Excretion of Histomonas meleagridis following experimental co-infection of distinct chicken lines with Heterakis gallinarum and Ascaridia galli.

BACKGROUND: Histomonosis is a severe re-emerging disease of poultry caused by Histomonas meleagridis, a protozoan parasite which survives in the environment via the cecal worm Heterakis gallinarum. Following infection, the parasites reside in the ceca and are excreted via host feces. In the present work, male birds of conventional broiler (Ross 308, R), layer (Lohmann Brown Plus, LB) and a dual-purpose (Lohmann Dual, LD) chicken line were infected with 250 embryonated eggs of Ascaridia galli and Heterakis gallinarum, respectively, with the latter nematode harboring Histomonas meleagridis, to investigate a co-infection of nematodes with the protozoan parasite in different host lines. METHODS: In weekly intervals, from 2 to 9 weeks post infection (wpi), individual fecal samples (n = 234) from the chickens were collected to quantify the excretion of H. meleagridis by real-time PCR and to determine the number of nematode eggs per gram (EPG) in order to elucidate excretion dynamics of the flagellate and the nematodes. This was further investigated by indirect detection using plasma samples of the birds to detect antibodies specific for H. meleagridis and worms by ELISA. The infection with H. meleagridis was confirmed by histopathology and immunohistochemistry to detect the flagellate in the cecum of representing birds. RESULTS: The excretion of H. meleagridis could already be observed from the 2nd wpi in some birds and increased to 100% in the last week of the experiment in all groups independent of the genetic line. This increase could be confirmed by ELISA, even though the number of excreted H. meleagridis per bird was generally low. Overall, histomonads were detected in 60% to 78% of birds with temporary differences between the different genetic lines, which also showed variations in the EPG and worm burden of both nematodes. CONCLUSIONS: The infection with H. gallinarum eggs contaminated with H. meleagridis led to a permanent excretion of the flagellate in host feces. Differences in the excretion of H. meleagridis in the feces of genetically different host lines occurred intermittently. The excretion of the protozoan or its vector H. gallinarum was mostly exclusive, showing a negative interaction between the two parasites in the same host.

Redescription of Cruzia americana Maplestone, 1930 (Nematoda: Kathlaniidae) a parasite of Didelphis virginiana (Kerr) (Mammalia: Didelphidae) in the USA.

Cruzia americana Maplestone, 1930 is a common nematode parasite of opossums in North America. However, our present knowledge on the morphology of this species is still limited and its validity is uncertain. In the present study, specimens of C. americana collected from the type-host Didelphis virginiana (Kerr) (Mammalia: Didelphidae) in the USA were studied using light microscopy and, for the first time, scanning electron microscopy (SEM). The SEM observations revealed the internal structures of the pharynx of C. americana and the presence of pharyngeal lamellae rather than pharyngeal teeth/tooth-like structures. In addition, the detailed morphology of the lips, vulva, eggs and phasmids in females and the caudal papillae in males are also reported for the first time.

Distribution of cysts of Strongyluris sp. (Nematoda) in the pallial system of Achatina fulica Bowdich, 1822 from Vila Dois Rios and Vila do Abraão, Ilha Grande, Angra dos Reis, Rio de Janeiro / Distribuição de cistos de Strongyluris sp. (Nematoda) no complexo pallial de Achatina fulica Bowdich, 1822 da Vila Dois Rios e da Vila do Abraão, Ilha Grande, Angra dos Reis, Rio de Janeiro

Abstract This work aimed to assessing Strongyluris sp. cysts distribution pattern in the several inner organs from pallial system of Achatina fulica Bowdich, 1822. Also we verified if there is a relationship between the mollusk size and the number of specimens from parasites collected from two touristic villages in Ilha Grande (Angra dos Reis, Rio de Janeiro state): Vila Dois Rios (VDR) and Vila do Abraão (ABR). The samples were obtained through a field work conducted bimonthly during 2007, 2008, 2010, and 2011, at both locations. Height and width were measured from shells collected, and the all specimens were classified in different classes: class 1 - <4.0 cm, class 2 - 4.1-9.0 cm and class 3 - < 9.0 cm. After the specimens were dissected in order to find and count the number cysts in the pallial system. In specimens from both locations, the pulmonary and secondary veins showed a high number of cysts. No significance difference was found both in the abundance of cysts among the specimens in ABR (p=0.138) and VDR (p=0.181). Achatina fulica showed different intensities of cyst infection based on the size classes: the class-3 specimens, at both locations, showed the greatest cyst average (ABR Anova F= 3.8; p=0.02); (VDR T of Student T= -2.04; p=0.04). The results suggested that the highest number of cysts in the vascularized area in pallial system of A. fulica was a consequence of a greater hemolymph circulation in that area, delivering more nutrients for larvae development. We think that bigger individuals host a higher number of cysts, as they usually present a larger biomass and a larger area of the pallial system, allowing an efficient parasite colonization. Other possible explanation could be the long exposure of the molluscs of class 3 to the parasites, which allowed a longer time to the larvae to allocate themselves.

