Sex hormone changes induced by the parasite lead to feminization of the male host in murine Taenia crassiceps cysticercosis

Female mice are more susceptible to Taenia crassiceps (TC) infection than males. However, after a month parasite load increases massively in both genders reaching thousands of parasites per host. The possibility of hormonal changes in the infected mice was envisaged. Sex hormones levels were assayed after different periods of infection, the parasites present in the peritoneal cavity were collected and gonads, uterus and seminal vesicles were weighed. In male mice, serum estradiol increased to levels 200 times their normal values whilst those of testosterone decreased 90% relative to controls. The weight of seminal vesicles was significantly diminished. Infected female mice also showed a slight increase in estrogen blood levels after 8 weeks of infection and the weight of the uterus was significantly increased relative to controls. Serum estradiol and testosterone were almost undetectable after gonadectomy. Cytokines such as IL-6 are capable of stimulating aromatase activity and we found that splenocytes from infected mice produced amounts of IL-6 higher than control as measured by ELISA. In conclusion T. crassiceps infection triggers a feminization process in the infected hosts. The gonads are required for the parasite to induce higher estrogen synthesis. IL-6 could be involved in the immunoendocrine mechanism used by the parasite to maintain a highly permissive environment for its rapid growth.

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.

Further evidence for the long distance dispersal of taeniid eggs

Autopsy of Soay Sheep on St. Kilda revealed the presence of cysticerci of Taenia hydatigena despite the absence of the definitive host on the island. Both the intensity of infection and the prevalence increased with age implying that the sheep did not acquire immunity to reinfection or superinfection. The sheep on average ingested approximately 2.4 eggs per annum. This is far below that expected if an infected dog had visited the island even on a single occasion. The data provide evidence that taeniid eggs are being transported against the prevailing wind by wildlife from at least the nearest inhabited land mass to St Kilda some 60 km distant.

Demonstration of scolex within calcified cysticercus cyst: its possible role in the pathogenesis of perilesional edema

PURPOSE

This study was performed to understand the relation between the scolex as demonstrated on gradient echo (GRE) imaging in a calcified cysticercus cyst and the development of perilesional edema that may be of value in understanding the pathogenesis of this entity.

METHODS

Twenty-one patients with solitary calcified lesion on computed tomography (CT), with seizures of recent onset (within 15 days), were selected for this study. All the patients were subjected to magnetic resonance imaging (MRI) including GRE imaging. The patients were grouped on the basis of presence or absence of perilesional edema around the calcified lesion on MRI.

RESULTS

There were 14 patients with perilesional edema, and seven patients had no evidence of edema. Of these 14 patients with perilesional edema, rim enhancement was detected in 13 patients on postcontrast MRI, whereas no enhancement was observed in one patient. The scolex was seen in all these 14 patients on GRE images. Of the seven patients without evidence of edema, the scolex was not seen in any of these patients on GRE imaging. In addition, there was no evidence of any contrast enhancement on postcontrast study in any of the patients in this group.

CONCLUSIONS

We conclude that the calcified cysts with scolex seen on GRE imaging are associated with perilesional edema. This is probably due to preservation of antigenic material in these calcified cysts, the release of which provokes an inflammatory response that may be responsible for the perilesional edema.

Neurocysticercosis and oncogenesis

Recent studies suggest that neurocysticercosis may be a risk factor for human cancer. Pathogenetic mechanisms explaining possible oncogenic effects of cysticerci include the following: (a) parasite-induced modulation of the host immune response that may be associated with loss of regulatory mechanisms implicated in the immunological surveillance against cancer; (b) transfer of genetic material from the parasite to the host, causing DNA damage and malignant transformation of host cells, and (c) chronic inflammation with liberation of nitric oxide and inhibition of tumor suppressor genes. Further research is needed to confirm the potential role of cysticercosis in the development of cancer. These studies should determine the presence of cysticercotic factors responsible for the transfer of genetic material and potential mutations in the tumor suppressor genes in proliferating astrocytes surrounding cysticercotic lesions. Additionally, the complex interaction between the immune state of the host with variable cytokine release and the presence of inflammatory cells releasing nitric oxide that cause DNA damage and impair tumor suppressive mechanisms needs to be investigated.

