Oncospheres of Taenia solium and T. saginata asiatica develop into metacestodes in normal and immunosuppressed mice.

Normal and immunosuppressed mice were infected with oncospheres of Taenia saginata asiatica and T. solium. Although normal ICR mice were not susceptible to these two parasites, cysticerci were recovered from the immunosuppressed ones following venous injection. For T. s. asiatica, immunosuppressed ICR mice had an infection rate of 12.5% and six cysticerci of this parasite were recovered from three males. After injection of T. solium oncospheres, a high infection rate of 57% was obtained and 23 cysticerci were collected from 13 male immunosuppressed ICR mice. The immunosuppressed C57 mice had the highest infection rate (100%) and cysticercus recovery rate (2.4%) for T. solium. The infection rate and cysticercus recovery rate in six normal C57 mice were 40% and 3% respectively. The immunosuppressed ICR, Balb/c and C3H mice were also susceptible to T. s. asiatica.     

Taenia saginata and T. hydatigena: intramuscular vaccination of calves with oncospheres

This is a preliminary attempt to immunize calves against bovine cysticercosis (Cestoda) by intramuscular injection of artificially hatched homologous or heterologous oncospheres. In the first two experiments five calves were vaccinated with the oncospheres of Taenia saginata. These calves, together with five controls, were subsequently challenged orally with the eggs of T. saginata. At autopsy all the vaccinated animals harbored a colony of living cysticerci at the site of injection. Three of these calves were completely protected against the oral challenge, and in the other two, only one, and two cysticerci, respectively were found in the sites of election. The five controls harbored 1154, 1680, 820, 960, and 1820 living cysticerci, respectively, in the sites of election.     

Sexual development of Taenia solium in hamsters from rodent-derived cysticerci

In order to determine whether Taenia solium can be maintained in the laboratory using rodents as definitive hosts, six nude rats, 20 immunosuppressed Mongolian gerbils and 20 immunosuppressed Syrian hamsters were each inoculated through a stomach tube with three cysticerci recovered from SCID mice. No adult worms of T. solium were found in the intestinal tract of any of these 46 rodents. In addition, five immunosuppressed Syrian hamsters were fed with the same number of cysticerci enclosed in rodent muscles from SCID mice. Two of these hamsters were found to be infected 40 days post-infection, each harbouring a sexually developed worm in the intestinal tract. Although no eggs were produced, prepatent infections may be possible if a longer time was allowed for worm development. Moreover, the maintenance of the life cycle of T. solium in the laboratory using the rodent model can be established.     

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.     

Hepatozoon cf. terzii (Sambon & Seligman, 1907) infection in the snake boa constrictor constrictor from north Brazil: transmission to the mosquito Culex quinquefasciatus and the lizard Tropidurus torquatus

Specimens of Hepatozoon-infected Boa constrictor constrictor were obtained from localities in Pará State, north Brazil. Gametocytes in erythrocytes of the peripheral blood measured 10 x 2.5-16.2 x 3.7 microns. They were similar to those described as Haemogregarina terzii by Sambon & Seligmann (1907) in B. c. constrictor, in that they did not distort the infected erythrocyte, and their dimensions approximated those given by Carini (1947). Lungs and liver of infected snakes contained actively dividing meronts of a single type, and cysts containing two to six cystozoites were also present in the liver. Our initial feeding of Culex quinquefasciatus on infected snakes consistently resulted in a heavy death-rate of the engorged mosquitoes, with only a few surviving till the 9th day post feeding. These contained numerous oocysts which were undivided or in early stages of division. A fifth and final experiment, however, provided a few mosquitoes surviving up to 21 days post infection (dpi), and these contained fully sporulated oocysts measuring 190-200 microns in diameter and containing over 60 sporocysts of 19-30 microns in diameter. The number of sporozoites in each sporocyst was estimated as approximately 50. The nature of the parasite's sporogonic cycle in the mosquito thus justifies inclusion of this haemogregarine in the genus Hepatozoon. Two wild-caught specimens of the lizard Tropidurus torquatus were fed with mosquitoes containing fully developed oocysts (21 dpi). When sacrificed, three months later, large numbers of dizoic, tetrazoic and hexazoic cysts were demonstrated in their livers. Cystozoites released from these cysts were shown to possess a conspicuous refractile body.     

