in which only the monomers of different species stick together, and (b) the invading binary diffusion-limited cluster-cluster aggregation (IBDLCA) in which additionally monomers of one of the two species are allowed to bond. In the two schemes, the mixed aggregates display self-similarity with a fractal dimension d(f) that depends on the relative molar fraction of the two species and on concentration. At a given concentration, when this molar fraction is small, d(f) approaches a value close to the reaction-limited cluster-cluster aggregation of one-component systems, and when the molar fraction is 0.5, d(f) becomes close to the value of the diffusion-limited cluster-cluster aggregation model. The crossover between these two regimes is due to a time-decreasing reaction probability between colliding particles, particularly at small molar fractions. Several dynamical quantities are studied as a function of time. The number of clusters and the weight-average cluster size display a power-law behavior only at small concentrations. The dynamical exponents are obtained for molar fractions above 0.3 but not at or below 0.2, indicating the presence of a critical transition between a gelling to a nongelling system. The cluster-size distribution function presents scaling for molar fractions larger than 0.2.

Differentiating Taenia solium and Taenia saginata infections by simple hematoxylin-eosin staining and PCR-restriction enzyme analysis

Species-specific identification of human tapeworm infections is important for public health purposes, because prompt identification of Taenia solium carriers may prevent further human cysticercosis infections (a major cause of acquired epilepsy). Two practical methods for the differentiation of cestode proglottids, (i) routine embedding, sectioning, and hematoxylin-eosin (HE) staining and (ii) PCR with restriction enzyme analysis (PCR-REA), were tested on samples from 40 individuals infected with T. solium (n = 34) or Taenia saginata (n = 6). Microscopic examination of HE staining of sections from 24 cases, in which conserved proglottids were recovered, clearly revealed differences in the number of uterine branches. Distinct restriction patterns for T. solium and T. saginata were observed when the PCR products containing the ribosomal 5.8S gene plus internal transcribed spacer regions were digested with either AluI, DdeI, or MboI. Both HE histology and PCR-REA are useful techniques for differentiating T. solium from T. saginata. Importantly, both techniques can be used in zones of endemicity. HE histology is inexpensive and is currently available in most regions of endemicity, and PCR-REA can be performed in most hospital centers already performing PCR without additional equipment or the use of radioactive material.

Magnitude of the disease burden from neurocysticercosis in a developing country

Cysticercosis contributes to higher epilepsy rates in developing countries than in industrialized ones, yet no estimate exists for the associated burden of disease. We used epidemiological data on neurocysticercosis in Peru to calculate the burden of disease and applied our model to the other countries of Latin America where neurocysticercosis is endemic to determine a regional estimate. Analysis of 12 population-based community studies demonstrated that neurocysticercosis was endemic in highland areas and high jungles, with seroprevalences from 6% to 24%. In one community, the adult seizure disorder rate was 9.1% among seropositive persons versus 4. 6% among seronegative persons; we used this difference for estimates. On the basis of average prevalence rates in areas of endemicity of 6%-10%, we estimated that there are 23,512-39,186 symptomatic neurocysticercosis cases in Peru. In Latin America, an estimated 75 million persons live in areas where cysticercosis is endemic, and approximately 400,000 have symptomatic disease. Cysticercosis contributes substantially to neurological disease in Peru and in all of Latin America.

Persistence of passively transferred antibodies in porcine Taenia solium cysticercosis. Cysticercosis Working Group in Peru

We evaluated the presence and persistence of anticysticercal antibodies in piglets born to Taenia solium infected sows. Infected sows from a disease-endemic area of Peru were transported to a nondisease-endemic area and impregnated. Serum samples were collected from sows and piglets on Day 2 through Week 35 after birth. Using an immunoblot specific for cysticercosis, Ig isotypes to 7 cyst antigens were measured and quantified. Serum samples from the piglets contained detectable antibodies from Week 1 through Week 35 (27 weeks after weaning). The primary Ig isotype present in both sows and piglets was IgG. Antibodies did not appear in piglet serum samples until after suckling, demonstrating that anti-cysticercal antibodies are transferred solely via colostrum. Our data have shown that maternally transferred antibodies to cyst antigens may persist through much of a pig's life. Therefore, the presence of passively transferred antibodies must be considered in studies that examine the prevalence of cysticercosis in pigs. Furthermore, when designing control strategies for cysticercosis, careful evaluation and selection of sentinel pigs becomes a crucial component of sentinel selection.

