Some aspects of histochemical studies on the parasite and tissue reaction in bovine cysticercosis

Histochemical studies on the cysticercus and surrounding tissue reaction were performed at various intervals after experimental infection. It was found that acid mucosubstances and proteins with SH- and SS-groups appeared first in the granulation tissue around the cysticercus (on about day 14 p.i.) and only later (on day 28 p.i.) in the tegument of the cysticercus where they were localized in the rim of microtriches. This envelope consisting of mucosubstances and proteins seems to be identical with the electron-dense substance found on the surface of developing cysticercus during electron-microscopical studies. It is considered to be a mimicry enabling the cysticerci to survive even in an immunologically unfavourable environment. Phospholipids were found in activated fibroblasts and in some cells of macrophage type on days 21 and 30 p.i. and in a large number in subtegumental cells of cysticercus on days 28-34 p.i. This phenomenon seems to be correlated with the increased activity of subtegumental cells of the larva in this period. In morphologically fully differentiated cysticerci, the reaction for phospholipids in subtegumental cells and distal cytoplasm was only feebly positive. Phospholipids were not detected in the rim of microtriches at any time after infection.     

Tissue reaction in the heart of cattle with a spontaneous and artificial Cysticercus bovis infection.

Results of detailed studies on tissue reactions to Cysticercus bovis in the heart of cattle, together with a comparison of findings in animals with spontaneous and experimental infection, and an evaluation of tissue reactions in relation to the location, morphology and morphogenesis of C. bovis provided evidence for the fact that in general, the response of the heart to the presence of C. bovis was an inflammatory reaction characterized by the origin of a pseudoepithelial border and a zone of granulation tissue. Later, when necrotic changes started to affect the cysticercus, the inflammatory reaction started to develop anew. It was accompanied by an exudation and a subsequent resorption. Characteristic features were focal necroses both of the exudate and the inflammatory border followed by a dystrophic calcification, focal necroses and a dystrophic calcification of individual collagenous fibres and groups of these fibres in addition to a regular appearance of necrotic-like foci typical of a reaction to C. bovis. The location of the cysticercus in a certain part of the lymphatic system of the heart and in skeletal muscles was shown to have a considerable effect on the course of the inflammatory reaction. Differences in the development of the inflammatory reaction explained concomitant findings of dead and live cysticerci at the same time after an experimental infection.     

Tissue reaction after subcutaneous injection of Taenia saginata oncospheres

After subcutaneous injection of T. saginata oncospheres, a slight swelling is visible at the site of injection first after 13 days. Conspicuous projecting nodes appear after 3-4 weeks. Histological examinations of the site of injection revealed the following changes: On days 3 and 4 p.i.--edema, focal necrosis and haemorrhage, exudation of leukocytes, activation of monocytes and fibroblasts. On day 7 p.i.--in addition to edema and foci of eosinophiles, a striking activation of monocytes and fibroblasts, focal accumulation of macrophages, proliferation of blood capillaries and formation of collagen. On day 10 p.i.--eosinophiles and light macrophages around the larvae, fibroplastic granulation tissue at the periphery and collagenous connective tissue abundant. Hyperplasia of lymphoid tissue starts to appear at this time. On days 13-14 p.i.--a large amount of newly formed connective tissue in granulation tissue, diffuse infiltration of eosinophiles and hyperplasia of lymphatic tissue. On days 19-34 p.i.--haemorrhage around the cysticerci, activation of macrophages, phagocytizing erythrocytes. Endothelia of blood capillaries proliferate; lymphatic follicles are formed at the periphery of nodular affection which appears after inoculation of oncospheres. On day 34 p.i.--distinct formation of a pseudocyst. At the period from 53th to 61st day after injection, there is a mature collagenous connective tissue among the cysts, but still strongly infiltrated with cells. Clusters of siderophages are visible in connective tissue septa between the cysts.     

