Within-host mechanisms of immune regulation explain the contrasting dynamics of two helminth species in both single and dual infections.

Variation in the intensity and duration of infections is often driven by variation in the network and strength of host immune responses. While many of the immune mechanisms and components are known for parasitic helminths, how these relationships change from single to multiple infections and impact helminth dynamics remains largely unclear. Here, we used laboratory data from a rabbit-helminth system and developed a within-host model of infection to investigate different scenarios of immune regulation in rabbits infected with one or two helminth species. Model selection suggests that the immunological pathways activated against Trichostrongylus retortaeformis and Graphidium strigosum are similar. However, differences in the strength of these immune signals lead to the contrasting dynamics of infections, where the first parasite is rapidly cleared and the latter persists with high intensities. In addition to the reactions identified in single infections, rabbits with both helminths also activate new pathways that asymmetrically affect the dynamics of the two species. These new signals alter the intensities but not the general trend of the infections. The type of interactions described can be expected in many other host-helminth systems. Our immune framework is flexible enough to capture different mechanisms and their complexity, and provides essential insights to the understanding of multi-helminth infections.

Phenotypic plasticity and local adaptation in freeze tolerance: Implications for parasite dynamics in a changing world.

Marshallagia marshalli is a multi-host gastrointestinal nematode that infects a variety of artiodactyl species from temperate to Arctic latitudes. Eggs of Marshallagia are passed in host faeces and develop through three larval stages (L1, L2, and L3) in the environment. Although eggs normally hatch as L1s, they can also hatch as L3s. We hypothesised that this phenotypic plasticity in hatching behaviour may improve fitness in subzero and highly variable environments, and this may constitute an evolutionary advantage under current climate change scenarios. To test this, we first determined if the freeze tolerance of different free-living stages varied at different temperatures (-9 °C, -20 °C and -35 °C). We then investigated if there were differences in freeze tolerance of M. marshalli eggs sourced from three discrete, semi-isolated, populations of wild bighorn and thinhorn sheep living in western North America (latitudes: 40°N, 50°N, 64°N). The survival rates of eggs and L3s were significantly higher than L1s at -9 °C and -20 °C, and survival of all three stages decreased significantly with increasing freeze duration and decreasing temperature. The survival of unhatched L1s was significantly higher than the survival of hatched L1s. There was no evidence of local thermal adaptation in freeze tolerance among eggs from different locations. We conclude that developing to the L3 in the egg may result in a fitness advantage for M. marshalli, with the egg protecting the more vulnerable L1 under freezing conditions. This phenotypic plasticity in life-history traits of M. marshalli might be an important capacity, a potential exaptation capable of enhancing parasite fitness under temperature extremes.

Endoparasitos em veados-catingueiros (Mazama gouazoubira) mantidos em cativeiro no Semiárido Paraibano / Endoparasites in brown brocket deer (Mazama gouazoubira) kept in captivity in the Semiarid of Paraíba

Objetivou-se investigar a ocorrência de endoparasitos em veados-catingueiros (Mazama gouazoubira) pertencentes a uma propriedade conservacionista no município de Sousa, Paraíba. Foram realizadas coletas de fezes em sete animais que foram submetidas às técnicas de sedimentação espontânea, centrífugo-flutuação em solução de sacarose, contagem de ovos por grama de fezes (OPG), contagem de oocistos por grama de fezes (OoPG) e coproculturas. Foram avaliados os locais de criação dos animais, para obtenção das informações acerca do manejo sanitário e alimentar. Em todas as amostras observaram-se ovos da Superfamília Trichostrongyloidea(OPG 200 ± 100) ecoccídios(OoPG 1500 ± 300). Nas coproculturas, 100% das larvas infectantes pertenciam ao gênero Trichostrongylus. Foram constatados oocistos do gênero Cystoisospora em todas as amostras. Em uma fêmea, que apresentou OoPG 1800, observaram-se sinais clínicos como apatia, anorexia, desidratação e diarreia intermitente, condizentes com Coccidiose. Este animal recebeu tratamento com a associação de sulfametoxazol e trimetropim, por sete dias, havendo melhora clínica. Erros de manejo foram observados na propriedade, como o convívio de M. gouazoubira com bovinos, ovinos e caprinos, alimentação inadequada à base de ração industrializada para equinos, bebedouros improvisados e não higienizados, e acúmulo de sujeira dos ambientes frequentados pelos animais. Concluiu-se que os veados-catingueiros estavam parasitados por helmintos (Trichostrongylus sp.) e protozoários (Cystoisospora spp.), podendo estas infecções estarem associadas ao convívio destes animais com ruminantes domésticos. Este estudo apresenta o primeiro relato da infecção por Cystoisospora spp. em M. gouazoubira.