Human and porcine Taenia solium infection in a village in the highlands of Cusco, Peru. The Cysticercosis Working Group in Peru

A serological survey was performed using the enzyme-linked immunoelectrotransfer blot assay (EITB) in a village in the highlands of Peru where there are three distinct but close neighborhoods, to determine if there is a direct relationship between human and porcine Taenia solium infection. One hundred and eight out of 365 individuals were sampled, and 14 were seropositive (human seroprevalence 13%). Most seropositive individuals were neurologically asymptomatic. Thirty-eight out of 89 sampled pigs (43%) were seropositive. There was a clear geographical clustering of cases, and positive correlation between human and porcine seroprevalence found when comparing the three neighborhoods. Cysticercosis is an important cause of neurological morbidity in most developing countries, and control/eradication trials are now being increasingly applied. Porcine serology provides an appropriate indicator of T. solium environmental contamination and should be used to estimate the risk of infection when evaluating control measures.

Development of a serologic assay to detect Taenia solium taeniasis

We developed a serologic assay to identify adult Taenia solium tapeworm carriers using excretory/secretory (TSES) antigens collected from in vitro cultured T. solium tapeworms. To identify taeniasis-specific antigens we used an immunoblot assay with serum samples from T. solium tapeworm carriers and cysticercosis patients. Antigens were identified that reacted with antibodies present in serum samples from taeniasis cases and not with those from cysticercosis patients. Using serum samples collected from persons with confirmed T. solium tapeworm infections, the test was determined to be 95% (69 of 73) sensitive. Serum samples (n = 193) from persons with other parasitic infections, including T. saginata tapeworm infections, do not contain cross-reacting antibodies to TSES, indicating that the assay is 100% specific. These data suggest that the immunoblot assay using TSES antigens can be used to identify persons with current or recent T. solium tapeworm infections and provides a new, important tool for epidemiologic purposes, including control and prevention strategies.

Increased prevalence of cysticercosis and taeniasis among professional fried pork vendors and the general population of a village in the Peruvian highlands. Cysticercosis Working Group in Peru

Two different populations in Saylla, a Peruvian village near Cusco, known for chicharrones, a local pork dish, were surveyed by serology and stool examination to determine the prevalence and epidemiologic characteristics of Taenia solium infection. Group I (n=43), the chicharroneros, were members of families professionally devoted to the making and selling of chicharrones, and Group II (n=102) was a sample of the general population of the same village. Unlike people in Group I, general villagers only occasionally prepare or sell this food product, and then only to their neighbors or relatives. The prevalence of taeniasis was extremely high (8.6%) for the chicharroneros and 3% for the general villagers. Seroprevalence for cysticercosis by immunoblot was similarly high in both groups (23.3% and 23.8%, respectively). Being female, older than 30, and having daily contact with pork were factors strongly associated with a positive serologic result for cysticercosis in the chicharroneros, whereas males were more frequently seropositive in the general villagers group. Antibody reaction to more antigen bands in immunoblots and neurologic symptoms were more common among the chicharroneros. Also, in the general villagers group, seroprevalence increased with each exposure factor, ranging from 9.4% in individuals who did not raise pigs to 50% in the small subgroup that raised pigs, butchered their own animals, sold pork, and sold chicharrones, suggesting that these activities are related to increased risk for tapeworm or larval infection.

