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Comparative studies were done to test the practicability of various methods of detection in bovine sarcosporidiosis. Macroscopic examination of meat, trichinoscopy and artificial digestion were carried out using meat from the heart and oesophagus. A total of ninety-one random animals were involved. It was concluded that artificial digestion of trypsin is the method of choice (practical, sensitive). As much as 100 per cent of the animals were found to be infected with Sarcocystis spp.

We have cloned blood trypomastigotes from infected mice and found that Trypanosoma cruzi strains are composed of heterogeneous populations that dramatically vary (more than 100 fold) in their abilities to attach to and enter rat heart myoblasts. Trypomastigote clones were distinctively separated into highly and weakly infective groups presenting higher and lower rates of attachment to myoblasts, respectively. Each trypomastigote clone maintained the same profile of attachment and internalization into heart myoblasts when tested at different periods of time. This pattern did not change when the parasites were incubated in fresh medium before being exposed to heart myoblasts. Highly and weakly infective clones show differences at the cell surface level, particularly with regard to a 83 kDa glycoprotein. We have identified this 83 kDa glycoprotein as the parasite membrane ligand that specifically binds to rat heart myoblasts. The binding of the biotinylated 83 kDa to myoblasts is inhibited by cold excess in Western blots, as indicated by laser densitometry. In addition, the specific binding of this molecule to myoblasts is saturable and is greater in highly than in weakly infective trypomastigote clones. Highly invasive trypomastigote clones express this glycoprotein in more abundance on their surface than weakly infective trypomastigote clones. These results indicate that the 83 kDa glycoprotein present on the surface of T. cruzi trypomastigotes mediates the attachment of the parasite to heart myoblasts.

Heart, esophagus, diaphragm and skeletal muscle obtained from various herbivores on the National Bison Range were examined grossly for Sarcocystis. Sarcocystis was found in 81, 50, 50, and 13% of the mule deer, (Odocoileus hemionus), white-tailed deer (O. virginianus), elk (Cervus elaphus), and bison (Bison bison), respectively.

Besnoitia cysts in the heart of a lizard (Lacerta dugesii) from the islands of Madeira are the first record of besnoitiosis in a poikilothermic animal in the Old World. The size of the cysts corresponds to those found in lizard genera (Basiliscus and Ameiva) from Panama which belong to B. darlingi. Up to now nothing is known concerning the life cycle of this species from Madeira but it seems possible that cats function as definitive hosts as well as in the other species.

Tissue parasitism, inflammatory process (histologic methods) and sympathetic denervation (glyoxylic acid-induced histofluorescence for demonstration of catecholamines) were studied in the heart (atrium and ventricle) and the submandibular gland of rats infected with the Y strain of Trypanosoma cruzi. In the heart paralleling intense parasitism and inflammatory process, the sympathetic denervation started at day-6 of infection and at the end of the acute phase (day 20) practically no varicose nerve terminals were found in both myocardium and vessels. In the submandibular gland, in spite of the rarity of amastigote pseudocysts and the scarcity of inflammatory foci, slight to moderate (days 13-15 of infection) or moderate to severe denervation (day 20) was found. At day 120 of infection both organs exhibited normal pattern of sympathetic innervation and only the heart showed some inflammatory foci and rare pseudocysts (ventricle). Our data suggest the involvement of circulating factors in the sympathetic denervation phenomena but indicate that local inflammatory process is, at least, an aggravating factor.

The clinical picture of myocarditis was studied in 72 patients with toxoplasmic infection and in 44 patients not suffering from this infection. Comparison of the clinical signs of myocarditis in these two groups showed that myocarditis of toxoplasmic etiology has no characteristic features. The only distinction between these two groups was the different frequency of various symptoms. In view of this, methods of laboratory diagnosis of toxoplasmosis acquire much significance.

