Pilot project to investigate over-wintering of free-living gastrointestinal nematode larvae of sheep in Ontario, Canada.

This study investigated the overwintering survival and infectivity of free-living gastrointestinal nematode (GIN) stages on pasture. The presence of GIN larvae was assessed on 3 sheep farms in Ontario with a reported history of clinical haemonchosis, by collecting monthly pasture samples over the winter months of 2009/2010. The infectivity of GIN larvae on spring pastures was evaluated using 16 tracer lambs. Air and soil temperature and moisture were recorded hourly. Free-living stages of Trichostrongylus spp. and Nematodirus spp. were isolated from herbage samples. Gastrointestinal nematodes were recovered from all tracer lambs on all farms; Teladorsagia sp. was the predominant species. Very low levels of Haemonchus contortus were recovered from 1 animal on 1 farm. The results suggest that Haemonchus larvae do not survive well on pasture, while Teladorsagia sp., Trichostrongylus spp. and Nematodirus spp. are able to overwinter on pasture in Ontario and are still infective for sheep in the spring.

Projet pilote pour faire enquête sur l'hivernage des larves de nématodes gastro-intestinaux libres chez les moutons en Ontario, au Canada. Cette étude a examiné la survie à l'hivernage et le pouvoir infectieux des stades des nématodes gastro-intestinaux (NGI) libres dans les pâturages. La présence de larves de NGI a été évaluée en recueillant des échantillons mensuels dans le pâturage pendant les mois de l'hiver 2009­2010 dans 3 fermes ovines en Ontario avec des antécédents documentés d'hémonchose clinique, tandis que le pouvoir infectieux des larves de NGI sur les pâturages du printemps a été évaluée en utilisant 16 agneaux sentinelles. La température et l'humidité de l'air et du sol ont été notées toutes les heures. Les stades libres de Trichostrongylus spp. et de Nematodirus spp. ont été isolés d'échantillons d'herbage. Les NGI ont été récupérés de tous les agneaux sentinelles dans toutes les fermes et Teladorsagia sp. était l'espèce prédominante. De très faibles taux d'Haemonchus contortus ont été récupérés chez 1 animal dans 1 ferme. Les résultats suggèrent que les larves d'Haemonchus ne survivent pas bien dans le pâturage, tandis que Teladorsagia sp., Trichostrongylus spp. et Nematodirus spp. peuvent survivre l'hiver dans le pâturage de l'Ontario et être toujours infectieux pour les moutons au printemps.(Traduit par Isabelle Vallières).

Brugia pahangi: immunization with early L3 ES alters parasite migration, and reduces microfilaremia and lymphatic lesion formation in gerbils (Meriones unguiculatus).

Previous studies have shown that intradermally (ID) injected Brugia pahangi L3 s migrate through various tissues and into the lymphatics of gerbils in a distinct pattern. Excretory/secretory products (ES) produced at the time of invasion of B. pahangi are likely to be important in this early migration phase of the parasite life cycle in their rodent host. Hence, early L3 ES was collected from 24h in vitro cultures of B. pahangi L3 larvae and used in immunization experiments to investigate the effect of immunity to early L3 ES on worm migration, survival and development of B. pahangi. Immunization of gerbils with ES in RIBI adjuvant produced antibodies to numerous ES proteins eliciting a strong humoral response to ES and indirect fluorescent antibody (IFA) assay using anti-ES serum recognized the ES proteins on the surface of B. pahangi L3 larvae. Following ES immunization, gerbils were challenged either ID or intraperitoneally (IP) with 100 L3 s of B. pahangi and euthanized at 3 or 106 days post inoculation (DPI). Immunization with early ES slowed the migration of ID inoculated L3 at 3 DPI and significantly altered the locations of adult worms at 106 DPI. Immunization did not induce protection in any treatment group. However, immunized animals had significantly fewer microfilariae per female worm suggesting the antigens in ES are important in microfilariae development or survival in the host. The number of lymphatic granulomas was also significantly reduced in ES immunized animals. It is important to note that microfilariae serve as a nidus in these granulomas. Our results shows immunization with early Brugia malayi L3 ES alters the worm migration, affects circulating microfilarial numbers and reduces lymphatic granulomas associated with B. pahangi infection in gerbils.

Brugia filariasis differentially modulates persistent Helicobacter pylori gastritis in the gerbil model.