Outcome of short-term antiepileptic treatment in patients with solitary cerebral cysticercus granuloma

OBJECTIVES

The duration of antiepileptic drug (AED) therapy in cases of solitary cerebral cysticercus granuloma (SCCG) presents a major dilemma and the efficacy of short-term (6 months) vs long-term (2 years) AED therapy has been studied.

MATERIALS AND METHODS

Prospective randomized study of short-term vs long-term AED treatment with SCCG has been undertaken. A total of 206 subjects with new onset seizures with SCCG were randomized into two groups: group A (98 patients) were treated for 6 months and group B (108 patients) were treated for 2 years with AED therapy. The patients were evaluated periodically during and at least 18 months after the tapering of drugs.

RESULTS

Partial seizures with or without secondary generalization has been found to be the commonest manifestation occurring in 80.6% of patients with SCCG. In group A 66.3% and in group B 57.4% patients showed complete resolution of computerized tomographic lesion and rest had punctated residual calcification. Statistically, no significant difference in the recurrence of seizures was found in two groups with disappearance of lesion but the difference between calcified residua and complete resolution subset was significant. In patients having residual calcification, 42.2% in group A and 21.7% in group B had recurrence of seizures and the difference was statistically significant (Z = 1.97, P < 0.05).

CONCLUSIONS

The study revealed that SCCG with epilepsy is a benign self-limiting disease. A longer duration of therapy is not warranted in patients having total resolution of lesion. Calcified lesion was found to be the most common cause of recurrence of seizures. Higher recurrence rate was observed in short-term therapy in patients having calcified lesions and may require long-term AED treatment.

Experimental infection model for Taenia solium cysticercosis in swine. Cysticercosis Working Group in Peru

A novel method for infecting pigs with Taenia solium using an intramuscular innoculum of oncospheres was investigated in a series of five experiments in 18 animals. The model is simple to perform, requires a minimal number of oncospheres, permits multiple infections per animal, and decreases the variation inherent in oral infection models. This intramuscular oncosphere assay (IMOA) may provide a valuable tool to evaluate therapeutic agents or potential vaccines for cysticercosis.

Cysticercus fasciolaris infection induced oxidative stress and apoptosis in rat liver: a strategy for host-parasite cross talk

Parasitic helminths have developed various strategies to induce or inhibit apoptosis in the cells of their host, thereby modulating the host's immune response and aiding dissemination to the host. Cysticercus fasciolaris, the larval form of Taenia taeniaeformis, parasitized different intermediate hosts like rats, rabbits, etc. and is cosmopolitan in distribution. In the present study, we have investigated host-parasite interactions and the resulting effect of C. fasciolaris in the liver of rat. Histology of the infected livers showed dilation and damages of hepatic cells near the parasite. Infected liver cells showed an increase in DNA fragmentation and chromatin condensation compared to the normal liver. Acridine orange and ethidium bromide dual staining revealed the presence of apoptotic cells in the infected liver. The decline in the mitochondrial membrane potential in the infected liver suggested that the observed apoptosis is mitochondria mediated. Occurrence of an elevated level of active executioner caspases 3/7 in the infected rat liver further confirms the occurrence of apoptosis. Different antioxidant enzymes were also evaluated and revealed a notable decline in the level of glutathione and glutathione-S-transferase activity leading to the augmented generation of reactive oxygen species. Results of the present study revealed that C. fasciolaris infection leads to apoptosis in the liver of rats which may be a surviving strategy for the parasitic larvae.