Resumo O objetivo do estudo foi analisar o padrão de distribuição dos cistos de Strongyluris sp. nos diversos órgãos do complexo pallial de Achatina fulica Bowdich, 1822 e verificar se existe relação entre o tamanho do molusco e o número de parasitos em espécimes procedentes de dois vilarejos da Ilha Grande, Vila Dois Rios (VDR) e Vila do Abraão (ABR), município de Angra dos Reis, Rio de Janeiro. As coletas foram realizadas bimestralmente nos anos de 2007, 2008, 2010 e 2011 nas duas localidades. A altura e largura das conchas foram medidas, os espécimes classificados em classe 1 - <4,0 cm; classe 2 - 4,1-9,0 cm e classe 3 - < 9,0 cm e posteriormente dissecados sob estereomicroscópio para a busca e contagem dos cistos no complexo pallial. Em ambas localidades, VDR e ABR, as veias pulmonares e secundárias apresentaram predominância de alocação dos cistos. Não foi encontrada diferença na abundância de cistos entre os espécimes de ABR (p=0,138) e VDR (p=0,181). Achatina fulica apresentou intensidades diferentes de infecção de acordo com as classes de tamanho: os espécimes pertencentes a classe 3, nas duas localidades, apresentaram a maior média de cistos visíveis (ABR Anova F= 3,8; p=0,02); (VDR T de Student T= -2,04; p=0,04). Os resultados sugerem que o maior número de cistos na região vascularizada de A. fulica foi decorrente do maior aporte de hemolinfa nesta área, proporcionando mais nutrientes para o desenvolvimento das larvas. Acreditamos que indivíduos maiores albergam um elevado número de cistos, pois, geralmente, apresentam maior biomassa e maior área da cavidade pallial, possibilitando uma eficiente colonização dos parasitos, outra causa pode ser explicada pelo maior tempo de exposição dos moluscos da classe 3 aos parasitas, que possibilitou um período maior para as larvas se alocarem.

Distribution of cysts of Strongyluris sp. (Nematoda) in the pallial system of Achatina fulica Bowdich, 1822 from Vila Dois Rios and Vila do Abraão, Ilha Grande, Angra dos Reis, Rio de Janeiro.

This work aimed to assessing Strongyluris sp. cysts distribution pattern in the several inner organs from pallial system of Achatina fulica Bowdich, 1822. Also we verified if there is a relationship between the mollusk size and the number of specimens from parasites collected from two touristic villages in Ilha Grande (Angra dos Reis, Rio de Janeiro state): Vila Dois Rios (VDR) and Vila do Abraão (ABR). The samples were obtained through a field work conducted bimonthly during 2007, 2008, 2010, and 2011, at both locations. Height and width were measured from shells collected, and the all specimens were classified in different classes: class 1 - <4.0 cm, class 2 - 4.1-9.0 cm and class 3 - < 9.0 cm. After the specimens were dissected in order to find and count the number cysts in the pallial system. In specimens from both locations, the pulmonary and secondary veins showed a high number of cysts. No significance difference was found both in the abundance of cysts among the specimens in ABR (p=0.138) and VDR (p=0.181). Achatina fulica showed different intensities of cyst infection based on the size classes: the class-3 specimens, at both locations, showed the greatest cyst average (ABR Anova F= 3.8; p=0.02); (VDR T of Student T= -2.04; p=0.04). The results suggested that the highest number of cysts in the vascularized area in pallial system of A. fulica was a consequence of a greater hemolymph circulation in that area, delivering more nutrients for larvae development. We think that bigger individuals host a higher number of cysts, as they usually present a larger biomass and a larger area of the pallial system, allowing an efficient parasite colonization. Other possible explanation could be the long exposure of the molluscs of class 3 to the parasites, which allowed a longer time to the larvae to allocate themselves.

Heterakis gallinarum, the Cecal Nematode of Gallinaceous Birds: A Critical Review.

