Study of surface carbohydrates in Galba truncatula tissues before and after infection with Fasciola hepatica

The presence and distribution of surface carbohydrates in the tissues of Galba truncatula snails uninfected or after infection with Fasciola hepatica as well as on the surface of the snail-pathogenic larval stages of the parasite were studied by lectin labelling assay. This is an attempt to find similarities that indicate possible mimicry, utilised by the parasite as an evasion strategy in this snail-trematode system. Different binding patterns were identified on head-foot-mantle, hepatopancreas, genital glands, renopericardial complex of the host as well as of the snail-pathogenic larval stages of F. hepatica. The infection with F. hepatica leads to changes of labelling with Glycine max in the head-mantle cells and Arachis hypogaea in the tubular epithelium of the hepatopancreas. The lectin binding on the other snail tissues is not changed by the development of the larvae. Our data clearly demonstrated the similarity in labelling of G. truncatula tissues and the surface of the snail-pathogenic larval stages of F. hepatica. The role of glycosylation of the contact surfaces of both organisms in relation to the host-parasite interactions is also discussed.

Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions.

BACKGROUND: The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse. METHODOLOGY/PRINCIPAL FINDINGS: Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains) of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection) of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i.) to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25%) of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg muscle. CONCLUSION/SIGNIFICANCE: This study reevaluated in depth the rat model of toxoplasmosis visualizing cyst rupture and clarified many aspects of the biology of the parasite useful for future investigations.

[Cryptosporidium and Giardia as water contaminant pathogens in Hungary]. / Cryptosporidium és Giardia mint vízszennyezo patogének Magyarországon.

INTRODUCTION: Many species of Cryptosporidium, and two assemlages of Giardia duodenalis cause typically acute diaorrhoea in human. The oocysts and cysts of these parasites excreted in faeces are capable of infecting other hosts and those are environmentally stable. AIM: The aims of the study were to evaluate the prevalence and genotypes of Cryptosporidium and Giardia species from different water sources as well as to monitor and characterize the (oo)cyst contamination sources in watersheds. In addition, an epidemiological study was performed in three selected settlements. METHOD: Wide range of modern epidemiological and molecular detection methods have been applied. RESULTS: (Oo)cysts densities were associated with water receiving effluents of sewage treatment plants or originating from a forest environment. It was confirmed, that cattle can be a source of Cryptosporidium oocysts at watersheds and aquatic birds can play a role in the environmental dissemination of these protozoa. The epidemiological study demonstrated a specific epidemiological situation, giving essential evidence about giardiasis in asymptomatic carriers. The applied novel detection technology was found to be cost effective and simple procedure for screening catchments to identify those that require further treatment and more detailed microscopic counts. CONCLUSIONS: The presented results contribute to a better understanding the epidemiology and relevance of waterborne parasites, their surveillance and performance of future control measures to prevent waterborne infections in Hungary.

Excystation signals do not isolate gregarine gene pools: experimental excystation of Blabericola migrator among 11 species of cockroaches.

An experimental excystation assay was used to test the potential species isolating effects of excystation signaling among gregarines. Oocysts of a single gregarine species, Blabericola migrator , were tested for activation, excystation, and sporozoite motility by using intestinal extracts from 11 species of cockroaches representing a cohesive phylogeny of 7 genera, 3 subfamilies, and 2 families of Blattodea. Sporozoite activation, excystation, and motility were observed for all excystation assay replications using intestinal fluid from blaberid hosts, but delayed activation or excystation was observed for all assay replications using intestinal fluid from hosts in the family Blattidae. The results illustrate a trend toward a generalized excystation signal among gregarines that is conserved across the host clade at a subfamily or family level but that is unlikely to play a significant role as a species-isolating mechanism among sibling gregarine species.

Prevalence and genotypes of Toxoplasma gondii in feline faeces (oocysts) and meat from sheep, cattle and pigs in Switzerland.

The protozoan parasite Toxoplasma gondii infects almost all warm blooded animal species including humans, and is one of the most prevalent zoonotic parasites worldwide. Post-natal infection in humans is acquired through oral uptake of sporulated T. gondii oocysts or by ingestion of parasite tissue cysts upon consumption of raw or undercooked meat. This study was undertaken to determine the prevalence of oocyst-shedding by cats and to assess the level of infection with T. gondii in meat-producing animals in Switzerland via detection of genomic DNA (gDNA) in muscle samples. In total, 252 cats (44 stray cats, 171 pet cats, 37 cats with gastrointestinal disorders) were analysed coproscopically, and subsequently species-specific identification of T. gondii oocysts was achieved by Polymerase Chain Reaction (PCR). Furthermore, diaphragm samples of 270 domestic pigs (120 adults, 50 finishing, and 100 free-range animals), 150 wild boar, 250 sheep (150 adults and 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, and 130 adult cows) were investigated by T. gondii-specific real-time PCR. For the first time in Switzerland, PCR-positive samples were subsequently genotyped using nine PCR-restriction fragment length polymorphism (PCR-RFLP) loci (SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) for analysis. Only one of the cats shed T. gondii oocysts, corresponding to a T. gondii prevalence of 0.4% (95% CI: 0.0-2.2%). In meat-producing animals, gDNA prevalence was lowest in wild boar (0.7%; 95% CI: 0.0-3.7%), followed by sheep (2.0%; 95% CI: 0.1-4.6%) and pigs (2.2%; 95% CI: 0.8-4.8%). The highest prevalence was found in cattle (4.7%; 95% CI: 2.8-7.2%), mainly due to the high prevalence of 29.8% in young calves. With regard to housing conditions, conventional fattening pigs and free-range pigs surprisingly exhibited the same prevalence (2.0%; 95% CI: 0.2-7.0%). Genotyping of oocysts shed by the cat showed T. gondii with clonal Type II alleles and the Apico I allele. T. gondii with clonal Type II alleles were also predominantly observed in sheep, while T. gondii with mixed or atypical allele combinations were very rare in sheep. In pigs and cattle however, genotyping of T. gondii was often incomplete. These findings suggested that cattle in Switzerland might be infected with Toxoplasma of the clonal Types I or III, atypical T. gondii or more than one clonal Type.