Experimental infection with Taenia saginata (Poland strain) in Taiwanese pigs

Two 22-day-old Landrace-Small Ear Miniature (L-SEM) pigs, five 45 to 66-day-old Small Ear Miniature (SEM) pigs, and one 16-day-old Holstein calf were each fed 1000, 3000 or 10,000 Taenia saginata (Poland strain) eggs respectively and killed 34-77 days after inoculation. Four of the five SEM pigs and the Holstein calf were susceptible to this parasite. However, two L-SEM pigs and one SEM pig remained negative. The cysticerci recovery rates for the SEM pig and Holstein calf were 36% and 3%, respectively. All cysticerci from the SEM pigs were found in the livers, more in the parenchyma (89%) than on the surface (11%). Only eleven cysticerci in two SEM pigs were mature and the remainder were either immature, degenerated or calcified. The cysticerci in the calf were distributed throughout the body: leg muscles (248), heart (27), tongue (17), intercostal muscles (14), diaphragm (5), kidney (1) and liver (1). Most (299) of the cysticerci were mature, one was immature and 13 were degenerated or calcified. The length, width, diameter of the protoscolex and sucker of the cysticerci from the calf were larger than those from the SEM pigs. However, the diameter of the rostellum of the latter was slightly larger than the former. Hooklets were not found on any mature cysticercus recovered. The results of the present study provide evidence that the SEM pig can be used as an experimental intermediate host for T. saginata.

Antigen-specific suppression of cultured lymphocytes from patients with neurocysticercosis

The biological parasite-host interactions involved in neurocysticercosis (NC) are of a complex nature. A lymphoproliferation assay was performed using mononuclear cells from 11 patients with NC, who were classified according to the alterations obtained by imaging examinations. Antigen extracts from the membrane and/or scolex of Taenia solium and from the vesicular fluid of Taenia crassiceps were used. Mononuclear cells from patients with NC showed antigen-specific suppression when compared with a control group. The patients presenting calcified cysts showed higher suppression when compared with patients in the active phase of disease. The antigen in the vesicular fluid of T. crassiceps seems to play a suppressor role in vitro, completely inhibiting cell proliferation induced by the mitogens phytohaemagglutinin, concanavalin A and pokeweed mitogen.

New insights in cysticercosis transmission

Taenia solium infection causes severe neurological disease in humans. Even though infection and exposure to swine cysticercosis is scattered throughout endemic villages, location of the tapeworm only explains some of the nearby infections and is not related to location of seropositive pigs. Other players might be involved in cysticercosis transmission. In this study we hypothesize that pigs that carry nematodes specific to dung beetles are associated with cysticercosis infection and/or exposure. We carried out a cross-sectional study of six villages in an endemic region in northern Peru. We euthanized all pigs (326) in the villages and performed necropsies to diagnose cysticercosis. For each pig, we counted cysticerci; measured anti-cysticercus antibodies; identified intestinal nematodes; tabulated distance to nearest human tapeworm infection; and recorded age, sex, productive stage, and geographic reference. For the purpose of this paper, we defined cysticercosis infection as the presence of at least one cysticercus in pig muscles, and cysticercosis exposure as seropositivity to anti-cysticercus antibodies with the presence of 0–5 cysticerci. Compared to pigs without nematode infections, those pigs infected with the nematode Ascarops strongylina were significantly associated with the presence of cysticerci (OR: 4.30, 95%CI: 1.83–10.09). Similarly, pigs infected with the nematode Physocephalus sexalatus were more likely to have cysticercosis exposure (OR: 2.21, 95%CI: 1.50–3.28). In conclusion, our results suggest that there appears to be a strong positive association between the presence of nematodes and both cysticercosis infection and exposure in pigs. The role of dung beetles in cysticercosis dynamics should be further investigated.