Heterakis gallinarum is a heavily prevalent poultry parasite that thrives in the ceca of various species of gallinaceous birds. It is a small roundworm, measuring between 4 and 15 mm long, in the family Heterakidae. Heterakis gallinarum has a direct life cycle not requiring an intermediate host to complete development, and it is generally believed that poultry raised at high density on litter are at greatest risk for accumulating large numbers of the nematode. This species typically only causes mild pathology that does not significantly affect bird performance. However, H. gallinarum is recognized as an economically important parasite by the poultry industry because its ovum serves as the vector for the protozoal parasite Histomonas meleagridis, the cause of histomonosis in poultry. Diagnosis of the nematode typically relies on fecal egg counts, which are prone to false negative diagnoses. Molecular tools are available for studying the nematode and diagnosing infected flocks. Treating and preventing H. gallinarum infection is made difficult due to the low efficacy of anthelmintics for eradicating H. gallinarum from infected birds and of disinfectants for destroying H. gallinarum ova on contaminated farms.

Estudio Recapitulativo- Heterakis gallinarum, el nematodo cecal de las aves gallináceas: una revisión crítica. Heterakis gallinarum es un parásito avícola muy prevalente que se desarrolla en el ciego de varias especies de aves gallináceas. Es un pequeño gusano redondo, que mide entre 4 y 15 mm de largo, de la familia Heterakidae. Heterakis gallinarum tiene un ciclo de vida directo que no requiere de un huésped intermedio para completar el desarrollo y en general se cree que las aves criadas en alta densidad en cama tienen un mayor riesgo de acumular grandes cantidades de nematodos. Esta especie generalmente solo causa una patología leve que no afecta significativamente el rendimiento de las aves. Sin embargo, H. gallinarum es reconocido como un parásito económicamente importante para la industria avícola debido a que sus huevos sirven como vector para el parásito protozoario Histomonas meleagridis, que es la causa de la histomoniasis en las aves. El diagnóstico del nematodo generalmente se basa en el recuento de huevos fecales, que puede establecer diagnósticos falsos negativos. Las herramientas moleculares están disponibles para estudiar el nematodo y diagnosticar las parvadas infectadas. El tratamiento y la prevención de la infección por H. gallinarum se dificultan debido a la baja eficacia de los antihelmínticos para erradicar H. gallinarum de las aves infectadas y de los desinfectantes para destruir los huevos de H. gallinarum en granjas infestadas.

Redescription of Maupasina weissi (Seurat, 1913) (Nematoda: Ascaridida) from sengis, Elephantulus spp. and Macroscelides proboscideus (Shaw) (Macroscelidea), in Africa.

Maupasina weissi (Seurat, 1913), is redescribed from the eastern rock sengi, Elephantulus myurus Thomas & Schwann, from Limpopo Province and compared with material collected from Free State and North West Provinces, South Africa, as well as the description of the type-material from South Tunisia. Distinguishing features of the species include a corona radiata of 12 pointed leaflike elements, a complex bipartite buccal capsule with 3 large bicuspid denticular lobes and 4 smaller club-shaped lobes and 11 (occasionally 10) pairs of cloacal papillae in the male. The complex taxonomic history of the genus Maupasina Seurat, 1917 is discussed. The probable misidentification of Macroscelides proboscideus Shaw, the short eared sengi, from North West Province, South Africa, as a host of M. weissi is explained, indicating that M. weissi occurs only in species of the genus Elephantulus Thomas & Schwann. The widely separated geographical regions, stretching the length of the African continent, in which M. weissi has been found are indicative of a conservative species with a broad geographical distribution. Tenebrionid beetles, up to 50% of stomach contents of E. myurus in Limpopo Province may act as intermediate hosts in the life-cycle of M. weissi.

Rhabdochona angusticaudata sp. n. (Nematoda: Rhabdochonidae) from the Japanese eel Anguilla japonica, and new records of some other nematodes from inland fishes in Japan.