Time-response curve of oxfendazole in the treatment of swine cysticercosis

Human Taenia solium cysticercosis is a major cause of epilepsy in developing countries, and porcine infection causes widespread economic losses because of infested pork. Recently, the use of oxfendazole (OFZ) for porcine cysticercosis provided, for the first time, an effective, single-dose treatment. We performed a controlled study to determine the time required between treatment with a single dose of OFZ and the death of cysticerci to define its applicability as preslaughter treatment or as a field control measure. Twenty naturally infected pigs were included in this study. Sixteen received a single dose (30 mg/kg) of OFZ, and were killed in groups of four at one, two, four, and 12 weeks after treatment. Four untreated controls were killed at week 12. No adverse reactions to OFZ were noted. A clear decrease in viability and number of cysts was evident after the first week after therapy, but even at week 4 some viable cysticerci were found in all samples. Twelve weeks after treatment, all meat appeared clear and only minuscule scars remained, except in one animal that had viable brain cysts. This study confirms the efficacy of a single dose of 30 mg/kg of OFZ for porcine cysticercosis but demonstrates that preslaughter treatment of pigs with OFZ will not be useful in controlling cysticercosis. The inclusion of porcine treatment with OFZ in mass cysticercosis control programs is, however, highly promising because it is a simple, effective, inexpensive, and potentially sustainable method for decreasing the porcine reservoir of cysticercosis in disease-endemic countries.

Treatment of porcine cysticercosis with oxfendazole: a dose-response trial

Taenia solium cysticercosis is an important public health problem in developing countries. Oxfendazole has been shown to be highly effective against porcine cysticercosis, when given as a single dose at 30 mg/kg bodyweight. This dose, however, was estimated from experience with albendazole. A controlled dose-response trial was therefore undertaken to determine the efficacy and safety of three concentrations of oxfendazole. Twenty-four naturally parasitised pigs were divided into four groups and treated with oxfendazole at 10 mg/kg, 20 mg/kg or 30 mg/kg, or left untreated. Eight to 10 weeks later the pigs were killed and the viability of the parasites assessed by evagination. No side-effects of oxfendazole treatment were observed. In the control group more than 90 per cent of the cysts were viable. Viable cysts were found in the muscle and brain of the pigs treated with 10 or 20 mg/kg oxfendazole. At 30 mg/kg there were no viable cysts in any of the tissues examined, indicating that this concentration of oxfendazole provided an effective treatment against porcine cysticercosis.

Albendazole therapy for neurocysticercosis: a prospective double-blind trial comparing 7 versus 14 days of treatment. Cysticercosis Working Group in Peru

OBJECTIVE

To compare the effectiveness of two regimens of albendazole therapy for neurocysticercosis.

DESIGN

Randomized, double-blind clinical trial.

SETTINGS

Patients admitted to neurologic wards in Lima, Peru.

PATIENTS

Adult patients with active neurocysticercosis demonstrated by CT and Western blot (immunoblot).

INTERVENTION

One week (n = 25) versus 2 weeks (n = 25) of albendazole therapy.

MEASUREMENTS

Decrease in the number of cysts on CT.

RESULTS

Effectiveness of albendazole was 78%, with no difference between the groups when compared 3 months after therapy. Complete cure was obtained in only 38% of patients. Patients with more than 20 cysts had poorer responses to therapy. The clinical course and EEG evolution improved in most patients. Side effects were present in 38% of patients, mainly mild, transient gastrointestinal symptoms. Therapy was also associated with exacerbation of neurologic symptoms. Two patients died in the first year after therapy, both because of aggregated infections of ventricle-peritoneal shunts. One-year follow-up CT showed lesions in three of 10 patients presumed to be cured 3 months after therapy.

CONCLUSIONS

Extension of albendazole therapy for more than 7 days adds no benefits for the patients.