In select Helicobacter pylori-infected populations with low gastric cancer, nematode coinfections are common and both helicobacter gastritis and filariasis are modeled in gerbils. We evaluated gastritis, worm counts, tissue cytokine gene expression levels and Th1/Th2-associated antibody responses in H. pylori and Brugia pahangi mono- and coinfected gerbils. H. pylori-associated gastritis indices were significantly lower 21 weeks post-infection in coinfected gerbils (p < or = 0.05) and were inversely proportional to worm counts (r(2) = -0.62, p < 0.003). Additionally, IFN-gamma, IL-1 beta, CXCL1, IL-4 and IL-10 mRNA levels in the gastric antrum reflected a significant host response to gastric H. pylori and as well as systemic filariasis (p < or = 0.05). Despite increasing worm burden (p < 0.05), gastritis progressed in coinfected gerbils (p < 0.03) becoming equivalent to H. pylori-infected gerbils at 42 weeks (p = 0.7). Pro- and anti-inflammatory mediator mRNA levels were notably downregulated in B. pahangi infected gerbils below uninfected control values, suggesting hyporesponsiveness to B. pahangi. Consistent with an increasing Th1 response to H. pylori, IgG2a (p < 0.01), IL-1 beta (p = 0.04) and CXCL1 (p = 0.006) responses significantly increased and IL-4 (p = 0.05) and IL-10 (p = 0.04) were decreased in coinfected gerbils at 42 weeks. Initial systemic responses to B. pahangi resulted in attenuated gastritis in coinfected gerbils, but subsequent filarid-associated hyporesponsiveness appears to have promoted H. pylori gastritis.

In vitro development of cyathostomin larvae from the third stage larvae to the fourth stage: morphologic characterization, effects of refrigeration, and species-specific patterns.

A mixed population of equine cyathostomin (Nematoda, Strongyloidea) infective third stage larvae (L3) was cultured in vitro using a cell-free medium. Some L3 were cultured immediately after Baermann collection from fecal cultures, while others were kept in water at 4 degrees C for 7 days before initiating the in vitro cultures. Cultures were examined daily for viability. At days 2, 7, 14 and 21 larvae were collected for identification of developmental stage and morphological changes, using both light and scanning electron microscopy. Larvae were classified as early L3 (EL3), developing L3 (DL3), late L3 (LL3) and fourth stage larvae (L4) on the basis of morphological features. Viability remained high throughout the entire study period in cultures of both non-refrigerated (84.7%) and refrigerated (77.4%) larvae. However, viability of the non-refrigerated was significantly greater from 7 through 21 days of culture. Significant differences were also observed in the percentage of DL3 between the non-refrigerated and refrigerated larval cultures by day 7. The highest percentage of DL3 larvae (22.5%) was reached at the end of study in those larvae that were not previously refrigerated. The data suggests that prior refrigeration decreases viability and slows L3 development. At day 21 LL3 larvae were only a small percentage of the DL3: 6.9 and 5% in non-refrigerated and refrigerated cultures, respectively. Few of these larvae freed themselves from the L3 cuticle and moulted to L4 stage. Characteristics of individual species in vitro developmental patterns were determined by the molecular identification of individual larvae in pools of larvae randomly collected at days 0 and 21. Seven species (Coronocyclus coronatus, Cylicostephanus goldi, Cylicostephanus longibursatus, Cyathostomum catinatum, Cylicocyclus nassatus, Cylicocyclus ashworthi, Petrovinema poculatum) were identified in the day 0 pool. The greatest tendency to develop in vitro was shown by the genus Cylicostephanus with the species C. goldi and C. longibursatus that developed to the LL3-L4 stages. C. nassatus, C. ashworthi and C. coronatus did not progress in their development beyond the EL3 stage, while no apparent signs of development were registered for C. catinatum.

Evaluation of immune response to orally administered Sterne strain 34F2 anthrax vaccine.

Present animal vaccines against Bacillus anthracis infection are capable of inducing protective immunity. However, due to the route of administration, the vaccine has limited or no use in wildlife especially in rural areas of the world. Hence, an oral vaccine is needed for controlling this disease. For proof of concept we used the commercially available Sterne strain 34F2 vaccine mixed with oral scarifying agents. Although the immunological response as measured by ELISA in this group was not equal to the parenterally inoculated animals, the results indicate that the oral administration of this vaccine with oropharyngeal mucosa scarifying agents mixed with feed can induce immune responses in goats.