Establishment and migration pattern of<Emphasis Type="Italic"> Toxocara canis</Emphasis> larvae in chickens

Migrations of Toxocara canis larvae were observed in experimentally infected chickens. Three groups of three chickens were inoculated orally with T. canis eggs. Within each group, individual chickens received either 5,000, 10,000, or 20,000 eggs. A group of infected chickens was then necropsied at either 1, 3 or 6 days post infection (dpi). The entire duodenum, spleen, liver, heart, lungs, right inner pectoral muscle, and brain were subjected to pepsin digestion for larval recovery. Larvae were predominately (>87%) recovered from the liver and lungs, and only a few larvae were seen in other organs or tissues in all chickens, with the exception of the duodenum at 1 dpi of chickens inoculated with 20,000 eggs. The percentage of total larval recovery varied widely among chickens (range: 0.4–16.7%). Similar numbers of larvae were distributed in the liver and lungs at 1 dpi. Subsequently, more larvae were found in the lungs than the liver at 3 dpi, whereas the larval distributions in the liver and lungs were reversed at 6 dpi. These observations suggest that T. canis larvae can migrate by a hepatopulmonary route in the chicken, and reinforces the possibility that chickens harboring migrating T. canis larvae may pose a zoonotic risk, especially if the liver is consumed.     

Effect of various doses of infectiveToxocara canis andToxocara cati eggs on the humoral response and distribution of larvae in mice

The effect of 5–2,500 infectiveToxocara canis and 5–1,000T. cati eggs on the humoral immune response and on the distribution of larvae in the organism was studied in paratenic hosts — inbred C57BL6/J mice. With each dose ofT. canis eggs the maximal antibody level was recorded on day 56 post infection and was followed by a moderate decline that lasted until day 154 of the experiment. A correlation between the antibody level and the egg count was observed only with the infective dose of 5–50 eggs. A more rapid occurrence of antibodies was recorded in mice infected with a high dose of eggs. In those given 5 and 7T. cati eggs the antibody level exceeded the extinction threshold value only from day 21 to day 84. Low doses ofT. canis (n=5) andT. cati (n=7) eggs caused a comparable distribution of larvae in mice, and the larval recoveries on day 70 post infection ranged between 10.00% and 25.74%. Following a dose of 500T. cati eggs, 22.28% of the larvae were recovered, although only 1.08% were localized in the brain. A dose of 1,000T. canis eggs yielded, 36.37% of the larvae, with as much as 28.13% being found in the brain.     

Toxocara canis in experimentally infected silver and arctic foxes

In two experiments, thirty-six farm foxes of two species were inoculated with various doses of infective Toxocara canis eggs or tissue larvae isolated from mice. In experiment I, six adult arctic foxes (Alopex lagopus; 11-month old) were each inoculated with 20,000 eggs and sacrificed 100, 220, or 300 days post infection (dpi), while ten silver fox cubs (Vulpes vulpes; 6–9-week old) were infected with varying doses of eggs (30–3000) and necropsied 120 dpi. In experiment II, two groups of five cubs and two groups of five adult silver foxes received both a primary inoculation and either one or two challenge inoculations: primary inoculation (day 0) with 400 embryonated eggs were administered to five cubs and five adults and another five cubs and five adults received 400 larvae. At 50 dpi, the first challenge inoculation (400 eggs) was inoculated in all animals. At 100 dpi, three animals from each group were necropsied. The remaining two animals in each group were received a second challenge inoculation of 400 tissue larvae on 100 dpi and were subsequently necropsied at 150 dpi. In both experiments, the highest numbers of larvae per gram (lpg) of tissue was found in the kidneys (100–300 dpi). In adult foxes receiving a high dose (20,000 eggs), increasing larval burdens were found in the kidneys over the course of the experiment (up to 300 dpi). The larval migration from the lungs to other tissues appeared to be dose-dependent with the highest larval burdens found in adult foxes. The faecal egg excretion, larval burden and intestinal worm burdens decreased from the first to the second challenge infection.     