Collections of parasitic nematodes of fishes from some freshwater and brackish-water localities in Honshu, Shikoku and Hokkaido, Japan, carried out in 1996-2009, yielded the following eight species: Hysterothylacium haze (Machida, Takahashi et Masuuchi, 1978) (Anisakidae), Paraquimperia sp., Pingus sinensis Hsü, 1933 (both Quimperiidae), Heliconema anguillae Yamaguti, 1935 (Physalopteridae), Rhabdochona angusticaudata sp. n., Rhabdochona zacconis Yamaguti, 1935 (both Rhabdochonidae), Ascarophis arctica Polyanskiy, 1952 (Cystidicolidae) and Eustrongylides sp. larvae (Dioctophymatidae). The new species, R. angusticaudata sp. n., described from the intestine of the Japanese eel Anguilla japonica Temminck et Schlegel in the Renjoji River, Shikoku, is mainly characterised by the presence of 14-16 anterior prostomal teeth, non-bifurcated deirids with rounded ends, the length of the left spicule (300-384 µm long), the right spicule with a dorsal barb and non-filamented eggs. The species of Paraquimperia Baylis, 1934 and A. arctica are reported from Japan for the first time. Based on light and scanning electron microscopical examinations, some new morphological data on H. haze, H. anguillae, R. zacconis and A. arctica are provided.

Early-Life Diet Affects Host Microbiota and Later-Life Defenses Against Parasites in Frogs.

Food resources can affect the health of organisms by altering their symbiotic microbiota and affecting energy reserves for host defenses against parasites. Different diets can vary in their macronutrient content and therefore they might favor certain bacterial communities of the host and affect the development and maintenance of the immune system, such as the inflammatory or antibody responses. Thus, testing the effect of diet, especially for animals with wide diet breadths, on host-associated microbiota and defenses against parasites might be important in determining infection and disease risk. Here, we test whether the early-life diet of Cuban tree frogs (Osteopilus septentrionalis) affects early- and later-life microbiota as well as later-life defenses against skin-penetrating, gut worms (Aplectana hamatospicula). We fed tadpoles two ecologically common diets: a diet of conspecifics or a diet of algae (Arthrospira sp.). We then: (1) characterized the gut microbiota of tadpoles and adults; and (2) challenged adult frogs with parasitic worms and measured host resistance (including the antibody-mediated immune response) and tolerance of infections. Tadpole diet affected bacterial communities in the guts of tadpoles but did not have enduring effects on the bacterial communities of adults. In contrast, tadpole diet had enduring effects on host resistance and tolerance of infections in adult frogs. Frogs that were fed a conspecific-based diet as tadpoles were more resistant to worm penetration compared with frogs that were fed an alga-based diet as tadpoles, but less resistant to worm establishment, which may be related to their suppressed antibody response during worm establishment. Furthermore, frogs that were fed a conspecific-based diet as tadpoles were more tolerant to the effect of parasite abundance on host mass during worm establishment. Overall, our study demonstrates that the diet of Cuban tree frog tadpoles affects the gut microbiota and defenses against parasitic gut worms of frogs, but these effects depend on the stage of the host and infection, respectively.

Morphological and molecular evidence for a new species of Pseudanisakis Layman & Borovkova, 1926 (Nematoda: Ascaridida), parasitizing Rajiformes in southern Southwest Atlantic waters.

Pseudanisakis argentinensis n. sp. is proposed to accommodate parasitic nematodes found in six skate species (Rajidae and Arhynchobatidae) examined from southern Southwest Atlantic waters. The new species differs from its congeners by the following combination of characters: a cupola on each lip, males with 8-12 pairs of precloacal genital papillae, a larger size for both males and females, a greater length-to-breadth ratio of the ventriculus and the presence of a small knob on the tip of the tail. Allometric growth was observed for several morphometric features; however, the slopes of the allometric relationships across host species exhibited non-significant differences and were considered as a strong evidence for conspecificity. Congruent results were obtained after the genetic characterization of the mitochondrial cytochrome c oxidase subunit 1 gene of worms obtained from different skate species, whose values of genetic divergence (1.3) lay within the range of intraspecific variation. Previous records of specimens referred to as Pseudanisakis tricupola in skates from South American waters are regarded as conspecific with P. argentinensis n. sp.

Understanding trophic interactions in host-parasite associations using stable isotopes of carbon and nitrogen.

