Toxocara canis- and Toxocara cati-Induced Neurotoxocarosis is Associated with Comprehensive Brain Transcriptomic Alterations

Toxocara canis and Toxocara cati are globally occurring zoonotic roundworms of dogs and cats. Migration and persistence of Toxocara larvae in the central nervous system of paratenic hosts including humans may cause clinical signs of neurotoxocarosis (NT). As pathomechanisms of NT and host responses against Toxocara larvae are mostly unknown, whole-genome microarray transcription analysis was performed in cerebra and cerebella of experimentally infected C57Bl/6J mice as paratenic host model at days 14, 28, 70, 98, and 120 post-infection. Neuroinvasion of T. cati evoked 220 cerebral and 215 cerebellar differentially transcribed genes (DTGs), but no particular PANTHER (Protein ANalysis THrough Evolutionary Relationships) pathway was affected. In T. canis-infected mice, 1039 cerebral and 2073 cerebellar DTGs were identified. Statistically significant dysregulations occurred in various pathways, including cholesterol biosynthesis, apoptosis signaling, and the Slit/Robo mediated axon guidance as well as different pathways associated with the immune and defense response. Observed dysregulations of the cholesterol biosynthesis, as well as the Alzheimer disease-amyloid secretase pathway in conjunction with previous histopathological neurodegenerative findings, may promote the discussion of T. canis as a causative agent for dementia and/or Alzheimer’s disease. Furthermore, results contribute to a deeper understanding of the largely unknown pathogenesis and host-parasite interactions during NT, and may provide the basis for prospective investigations evaluating pathogenic mechanisms or designing novel diagnostic and therapeutic approaches.

LARVAE AND ADULTS OF ASCAROPS SP. (NEMATODA: SPIROCERCIDAE) COLLECTED FROM THE STOMACH OF MAXOMYS WHITEHEADI (RODENTIA: MURIDAE) IN KALIMANTAN, INDONESIA

Third-stage larvae and adults of spiruroid nematodes were found from the stomach wall and stomach lumen, respectively, of Maxomys whiteheadi (Rodentia: Murinae) captured in Bukit Soeharto, Kalimantan, Indonesia. Close observation using light microscope and scanning electron microscope (SEM) revealed that it belongs to the genus Ascarops (Nematoda: Spirocercidae), possibly to Ascarops strongylina (Rudolphi, 1819). It is presumed that this species is parasitic in wild boars, Sus barbatus, in the forest of Kalimantan, and utilizes the murine as a paratenic host, in which it usually remains as third larval stage but can occasionally develop to adult stage.

The Role of Nile Tilapia (Oreochromis niloticus) in the Life Cycle of Toxocara spp.

The present study aimed to experimentally assess Nile tilapia as potential paratenic host of Toxocara spp. A total of 15 Nile tilapia (Oreochromis niloticus) were fed with 300 embryonated Toxocara canis eggs by oral gavage, while five others of the control group received distilled water. The fish were individually analyzed at 16, 24, 48, 72, and 240 h after inoculation. Water contamination was assessed, and tissue migration by liver, gastrointestinal tract (GIT), eyes, and central nervous system. A murine model was used as the paratenic host for egg infectivity assessment. Eggs and larvae were found in plastic tank water and fish GIT, ranging from 23 to 86% per fish. Eggs and larvae were recovered from the tank water (76.3%) and fish GIT (23.7%). The counting of eggs and larvae observed was negatively correlated with number of eggs and larvae in the water tank (rho = −0.698, p = 0.003). Shedding of embryonated eggs was first detected at 16 and up to 240 h, with significant egg and larvae yield decrease on water-shedding (p = 0.001) and in the GIT (p = 0.007). Although no T. canis larva was recovered in fish tissues, egg infectivity after fish GIT transit was experimentally confirmed by mice assessment. In conclusion, despite shedding viable embryonated eggs through the gastrointestinal tract, tilapias may not play a role as a suitable paratenic hosts for Toxocara spp., posing low risk of zoonotic transmission by fish meat consumption.

Good host - bad host: molecular and evolutionary basis for survival, its failure, and virulence factors of the zoonotic nematode Anisakis pegreffii

Parasitism is a highly successful life strategy and a driving force in genetic diversity that has evolved many times over. Consequently, parasitic organisms have adopted a rich display of traits associated with survival that guarantees an effective “communication” with the host immunity and a balance with surrounding microbiome. However, gain/loss of hosts along the evolutionary axis represents a complex scenario that as contemporary onlookers, we can observe only after a long time displacement. The zoonotic and monophyletic Anisakidae diverged from its terrestrial sister group Ascarididae 150-250 Ma, although a split from their common ancestral host, a terrestrial amniote, seemingly happened already in Early Carboniferous (360.47 Ma). Faced with the sea-level rise during the Permian-Triassic extinction (215 Ma), anisakids acquired a semiaquatic tetrapod host, and as a result of lateral host-switches in Cenozoic, colonised marine mammals, co-evolving with their “new hosts”. Although contemporary anisakids have lost the ability to propagate in terrestrial hosts, they can survive for a limited time in humans. To scrutinize anisakid versatility to infect evolutionary-distant host, we performed transcriptomic profiling of larvae infecting the accidental host (rat) and compared it to that of larvae infecting an evolutionary-familiar, paratenic host (fish). Identified differences and the modeling of handful of shared transcripts, provides the first insights into evolution of larval nematode virulence, warranting further investigation of shared transcript as potential drug therapy targets. Our findings have also revealed some key intrinsic cues that direct larval fate during infection.