The objective of this study was to investigate the occurrence of endoparasites in brown brocket deer (Mazama gouazoubira) belonging to a conservationist property in the municipality of Sousa, Paraíba. Fecal samples were collected in seven animals that were submitted to the techniques of spontaneous sedimentation, centrifugation-flotation in sucrose solution, egg count per gram of feces (EPG), oocyst count per gram of feces (OoPG) and coproculture. The breeding sites were evaluated to obtain information on Sanitary and food management. In all samples, eggs of the Trichostrongyloidea Superfamily (EPG 200 ± 100) and coccidia (OoPG 1500 ± 300) were observed. In the coprocultures, 100% of the infecting larvae belonged to the genus Trichostrongylus. Oocysts of the genus Cystoisospora spp. were found in all samples. In one female, who presented OoPG 1800, clinical signs such as apathy, anorexia, dehydration and intermittent diarrhea, consistent with Coccidiosis. This animal received treatment with the combination of sulfamethoxazole and trimetropim for seven days, with clinical improvement of the animal. Management errors were observed in the property, such as M. gouazoubira's conviviality with as cattle, sheep and goats, inadequate feed based on industrialized ration for horses, improvised and unhygienic drinking fountains, accumulation of dirt in the environments frequented by animals. They concluded that veados-catingueiros were parasitized by helminths (Trichostrongylus sp.) and protozoa (Cystoisospora sp.) infections may be associated with the coexistence of animals with domestic ruminants. This study presents the first report of Cystoisospora spp. in M. gouazoubira.

Bacteria isolated from parasitic nematodes--a potential novel vector of pathogens?

Bacterial pathogens are ubiquitous in soil and water - concurrently so are free-living helminths that feed on bacteria. These helminths fall into two categories; the non-parasitic and the parasitic. The former have been the focus of previous work, finding that bacterial pathogens inside helminths are conferred survival advantages over and above bacteria alone in the environment, and that accidental ingestion of non-parasitic helminths can cause systemic infection in vertebrate hosts. Here, we determine the potential for bacteria to be associated with parasitic helminths. After culturing helminths from fecal samples obtained from livestock the external bacteria were removed. Two-hundred parasitic helminths from three different species were homogenised and the bacteria that were internal to the helminths were isolated and cultured. Eleven different bacterial isolates were found; of which eight were indentified. The bacteria identified included known human and cattle pathogens. We concluded that bacteria of livestock can be isolated in parasitic helminths and that this suggests a mechanism by which bacteria, pathogenic or otherwise, can be transmitted between individuals. The potential for helminths to play a role as pathogen vectors poses a potential livestock and human health risk. Further work is required to assess the epidemiological impact of this finding.

[Travassosius rufus (Trichostrongylidae)--new for Poland nematode of beavers and comments about helminthfauna of these animals]. / Travassosius rufus (Trichostrongylidae)--nowy dla Polski nicien bobrów i uwagi o helmintofaunie tych zwierzat.

Two females of beaver from north-east Poland were necropsied. Moreover, 15 samples of feaces were examinated. Both necropsied beavers were infected with 46 and 362 specimens of trematode Stichorchis subtriquetrus (RUDOLPHI 1814). In stomach of one beaver were found 2800 specimens of nematode Travassosius rufus Khalil, 1922. It was the first registration of this species in Poland. Coproscopical examination showed eggs of S. subtriquetrus in all 15 fecal samples and eggs T. rufus in 5 samples.

Predatory behaviour of trapping fungi against srf mutants of Caenorhabditis elegans and different plant and animal parasitic nematodes.