Pathology of the migration phase of Taenia hydatigena (Pallas, 1766) larvae

The pathological picture of the migration phase of C. tenuicollis in pigs is characterized by a haemorrhagia within the liver parenchyma and under the liver surface. The haemorrhagia, which represents a migrational canal, is induced by the destruction of liver sinuses by migrating larvae. Approximately on day 10 p.i. a serofibrinous peritonitis occurs and free cysticerci appear in the exudate. On days 14-16 p.i. the exudative peritonitis may increase. The cysticerci are localized under the serosas or on them. On about day 10 p.i. even the pulmonary form of the disease may occur. On day 13 p.i. the cysticerci are present in the lumen of lung arteries or they migrate out of them. The changes in the lungs and on the pleura, as well as their dynamic changes, are identical with the changes in the liver and on the peritoneum. The period on days 21-24 p.i. is characterized by extensive synechiae of serosas and the cysticerci are firmly attached to the serosas. On day 35 p.i. the connective tissue adhesions persist and many of the cysticerci exhibit dystrophic changes or are dead and often already calcified. The wall of the pseudocyst, in which the cysticercus is situated, consists of the fibrocytes and serosa, and its cavity is not lined with endothelium, as it is the case in C. bovis and C. cellulosae.     

Symptomatology of taeniasis caused by Taenia saginata

The course of an infection with T. saginata has been studied for two years on a volunteer who had swallowed a 16-20 week-old Cysticercus bovis. The pathognomonic character of the infections was shown to be the spontaneous release of cestode proglottids first appearing in the faeces at day 87 p. i. An incidental release of a larger number of segments occurred after an excessive consumption of alcohol. The next release of proglottids followed after 42 to 88 days. The importance of the results of this observation both for the immediate study of the field case and an elucidation of the epidemiology of taeniasis has been evaluated in the present paper.     

Morphological and histochemical demonstration of hooks in the rostellar region of Cysticercus bovis.

Hooklets and early developmental stages of hooks were discovered in the tegument among the microtriches in the rostellar region of 83- and 108-day-old Cysticercus bovis. The cortical layer of hooks consists of proteins with tyrosine and SS groups. The rostellar sac and bulb are distinctly developed in the parenchyma of the rostellar region.     

Pathology of experimental Cysticercus bovis infection in the reindeer (Rangifer tarandus Linné, 1758)

In the present study, the tissue reaction of the brain, skeletal muscles and heart in experimental C. bovis infection of the reindeer is described. There is non-purulent cysticercal leptomeningites with formation of multinucleate symplasms in the cerebral meninges, and lymphocytic encephalitis in the superficial layers of the cerebral cortex. The tissue reaction around the morphologically differentiated cysticercus in the meningeal location is similar to that in muscle cysticercosis of cattle. In muscles and heart, larvae die very soon after infection and they are resorbed in the course of formation of fibroplastic granulation tissue around them. C. bovis reaches the infective stage in cerebral localization only. The authors suppose that this phenomenon is due to a certain degree of immunological tolerance in the brain.     

Immune response in rabbits experimentally infected with Ascaris suum

Immune response of rabbits experimentally infected with Ascaris suum was studied by indirect haemagglutination method. The animals were infected with the doses of 5,000, 10,000 and 20,000 infective eggs per animal. Positive reactions were observed from days 5-11 p.i., maximum reactions on days 11-19 p.i. A reinfection with the same doses (1x or 2x after 35 and 65 days) increased the antibody titre. The strongest individual reaction was recorded on day 19 p.i. in the group infected with the highest dose (titre 1 : 4096). The increased antibody titres persisted til the end of the experiment (82th day p.i.) in all groups.     

Some aspects of the presence of surface--associated acid mucosubstances on larval Taenia saginata infecting suitable and unsuitable hosts

The coat of acid mucosubstances occurring on the bladder surface was studied in Cysticercus bovis (larvae of Taenia saginata) developing in specific (cattle) and nonspecific (some other ruminants) intermediate hosts. In cysticerci developing in nonspecific intermediate hosts, this coat is absent or poorly developed even at the time when it is completely formed on the bladder surface of C. bovis from cattle. If the cysticercus develops up to the infective stage in a nonspecific intermediate host, it is usually localized outside the muscles: in the brain, lungs or liver. Its bladder is then also covered by a coat of acid mucosubstances. The absence or insufficient development of the protective coat on larvae in nonspecific intermediate hosts is explained by their early and strong tissue reaction.     