Fungi predatory activity on embryonated <Emphasis Type="Italic">Toxocara canis</Emphasis> eggs inoculated in domestic chickens (<Emphasis Type="Italic">Gallus gallus domesticus</Emphasis>) and destruction of second stage larvae

The objective of this study was to evaluate the infectivity of Toxocara canis eggs after interacting with isolated nematophagous fungi of the species Duddingtonia flagrans (AC001) and Pochonia chlamydosporia (VC4), and test the predatory activity of the isolated AC001 on T. canis second stage larvae after 7 days of interaction. In assay A, 5000 embryonated T. canis eggs previously in contact with the AC001 and VC4 isolated for 10 days were inoculated into domestic chickens (Gallus gallus domesticus), and then these animals were necropsied to collect material (digested liver, intestine, muscles and lungs) at 3-, 7-, 14-, and 21-day intervals after inoculation. In assay A, the results demonstrated that the prior interaction of the eggs with isolated AC001 and VC4 decreases the amount of larvae found in the collected organs. Difference (p?<?0.01) was observed in the medium larvae counts recovered from liver, lung, intestine, and muscle of animals in the treated groups when compared to the animals in the control group. At the end of assay A, a percentage reduction of 87.1 % (AC001) and 84.5 % (VC4) respectively was recorded. In the result of assay B, the isolated AC001 showed differences (p?<?0.01) compared to the control group, with a reduction of 53.4 % in the recovery of L₂. Through these results, it is justified to mention that prior interaction of embryonated T. canis eggs with the tested fungal isolates were efficient in reducing the development and migration of this parasite, in addition to the first report of proven predatory activity on L₂.     

Molecular and parasitological tools for the study of Ascaridia galli population dynamics in chickens

Experiments were first conducted to compare and evaluate different methods of Ascaridia galli larval recovery from the chicken intestine. The number of larvae recovered from the intestinal wall of chickens infected with 1000 embryonated A. galli eggs and killed 15 days post infection (p.i.) by three methods (ethylenediamine tetraacetic acid [EDTA], pepsin digestion and scraping) were compared. The EDTA and pepsin digestion were found to be the most efficient methods with no significant difference (P > 0.05) in the number of recovered larvae between the two. Subsequently, three different A. galli cohorts were established using the polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) technique. A 533-bp long region of the cytochrome c oxidase subunit 1 gene of the mitochondrial DNA was targeted and 22 A. galli females were allocated to three different haplotypes. The four females with the highest embryonation rate from each haplotype group (total 12 females) were selected and used to inoculate each of 12 chickens with a dose of 1000 embryonated eggs. The chickens were killed 15 days p.i. and A. galli larvae were recovered from the small intestinal wall by the EDTA method and by sieving the lumen content on a 90 µm sieve. DNA of 40 larvae from each of the three different haplotypes was extracted using a worm lysis buffer, and PCR-RFLP analysis of these larvae revealed the same haplotype as that of their maternal parent. The identification of distinguishable cohorts may be a powerful tool in population studies of parasite turnover within the animal host.     

Toxocara canis larvae viability after disinfectant—exposition

The effect of three routinely used disinfectants on the embryonary development of Toxocara canis eggs was evaluated both in vivo and in vitro. In the in vitro experiment, T. canis eggs were treated with the ethanol, sodium hypochlorite, and one commercial mix of benzalconium chloride and formaldehyde, and the embryonary development was assessed. After a period of 24 days incubation, ethanol was the best disinfectant because it prevented the development of the T. canis larvae 2 in the eggs, and sodium hypochlorite caused degeneration in 50% eggs. By using the commercial mix, 25% T. canis eggs developed to 2nd stage larvae. In the in vivo experiment, the embryonated eggs treated with the disinfectants were inoculated to mice, and their brain tissues were examined for larval presence on the 24th day postinfection. In addition, a control group was set up for comparison with the infected groups. No injury or T. canis larvae were observed in mice infected with sodium hypochlorite-treated eggs, opposite to that recorded in the animals infected with the commercial disinfectant-treated eggs. These results showed that both ethanol and sodium hypochlorite are very appropriate because of their full efficacy against infective T. canis eggs. Disinfection of kennels, animal shelters, cages, and veterinary clinics with one of these products to eliminate T. canis eggs and to avoid contamination is strongly recommended.     