BACKGROUND: Stable isotope analysis of carbon and nitrogen can deliver insights into trophic interactions between organisms. While many studies on free-living organisms are available, the number of those focusing on trophic interactions between hosts and their associated parasites still remains scarce. In some cases information about taxa (e.g. acanthocephalans) is completely missing. Additionally, available data revealed different and occasionally contrasting patterns, depending on the parasite's taxonomic position and its degree of development, which is most probably determined by its feeding strategy (absorption of nutrients through the tegument versus active feeding) and its localization in the host. METHODS: Using stable isotope analysis of carbon and nitrogen we provided first data on the trophic position of an acanthocephalan species with respect to its fish host. Barbels (Barbus barbus) infected only with adult acanthocephalans Pomphorhynchus laevis as well as fish co-infected with the larval (L4) nematodes Eustrongylides sp. from host body cavity were investigated in order to determine the factors shaping host-parasite trophic interactions. Fish were collected in different seasons, to study also potential isotopic shifts over time, whereas barbels with single infection were obtained in summer and co-infected ones in autumn. RESULTS: Acanthocephalans as absorptive feeders showed lower isotope discrimination values of δ 15N than the fish host. Results obtained for the acanthocephalans were in line with other parasitic taxa (e.g. cestodes), which exhibit a similar feeding strategy. We assumed that they feed mainly on metabolites, which were reprocessed by the host and are therefore isotopically lighter. In contrast, the nematodes were enriched in the heavier isotope δ 15N with respect to their host and the acanthocephalans, respectively. As active feeders they feed on tissues and blood in the body cavity of the host and thus showed isotope discrimination patterns resembling those of predators. We also observed seasonal differences in the isotope signatures of fish tissues and acanthocephalans, which were attributed to changes in food composition of the host and to seasonality in the transmission and development of acanthocephalans. CONCLUSIONS: This study provided first data on trophic interaction between an acanthocephalan species and its associated host, which support the tendency already described for other taxa with similar nutrition strategy (e.g. cestodes). Actively feeding taxa such as larval Eustrongylides sp., appear to act like predators as it can be seen from their isotope discrimination values. However, future research on additional host-parasite systems and especially on acanthocephalans is needed in order to corroborate these conclusions.

[The number of larvae and period of its production of Cosmocerca Ornata females (Nematoda: Cosmocercidae)].

The number of larvae in the Cosmocerca ornata (Dujardin, 1845) females from marsh frogs in vivo and period of larvae production of nematodes in vitro was studied. The number of larvae in females of nematodes and quantity of born larvae depend on the size of parasites. The largest C. ornata females had the highest number of larvae and the longest period of larvae production. The nematode sizes in its turn depends on density of infrapopulation of C. ornata and ambient temperature. The dependence of a number of the C. ornata larvae on the host age and sex and on a season of the year was revealed. Different phenotypes of amphibians showed no influence on the number of larvae inside nematode females. In the experiment C. ornata females remained viable up to 8 days, producing larvae up to 7 days. The optimum temperature for the larvae production constituted 24­28 °C. At a temperature of 12 °C and lower the nematode larvae output from females was stopped.

First record of Hysterothylacium sp. Moravec, Kohn et Fernandes, 1993 larvae (Nematoda: Anisakidae) infecting the ornamental fish Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae).

This study reports for the first time infection with Hysterothylacium sp. larvae in the ornamental fish Hyphessobrycon eques from the Paranapanema River, Jurumirim Reservoir, São Paulo State, Brazil. A sample of 33 specimens of H. eques was collected in October, 2011. Four specimens of H. eques were parasitized by Hysterothylacium sp. larvae in the intestine and coelomic cavity, with prevalence of 12.1%, mean intensity of infection of 1, and mean abundance of 0.121 ± 0.05. A total of 40 unidentified free-living nematodes were found in the stomach content of 17 fish. This fish species is introduced in the Paranapanema River. Invasive species may affect the native fauna given the introduction of pathogens and parasites. This study also complements data on the diet of H. eques due to the records of free-living nematode as part of the stomach content. Infections with Hysterothylacium sp. larvae may affect the biology of this fish and bring about profit losses to aquarists.

First record of Hysterothylacium sp. Moravec, Kohn et Fernandes, 1993 larvae (Nematoda: Anisakidae) infecting the ornamental fish Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae) / Primeiro registro de larvas de Hysterothylaciumsp. Moravec, Kohn et Fernandes, 1993 (Nematoda: Anisakidae) infectando o peixe ornamental Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae)

AbstractThis study reports for the first time infection with Hysterothylacium sp. larvae in the ornamental fish Hyphessobrycon eques from the Paranapanema River, Jurumirim Reservoir, São Paulo State, Brazil. A sample of 33 specimens of H. eques was collected in October, 2011. Four specimens of H. eques were parasitized by Hysterothylacium sp. larvae in the intestine and coelomic cavity, with prevalence of 12.1%, mean intensity of infection of 1, and mean abundance of 0.121 ± 0.05. A total of 40 unidentified free-living nematodes were found in the stomach content of 17 fish. This fish species is introduced in the Paranapanema River. Invasive species may affect the native fauna given the introduction of pathogens and parasites. This study also complements data on the diet of H. eques due to the records of free-living nematode as part of the stomach content. Infections with Hysterothylacium sp. larvae may affect the biology of this fish and bring about profit losses to aquarists.