Gastric hyperplasia and parietal cell loss in Taenia taeniaeformis inoculated immunodeficient mice

Immunodeficient mice were studied to determine their suitability as models in investigating the role of Taenia taeniaeformis larval products in the development of gastric hyperplasia. Recombinant active gene 2 (RAG2)-deficient and severe combined immune-deficient (SCID) mice were studied as candidate animal models. RAG2-deficient mice inoculated orally with T. taeniaeformis eggs developed gastric hyperplasia with alcian blue-periodic acid-Schiff-positive cell proliferation similar to those of rats. SCID mice inoculated with different doses and routes of T. taeniaeformis in vitro-hatched oncospheres and those orally inoculated with eggs resulted also in different degrees of gastric hyperplasia. Influence of inoculation forms of parasite, doses and routes of inoculation on initiation of hyperplastic gastropathy was suggested to be dependent on number and size of developed larvae. Both RAG2-deficient and SCID mice with hyperplastic mucosa were observed with significant loss of parietal cells. Apparent decrease in parietal cell number was observed in SCID mice at 2 weeks after intraperitoneal inoculation with oncospheres before hyperplastic lesions developed. Earliest occurrence of gastric hyperplasia in SCID mice was observed at 3 weeks after oral inoculation of in vitro-hatched oncospheres, sooner than orally inoculated rats. The results suggested that these immunodeficient mice could be used as animal models to study factors involved in T. taeniaeformis-induced gastric mucous cell hyperplasia.     

Taenia crassiceps organic acids detected in cysticerci

Taenia crassiceps cysticerci is used as an experimental model to cysticercosis studies; however there are subcutaneous cases of cysticercosis caused by these cysticerci. It remains unclear in the literature the energetic and fatty acid metabolism in cestodes. Its metabolic study may provide knowledge of pathways that may serve as potential anti-helminthic drugs sites of action. In this work we studied the citric acid cycle organic acids and the fatty acid oxidation in cysticerci removed from mice with 21 and 42 days of infection in two different evolutive stages: growing and final. The organic acids were extracted using perchloric acid and analyzed by HPLC methodology. We found significant statistically differences in oxalate, malate, lactate, and beta-hydroxybutirate concentrations between cysticerci. These results indicate the aerobic metabolism in vivo in spite of the low oxygen concentration of its habitat, and also indicate the presence of fatty acid oxidation as an alternative energetic source.     

Effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae

The effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae (L3) to rats were investigated. A significantly higher body length was observed in L3 from filter paper culture (597.3 +/- 32.2 microns) than those in fecal (509.9 +/- 35.0 microns) and nutrient broth culture (503.3 +/- 31.0 microns) (P < 0.05). Larval infectivity was assessed by exposing rats to 1,000 L3 from each culture and worms were recovered from the lungs and small intestines. Recovery rate of these worms did not show any significant difference. A significantly greater body length of adults was recorded in those corresponding to the L3 harvested from filter paper (2,777.5 +/- 204.4 microns) and nutrient broth culture (2,732.5 +/- 169.8 microns) than those corresponding to the L3 obtained from fecal culture (2,600.5 +/- 172.4 microns) (P < 0.05). Although worm fecundity and EPG counts differed among culture methods but worm burdens and course of infection did not. These findings suggest that the methods of cultures have a significant effect on the morphological development of the larvae to the L3 stage, but do not influence the infectivity to rats.     

Recent Situation of Taeniasis in Mongolia (2002-2012)

Epidemiological situation of taeniasis in Mongolia was assessed based on mitochondrial DNA identification of the parasite species. Multiplex PCR was used on a total of 194 proglottid specimens of Taenia species and copro-PCR and loop-mediated isothermal amplification (LAMP) assays were utilized for detection of copro-DNA of 37 fecal samples from taeniasis patients submitted to the Mongolian National Center for Communicable Diseases (NCCD) from 2002 to 2012. In addition, 4 out of 44 calcified cysts in beef kept in formalin since 2003 were evaluated for histopathological confirmation of cattle cysticercosis. All proglottid specimens and stool samples were confirmed to be Taenia saginata by multiplex PCR and by copro-PCR and LAMP, respectively. Cysts collected from cattle were morphologically confirmed to be metacestodes of Taenia species. T. saginata taeniasis was identified from almost all ages from a 2-year-old boy up to a 88-year-old woman and most prominently in 15-29 age group (37%, 74/198) followed by 30-44 age group (34.8%, 69/198 ) from 15 of Mongolia''s 21 provinces, while cattle cysticerci were found from 12 provinces. The highest proportion of taeniasis patients was in Ulaanbaatar, the capital of Mongolia.     