<Emphasis Type="Italic">Trichinella spiralis</Emphasis> reinfection: macrophage activity in BALB/c mice

The role of macrophages and their products—nitric oxide (NO) and superoxide anion (O₂ ⁻)—were examined in BALB/c mice reinfected with Trichinella spiralis. Mice were infected twice with 400 T. spiralis larvae; the secondary infection was performed 60 days after the primary one. Adult T. spiralis in intestines were detected from 5 to 20 days postprimary infection (dpi), and postreinfection (dpri), but the intensity of worm expulsion was greater and quicker after the reinfection. The highest muscle larvae numbers were detected from 60 dpi till 90 dpi (30 dpri), and thereafter, a great reduction was noted. The high numbers of macrophages in the peritoneal cavity of infected mice were obtained at 20 dpi, but the highest numbers of these cells from 10 to 30 dpri were observed. The production of NO by macrophages in infected mice was suppressed at 5 dpi, and then, NO release increased until 60 dpi. On the contrary, the long-lasting (5–30 dpri) suppression of NO production after T. spiralis reinfection was observed. The levels of NO in plasma and urine were lower in infected mice till 20 dpi; there were no differences in plasma and urine NO level after the reinfection in comparison to control uninfected animals. The production of O₂ ⁻ in peritoneal macrophages was inhibited during the first 2 weeks after infection, but the reinfection caused great increase in O₂ ⁻ production lasting 30 days.     

Detection and molecular characterization of ascarid nematode infection (Toxascaris leonina and Toxocara cati) in captive Asiatic lions (Panthera leo persica)

The objective of this study was to investigate the ascarid infection in Asiatic lions using scat samples, based on microscopic analysis, PCR amplification of the ITS-2 region of ribosomal DNA and sequence analysis of the amplicons. Microscopic analysis indicated the presence of eggs of Toxascaris leonina in eleven of the sixteen scat samples analysed and in one of these eleven scats eggs of Toxocara cati were also detected. In five of the scats eggs were not detectable. The presence of T. leonina in all the infected samples was also confirmed by PCR amplification of the ITS-2 of ribosomal RNA gene and five of these also showed amplicons corresponding to T. cati, respectively. Toxocara canis infection was not observed in any of the scat samples. Nucleotide sequence analysis of the ITS-2 region indicated 97% to 99% similarity with T. leonina and T. cati, respectively. To our knowledge, this is the first molecular characterization of ascarid infection in captive Asiatic lions from a zoological garden of India. This study also indicates that Asiatic lions are more prone to infection either with T. leonina or T. cati and the parasite is not host specific.     

Ascaridia galli in chickens: intestinal localization and comparison of methods to isolate the larvae within the first week of infection

This study was conducted to observe the localization and to compare methods for isolation of minute Ascaridia galli larvae in chicken intestine. Firstly, six 7-week-old layer pullets were orally infected with 2,000 embryonated A. galli eggs and necropsied either at 3, 5 or 7?days post infection (dpi). More than 95?% of the recovered larvae were obtained from the anterior half of the jejunoileum, suggesting this part as the initial predilection site for A. galli larvae. Secondly, the intestinal wall of one layer pullet infected with 20,000 A. galli eggs 3?days earlier was digested in pepsin?CHCl for 90?min. The initial 10?min of digestion released 51?% of the totally recovered larvae and the last 30?min of continuous digestion yielded only 5?%. This indicates that the majority of larvae were located superficially in the intestinal mucosa. Thirdly, 48 7-week-old layer pullets were infected with 500 A. galli eggs and necropsied at 3 dpi to compare three different larval isolation methods from the intestinal wall, viz., EDTA incubation, agar-gel incubation and pepsin?CHCl digestion, resulting in mean percentages of the recovered larvae: 14.4, 18.2 and 20.0?%, respectively (P?=?0.15). As conclusion, we recommended Pepsin?CHCl digestion as the method of choice for larval recovery from the intestinal wall in future population dynamics study due to high efficiency and quick and simple detection. The agar-gel method was considered to be a prerequisite for molecular and immunological investigations as the larvae were more active and fully intact.     