ResumoEste estudo reporta pela primeira vez infecção com larva de Hysterothylacium sp. no peixe ornamental Hyphessobrycon eques do rio Paranapanema, reservatório de Jurumirim, estado de São Paulo, Brasil. Uma amostra de 33 spécimens de H. eques foi coletada em Outubro de 2011. Quatro espécimes de H. eques estavam parasitados por larva de Hysterothylacium sp. no intestino de cavidade celomática, com prevalência baixa de 12,1%, intensidade média de infecção de 1 e abundância média de 0,121 ± 0,05. Um total de 40 nematóides livres não identificados foi encontrado no conteúdo estomacal de 17 peixes. Esta espécie de peixe é introduzida no rio Paranapanema. Espécies invasoras podem afetar a fauna nativa dada a introdução de patógenos e parasitas. Este estudo também complementa os dados de alimentação de H. eques devido os registros de nematoides de vida livre como parte do conteúdo estomacal. Infecções com larva de Hysterothylacium sp. afetam a biologia deste peixe e pode ocasionar prejuízos para aquaristas.

Egg production dynamics and fecundity of Heterakis gallinarum residing in different caecal environments of chickens induced by fibre-rich diets.

In modern husbandry systems, feed rations for laying hens may contain high levels of dietary fibre, which may only be fermented intestinally. Depending on fermentation properties, the type of dietary fibre may influence the intra-caecal environment constituting the predilection site of Heterakis gallinarum. We investigated egg production dynamics and fecundity of H. gallinarum residing in different caecal environments induced through different types of dietary fibre. Growing layers were fed a standard (CON) or an insoluble- (I-) or soluble- (S-) non-starch polysaccharides-(NSP) supplemented diet for the first 11 weeks (wk) of life in a twice-replicated experiment. At 3 wk of age, the birds were infected with 200 embryonated eggs of H. gallinarum. Starting from 3 wk post-infection (p.i.), individual daily total excreta were collected. The number of eggs per gram of faeces (EPG) was determined (N = 2240), and the number of eggs per day (EPD) were estimated. The birds were necropsied 8 wk p.i. and the worm burdens were quantified. The nematode began to lay eggs as early as 23 d.p.i. and thereafter laid on average 436 eggs/d. I-NSP- and S-SNP-supplemented diets expedited the onset of patency by approximately 5 days, and increased total egg excretion by 110% and 185%, respectively, due to higher worm counts. The latter diet (S-SNP) additionally increased total egg excretion by 94% due to enhanced fecundity. Longitudinally collected data showed that fecundity of the nematode (EPD/female) was relatively stable starting from the second week of the patent phase. Results suggest that NSP-induced enlargement of caeca favoured establishment of the nematode while effects of an intensified microbial fermentation through S-NSP were crucial for an enhancement in the worm fecundity. Based on the long-term data obtained from daily collections of total excreta in experimentally H. gallinarum-infected chickens, it is concluded that a diet enriched with pea bran as source of insoluble NSP increased worm egg production merely through elevated worm counts, whereas a diet supplemented with chicory root meal as source of soluble NSP elevated worm egg production through both increased worm counts, and more profoundly through enhanced fecundity.

Density related effects on lifetime fecundity of Heterakis gallinarum in chickens.