Clinical significance of neurocysticercosis in endemic villages. The Cysticercosis Working Group in Peru

Cerebral cysticercosis is the main cause of late-onset epilepsy in most developing countries. Data on the neuroepidemiology of cysticercosis in endemic populations is scarce. In an endemic village on the northern coast of Peru, 49 individuals with neurological symptomatology (41 epileptic and 8 non-epileptic) were screened for antibodies to Taenia solium, using a serum electroimmunotransfer blot assay. Fifteen subjects were seropositive, 14 (34%) of those with epilepsy but only one (13%) of those who were non-epileptic. A history of passing proglottides was associated with positive serology. Thirteen of the 15 seropositive individuals underwent cerebral computed tomography; only 7 (54%) were abnormal. A randomly selected sample of 20 pigs from the village was also tested, and 6 (30%) were seropositive. This study demonstrated the importance of cysticercosis in the aetiology of epilepsy in endemic villages and the close relationship between porcine and human infection.

Serologic evolution of neurocysticercosis patients after antiparasitic therapy. Cysticercosis Working Group in Peru

Neurocysticercosis is the main cause of acquired epilepsy in developing countries and is an emerging disease in the United States. Introduction of the immunoblot assay provided a new tool for the diagnosis and monitoring of neurocysticercosis. This study analyzed the relationship between clinical characteristics of cerebral infection (number and type of lesions) plus the baseline response on immunoblot and the changes observed after therapy. Reaction to all 7 diagnostic bands was associated with severe infection (more lesions). Seventeen patients (35%) had no active lesions on computed tomography (CT) 3 months after therapy and were considered cured. Although most cured patients remained seropositive after 1 year, 3 became seronegative before 9 months. In these 3 cases, the lesions had resolved on CT at 3 months. Persistent seropositivity does not necessarily indicate active infection. Serologic follow-up will be clinically helpful only in rare cases in which early antibody disappearance occurs.

Immunotherapy for porcine cysticercosis: implications for prevention of human disease. Cysticercosis Working Group in Peru

Taenia solium cysticercosis is an important cause of human disease in many developing countries. Porcine cysticercosis is a vital link in the transmission of this disease and impairs meat production. A treatment for porcine cysticercosis may be an effective way of preventing human disease that would also benefit pig farmers, facilitating control programs in disease-endemic regions. Previous research suggests that reinfection with cysticercosis or immunotherapy with cysticercal antigens may cause degeneration of cysticerci, potentially curing porcine cysticercosis. Therefore, a blinded, randomized, controlled study to assess the efficacy and safety of immunotherapy in 28 naturally parasitized pigs was performed. Four groups of pigs with similar weights were inoculated twice with membrane-enriched cysticercal antigens (MA), saline, aqueous-soluble crude cysticercal antigens (AA) in adjuvant (Freund's complete then incomplete), or adjuvant alone. Immunotherapy was well tolerated but had no consistent effect on the macroscopic appearance of cysticerci or eosinophil count. Histopathologic findings were variable, with both severe and minimal inflammatory reactions seen in adjacent cysticerci in all pigs. Nine (64%) of 14 pigs given immunotherapy developed new antibody bands on electroimmunotransfer blot compared with one (7%) of 14 control pigs (P < 0.01). Treatment with AA in adjuvant caused a significant increase in the proportion of cysticerci that failed to evaginate and were, therefore, not viable for infecting humans (34% for pigs given AA in adjuvant compared with 10% for adjuvant alone; P < 0.04). Although immunotherapy caused a statistically significant decrease in the viability of cysticerci, this immunologic reaction was not great enough to prevent human disease.

Treatment of porcine cysticercosis with albendazole

In a randomized, controlled study, the efficacy and safety of two different schemes of albendazole therapy for treatment of porcine cysticercosis were tested. Seventeen naturally infected pigs were divided into three groups and treated per os with albendazole (50 mg/kg single dose), albendazole (30 mg/kg every day for three days), or given no treatment, respectively. Serologic responses were monitored with the enzyme-linked electroimmunotransfer blot assay. Pigs were humanely killed 12 weeks after treatment, necropsied, and the number of parasites was recorded. Scolex evagination was used to assess viability of the cysts. Both albendazole-treated groups had significant side effects (anorexia, lethargy). Only a single viable cyst was recovered from the brain of one animal after therapy in the multiple-dose group, and the single-dose therapy left 11% of the cysts viable. In contrast, more than 90% of muscle cysts were found to be viable in the untreated group. Although albendazole therapy for three days was found to be highly effective, side effects and the need for multiple doses would still prevent its widespread use.