A pig infected with 2 x 10(5) sporocysts of Sarcocystis miescheriana which had survived the acute phase of the disease from 12 dpi until 17 dpi retarded in growth and finally died at 60 dpi. From gross pathological examination heart failure was assumed as the cause of death. Histopathologically severe Myocarditis eosinophilica fibrosa was diagnosed. The sections through the heart muscle contained numerous degenerating and some intact sarcocysts.

Myocardial fibrosis can occur as a complication of chronic infection of the heart with Trypanosoma cruzi (Chagas' disease) and can lead to serious disability. To assess whether there might be a direct relationship between intracellular parasitization and subsequent tissue fibrosis in this disease, we tested serum-free conditioned media from cultures of fibroblasts, vascular smooth-muscle cells, and myocardial cells for fibroblast-stimulating activity. Conditioned media from all infected cultures, but not from uninfected cultures, stimulated fibroblast [3H]thymidine incorporation, DNA and protein synthesis, and cell proliferation. Fibroblast-stimulating activity was also detected in extracts of amastigotes but not of trypomastigotes or epimastigotes. We conclude that parasitization of mesenchymal cells, including myocardial cells, results in elaboration of a fibroblast-stimulating factor(s), perhaps of parasite origin. We postulate that this factor may play a role in initiation of myocardial fibrosis in Chagas' disease.

In a survey in 1973 undertaken to determine the prevalence of Dirofilaria immitis in 100 dogs from a public pound in western New York, 2 dogs were found to be positive. Microfilariae of Dipetalonema sp were not present. Hearts and pulmonary blood vessels were dissected for adult worms, and blood samples were examined for microfilariae, using a modified Knott technique. Although adult heartworms and microfilariae have been recovered from wild foxes, coyotes, and wolves in New York, this is the first report of heartworm in domesticated dogs in the state.

We studied the role of surface GlcNAc residues on the surface of invasive (mouse-blood and insect-derived trypomastigotes) and non-invasive amastigote forms of Trypanosoma cruzi on parasite association with (i.e., surface binding plus internalization) macrophages and heart myoblasts. Removal of GlcNAc from the three forms of the parasite with beta-N-acetylglucosaminidase markedly increased the number of organisms per 100 cells and caused the organisms to associate with a greater percentage of host cells. N-Acetylglucosaminidase did not produce this effect after heat-inactivation and a substrate of the enzyme, N,N'-diacetylchitobiose, reduced it when it was present during the enzymatic treatment. The N-acetylglucosaminidase effect on T. cruzi was reversible after 2.5 h. When macrophages or myoblasts were treated with N-acetylglucosaminidase, their capacities to associate with blood or insect-derived trypomastigotes was reduced. Since removal of GlcNAc residues from the parasite surface increased their association with the host cells, GlcNAc would appear to interfere with the association process. On the other hand, GlcNAc residues on the host cell appear to favor the association.

In 2 cattle experimentally infected with Trypanosoma vivax, strain EATRO 1695, trypanosomes were found in the marginal sinus of one of several lymph nodes examined. One animal showed trypanosomes in a small focus in the interstitial tissue of the heart. It is concluded that Trypanosoma vivax can not be regarded as a strict plasma parasite.

Sarcocystis cruzi forms cysts in striated muscle of the bovine host following schizogony. The fine structure of the immature cyst within muscle fibers of the ventricular myocardium was studied in relation to its development and to the multiplication of parasites within it. The young cyst is enclosed by a cyst wall containing numerous small protuberances. Metrocytes within the cyst are irregular in shape and are separated from each other and the cyst wall by a thin layer of ground substance. The parasite multiplies by endodyogeny within the metrocyte. As the cyst enlarges, the host muscle fiber is disrupted and large protrusions are present in the cyst wall.