A survey of helminths in stray cats from Copenhagen with ecological aspects

At autopsy of 230 adult stray cats, 120 from backyards and 110 from gardens, the intestinal tract was scrutinized for helminths. The prevalence ofToxocara cati, Taenia taeniaeformis andDipylidium caninum was found to be 79%, 11% and 14%, respectively. Comparisons were made with the results of previous Danish investigations. The prevalence ofToxocara cati was found to be independent of time of collection and the sex and habitat of the cats and identical in cats with or withoutTaenia. This indicates that paratenic hosts do not play an important epizootiological role in the transmission ofT. cati. The intensity ofToxocara per cat followed a negative binomial pattern. The high prevalence ofT. cati combined with most cats having a low wormload shows that the cat population generally possesses a high degree of resistance against superimposed infections. The intensity of maleToxocara increases with the size of the worm population. This we consider to be an expression of increasing susceptibility of the cats. The prevalence ofT. taeniaeformis was significantly higher in garden cats, due to their greater opportunity for catching mice.D. caninum, however, was significantly more frequent in backyard cats, probably owing to better living condition for the flea larvae in backyards. For bothT. taeniaeformis andD. caninum a higher frequency was found in female cats, which is thought to be associated with their care for the kittens.     

<Emphasis Type="Italic">Toxocara canis</Emphasis> larvae reinfecting BALB/c mice exhibit accelerated speed of migration to the host CNS

Using a small animal imaging system, migratory activity of Toxocara canis larvae stained by carboxyfluorescein succinimidyl ester (CFSE) was observed post primary infection (PPI) and post reinfection (PR) of BALB/c mice. Each infection was performed with 1,000 larvae per mouse. Primary infections were performed with labeled larvae, while for challenge infections the reinfecting larvae were stained by CFSE. The worm burden in mouse organs was determined during a period from 6 h to 21 days and 4 months PPI and PR. In comparison with primary infections that led to the first larvae appearance in the brain after 60 h, greatly accelerated migration of the parasites administered 3 weeks PPI to the CNS and eyes of challenged mice was noted—in both organs the larvae appeared 6 h PR. In all challenged mice, reinfecting larvae prevailed in the resident parasite population. Preliminary experiments with Toxocara cati larvae also revealed early brain involvement in primarily infected mice. Staining of T. canis larvae by CFSE had no effect on the development of a humoral antibody response against T. canis excretory–secretory antigens. In ELISA, elevated levels of specific IgG and IgG1 were noted on day 14 PPI and the levels of antibodies increased till the end of experiment. Reinfection induced an increase in the levels of both antibodies. In terms of optical density, IgG1 antibodies gave higher values in all sera examined. In ELISA for IgG antibodies, an increase in the avidity index of around 50% was detected 1 month PPI; higher-avidity antibodies were also detected in sera of reinfected animals.     

The life cycle ofContracaecum osculatum (Rudolphi, 1802) sensu stricto (Nematoda,Ascaridoidea, Anisakidae) in view of experimental infections

Hatched, ensheathed third-stage larvae ofContracaecum osculatum, 300–320 m long, were shown to be infective to copepods, to nauplius larvae of {jtBalanus} and to small specimens of fishes (sticklebacks, 0-group eelpout). Other fishes such as gobies and small flatfishes became infected by ingesting infected crustaceans. Cod were infected by being given infected small fishes. In the crustacean paratenic hosts, little growth of the larvae occurred, if any. In the liver sinusoids of sticklebacks and gobies the length of most of the unencapsulated third-stage larvae had not even doubled within 6 months of infection. The fate of larvae (max. 2 mm long) given to cod via infected intermediate fish hosts was apparently decided by the size of the larvae only. Small larvae became encapsulated and eventually died in the liver and wall of the gastrointestinal tract. Larger larvae migrated to the liver parenchyma, where some grew to a length of as much as 10 mm. The growth of the larvae in sticklebacks was shown not to be affected by an increase in temperature (infected fish being transferred from 8° to 14° and 20°C), by the intensity of infection and, partly, by the age of infection (e.g some 2-week-old and 6-month-old larvea were of identical size). In the liver and mesentery of plaice the third-stage larvae developed via copepod paratenic hosts to infectivity (i.e. to more than 4 mm in length), showing that the life cycle may be completed with an optional paratenic invertebrate host and only one intermediate fish host. In combination with earlier results showing that the ensheathed third-stage larva (not the second stage) emerges from the egg and with literature data on the occurrence of larvae in fishes and the presence of fourth-stage larvae and adults predominantly in the stomach of grey seals, the life cycle ofC. osculatum is shown experimentally for the first time.     