Risk factors associated with the occurrence of Cryptosporidium parvum infection in calves / Fatores de risco associados à ocorrência de infecção por Cryptosporidium parvum em bezerros

Cryptosporidium parvum oocysts were detected in feces of dairy calves raised in Rio de Janeiro State and the risk factors involved in the infection were determined. A hundred calves aging up to 12-month-old from 13 dairy farms were sampled. Polymerase chain reaction was used to detect the presence of oocysts. The zoonotic C. parvum species was detected in 45 percent animals. Statistical risk factors analyses revealed an association between infection and animals raised in technical systems such as the use of milking equipment, milking cooler, and water trough(P<0.05).

Detectaram-se oocistos de Cryptosporidium parvum em fezes de bezerros leiteiros no estado do Rio de Janeiro e analisaram-se os fatores de risco envolvidos na infecção dos animais. Cem bezerros com idades de 0 a 12 meses, provenientes de 13 propriedades rurais, foram amostrados, e suas fezes examinadas pela reação em cadeia da polimerase para a detecção dos oocistos. A espécie zoonótica C. parvum foi detectada em 45 por cento dos animais. As análises estatísticas dos fatores de risco revelaram haver associação entre infecção e animais criados em propriedades tecnificadas, que usam ordenha mecanizada, resfriamento de leite e fazendas que continham reservatórios de água à disposição dos animais (P<0,05).

Detection of Toxoplasma gondii oocysts in environmental samples from public schools.

The number of Toxoplasma gondii oocysts that can be found in random environmental samples is probably low; in addition, these cysts may be confused with Hammondia spp. and Neospora spp. oocysts. The aim of the present work was to evaluate the presence of T. gondii oocysts in the soil of public elementary schools in the northwest area of the state of São Paulo, Brazil using mouse bioassays. A comparison was made between the different available bioassay techniques, such as squash, histopathology, immunohistochemistry and indirect fluorescent antibody test (IFAT). T. gondii was isolated by bioassay in mice (squash brain samples) from 22.58% (7/31) of the school playgrounds. Immunohistochemistry and IFAT showed positive results in 32.26% (10/31) and 25.80% (8/31) of samples, respectively. The sensitivity and specificity of the immunohistochemistry method were 85.71% and 83.33%, respectively. The IFAT results showed 100% sensitivity and 95.83% specificity. The presence of T. gondii was not detected in histopathological examinations. The results of the present study strongly suggest that T. gondii oocysts are widely distributed in elementary public schools in the region that was evaluated, likely constituting the main contamination source for these children. Educational programs directed at reducing environmental contamination with T. gondii would eventually lower the cost of treating humans for clinical toxoplasmosis. It is also possible to conclude that the use of IFAT in mouse bioassays can be recommended without the need for brain cysts research, which is extremely difficult and laborious.

Long-term study of Cryptosporidium and Giardia occurrence and quantitative microbial risk assessment in surface waters of Arizona in the USA.

A four-year systematic study of microbial water quality in the surface waters of central Arizona was performed. The objectives of this study were to investigate the occurrence of microbial pathogens and indicators in the waters. A total of 192 water samples from five sites were analyzed for Cryptosporidium, Giardia, and various microbial and physical indicators. Ten percent (16/162) of the samples collected using EnviroChek filters were positive for Cryptosporidium oocysts, whereas no oocysts (<1 in 5 L) were detected in the grab samples (0/30). Giardia cysts were detected in 10% (3/30) of the grab samples and in 27% (44/162) samples collected using EnviroChek filters. Mean concentrations of oocysts in the source waters at the treatment plants were lower than the Bin 1 category of the USEPA Long Term 2 Enhanced Surface Water Treatment Rule; therefore no additional treatment is required by the plants. The annual risks of infection from Cryptosporidium met the annual acceptable risk of 10(-4) at all sampling sites, whereas the risks of Giardia infection at the Verde River and the Salt River were 5.70E-04 and 2.66E-04, respectively.

