Development of some larval nematodes in experimental and natural animal hosts: an insight into development of pathological lesions vis-a-vis host-parasite interactions.

Infective third-stage larvae of three spiruroid nematodes, Ascarops strongylina and Physocephalus sexalatus of pigs and Spirocerca lupi of dogs, were recovered from 14 species of coprophagous beetles belonging to 4 different genera. These larvae were fed to rabbits and/or guinea pigs to study their development in these experimental hosts. Larvae of A. strongylina reached the adult stage in all rabbits and one guinea pig. The adult worms recovered in these hosts were 40% and 4%, respectively, and became diminutive in comparison to their natural hosts. The larvae of P. sexalatus became reencysted in the gastric wall of rabbits inducing marked pathological changes. The infective larvae of S. lupi became reencapsulated in the stomach wall of the rabbit and also showed development in the aortic wall. Adults of Toxocara canis of dog, collected from 5 different regions of the Indian subcontinent, varied significantly in size. The mouse passage of infective larvae of one of these types led to the recovery of the adults from the experimental dogs that were smaller in size and caused severe pathology in natural experimental hosts. Developmental effects shown in experimental hosts and host specificity are of value in understanding the evolution of nematode parasitism.

Distribution patterns of Procamallanus (Spirocamallanus) inopinatus (Nematoda: Camallanidae) and its interactions with freshwater fish in Brazil.

This study used information about Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas & Pereira, 1928 that had been published over a period of more than 90 years to investigate the infection and distribution patterns of this nematode in teleost freshwater fish in Brazil. This study was carried out using 181 samples from 82 fish species in 19 families within the five orders, with predominance of Characiformes species (71.6%). We organized a matrix-based parasite-host system in which the fish species were classified in different trophic levels and parasitic infection parameters according data available on host fish species with different life histories and geographic distributions across Brazilian hydrographic basins. Procamallanus (S.) inopinatus showed prevalence ranging from low to moderate, low abundance, low intensity, typically aggregated dispersion, and preferential infection of the hosts' gastrointestinal tract. There was difference in prevalence between detritivorous, omnivorous, carnivorous and piscivorous hosts, but no difference in intensity and abundance was found due to similarity in the communities of this endoparasite among the host fish species. The geographic distribution of this parasite encompasses the river of the Amazon, Paraná, São Francisco, North Atlantic, South Atlantic and Eastern basins. Lastly, suggestions regarding the life cycle of P. (S.) inopinatus, with its potential intermediate hosts, were discussed.

Infectivity of two nematode parasites, Camallanus lacustris and Anguillicola crassus, in a paratenic host, the three-spined stickleback Gasterosteus aculeatus.

Three-spined sticklebacks Gasterosteus aculeatus are frequent paratenic hosts of the nematode parasites Anguillicola crassus and Camallanus lacustris. As paratenic hosts, sticklebacks could spread infection by carrying high numbers of infective stages. In contrast, low infective ability of either parasite for the paratenic host could hinder the spread of infection. In the present study, G. aculeatus was, for the first time, infected under controlled laboratory conditions with defined doses of the parasites. Sticklebacks were exposed to 6, 12, 18 and 24 parasite larvae to determine the infective ability of the 2 nematode species. There were significantly higher infection rates for C. lacustris (18 to 49%) than for A. crassus (4 to 14%) at each exposure dose. In C. lacustris-infected sticklebacks, infection rates tended to be highest after exposure to 12 C. lacustris larvae and lowest after exposure to 24 parasites. In A. crassus-infected sticklebacks, no effect of parasite exposure dose on infection rates was observed. Immunity parameters such as respiratory burst activity and lymphocyte proliferation of head kidney leukocytes recorded 18 wk post exposure were not significantly affected by either parasite or exposure dose. Granulocyte:lymphocyte ratios were elevated only within the stickleback group showing the highest infection intensity of C. lacustris, i.e. to those exposed 18 parasites.

Distribution patterns of Procamallanus (Spirocamallanus) inopinatus (Nematoda: Camallanidae) and its interactions with freshwater fish in Brazil / Padrões de distribuição de Procamallanus (Spirocamallanus) inopinatus (Nematoda: Camallanidae) e suas interações com peixes de água doce do Brasil

Abstract This study used information about Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas & Pereira, 1928 that had been published over a period of more than 90 years to investigate the infection and distribution patterns of this nematode in teleost freshwater fish in Brazil. This study was carried out using 181 samples from 82 fish species in 19 families within the five orders, with predominance of Characiformes species (71.6%). We organized a matrix-based parasite-host system in which the fish species were classified in different trophic levels and parasitic infection parameters according data available on host fish species with different life histories and geographic distributions across Brazilian hydrographic basins. Procamallanus (S.) inopinatus showed prevalence ranging from low to moderate, low abundance, low intensity, typically aggregated dispersion, and preferential infection of the hosts' gastrointestinal tract. There was difference in prevalence between detritivorous, omnivorous, carnivorous and piscivorous hosts, but no difference in intensity and abundance was found due to similarity in the communities of this endoparasite among the host fish species. The geographic distribution of this parasite encompasses the river of the Amazon, Paraná, São Francisco, North Atlantic, South Atlantic and Eastern basins. Lastly, suggestions regarding the life cycle of P. (S.) inopinatus, with its potential intermediate hosts, were discussed.