The initial infection process of nematode-trapping fungi is based on an interaction between the trapping structure of the fungus and the surface of the nematode cuticle. A bioassay was designed to investigate the predatory response of several isolates of nematode-trapping fungi against 3 mutants of Caenorhabditis elegans (AT6, AT10 and CL261), which have been reported to differ in the reaction of their cuticle to antibodies and lectins. The bioassay was also applied to infective larvae of animal (Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta and Trichostrongylus axei) and plant (Meloidogyne spp.) parasitic nematodes. Differences in trapping ability were most marked in the first 24 h, and were density dependent. Although the isolate of Arthrobotrys responded very rapidly in the first 24 h, Duddingtonia flagrans was generally the most effective isolate and Monacrosporium responded relatively poorly throughout all experiments. All the fungi tested trapped the srf mutants of C. elegans more efficiently than the wild type, and there were differences between the different srf mutants of C. elegans. Differences in trapping ability were also observed between different isolates of D. flagrans; similarly, differences in trapping behaviour were observed not only amongst the different species of plant-parasitic nematodes, but also between the sheathed and exsheathed larvae of the animal-parasitic nematodes.

Encontro de ovos de Trichostrongylideo e Trichuris Trichiura em corpo mumificado do período colonial brasileiro / The finding of eggs of Trichostrongylideo and Trichuris Trichiura in mummies of the Brazilian colonial period

Refere-se ao exame de três corpos mumificados encontrados no poräo de uma igreja no município de Itacambira, em Minas Gerais, que revelou a presença de ovos de Trichuris Trichiura e de Ancilostomidae.

Encontro de ovos de Trichostrongylideo e Trichuris Trichiura em corpo mumificado do período colonial brasileiro / The finding of eggs of Trichostrongylideo and Trichuris Trichiura in mummies of the Brazilian colonial period

Refere-se ao exame de três corpos mumificados encontrados no poräo de uma igreja no município de Itacambira, em Minas Gerais, que revelou a presença de ovos de Trichuris Trichiura e de Ancilostomidae.(AU)

[Two trichostrongyloid nematodes parasitic in an African murid. III. Physiologic duality of infective larvae; as correlated with seasonal rhythms]. / Sur deux Nématodes trichostrongyloides parasites d'un Muridé africain. III. Dualité physiologique des larves infestantes, liée aux rythmes saisonniers.

The third stage (the infective stage) of both species, Neoheligmonella dossoi and N. tranieri, appears simultaneously in the coprocultures in two different forms: sheathed larvae and exsheathed larvae. The exsheathed larvae show a much higher infection rate than the sheathed ones, but the last ones could exsheathed under some conditions. These larvae are called: "larvae exsheathed by aging". The percentage of exsheathed larvae is higher from April to October, this period corresponding to the rainy season on the Ivory Coast. Considering the host biological characteristics (sedentary, isolated, humid burrows) and the fact that the infection lasts 2 to 4 months, the transmission of the two Trichostrongylid species seems particularly well adapted to local conditions. Transmission appears to follow two infestation strategies, depending on the season: --A "rainy season strategy" characterized by an important initial production of larvae of which a great number are exsheathed larvae, with strong infective potential. --A "dry season strategy" characterized by sheathed larvae, produced more regularly, having a weaker infective potential, and able to exsheathe progressively.

Studies on Haemonchus contortus. III. Titration of Trichostrongylus axei and explusion of H. contortus.

Groups of Merino weaners were dosed with infective larvae of Trichostrongylus axei in numbers ranging from 20 000-50 000 and challenged 3 months later with 50 000 infective larvae of Haemonchus contortus. When the dose of infective larvae of T. axei was given on Day 0 and the balance on Day + 14, efficacy against H. contortus was > 60% in > 60% of sheep (P < 0, 1). A single dose of 40 000 or 50 000 infective larvae of T. axei was > 80% effective against H. contortus in > 80% of sheep (P < 0, 01). Two doses of 20 000 infective larvae of T. axei followed by a challenge with H. contortus 31-33 days after the initial dose caused a reduction of > 50% in > 50% of sheep (P < 0, 1). This rose to > 60% in > 60% of sheep if the doses of 25 000 infective larvae of T. axei were followed by a challenge with H. contortus 45 days after the initial dose of T. axei. Most of the challenge doses of infective larvae of H. contortus were rejected within 3 days. Surviving worms were retarded in the 4th stage and only a few developed to the 5th or adult stage.