Use of sentinel pigs to monitor environmental Taenia solium contamination. The Cysticercosis Working Group in Peru (CWG)

We tested a novel approach to assay Taenia solium prevalence using the enzyme-linked immunoelectrotransfer blot assay in sentinel piglets to determine environmental contamination with T. solium eggs in a disease-endemic zone in Peru. Twelve sentinel piglets from an area where the disease is not present were tested at two months of age, moved to an area where the disease is endemic, and retested at the of age nine months. Sentinel piglets native from this T. solium-endemic area were also tested concurrently at two and nine months of age. Of the non-native pigs, 33% (4 of 12) acquired new infection. Of the 28 native pigs tested, 64% (18 of 28) acquired the infection. In a subset of the native piglets from seronegative sows, 44% (4 of 9) were infected at five months of age. Serodiagnosis of sentinel piglets is a practical method to detect T. solium eggs in the environment. Furthermore, it permits indirect assessment of human risk, which may be useful for monitoring the efficacy of intervention programs.

Prevalence and comparison of serologic assays, necropsy, and tongue examination for the diagnosis of porcine cysticercosis in Peru

Swine cysticercosis, a severe zoonotic disease which is part of the Taenia solium life cycle, causes major economic losses in pig husbandry. Throughout South America, farmers diagnose cysticercosis by examining the tongues of their pigs for cysticercus nodules. Farmers do not bring pigs believed to be infected to the slaughterhouse for fear of confiscation. Therefore, reliable statistics on porcine cysticercosis can only be acquired at the household level. We examined the utility of the tongue test as a diagnostic tool for porcine cysticercosis. The results of the tongue test was compared with 2 serologic methods for the detection of cysticercosis, the enzyme-linked immunosorbent assay (ELISA) and the enzyme-linked immunoelectrotransfer blot assay (EITB), and with necropsy results. We examined 11 animals from an endemic area (Huancayo) and 42 animals from an area free of cysticercosis (Lima). The tongue test has a sensitivity of 70% and a specificity of 100%, the EITB a sensitivity and specificity of 100%, and the ELISA a sensitivity of 79% and a specificity of 75%. Thus, the tongue examination, being a test essentially without cost and having fair sensitivity and high specificity, can be useful in epidemiological surveys. Prevalence for porcine cysticercosis in Huancayo is 23.4% by tongue examination, 31.2% by necropsy, 37.7% by ELISA, and 51.9% by EITB.

gamma-Butyrolactone effects on behavior induced by dopamine agonists

gamma-Butyrolactone (GBL) potently inhibits stereotyped behavior induced by indirect (amphetamine and methylphenidate) and direct (apomorphine) dopamine agonists. Amphetamine induces a dose-response partial reversal of the GBL effect. The GABA antagonist, bicuculline, only partially reverses the GBL inhibition of apomorphine activity, indicating that GBL may be acting through mechanisms in addition to effects on GABA.

Reduction of blood pressure with calcium supplementation in young adults

Epidemiologic and animal studies have suggested an inverse relationship between calcium intake and BP. Furthermore, calcium intake seems to be inversely correlated with the incidence of eclampsia in pregnancy. In a randomized clinical trial, young adults were allocated to a calcium-supplemented group receiving 1 g/day of elemental calcium (15 men and 15 women) or a placebo group (14 women and 13 men) for a period of 22 weeks. The calcium-supplemented group showed a significant decrease in diastolic BP; this effect was stabilized after nine weeks in women and six weeks in men. The reduction in diastolic BP was 5.6% and 9% from the initial values for women and men, respectively. This study supports epidemiologic and animal evidence of the effect of calcium intake on BP and suggests the need for more research exploring the mechanisms involved in the observed effect.