Taenia solium: Development of an Experimental Model of Porcine Neurocysticercosis

Human neurocysticercosis (NC) is caused by the establishment of Taenia solium larvae in the central nervous system. NC is a severe disease still affecting the population in developing countries of Latin America, Asia, and Africa. While great improvements have been made on NC diagnosis, treatment, and prevention, the management of patients affected by extraparenchymal parasites remains a challenge. The development of a T. solium NC experimental model in pigs that will allow the evaluation of new therapeutic alternatives is herein presented. Activated oncospheres (either 500 or 1000) were surgically implanted in the cerebral subarachnoid space of piglets. The clinical status and the level of serum antibodies in the animals were evaluated for a 4-month period after implantation. The animals were sacrificed, cysticerci were counted during necropsy, and both the macroscopic and microscopic characteristics of cysts were described. Based on the number of established cysticerci, infection efficiency ranged from 3.6% (1000 oncospheres) to 5.4% (500 oncospheres). Most parasites were caseous or calcified (38/63, 60.3%) and were surrounded by an exacerbated inflammatory response with lymphocyte infiltration and increased inflammatory markers. The infection elicited specific antibodies but no neurological signs. This novel experimental model of NC provides a useful tool to evaluate new cysticidal and anti-inflammatory approaches and it should improve the management of severe NC patients, refractory to the current treatments.     

A ten-year survey of Giardia cysts in drinking water supplies of Seoul, the Republic of Korea

To understand the distribution of Giardia cysts in drinking water supplies in Seoul, Korea, we collected water samples quarterly at 6 intakes in the Han River, its largest stream and 6 conventional water treatment plants (WTPs) serving drinking water, from 2000 to 2009. Giardia cysts in each of 10 L water were confirmed in 35.0% of intake water samples and the arithmetic mean was 1.65 cysts/10 L (range 0-35 cysts/10 L). The lowest cyst density was observed at Paldang and Kangbuk intakes, and the pollution level was higher at 4 intakes downstream. It seemed that these 4 intakes were under influence of Wangsuk stream at the end of which cysts were found in all samples with the mean of 140 cysts/10 L. The annual mean number of cysts was 0.21-4.21 cysts/10 L, and the cyst level at the second half of the 10 years was about 1/5 of that at first half on average. The cysts were more frequently found in winter, and their mean density was 3.74 cysts/10 L in winter and 0.80-1.08 cysts/10 L in other seasons. All finished water samples collected at 6 WTPs were negative for Giardia in each of 100 L sample for 10 years and cyst removal by physical process was average 2.9-log. It was concluded that conventional water treatment at 6 WTPs of Seoul appears to remove the cysts effectively under the present level of their source water. Domestic wastewater from the urban region could be an important source of Giardia pollution in the river.     

Echinococcus granulosus: development of an intermediate host mouse model for use in vaccination studies.

A mouse model has been developed to evaluate potential protective antigens which could render intermediate hosts resistant to a challenge infection with Echinococcus granulosus eggs. DBA/2J, CBA/J, Balb/cJ, C57/B16J and CF-1 mice were initially infected orally and parenterally with eggs, hatched eggs or activated oncospheres. Generally less than 1% of the oral dose established as cysts. Mean cysts counts were increased when Balb/cJ mice were injected intraperitoneally or intravenously with activated oncospheres. A challenge regime using 600 activated oncospheres injected intraperitoneally into adult Balb/cJ mice was subsequently adopted yielding means of 15-51 cysts per mouse. When activated oncospheres were injected intraperitoneally into Balb/cJ, DBA/2J and CF-1 mice, cysts were restricted to the peritoneal cavity. Activated oncospheres injected intravenously, however, lodged almost exclusively in the lung and thoracic cavity, except in DBA/2J mice where 55% lodged in the liver. This anatomical localization enabled the outcome of prior infection and challenge to be monitored separately. Prior infection rendered Balb/cJ mice fully resistant to subsequent challenge.     