In endemic areas, pigs acquire cysticercosis when ingesting Taenia solium eggs that have been released into the environment in the feces of a person infected with T. solium. The present study has found evidence that players, such as dung beetles, might be involved in further dissemination of the parasite into the environment. Specifically, we found an association between helminths, for whom dung beetles act as an intermediate host, and porcine cysticercosis infection and exposure after adjusting for other porcine cysticercosis predictors such as distance to tapeworm carrier and age. Although the study does not evaluate dung beetles directly, parasites specific to dung beetles serve as a novel proxy to evidence the potential role of dung beetles in the epidemiology of cysticercosis. Therefore, it is important that further studies elucidate the role of other players in cysticercosis transmission in order to better explain the reemergence and persistence of cysticercosis after elimination and control efforts. In addition, vector populations could potentially be used as markers for cysticercosis in the communities.

The economic impact of pig-associated parasitic zoonosis in Northern Lao PDR

The parasitic zoonoses human cysticercosis (Taenia solium), taeniasis (other Taenia species) and trichinellosis (Trichinella species) are endemic in the Lao People's Democratic Republic (Lao PDR). This study was designed to quantify the economic burden pig-associated zoonotic disease pose in Lao PDR. In particular, the analysis included estimation of the losses in the pork industry as well as losses due to human illness and lost productivity. A Markov-probability based decision-tree model was chosen to form the basis of the calculations to estimate the economic and public health impacts of taeniasis, trichinellosis and cysticercosis. Two different decision trees were run simultaneously on the model's human cohort. A third decision tree simulated the potential impacts on pig production. The human capital method was used to estimate productivity loss. The results found varied significantly depending on the rate of hospitalisation due to neurocysticerosis. This study is the first systematic estimate of the economic impact of pig-associated zoonotic diseases in Lao PDR that demonstrates the significance of the diseases in that country.

Taenia eggs in a stabilization pond system with poor hydraulics: concern for human cysticercosis?

The objective of this study is to compare the removal of Taenia eggs to the removal of Ascaris eggs in a wastewater stabilization pond system consisting of three ponds in series, where the hydraulic residence time distribution has been characterized via a tracer study supported by computational fluid dynamics modeling. Despite a theoretical hydraulic retention time of 30 days, the peak dye concentration was measured in the effluent of the first pond after only 26 hours. The smaller-sized Taenia eggs were detected in higher concentrations than Ascaris eggs in the raw wastewater. Ascaris eggs were not detected in the pond system effluent, but 45 Taenia eggs/L were detected in the system effluent. If some of these eggs were of the species Taenia solium, and if the treated wastewater were used for the irrigation of crops for human consumption, farmers and consumers could potentially be at risk for neurocysticercosis. Thus, limits for Taenia eggs in irrigation water should be established, and precautions should be taken in regions where pig taeniasis is endemic. The results of this study indicate that the theoretical hydraulic retention time (volume/flow) of a pond is not always a good surrogate for helminth egg removal.

Development of Taenia saginata asiatica metacestodes in SCID mice and its infectivity in human and alternative definitive hosts

Development of Taenia saginata asiatica metacestodes in SCID mice, and its infectivity in humans, golden hamsters, and Mongolian gerbils as alternative definitive hosts, were investigated. Cysticerci were recovered from SCID mice that were subcutaneously injected with hatched oncospheres of T. s. asiatica. The morphological changes of metacestodes were observed. The recovered cysticerci were fed to gerbils, hamsters and humans, to check for their infectivity. Tapeworms were recovered from gerbils and hamsters fed with 20 to 45 week-old cysticerci, and proglottids excretions were observed in human volunteers fed with 45 week-old cysticerci. However, no tapeworms were recovered from gerbils fed with 10 week-old cysticerci. Our results suggest that T. s. asiatica oncospheres needed more than 20 weeks to develop to maturity in SCID mice to be infective to both their natural and alternative definitive hosts.