Histopathological changes in the liver tissue of house mouse and common vole during sarcocytosis

The asexual reproduction of Sarcocystis dispersa was studied in the liver of the house mouse. Histopathological examinations revealed infection of parenchymal cells with the parasite and diffuse cellular infiltrations with the presence of polymorphonuclear cells, monocytes and eosinophilic leukocytes. The volume and number of cellular infiltrates increased gradually from day 3 till day 10 p.i. Then appeared necrotic foci and both phenomena reached the maximum on days 10-12 p.i. On days 21-34 p.i., no changes occurred in the tissue and the liver healed without scars. The infection of common vole with Sarcocystis cernae sporocysts caused cellular infiltrations in the liver around the portobiliary veins. The parasite was present from day 3 till day 7 p.i. The histopathological picture of liver changes was similar to that in the house mouse.     

Variation in the pathogenicity of two Turnip mosaic virus isolates in wild UK Brassica rapa provenances

Brassica rapa can be infected with Turnip mosaic virus (TuMV) as a result of manual inoculation or aphid transmission, but infected plants have not been found in the field. In this study, B. rapa plants grown from seed collected from two field sites in southern England were mechanically inoculated with one of two distinct isolates (pathotypes) of TuMV under glasshouse conditions. These had either been isolated from Brassica oleracea growing wild in Wales, (GBR 83, pathotype 3) or Dorset (GBR 98, pathotype 1). Use of ELISA as an index of infection in manually inoculated B. rapa showed that although seed provenance had a small effect on the proportion of plants infected, the biggest factor was the virus isolate. Both virus isolates infected both lines of B. rapa , but invaded at different rates, although both resulted in easily discernible symptoms. The severity of symptoms was not related to amounts of virus in the infected plants. A significantly greater proportion of plants were infected with GBR 83 at 45 days post-inoculation (d.p.i.) than GBR 98. but GBR 98 caused significantly more severe and obvious symptoms as well as greater mortality at 119 d.p.i., in plants from both sites than GBR 83.     

Protective effects of caffeic acid phenethyl ester on rotenone-induced myocardial oxidative injury

Rotenone, an insecticide, causes toxicity through inhibition of mitochondrial electron transport chain at complex I and oxidative injury to the tissues. The aim of the present study was to determine in vivo effects of rotenone on myocardium and cardio-protective effects of caffeic acid phenethyl ester (CAPE), an antioxidant agent, against rotenone toxicity in rats. The rats were divided into three groups: untreated control, rotenone (2.5 mg/kg/day for 60 days, i.p.) and rotenone + CAPE groups. CAPE was administrated i.p. 10 μmol/kg/day for 62 days started two days before first dose rotenone injection. The malondialdehyde, nitric oxide levels and xanthine oxidase activity of rotenone group was significantly higher than control and rotenone + CAPE groups (p < 0.05). However, catalase activity in the rotenone group was decreased in comparison with the other groups (p < 0.05). The superoxide dismutase activity of rotenone group was insignificantly decreased compared to the others. In conclusion, rotenone caused lipid peroxidation in myocardial tissue and CAPE treatment prevented this rotenone-induced lipid peroxidation in rats. CAPE might be a cardio-protective agent against myocardial toxicities.     

Development of Procamallanus saccobranchi (Nematoda: Camallanidae), a parasite of a freshwater fish in India

The development of the nematode Procamallanus saccobranchi Karve, 1952, a parasite in the stomach of the fish Heteropneustes fossilis (Bloch), was studied in Mesocyclops crassus (Fischer) and Mesocyclops leuckarti (Claus). After being ingested by the copepods the nematode first-stage larvae penetrated into the haemocoel of the intermediate host; there they moulted twice (on days 3 and 5 p.i. at 28-30 degrees C) attaining the third, infective stage. The definitive host H. fossilis acquired infection by feeding on copepods harbouring infective-stage larvae; in the stomach of this definitive host, the larvae were observed to undergo two more moults. The third moult occurred on day 13 p.i. and the fourth moult on day 38 p.i. and day 66 p.i. in "male" and "female" larvae, respectively. The larval stages, including the moulting forms are described and illustrated.     