Caryospora matatu n. sp., a new coccidian parasite (Apicomplexa: Eimeriidae) from the horned bush-viper,Atheris ceratophorus Werner, 1895 from Tanzania

Caryospora matatu n. sp. is the first species of coccidia reported from the a horned bush viper, Atheris ceratophorus endemic to Tanzania. Oocysts are spherical or slightly subspherical, 19.8 (16-23) microns, a micropyle and an oocyst residuum are absent, a single polar granule is present. An oocyst wall is bilayered, approximately 1.5 microns thick, brownish and distinctly pitted. Sporocysts are ellipsoidal, 15.6 (12.5-17.0) x 10.1 (8-12) microns, tightly fitting an internal oocyst diameter, Stieda and substieda bodies are present. An experimental inoculation of SCID mice did not confirm a facultatively heteroxenous life cycle in the studied coccidium. Morphology and evolutionary history of Caryospora species from viperids is is reviewed and discussed.     

Experimental infection of Philippine Taenia in domestic animals.

In the present study, six 34-44-day-old Small-Ear-Miniature pigs and one 14-day-old Holstein calf were each fed 10,000 Philippine Taenia eggs and sacrificed 27-43 days after inoculation. The infection rate was 100% for both pigs and calf with cysticerci recovery rates of 11 and 6%, respectively. A total of 6431 cysticerci were recovered only from the livers of the six pigs and 597 only from the liver of the calf; more occurred in the parenchyma (pigs 75%, calf 83%) than on the surface (pigs 25%, calf 17%). Mature cysticerci were found in four of the six pigs. A total of 317 cysticerci recovered from the pig livers were mature and the rest were either immature (926), degenerate or calcified (5188). All 597 cysticerci recovered from the liver of the calf were degenerate or calcified. Measurements of length, width, diameter of protoscolex, rostellum, and sucker and hooklet pattern indicated that Philippine Taenia is very similar to Taenia from Taiwan, Korea, Indonesia and Thailand and very different from classical T. saginata and T. solium.     

Eimeria pipistrellus n. sp. from Pipistrellus kuhlii (Chiroptera: Vespertilionidae) in Saudi Arabia

Fecal samples from 12 Pipistrellus kuhlii captured at Shagrah, Saudi Arabia, were examined for coccidia and three (25%) found to harbor a undescribed eimerian, herein described as Eimeria pipistrellus n. sp. Sporulated oocysts were subspherical, 24.8 x 23.2 (22-27 x 20-25) microns, with a bilayered and smooth wall. The micropyle was absent, but a large oocyst residuum and a single polar granule were present. Sporocysts were ovoid, 11.6 x 8.3 (10.5-13 x 7.5-9) microns, with a prominent Stieda body, but without a substiedal body; sporozoites lay head to tail in sporocysts and contained one large posterior refractile body. Eimeria pipistrellus n. sp. is the 3rd species of the genus Eimeria found from bats of the genus Pipistrellus.     

Localisation of three host-protective oncospheral antigens of Taenia ovis

Immunohistochemistry, confocal immunofluorescence and immunogold labelling were used to determine the localisation of the host-protective antigens To16, To18 and To45W in Taenia ovis oncospheres. During maturation of the adult tapeworm the antigens were initially seen as diffuse staining in the developing oncospheres but in mature oncospheres four distinct cells stained positively for the antigens. Confocal fluorescence microscopy using different fluorophores revealed that each of the antigens co-localises within the same cells in the oncosphere. No surface localisation was seen in non-activated or recently activated parasites. Immunogold labelling of non-activated oncosphere sections viewed in transmission electron microscopy revealed labelling of bilateral cells, however the identities of these cells was unclear due to deficiencies in the current level of understanding of oncosphere ultrastructure. Localisation of all the antigens changed dramatically after oncospheres were activated in vitro with each of the antigens being dispersed more generally throughout the parasite parenchyma. During development of the parasites in in vitro culture, surface localisation of the proteins was seen in parasites after 3 or more days in culture. All three antigens were found to be completely absent in parasites by 15 days of culture. The location of the host-protective antigens suggests that initially the invading oncospheres are not susceptible to vaccine-induced antibody and complement mediated attack, but that as the parasites mature, the host-protective antigens come to be associated with the parasite’s surface, rendering them susceptible to immune attack.     