Taenia crassiceps cysticercosis in mice does not increase the carcinogenic effect of methyl-nitrosourea

An association between brain cysticercosis and malignant neoplasms in humans has recently been reported. To explore the possibility of a potentiating effect of cysticercosis on carcinogenesis mice infected with Taenia crassiceps cysticerci were exposed to the carcinogenic substance methyl-nitrosourea; 35% of them developed lymphoma, in contrast with 50% of control non-infected animals exposed to MNU. In this experimental model of cysticercosis we did not find a potentiating effect of peritoneal cysticercosis on the carcinogenicity of MNU.

Distinguishing patients with idiopathic epilepsy from solitary cysticercus granuloma epilepsy and biochemical phenotype assessment using a serum biomolecule profiling platform

A major source of epilepsy is Neurocysticercosis (NCC), caused by Taenia solium infection. Solitary cysticercus granuloma (SCG), a sub-group of NCC induced epilepsy, is the most common form of NCC in India. Current diagnostic criteria for SCG epilepsy require brain imaging which may not be available in communities where the disease is endemic. Identification of serum changes and potential biomolecules that could distinguish SCG epilepsy from idiopathic generalized epilepsy (IE), without the initial need for imaging, could assist in disease identification, understanding, and treatment. The objective here was to investigate, using mass spectrometry (MS), sera biomolecule differences between patients with SCG epilepsy or IE to help distinguish these disorders based on physiological differences, to understand underlying phenotypes and mechanisms, and to lay ground work for future therapeutic and biomarker analyses. Sera were obtained from patients with SCG or IE (N = 29 each group). Serum mass peak profiling was performed with electrospray ionization (ESI) MS, and mass peak area means in the two groups were compared using leave one [serum sample] out cross validation (LOOCV). Serum LOOCV analysis identified significant differences between SCG and IE patient groups (p = 10-20), which became non-significant (p = 0.074) when the samples were randomly allocated to the groups and reanalyzed. Tandem MS/MS peptide analysis of serum mass peaks from SCG or IE patients was performed to help identify potential peptide/protein biochemical and phenotypic changes involving these two forms of epilepsy. Bioinformatic analysis of these peptide/protein changes suggested neurological, inflammatory, seizure, blood brain barrier, cognition, ion channel, cell death, and behavior related biochemical systems were being altered in these disease states. This study provides groundwork for aiding in distinguishing SCG and IE patients in minimally invasive, lower-cost manners, for improving understanding of underlying epilepsy mechanisms, and for further identifying discriminatory biomarkers and potential therapeutic targets.

The effect of gamma radiation on the cysticerci of Taenia solium

Cysticerci of Taenia solium were exposed to gamma radiation in doses varying from 20-140 krad. Radiation had an adverse effect on the ability of the cysticerci to evaginate in vitro after a time lag of 9 days. This effect was most marked at doses of 100 krad and higher, thus no cysticerci exposed to 140, 120 and 100 krad evaginated after 12, 18 and 21 days, respectively. On Day +24, when 60% of the control cysticerci evaginated, 55%, 50%, 30% and 40% of the cysticerci exposed to 20, 40, 60, and 80 krad, respectively, evaginated in vitro. Cysticerci exposed to radiation doses of 20-120 krad are as infective to golden hamsters as are unirradiated cysticerci. Cestodes resulting from irradiated cysticerci, however, cannot maintain themselves indefinitely, and are excreted or digested at varying times from Day +12 onwards. Moreover, cestodes resulting from such irradiated cysticerci do not grow, but are resorbed, and finally consist of only a scolex. By Day +30 the mean length of the worms resulting from the unirradiated cysticerci is 173,8 mm, while those resulting from cysticerci exposed to 20 and 40 krad consist of scolices only and the hamsters fed material exposed to 60 krad were negative. It appears, therefore, that radiation inhibits the ability of the cells in the neck region to divide and thus form new proglottids. Carcasses infested with cysticercosis can possibly be rendered fit for human consumption by exposure to gamma radiation at doses between 20 and 60 krad.