Experimental infection of immunocompetent and immunodeficient mice with Encephalitozoon cuniculi

An experimental infection with the microsporidian Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 was studied using a model of immunocompetent BALB/c mice and immunodeficient SCID mice. The course of infection after intraperitoneal inoculation of E. cuniculi spores was evaluated using the presence of spores in peritoneal macrophages as a criterion. First significant decrease in the proportion of infected cells was recorded on day 9 post infection (p.i.) in BALB/c mice. From day 14 p.i. no spores were observed in macrophages from BALB/c mice, while the number of infected macrophages from SCID mice increased until the death of the mice. The natural killer (NK) cell activity of mouse splenocytes was compared with the production of interferon gamma (IFN-gamma) by these cells. While in BALB/c mice NK activity peaked on days 9 and 14 p.i., in SCID mice the marked increase of NK activity was recorded close before death of mice, on day 21 p.i. in correlation with the production of IFN-gamma. Production of specific antibodies was demonstrated from day 9 p.i. in sera from BALB/c mice. It is concluded that intraperitoneal infection of SCID mice with spores of E. cuniculi results in the marked increase in the number of peritoneal exudate cells and in the percentage of infected cells close before death of mice. Neither high activity of NK cells nor increased production of IFN-gamma are sufficient for the recovery of SCID mice from an E. cuniculi infection.     

The feeding mechanism of intracellular muscle larvae, Trichinella nativa Britov et Boev, 1972 and T. pseudospiralis Garkavi, 1972

We confirmed, with the electron microscope, that Trichinella larvae feed directly on the host tissue during their initial development. They suck, by means of a stylet acting as a piston, all components of the muscle cell which develops into a nurse cell, into their oral cavity. The stylet is controlled by a muscle retractor. At day 10 p.i., fragments of myofilaments and glycogen are present in the oesophagus of the larva of T. nativa, mitochondria occur in it at day 20 p.i. During the larval growth of T. pseudospiralis, remnants of a contractile material are present in the digestive system. The composition of the food ingested by the larva is in agreement with the development of changes in the muscle fibre. Initial changes in the fibre caused by the two Trichinella species are comparable, later changes are not. T. pseudospiralis influences the character of changes by its uninterrupted movement inside the fibre. From days 50-90 p.i. with T. pseudospiralis, a focally distributed sarcotubular system proliferates irregularly in different sites of the fibre. This is in contrast to a heavy proliferation of tubules inside a concentric membranous system around the larva of T. nativa becoming enclosed in a capsule. The larva which has ceased to feed on the host tissue at this time, feeds apparently on low-molecular substances of the membranous system transported from the surrounding vascular system which has increased in quantity in the endomysium. In the later course of the infection, the enzymatic activity of the AIP and the SDH increases in the vicinity of the larva of T. nativa, i.e., in the sarcoplasm inside the capsule.(ABSTRACT TRUNCATED AT 250 WORDS)     

Persistence of the fungicides thiabendazole, carbendazim and prochloraz-Mn in mushroom casing soil

The persistence of the fungicides thiabendazole, carbendazim and prochloraz-Mn in mushroom casing soil was determined following their application at rates commonly used in the UK mushroom industry. Following drench applications, the concentration of all active ingredients was always higher in the top half of the casing soil layer than in with the bottom half. When carbendazim and prochloraz-Mn were applied using half the recommended volume of water per unit area, there was a tendency for carbendazim concentrations to be even higher in the top half of the casing soil, compared with the standard treatment, while concentrations of prochloraz-Mn were similar, irrespective of the volume of water used. Carbendazim and prochloraz-Mn concentrations in the top half of the casing layer decreased to < or = 13 mg kg(-1) by day 28/29, following different applications, whereas the thiabendazole concentration was consistently high during the course of the crop, being < or = 83 mg kg(-1) at day 31. Fungicides that do not persist at high concentrations in mushroom casing soil for the duration of the crop may not give good control of mushroom pathogens, particularly if the fungicide concentration falls to a level which is close to the EC50 value.     