BACKGROUND: Density related effects, both inverse density- and density-dependent, contribute to regulating population dynamics of parasites. We investigated whether density related effects are directly controlling lifetime fecundity of Heterakis gallinarum. METHODS: Daily total numbers of H. gallinarum eggs in faeces samples (N = 1365) from chickens (N = 39) were quantified starting from 3 weeks (wk) post-infection (p.i.). The birds were necropsied 8 wk p.i., and intensity and demographic characteristics of infrapopulations were determined. Density related effects on cumulative egg excretion (CEE), lifetime fecundity and worm length were investigated with a segmented regression analysis. RESULTS: For CEE, lifetime fecundity and female worm length, we determined highly similar parasite intensity thresholds (52-54 worms), which separated infrapopulations for influences of inverse density- and density dependence. CEE increased as parasite intensity increased up to an intensity of 52 worms. After this threshold, the relationship followed more of a horizontal line indicating impaired worm fecundity at higher parasite intensities. Lifetime fecundity was enhanced linearly in infrapopulations with up to 54 worms, but thereafter decreased gradually with increasing infrapopulation size. Female worm length increased linearly with elevating parasite intensity up to a threshold of 54 worms and thereafter declined with a rate of -0.014 mm for each additional worm. Lifetime fecundity and female worm length did not significantly differ between infrapopulations below and above the thresholds (P > 0.05). Lifetime fecundity was positively associated with the percentage of male worms (r = 0.44; P < 0.001), but negatively with absolute deviation from the theoretically expected sex-ratio in the infrapopulations (r = -0.56; P = 0.005). These relationships were stronger in infrapopulations below the threshold (r = 0.51 and -0.61, respectively), and were not significantly different from zero in the infrapopulations above the threshold (P > 0.05). CONCLUSIONS: Egg production of H. gallinarum is regulated by the effects of both inverse density- and density-dependent mechanisms, which result in similar average lifetime fecundity below or above intensity thresholds. In infrapopulations below the intensity thresholds, inverse density dependence effects on lifetime fecundity appear to result partly from sex-ratio fluctuations and impaired mating success of the nematode.

The first report of new species: Trichuris landak n. sp.

OBJECTIVE: To study nematode parasites morphology of Hystrix javanica (H. javanica), both through the feces and internal organs. METHODS: Feces were observed by direct smear method, internal organs were observed after dissecting the host. Specimens for light microscopy examination were fixed with 70% warm alcohol, cleared and mounted in lactophenol for wet mounting. Specimens for SEM examination were postfixed in cacodylate buffer and glutaraldehyde, dehydrated through a graded series of alcohol and freeze dried. The specimens were attached to stubs with double cello-tape, coated with gold and observed with a JSM5310 LV electron microscope. Figures were made with the aid of a drawing tube attached to Olympus compound microscope, other figures were photographs of scanning electron microscope images. Measurements were given in micrometers as the mean followed by the range in parentheses, unless otherwise stated. RESULTS: The nematode species found in the intestine of H. javanica are Gireterakis girardi and a new species, Trihuris landak. The new species differs with previously reported species from Hystrix because of having stylet and short cervical alae. The pattern of bacillary band is closed to Trichuris trichiurus, the species that infect human, but differs because the surface of its vulva is not covered with densely spine. CONCLUSIONS: The species of nematodes found on H. javanica were Gireterakis girardi and a new species Trichuris landak n.sp. Those two species are newly recorded in Indonesia.

New host and distribution records for Aplectana hamatospicula (Ascaridida: Cosmocercidae) in Gastrophryne olivacea (Anura: Microhylidae) from the Great Plains U.S.A.

Aplectana hamatospicula is a nematode that parasitizes the large intestine of anurans, and has been reported from bufonids, eleutherodactylids, hylids, microhylids, and ranids from North and Central America. Aplectana hamatospicula was first described, over 70 yr ago, from Hyla eximia and Bufo peltocephalus from Mexico and Cuba, respectively, and reported from Gastrophryne carolinensis from Florida. Since then there have been no reports of this nematode in North America north of Mexico. The life cycle of A. hamatospicula is not known, and there is limited information on Aplectana spp. from North America. During 2010-2011, we collected 351 anurans of 8 species from 4 locations in Stillwater, Payne County, Oklahoma, U.S.A., and examined them for the presence of Aplectana spp. Of the 8 species of anurans surveyed, A. hamatospicula infected only the Great Plains narrowmouth toad (Gastrophryne olivacea). The prevalence of A. hamatospicula was 85.7% (12/14) with a mean abundance of 28.4 + 24.0 and a mean intensity of 33.1 + 22.8 worms per infected toad. We provide new morphological measurements for male and female A. hamatospicula along with new locality records for this nematode in North America.

Galectins in the abdominal cavity of the conger eel Conger myriaster participate in the cellular encapsulation of parasitic nematodes by host cells.

Congerin is a proto-type galectin distributed on the skin and mucosal epithelia of the upper digestive tract of the Japanese conger eel Conger myriaster. It has at least 2 isotypes, namely, congerin I and II, and plays a role in bio-defense at the body surface. In the current study, we identified both isotypes in the peritoneal fluid and peritoneal cells of C. myriaster by western blot and mass spectrometry (MS)/MS analysis. Cucullanus nematodes parasitize the abdominal cavity of C. myriaster, and immunohistochemical analyses demonstrated that congerins can bind to both the body surface of the encapsulated nematodes and the encapsulating cells. Furthermore, adhesion of the peritoneal cells to Sepharose particles was greatly accelerated when the microspheres were coated with congerin. Indeed, this effect was significantly hampered by the addition of lactose. These results indicate that congerin participates in the cellular encapsulation of the Cucullanus nematode via the induction of cellular adhesion to the parasites depending on lectin-glycoside recognition.