Detection of Cryptosporidium oocysts in fresh and frozen cattle faeces: comparison of three methods.

AIMS: The aim of this study was to compare the performance of three commonly used screening tests for Cryptosporidium oocysts in fresh and frozen cattle faeces. METHODS AND RESULTS: Twenty-nine freshly voided faecal samples were collected from calves from three farms in the northwest of England. Three diagnostic tests for Cryptosporidium were carried out on each sample both before and after freezing - the modified Ziehl-Neelsen (MZN) and auramine phenol (APh) stains and a commercial enzyme immunoassay (EIA) kit, the ProSpecT Cryptosporidium Microplate assay (Remel, Lenexa, KS). Twelve samples were deemed positive by the reference standard (polymerase chain reaction, PCR). There were some discrepancies between the results of the screening tests and the levels of agreement were quantified. The sensitivity and specificity of each method was determined, with PCR as the gold standard. Sensitivity and specificity of the MZN stain was optimized when samples with fewer than two oocyst-like bodies were classified as negative. CONCLUSIONS: All three screening methods used were effective in detecting Cryptosporidium infection in both fresh and frozen calf faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has highlighted the value of determining characteristics of tests used for diagnosis and epidemiological studies.

Pathogenicity of the protozoan parasite Marteilioides chungmuensis in the Pacific oyster Crassostrea gigas.

Marteilioides chungmuensis is an ovarian parasite that causes nodule-like structures to appear on the gonads of female Pacific oysters, Crassostrea gigas. It is known that the prevalence of infection increases in summer and decreases from autumn to spring. To investigate the decrease in prevalence of infection and pathogenicity of the parasite, a biopsy method was developed to detect infected oysters, which were then monitored to calculate the mortality rate. Mortality of infected oysters was recorded monthly and changes in reproductive development observed histologically. Compared with control groups, a significant difference in mortality was observed in infected oysters in September and October. Histological observations showed that infected oysters produced oocytes continuously, even in autumn when healthy oysters were reproductively inactive. This prolonged spawning activity of infected oysters resulted in nutritional wasting and mortality. From December onwards, however, almost all infected oysters survived, though the infection persisted. Infection intensity decreased gradually from December. Histological observations revealed that, in winter, infected oysters released infected and uninfected oocytes through the genital canal. The gonad subsequently degenerated and was replaced with connective tissue, as in normal, healthy spent oysters. The results revealed that prevalence of infection decreased from September to May. It is hypothesised that the decline in prevalence within the epizootic area in autumn occurred because infected oysters died and that the winter decrease was due to recovery from infection.

Pleomorfismo de oocistos de Cystoisospora felis (Wenyon, 1923) Frenkel, 1977 (Apicomplexa: Cystoisosporinae) induzido por differentes fontes de infecção / Pleomorfism of Cystoisospora felis (Wenyon, 1923) Frenkel, 1977 (Apicomplexa: Cystoisosporinae) oocysts induced by different sources of infection

Com o objetivo de avaliar as diferenças morfométricas dos oocistos esporulados de Cystoisospora felis oriundos de diferentesfontes de infecção: natural em gatos peri-domiciliados, experimental induzida por oocistos esporulados e experimental induzidapor hipnozoítas em vísceras de camundongos pré-inoculados por via oral com 106 oocistos esporulados de C. felis, foramutilizados 40 gatos, sendo 28 oriundos de áreas peridomiciliares do município de Seropédica, estado do Rio de Janeiro, dosquais foram obtidos oocistos de C. felis por infecção natural e 12 livres de coccídios, nascidos em laboratório. Estes últimosforam divididos em dois grupos com seis animais cada, que receberam por via oral inóculo contendo 106 oocistos esporuladose vísceras de camundongos inoculados previamente com C. felis, respectivamente. Os oocistos provenientes das três fontesde infecção foram diferentes entre si quando se consideraram os diâmetros polar e equatorial. No entanto, em relação aoíndice morfométrico, não houve variação. Os oocistos provenientes de infecção por vísceras foram pouco homogêneos emrelação aos oocistos oriundos de infecção experimental com oocistos esporulados e de infecção natural.

The present work aimed at to evaluate morphological differences that can be observed on Cystoisospora felis oocysts fromnatural, oocyst-borne experimental infection and mice viscera-borne experimental infection. For this reason, forty cats wereused in this experiment. Twenty-eight cats were taken in the municipality of Seropédica, State of Rio de Janeiro, which werecorresponded to natural infection and twelve coccidia-free kittens which were borne inside laboratory facilities. These coccidia-free cats were divided into two groups with six animals each: the first group was inoculated with 106 sporulated oocysts and thesecond one with mice visceras previously inoculated with 106 sporulated oocysts. Oocysts shed by these kittens submitted tothree sources of infection were different from each other, when were considered the length and width, although there was notvariation on the shape index of them. Oocysts proceeding from kittens fed on mice visceras showed lower homogeneity incomparison to oocysts that came from oocyst-to-oocyst experimental and natural infections.