Correlation of the results of IFAT-DASS and ELISA tests in experimental cysticercosis of mice

The sera of mice experimentally infected with Taenia crassiceps were tested for the occurrence of the antibodies by the enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence using defined antigen substrate spheres (IFAT-DASS). Results of both tests were compared. From day 11 p.i. until the end of the experiment (day 108 p.i.) antibodies were detected by both tests. The maximal intensity of the ELISA and IFAT-DASS reactions was observed between days 63 and 94 and days 14 and 46 p.i., respectively. ELISA is an easy-to-do and objectively appraisable method, IFAT-DASS is more suitable for testing antigens weakly adsorbing to polystyrene plates.     

Regeneration in mouse skeletal muscle injured by Trichinella larvae

During the infection caused by Trichinella pseudospiralis serious damage to muscles is partly compensated with regeneration process. Short, thin fibrillae with central position of the nuclei--regenerating myotubes originate 20--40th day post infection in endomysial tubes remaining after damaged muscle fibres, left by migrating larva. On the 10th day post infection in the vicinity of moving larva activation of nuclei and increased origin of satellite cells under basal membrane occur. With development of the infection endothelia in the vicinity of altered fibrillae are increasing in number but there is small inflammatory and fibroproductive reaction only. During the infection caused by Trichinella spiralis and T. nativa, alteration of muscle fibres is accompanied by early inflammatory and fibroproductive reaction towards immediate surroundings of larvae. In a changed segment of muscle fibre with the larva--in pseudocyst there is altered basal lamina as well, built in increased glycocalyx and in the course of 20 days encased by connective tissue. Revascularisation and regeneration in a short damaged segment does not occur even during long-lasting infection because of separation by capsule.     

Studies on amoebae and cysts associated with the isolation of Spongospora subterranea f.sp. subterranea in vitro

New evidence is presented to support the contention that the amoeba/cyst colonies isolated from surface-sterilized Spongospora subterranea f.sp. subterranea -infected potato tubers and spore balls have a saprophytic phase but are contaminants and not S. subterranea. Amoebae isolated from infected tissues and spore balls formed colonies associated with bacteria on 1% water agar at 18°C and encysted after 5–7 days. These cysts were morphologically distinct from the resting spores of S. subterranea and were formed singly or in a layer, unlike the spore ball (cystosorus) of S. subterranea . Amoebae, cysts and mixtures of amoebae and cysts in primary, secondary and tertiary subcultures failed to infect tomato roots. PCR amplification of DNA from amoebae, cysts and spore balls using the S. subterranea -specific primer pair SsF/R generated a 434-bp product from S. subterranea spore balls only and not from amoebae or cysts. When an amoeba/cyst-specific primer pair AmF/R was designed and used for PCR amplification, a single 411-bp product was generated from DNA of amoebae and cysts, but not from DNA of S. subterranea spore balls. These results are discussed in relation to earlier reports claiming the successful isolation of S. subterranea and other plasmodiophorids in vitro .     

The dynamics of eosinophilia in concurrent infections with Trichinella spiralis Owen, 1835 and Toxascaris leonina Linstow, 1909

The concurrent infection with larvae of Trichinella spiralis and eggs of Toxascaris leonina was studied under various conditions using 75 male white mice. The changes in content of eosinophilic leucocytes in the blood, as well as the total number and distribution of larvae of both parasites in different body tissues were demonstrated. The primary infection with Toxascaris leonina caused an increase in the number of eosinophilic leucocytes from day 4 p.i., whereas the infection with Trichinella spiralis larvae induced an increase only from day 7 p.i. An antagonism was observed between the two parasite species: the primary infection with T. leonina led to a decrease in the total number of muscle larvae of T. spiralis, and, vice versa, the primary infection with T. spiralis suppressed the development of T. leonina.