The effect of inoculum size and time on the distribution of Toxocara canis larvae in the mouse was investigated by recovering larvae from various body regions 7, 14, 28, and 56 days after administration of either 200, 600 or 1,000 infective eggs to groups of ten male mice. An analysis of variance of larval recoveries from the carcass, liver, brain and cardiopulmonary system suggests that inoculum size was a significant factor determining the proportional recovery for each of these sites. Length of infection was significant in relation to numbers of larvae in the anterior carcass, genitourinary system, brain and heart plus lungs, while length of infection and inoculum size acting in concert influenced the numbers of larvae recovered from the carcass, liver, brain, heart and lungs. Crowding effects, manifested as altered dispersion rates, were seen in the heavier infections.

Micronema, normally free-living in soil and humus, rarely invades and reproduces in the central nervous system, kidneys, lungs, maxillae and nasal cavity of equines. Two Micronema infections causing fatal meningoencephalomyelitis in man have been reported from Canada and Texas. Here we report a third infection in a 54-year-old black man, resident of Washington, D.C., who probably acquired the infection from decubitus ulcers. The worms in this patient were in the liver, heart and brain. The Micronema species was not identified.

Megazol, nifurtimox, benznidazol and allopurinol were investigated, by light and electron microscopy, for their action on T. cruzi. Both the direct effect upon amastigote and trypomastigote forms and the effect upon the interaction of heart muscle cells (HMC) with bloodstream trypomastigotes were studied. The proliferation of amastigotes in Warren medium was inhibited in a dose-dependent manner by megazol, nifurtimox and benznidazol. Treatment of amastigotes (25-50 microM/24 h) and trypomastigotes (25 microM/24h) led to several ultrastructural alterations in the parasites. These three drugs also had a potent effect on the treatment of infected heart muscle cells when added at the beginning of the interaction or after one or three days of infection. The interiorized parasites showed a similar pattern of ultrastructural alterations as observed by the direct effect on the amastigotes. The primary heart muscle cell culture proved to be a suitable model for the study of drugs on intracellular parasites. Likewise, the amastigote proliferation in axenic medium was shown to be an adequate assay for an initial trial of drugs. These parameters seem very reliable to us for a systematic investigation of the mechanism of action of new drugs.

A single juvenile male raccoon (Procyon lotor) was found naturally infected with Dirofilaria immitis. Two immature female worms were found in the heart of this raccoon at necropsy. Lesions attributable to the presence of these parasites were not found. Histopathologic examination of various tissues did not reveal any microfilariae. The raccoon may serve as an aberrant definitive host for this parasite, however, patent infections have not been reported.

By the means of light-microscopic cytological enzymatic methods, the presence of several enzymes (NAD.H and NADP.H-tetrazolium reductases, in addition to alcohol, succinate, isocitrate, glucose-6-phosphate, beta-hydroxybutyrate and glutamate dehydrogenases) has been studied in the tissue cysts of S. bovicanis. A mixed character of oxidative metabolism in the cyst stages is suggested, the involvement of gluconeogenesis being proposed. Neither beta-hydroxybutyrate nor alcohol dehydrogenase activity was demonstrated indicating the absence or a very low rate of lipid metabolism, and suggesting that the process of glycolysis may end with malate formation. From the low activity level of succinate dehydrogenases it is concluded that the citric acid cycle plays presumably a secondary role, if at all, in the energy supply of the cyst stages. Also, a low activity of glucose-6-phosphate dehydrogenases is pointed out. Thus, it is proposed that glycolysis may be primary, if not the only, oxidative pathway in the cyst stages.

Golden hamsters were used to determine whether intraperitoneal Zn supplementation can improve the outcome of infection with Schistosoma mansoni. The animals were divided into two groups; one received an initial intraperitoneal dose of Zn chloride (0.75 mg 100 g body wt.-1) followed by booster doses (0.25 mg 100 g body wt.-1) twice weekly for four weeks, the other group received no Zn supplement. After one week, when the initial and one booster doses were given, half of the animals in each group were exposed to S. mansoni cercariae for two hours using body immersion technique. After five weeks (one week after the final Zn supplement) the animals were killed, their worm burdens determined and their livers, kidneys, spleens, hearts and sera examined. There was a significant reduction in total worm counts in the Zn supplemented group (P less than 0.05). Also, Zn supplementation of infected animals protected them against the hepatomegaly which is very often associated with schistosomiasis. Spleen weight and Zn uptake were highest in the infected Zn supplemented group, indicating that this organ requires larger amounts of Zn to perform its various Zn-dependent immunological functions. The data suggest that Zn may enhance the ability of the body organs to resist some of the harmful effects of schistosomal infection.