Four events of host switching in Aspidoderidae (Nematoda) involve convergent lineages of mammals.

The Great American Interchange resulted in the mixing of faunistic groups with different origins and evolutionary trajectories that underwent rapid diversification in North and South America. As a result, groups of animals of recent arrival converged into similar habits and formed ecological guilds with some of the endemics. We present a reconstruction of the evolutionary events in Aspidoderidae, a family of nematodes that infect mammals that are part of this interchange, i.e., dasypodids, opossums, and sigmodontine, geomyid, and hystricognath rodents. By treating hosts as discrete states of character and using parsimony and Bayesian inferences to optimize these traits into the phylogeny of Aspidoderidae, we reconstructed Dasypodidae (armadillos) as the synapomorphic host for the family. In addition, 4 events of host switching were detected. One consisted of the switch from dasypodids to hystricognath rodents, and subsequently to geomyid rodents. The remaining set of events consisted of a switch from dasypodids to didelphid marsupials and then to sigmodontine rodents. The reconstruction of the ancestral distribution suggests 3 events of dispersal into the Nearctic. Two of these invasions would suggest that 2 different lineages of dasypodid parasites entered the Northern Hemisphere at different times, which is consistent with the presence of 2 lineages of armadillos in Mexico.

Precision, repeatability and representative ability of faecal egg counts in Heterakis gallinarum infected chickens.

This study investigated whether a precise and repeatable quantification of Heterakis gallinarum egg excretion, which considerably reflects the actual worm burdens, can be achieved based on collection of the daily total amount of faeces from chickens. Three-week-old birds (N=64) were infected with 200 embryonated eggs of H. gallinarum, and placed into individual cages 3 wk after infection for 5 wk to collect daily faeces (N=2240). The total daily faeces was mixed and a randomly taken sample per bird was analyzed to estimate the numbers of eggs per gram of faeces (EPG) and total number of eggs excreted within 24h (EPD). A total of 235 daily faecal collections were randomly selected and further examined to determine between and within sample variations of EPG counts as a measure of precision. For this, two random faecal samples were taken from the daily produced faeces by a bird, and the EPG was determined for each of the samples (EPG1 and EPG2). The second faecal sample was analyzed once more to determine a parallel EPG2 count (EPG2a) of the suspended sample. Precision of an EPG count was defined as its relative closeness to the average of two EPG counts using a relative asymmetry index (Index(EPG)). At an age of 11 wk, i.e. 8 wk p.i. the birds were slaughtered and their worm burdens were determined. There were no significant differences between EPG1 and EPG2 (P=0.764) nor between EPG2 and EPG2a (P=0.700), suggesting that the differences between or within the samples were not different from zero. Correlations between EPG counts, as between and within sample coherences, were r=0.85 and r=0.86, respectively. Precision of EPG counts, as measured by Index(EPG), was not influenced by consistency (P=0.870) and total amount of faeces (P=0.088). However, concentration of eggs in faeces (mean EPG) had a significant effect on the precision of the EPG counts (P<0.001). Similar results were also observed for the within sample precision (Index(EPG2)). A segmented regression analysis indicated an abrupt change in the precision of EPG counts as the response to changing egg concentration in the examined faecal samples. The precision of analyses remarkably heightened up to a breakpoint with an EPG count of ≤ 617. A similar breakpoint was also determined for within sample precision (EPG2 ≤ 621). Moderate repeatabilities (R=0.49) for EPG and EPD were estimated in the first week of egg excretion, whereas the estimates were higher (R=0.67-0.84) in the following weeks. Correlations between number of female worms with daily measured EPG and EPD increased to an almost constant level (r ≥ 0.70; P<0.05) in a few days after the nematode excreted eggs and predominantly remained so for the rest of the sampling period. It is concluded that mixing daily total faeces provides samples with random homogenous distribution of H. gallinarum eggs. Precision of the EPG counts increases as the egg concentration in faecal sample increases. Egg excretion of H. gallinarum, quantified either as EPG or EPD, is highly repeatable and closely correlated with the actual worm burden of birds starting as early as in 5 th wk of infection.