Experimental infection with Baylisascaris potosis in chickens

SummaryThe larvae of the genus Baylisascaris can cause larva migrans in mammals and birds. This study investigated the larval migration of Baylisascaris potosis, the roundworm of kinkajou (Potos flavus), in chickens and the associated clinical manifestations of the host. Thirty-six 3-week-old chickens divided into 6 groups were orally inoculated with 3,000 B. potosis eggs/chick. Each group of chicken was necropsied at days 1, 2, 3, 7, 30 and 90 PI (post inoculation), and the number of larvae in various organs were counted until day 90 PI. No clinical signs were observed in chickens during the study. Larvae were detected from the liver, lungs or breast-muscles of 13/36 (36.1%) chickens. The mean total number of larvae in the liver, lungs and breast-muscles at days 1, 2, 3, 7, 30 and 90 PI were 0.34, 0.17, 1.66, 1.01, 0.17 and 0, respectively. No larvae were found in the brain, eyes, hid-limb muscles, heart, kidneys and spleen. Although infectivity of larvae in egg-inoculated chickens was low, the present study demonstrated that B. potosis larvae can migrate in chickens tissues up to day 30 PI. The result suggests that chickens can serve as a paratenic host for B. potosis and may underline a public health importance of B. potosis infection as a potential foodborne disease in humans.

LARVAS DE HYSTEROTHYLACIUM SP (NEMATODA: RAPHIDASCARIDIDAE) EN EL PEZ VOLADOR EXOCOETUS VOLITANS LINNAEUS, 1758 (EXOCOETIDAE, BRUUN, 1935)) LIMA, PERÚ

Anisakidosis is an infection caused mainly by Anisakis simplex (Rudolphi, 1809), Pseudoterranova decipiens (Krabbe, 1878) Gibson, 1983 and very low frequency around the world by Contracaecum osculatum (Rudolphi, 1802) Baylis, 1920 and Hysterothylacium aduncum (Rudolphi, 1802). In Peru, Deardorff & Overstreet, 1982 en has been identified in Coryphaena hippurus Linnaeus, 1758, but there is no record of the morphometric characteristics of third instar larval stages in smaller teleost fishes. Given the importance of the flying fish Exocoetus volitans Linnaeus, 1758 in the trophic chain of C. hippurus, we believe that this fish would have a very important role in the biological cycle of Hysterothylacium sp. as a paratenic host. The objective of the present work was to identify the morphometric characteristics of the nematode larvae found in E. volitans and to determine their prevalence (P), mean intensity (IM) and mean abundance (AM). The sample consisted of 51 specimens of E. volitans, which were acquired in the fishing terminal of the district of Ventanilla, Callao. The collection and identification was done applying conventional methods and techniques. The presence of third stage larvae of Hysterothylacium sp. in gills and intestine is located mainly in the visceral surface and muscle tissue of E. volitans. Infected fish showed a prevalence of 90% (46/51), mean intensity of 58 with an intensity range of (1 - 1720) and a mean abundance of 52.11. Third stage larvae of Hysterothylacium sp. and parasitic indexes in E. volitans are identified for the first time in Peru.

A new millipede-parasitizing horsehair worm, Gordius chiashanus sp. nov., at medium altitudes in Taiwan (Nematomorpha, Gordiida)

Gordius chiashanussp. nov., a newly described horsehair worm that parasitizes the Spirobolus millipede, is one of the three described horsehair worm species in Taiwan. It is morphologically similar to G. helveticus Schmidt-Rhaesa, 2010 because of the progressively broadening distribution of bristles concentrated on the male tail lobes, but it is distinguishable from G. helveticus because of the stout bristles on the mid-body. In addition, a vertical white stripe on the anterior ventral side and areoles on the inside wall of the cloacal opening are rarely mentioned in other Gordius species. Free-living adults emerged and mated on wet soil under the forest canopy in the winter (late November to early February) at medium altitudes (1100–1700 m). Mucus-like structure covering on the body surface, which creates a rainbow-like reflection, might endow the worm with high tolerance to dehydration. Although Gordius chiashanussp. nov. seems to be more adaptive to the terrestrial environment than other horsehair worm species, cysts putatively identified as belonging to this hairworm species found in the aquatic paratenic host, Ephemera orientalis McLachlan, 1875, suggest the life cycle of Gordius chiashanussp. nov. could involve water and land. The free-living adults emerged from the definitive hosts might reproduce in the terrestrial environment or enter an aquatic habitat by moving or being washed away by heavy rain instead of manipulating the behavior of their terrestrial definitive hosts.