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.     

Formation of actin filament bundles in the ring canals of developing Drosophila follicles

Growing the intracellular bridges that connect nurse cells with each o ther and to the developing oocyte is vital for egg development. These ring canals increase from 0.5 microns in diameter at stage 2 to 10 microns in diameter at stage 11. Thin sections cut horizontally as you would cut a bagel, show that there is a layer of circumferentially oriented actin filaments attached to the plasma membrane at the periphery of each canal. By decoration with subfragment 1 of myosin we find actin filaments of mixed polarities in the ring such as found in the "contractile ring" formed during cytokinesis. In vertical sections through the canal the actin filaments appear as dense dots. At stage 2 there are 82 actin filaments in the ring, by stage 6 there are 717 and by stage 10 there are 726. Taking into account the diameter, this indicates that there is 170 microns of actin filaments/canal at stage 2 (pi x 0.5 microns x 82), 14,000 microns at stage 9 and approximately 23,000 microns at stage 11 or one inch of actin filament! The density of actin filaments remains unchanged throughout development. What is particularly striking is that by stages 4-5, the ring of actin filaments has achieved its maximum thickness, even though the diameter has not yet increased significantly. Thereafter, the diameter increases. Throughout development, stages 2-11, the canal length also increases. Although the density (number of actin filaments/micron2) through a canal remains constant from stage 5 on, the actin filaments appear as a net of interconnected bundles. Further information on this net of bundles comes from studying mutant animals that lack kelch, a protein located in the ring canal that has homology to the actin binding protein, scruin. In this mutant, the actin filaments form normally but individual bundles that comprise the fibers of the net are not bound tightly together. Some bundles enter into the ring canal lumen but do not completely occlude the lumen. all these observations lay the groundwork for our understanding of how a noncontractile ring increases in thickness, diameter, and length during development.     

Porcine model of neurocysticercosis by intracarotid injection of Taenia solium oncospheres: Dose assessment,infection outcomes and serological responses

BackgroundNeurocysticercosis (NCC) is the infection of the human central nervous system (CNS) by Taenia solium larvae that cause significant neurological morbidity. Studies on NCC pathophysiology, host-parasite interactions or therapeutic agents are limited by the lack of suitable animal models. We have previously reported that carotid injection of activated T. solium oncospheres directs parasites into the CNS and consistently reproduces NCC. This study assessed the minimal dose required to consistently obtain NCC by intracarotid oncosphere injection and compared antigen and antibody response profiles by dose-group.Methods/Principal findingsThree groups of pigs were infected with either 2500 (n = 10), 5000 (n = 11), or 10000 (n = 10) oncospheres. Two pigs died during the study. Necropsy exam at day 150 post-infection (PI) demonstrated viable NCC in 21/29 pigs (72.4%), with higher NCC rates with increasing oncosphere doses (4/9 [44.4%], 9/11 [81.8%] and 8/9 [88.9%] for 2500, 5000, and 10000 oncospheres respectively, P for trend = 0.035). CNS cyst burden was also higher in pigs with increasing doses (P for trend = 0.008). Viable and degenerated muscle cysticerci were also found in all pigs, with degenerated cysticerci more frequent in the 2500 oncosphere dose-group. All pigs were positive for circulating parasite antigens on ELISA (Ag-ELISA) from day 14 PI; circulating antigens markedly increased at day 30 PI and remained high with plateau levels in pigs infected with either 5000 or 10000 oncospheres, but not in pigs infected with 2500 oncospheres. Specific antibodies appeared at day 30 PI and were not different between dose-groups.Conclusion/SignificanceIntracarotid injection of 5000 or more oncospheres produces high NCC rates in pigs with CNS cyst burdens like those usually found in human NCC, making this model appropriate for studies on the pathogenesis of NCC and the effects of antiparasitic treatment.