The biological characterization of the Trypanosoma cruzi clone Dm 28c in terms of its growth in LIT medium, cell-cycle, infectivity to mice and interaction with professional and non-professional phagocytic cells shows that it behaves as a bona fide T. cruzi representant. The biological properties of this myotropic clone do not change according to the origin of the trypomastigote forms (i. e., from triatomines, infected mice, cell-culture or from the chemically defined TAUP and TAU3AAG media). In addition Dm 28c metacyclic trypomastigotes from TAU3AAG medium display a high infectivity level to fibroblasts and muscle cells. Experiments on binding of cationized ferritin to trypomastigotes surface show the existence of cap-like structures of ferritin in regions near the kinetoplast, however the nature and role of these anionic sites remain to be determined. The results indicate that metacyclic trypomastigotes from the Dm 28c clone obtained under chemically defined conditions reproduce the biological behaviour of T. cruzi, rendering this system very suitable for the study of cell-parasite interactions and for the isolation of trypanosome relevant macromolecules.

An evaluation of the tissue reaction to Cysticercus bovis in the liver of calves with an artificial infection and that of oxen with a natural infection provided evidence for the fact that the liver of these animals responded to an infection with C. bovis with an extensive granulomatous reaction. A comparison of tissue reaction to cysticerci at an identical stage of development showed that the reaction of the liver parenchyma was much more intensive than that of the heart and the skeletal muscles. In the described cases, this intensive reaction caused the death of the cysticerci before the completion of their development. Evidence was obtained for the first time that also in the liver C. bovis was located in the lymphatic vessels.

The capacity of blood (trypomastigote) forms of Trypanosoma cruzi to infect mouse peritoneal macrophages or rat heart myoblasts in vitro was inhibited by treatment of the trypomastigotes with DL-alpha-difluoromethylarginine (F2Me Arg), monofluoromethylagmatine, or (E)-alpha-monofluoromethyl-3-4-dehydroarginine--all irreversible inhibitors of arginine decarboxylase. Similar results were obtained when F2MeArg-treated parasites were incubated with rat heart myoblasts. The inhibitory effects were characterized by marked reductions in both the proportion of infected cells and the number of parasites per 100 host cells. The concentrations of the arginine decarboxylase inhibitors that affected infectivity had no detectable effect on either the concentration or motility of the parasite and, therefore, could not have affected the collision frequency. F2MeArg appeared to inhibit the ability of T. cruzi to penetrate the host cells since the drug had no significant effect on the extent of parasite binding to the surface of the host cells. The inhibitory effect of F2MeArg was markedly reduced or abrogated in the presence of either agmatine or putrescine, as would have been expected if F2MeArg acted by inhibiting arginine decarboxylase. Addition of F2MeArg to macrophage or myoblast cultures immediately after infection or at a time when virtually all of the intracellular parasites had transformed into the multiplicative amastigote form, resulted in a markedly reduced parasite growth rate. This effect was also prevented by exogenous agmatine. These results indicate the importance of polyamines and polyamine biosynthesis in the following two important functions of T. cruzi: invasion of host cells and intracellular multiplication. Furthermore, concentrations of the inhibitors tested that affected the parasite did not alter the viability of the host cells, the cellular density of the cultures, or the ability of uninfected myoblasts to grow. Thus, arginine decarboxylase inhibitors may have a potential application in chemotherapy against T. cruzi infection.