Experimental studies on physiological and morphological aspects of Cysticercus cellulosae in pigs

Three Small-Ear-Miniature, 3 Landrace-Small-Ear-Miniature, and one Douc-Yorkshire-Landrace pigs were inoculated orally with 100 000 eggs of Zhengzhou strain or 10 000 eggs of Harbin strain of Taenia solium. A total of 3739 cysticerci were recovered from 3 Small-Ear-Miniature and 3 Landrace-Small-Ear-Miniature pigs, giving an infection rate of 85.7% and a cysticercus recovery rate of 1.1%. The predilection sites of Cysticercus cellulosae in descending order were leg muscles, abdominal muscles, thoracic muscles, liver, head muscles, diaphragm, tongue, heart, trachea, and omentum/testes. Except 2 calcified cysticerci in the tongue, 2 in the heart, and 176 in the liver, the remaining cysticerci were all alive. The greatest number of cysticerci per 100 g of muscles or viscera was found in the head muscles, followed by the leg, diaphragm, heart, tongue, thoracic, abdominal, omentum, testes, and trachea. All cysticerci were evaginated in pig's bile after fluid was drawn out from cysticerci, whereas evagination occurred in only 83.2% of those without fluid drawing. In 364 evaginated cysticerci, the mean length and width of scolex, proglottid, and bladder, and diameter of rostellum and sucker were 826 x 747 microm, 5,370 x 1,734 microm, 2,885 x 3,002 microm, 155 microm, and 253 microm, respectively. In the protoscolex, the mean number of segments was 33. Each cysticercus had 2 rows of rostellar hooks on the scolex, and the mean length and width of inner and outer hooks were 151 x 18 microm and 117 x 14 microm, respectively. The number of paired hooks ranged from 10 to 18.

Development of Taenia asiatica cysticerci to infective stage and adult stage in Mongolian gerbils

The development of metacestodes and adult worms of Taenia asiatica in Mongolian gerbils (Meriones unguiculatus) were observed. Cysticerci were recovered from gerbils subcutaneously injected with hatched oncospheres. The recovery rate ranged from 0.1 to 3.2%. No cysticerci were recovered from the orally inoculated gerbils. The infectivity of the cysticerci recovered at 48 weeks post-infection was evaluated. Tapeworms were recovered on day 14 post-infection from the small intestine of 5 of 11 gerbils, with a recovery rate of 27% (6 worms recovered/22 worms inoculated). Three and four adult worms were recovered from two human volunteers who ingested five cysticerci after 4 months post-infection. In worms recovered from gerbils, segmentation and genital primordia in the posterior proglottids and hooklets in the residual rostellum were observed. The results indicate that gerbils can serve as an alternative intermediate host and that partial development of the adult worm stage occurs in gerbils.

[Test of the vitality and infectiousness of the beef tapeworm (Cysticercus bovis)]

The vitality and infectiosity of Cysticercus bovis can be determined by means of a relatively simple in vitro method. Mobility and evagination are 2 parameters for estimating vitality as well as infectiosity. The mobility-evagination-relationship (MER) is an excellent basis for investigating the mobility over 20 h, because 2 parameters are involved. Of special interest was the fact that the first part of MER (after 1 h) is the period for the short-time-test (control of vitality), and the second part of MER (after 18 to 20 h) is the period for the long-time-test (control of infectiosity). Mobility and evagination of metacestodes were tested in activator solution (100 ml physiological saline + 6 ml fresh swine bile) at a temperature of 38 degrees C and a pH of 7.0. This in vitro method may be useful in determining the vitality of fresh and older Cysticercus bovis and of those exposed to smoking.

Cysticercosis of breast--a case report

Cysticercosis can affect any organ or tissue of the body. Involvement of the breast is a rare presentation. In this report we present a case of 22 years young married woman who came with the history of painless mobile swelling in the right side of the breast. An excision biopsy was carried out. Histopathological examination revealed the presence of typical cysticercus larva and a definite diagnosis of cysticercosis was made. To conclude, cysticercosis of the breast is rare and it should be considered as a differential diagnosis for a lump in the breast.