Resumo O objetivo deste estudo foi utilizar as informações sobre a Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas & Pereira, 1928, publicadas ao longo de mais de 90 anos (1928 e 2019), para a busca de padrões de infecção e distribuição desse nematoide em peixes de teleósteos de água doce, no Brasil. Este estudo foi realizado usando-se 181 amostras de 82 espécies de peixes de 19 famílias, distribuídas em cinco ordens, com predominância de espécies de Characiformes (71.6%). Foi organizado um sistema parasito-hospedeiro em matrizes com espécies de peixes de acordo com cinco níveis tróficos. Foram usados parâmetros de infecção parasitária (prevalência, intensidade e abundância), conforme os dados disponíveis para peixes hospedeiros com diferentes histórias de vida e distribuição geográfica em diferentes bacias do Brasil. Procamallanus (S.) inopinatus mostrou prevalência variando de baixa a moderada, baixa abundância, baixa intensidade, dispersão tipicamente agregada e infecção preferencial pelo trato gastrointestinal dos hospedeiros. Houve diferença na prevalência entre hospedeiros detritívoro, onívoro, carnívoro e piscívoro, mas não foram encontradas diferenças na intensidade e abundância de P. (S.) inopinatus, devido a uma similaridade na comunidade desse endoparasito entre os hospedeiros. Esse parasito tem distribuição geográfica nos sistemas das bacias do Rio Amazonas, Rio Paraná, Rio São Francisco, Atlântico Norte, Atlântico Sul e Leste, e esses achados foram discutidos. Por fim, o ciclo de vida de P. (S.) inopinatus, com potenciais hospedeiros intermediários, foi finalmente sugerido e discutido.

Oxyspiruriasis in zoo birds.

Oxyspiruriasis caused by the bird eyeworm, Oxyspirura mansoni, a thelaziid nematode, in three species of pheasants, 3 Chrysolophus pictus (golden pheasant), 7 Lophura nycthemera (silver pheasant) and 9 Phasianus colchicus (common pheasant) in Zoo Negara Malaysia are reported. Birds with the disease were treated with a solution of 0.5% iodine or 0.5% lysol. Antistress powder for 4 days in water and non-strep vitamin powder in water was also provided. Control measures included removal of the cockroach intermediate host, Pycnoscelus surinamensis (Surinam cockroach) from the vicinity of the birds. The golden pheasant is a new host for O. mansoni in peninsular Malaysia.

Prevalence and the associated lesions of Cheilospirura (Acuaria) hamulosa in the indigenous chicken of Kashmir Valley, India.

The present investigation reports the results from a 2-yr study conducted on the prevalence and associated lesions of the nematode Cheilospirura (Acuaria) hamulosa (Nematoda, Acuarioidea) in a sample size of 478 indigenous fowl collected from different localities of Kashmir Valley, India. The investigation revealed the annual prevalence for the nematode for the first and second yr of study to be 3.4% (8/233) and 3.7% (9/245), respectively, with an overall prevalence of 3.5% (17/478). Parasitized birds did not present with clinical signs. Despite the low parasite burdens, the lesions induced by C. hamulosa were severe. Histological examination of the infected gizzard revealed discrete and coalescing nodular and cystic lesions in the mucosa and musculature which contained sections of the parasite. Cellular reaction in the lesions was characterized by a large number of lymphocytes, monocytes, plasma cells, heterophils, and, in some of the sections, severe eosinophilic reaction. The mucosa and submucosa showed markedly thickened and diffuse mononuclear infiltration as well as reactive lymphoid nodules.

Ultrastructure of the body wall of infective larvae of Cystidicoloides ephemeridarum (Nematoda, Cystidicolidae) from mayflies.

Scanning and transmission electron microscopic examinations of tissue-dwelling third-stage larvae of the nematode Cystidicoloides ephemeridarum from the intermediate host (Ephemera danica) were carried out with respect to the morphological changes in the body wall associated with the transfer from the intermediate to the definitive host. The ultrastructure of the cephalic end and zonation of the somatic cuticle of infective larvae basically correspond with those of adults. The somatic cuticle is composed of a fuzzy epicuticle, an outer and inner cortical zone, a median zone and a basal zone consisting of three subzones. Globular bodies are absent from the median zone of the infective larvae. The lateral hypodermal cords of the infective larvae are cellular, consisting of a median cell enclosed by two sublateral cells. The excretory canal is present within each of the lateral cord in both the infective and adult stages. Walls of the excretory canals contain Golgi-derived vesicles which communicate with the lumen of the canal. Large deposits of glycogen, suggesting anaerobic respiration, are present in the hypodermal cords and noncontractile parts of the muscle cells of the third-stage larvae within the intermediate host.

Ultrastructure of the body wall of Cystidicoloides ephemeridarum (Nematoda, Cystidicolidae) in relation to the histopathology of this nematode in salmonids.

Light, scanning and transmission electron microscope examinations of adult Cystidicoloides ephemeridarum nematodes, parasitic in the stomach of brown trout (Salmo trutta fario L.), revealed that the body wall is composed of a cuticle, a hypodermis and longitudinally oriented somatic musculature. The body cuticle is composed of a trilaminated epicuticle, an outer and inner cortical zone, a median zone with globular bodies and a basal zone consisting of three subzones. Massive cuticle in the three zones and an osmiophilic lining is present in the buccal capsule. Armament is absent both from the buccal capsule and the head end. The surface of the body is transversely striated with cortical annuli. The only specialized attachment devices of C. ephemeridarum are the flexible overlapping margins of the annuli which are elongated in the first third of the body. Together with the sucking pressure of the oesophagus, they seem to play a role in the penetration and mechanical damage of the host's tissue. The hypodermis appears to be syncytial. Up to 300 worms were present in the bolus of food consumed by the host, or attached by their head ends in the lamina epithelialis, which resulted in localized disruptions of the mucosal epithelium with no inflammation. Infection with C. ephemeridarum seems to be a temporary, season-dependent event of mild pathogenicity.