Previous experiments have shown that the infectivity of virulent trypomastigotes in L-cell culture was much more intensive not only for macrophages but also for newly cultured fibroblasts from the mouse heart as compared to low-virulent trypomastigotes in L-cell culture which had been derived from the same strain. On the other hand, the infectivity of virulent trypomastigotes for L-cells was less intensive. In the present work, new fibroblasts derived from muscles, skin, heart and kidney of newborn mice and established fibroblasts from mouse muscles were examined in terms of their susceptibility to trypomastigotes of different virulence. A slight difference of susceptibility to virulent trypomastigotes among new fibroblasts from different sources was found, i.e. fibroblasts derived from muscles and skin were more susceptible than those from heart and kidney. Growth of low-virulent trypomastigotes was suppressed in all new fibroblasts. This suppression was explained by the result that amastigote proliferation of a low-virulent strain was much slower in new fibroblasts from mouse muscles in spite of a similar penetrative ability of both kinds of trypomastigotes. Furthermore, a slight decrease in the susceptibility of new fibroblasts to virulent trypomastigotes was found depending on the length of time fibroblasts had been maintained.

A total of 329 human serum samples were collected from the clinics of internal medicine of Obihiro city and its suburbs and were screened for Toxoplasma antibody level using the latex agglutination microtiter method (LA). Ninety-one (27.7%) were positive, 4 (1.2%) were equivocal and 234 (71.1%) were negative. Positive reactants were highest in the age group of 55-74 years old. A relatively high percentage on positive reactants was observed in patients with accompanying cardiac and cerebral disorders, i.e., 33.3% and 35.6%, respectively. ICR-JCL mice were infected with 10(2) tachyzoites of the S-273 strain of T. gondii intraperitoneally. Chronic cases were obtained from those mice which survived the first infection without any further challenge 1 month later. Therapy was carried out by administering acetylspiramycin or spiramycin per os at a dose of 8 mg/0.5 ml per mouse per day for 30 days. After the end of therapy, brain and heart emulsions were made, and passaged to clean mice and observed for 30 days. Antibody titers were also monitored during the course of treatment using the LA microtiter method. In the acute cases, antibody titers were observed to gradually increase from the end of treatment up to 10 weeks. Antibody titers of the chronic cases were maintained at high levels before the start of treatment and up to its termination. Most of the mice subinoculated with brain emulsions obtained from the acute cases, both in the control and treatment groups, died. However, all of the mice subinoculated with heart emulsions from both treatment groups, survived. In the chronic cases, all mice subinoculated with brain emulsions from all groups died. A few survived the heart passages from both treatment groups, however, they showed very high reactions to the LA microtiter method.

The removal of N-linked oligosaccharides by peptide-N4-[N-acetyl-beta-glucoseaminyl]asparagine amidase (previously known as aspartoglycosylamine amidohydrolase and abbreviated N-glycanase) from the surface of blood or insect-transmissible forms of Trypanosoma cruzi markedly increased the capacity of these organisms to associate with (i.e., bind and penetrate) either mouse peritoneal macrophages or rat heart myoblasts. This effect was evidenced by a significant elevation in both the percentage of infected host cells and the average number of parasites per 100 cells. Conversely, N-glycanase treatment of either host cell markedly reduced both parameters to levels significantly below those obtained with cells mock treated with medium alone. The N-glycanase effect on the parasites was inhibited by heat inactivation of the enzyme or by the presence of fetuin, an N-glycanase substrate. The enhanced capacity of N-glycanase-treated T. cruzi to engage the host cells started to subside 2 h after the treatment, indicating the reversibility of the effect. The decreased reactivity of N-glycanase-treated macrophages or myoblasts with T. cruzi suggests that N-linked oligosaccharides on these host cells are involved in the initial phase of the cell infection process. Instead, because T. cruzi interacted more effectively with host cells after treatment with N-glycanase, parasite surface N-linked oligosaccharides would seem to interfere with the association.

Different tissues and organs of mice infected with Trypanosoma cruzi trypomastigotes have been examined for the presence of parasites and parasitic antigens during both the acute and the chronic phases of infection. Specimens of skeletal and cardiac muscles, spleen, liver, brain and sciatic nerves were studied by histological and immunological methods. During the acute phase of infection, the parasites were commonly observed in these tissues. In the chronic phase of the experimental infection, pseudocysts filled with amastigotes were seen in less than 1% of the tissue sections, while immunohistological methods showed that T. cruzi antigens were present in 11% of the inflammatory infiltrates. These findings suggest that antigenic stimulation persists throughout the chronic phase, even though the parasites are not morphologically detectable.

Sarcocystis sp. was diagnosed in the skeletal muscle of a cat and myocardium of a dog and cat. The cysts were similar in size and structure when examined by light and transmission electron microscopy. The 3 animals were debilitated and probably immunocompromised due to pancytopenia or terminal neoplasia.

The ultrastructure of the cyst wall of two types of sarcocysts from roe deer is described. In the thin-walled cyst (wall thickness 0.18-00.26 micrometer), the primary cyst wall forms long, finger-shaped protrusions distant from one another and running in parallel with the surface of the cyst (Figs. 1a--d, FP). No fibrils are observable in the protrusions. The primary cyst wall between them forms numerous bubble-like invaginations (Fig. 1c, arrows). In the thick-walled cysts (wall thickness 4.9--7.49 micrometer), the primary cyst wall forms massive, palisade-like protrusions lying close one to another (Figs. 2a, c). There are numerous fibrillar and tubular structures in these protrusions (Fig. 2d), and the primary cyst wall occasionally forms shallow invaginations at the base of some protrusions (Fig. 2b). The unit membrane onthe surface of some protrusions is slightly undulated and covered with a layer of short and thick bars on the outside. The sarcocysts found in roe deer are compared with those from cattle and sheep.

Cysts of Sarcocystis grueneri from cardiac muscle of reindeer (Rangifer tarandus) in Norway were examined by transmission electron microscopy. The limiting unit membrane of the cyst proper formed regularly spaced invaginations into the cyst at numerous sites coinciding with interruptions in the underlying osmiophilic layer. The primary cyst wall formed numerous strip-like, sinuous protrusions, which were 30-40 nm thick, 150-300 nm wide and up to 4.5 microns long, and were running in parallel with the surface of the cyst. Generally the protrusions were arranged in several closely spaced layers compressed against the cyst. The nature and arrangement of the protrusions render them undetectable by light microscopy. Cyst ground substance divided the interior of the cyst into compartments containing typical sarcosporidian metrocytes and cystozoites. The cysts of S. grueneri from reindeer were ultrastructurally similar to cysts reported from red deer, roe deer and moose by other workers. The possibility that these cervids are hosts for a common Sarcocystis species is discussed.

The hearts, masseter muscles, tongues and laryngeal muscles from 200 cattle aged 10 to 11 months, and 100 cattle aged 20 to 21 months, which had been reared on sewage-irrigated pastures at the Melbourne and Metropolitan Board of Works Farm, Werribee, Victoria, were examined for infection with cysticerci of Taenia saginata by slicing in the laboratory and the result obtained were compared with those recorded during normal meat inspection procedures at the abattoir. Of the 10 to 11-month-old cattle 51-5% were found to be infected and 8% of the total animals harboured viable cysticerci. Of the 20 to 21-month-old animals 33% were infected, and, even at this age, 8% of the animals still carried viable cysticerci. On-line meat inspection at the abattoir detected significantly fewer infections than did laboratory slicing.

An opportunistic infection with Toxoplasma gondii is a rare complication in the immunocompromised host following bone marrow transplantation. In addition to the variability in the clinical picture, difficulty in interpretation of the antibody titers is one of the main obstacles limiting early diagnosis of manifest toxoplasmosis. This report deals with 3 patients out of 86 bone marrow transplant recipients who had manifest toxoplasmosis mainly affecting the central nervous system and cardiac muscle. The clinical picture was that of acute disseminated encephalitis and myocarditis, while the nature of the disease was only disclosed at autopsy.