Vertical transmission of<Emphasis Type="Italic"> Toxocara cati</Emphasis> Schrank 1788 (Anisakidae) in the cat

In eight cats and their offspring the mode of transmission of Toxocara cati following natural and experimental infection was investigated in three experiments. In experiments 1 and 2 the kittens of four cats with a chronic natural infection and of four cats with an acute experimental infection, respectively, were examined. In experiment 3 two queens of experiment 2 were mated again to examine whether in the adult cat dormant larvae exist in the tissue, that can be reactivated during pregnancy or lactation to infect the offspring. Additionally, the muscle tissue and organs of two adult cats, one with chronic one with acute infection, were examined for hypobiotic larvae. Pre-natal infections with T. cati did not occur in experiments 1 or 2. In none of the kittens that were examined directly after birth were larvae found. In the offspring of experiment 1 one single larva of T. cati was found 28 days post-partum. Whereas in the kittens of experiment 2 up to 333 larvae were found in one animal. Lactogenic transmission of larvae occurs after acute infection of the queen during late pregnancy but not during chronic natural infection. There is no evidence for the existence of arrested somatic larvae in the adult cat as an important host-finding strategy in the life cycle of T. cati. Following milk-borne infections, the majority of larvae seem to undergo direct development in the intestine without tracheal migration. Only a small number of larvae was found in other organs.     

On the life-cycle of subulura suctoria,a caecal nematode of poultry in egypt

Summary By random examination of various insects for cysticercoides of tapeworms, larvae of round worms were encountered attached to the intestinal wall of beetles, Ocnera hispida and Blaps polycresta. The morphological features of the larvae were discussed and materials from infected beetles were fed to chicken and we obtained embryonated eggs from their droppings and on making post-mortum examination of chicken, adult Subulura suctoria worms were found.With 3 Figures in the text     

Antigen-induced protection against infection withToxocara vitulorum larvae in mice

Larvae ofToxocara vitulorum hatched and migrated in the tissues of normal mice. Larvae survived in reasonable numbers, particularly in the liver and, to a lesser extent, in the lungs and kidneys, for at least 4–7 days and in muscles, albeit only in low numbers, for at least 3 weeks. Oral infection of mice on three or more occasions withT. vitulorum eggs induced protection against a challenge infection with eggs ofT. vitulorum. Prior parenteral immunization of mice with a variety ofT. vitulorum soluble antigens (extracts, excretions/secretions, or perienteric fluid and their fractions) from adult parasites and/or infective larvae induced statistically significant protection against infection. The most effective protective immunogens were three or more injections with perienteric fluid from adults (100% protection) and excretions/secretions from infective larvae ofT. vitulorum (>92% protection).     

Matrix metalloproteinases activation in Toxocara canis induced pulmonary pathogenesis

BackgroundToxocara canis, a source of visceral larva migrans, causes toxocariasis and induces respiratory symptoms. The reasons by which the pulmonary pathological alteration in the lungs infected with T. canis remain unclear.MethodsThe involvement of the pulmonary pathological alteration by histology, enzyme activity, and Western blot analysis in the lungs of BALB/c mice after the infection of 2000 embryonated eggs.ResultsThe pathological effects gradually increased after the infection culminated in severe leukocyte infiltration and hemorrhage from days 4–14 post-inoculation. Gelatin zymography using substrate showed that the relative activity of matrix metalloproteinase (MMP) −9 and MMP-2 significantly increased in T. canis-infected mice. Western blot analysis indicated that the MMPs protein level of fibronectin monomer significantly increased in T. canis-infected mice compared with that in uninfected control. T. canis larvae mainly initiated leukocyte infiltration and hemorrhage in the lungs.ConclusionThese phenomena subsequently induced the activities of MMPs in parallel with the pathological changes in early stage pulmonary inflammation. In conclusion, T. canis larval migration activated the MMPs and caused pulmonary pathogenesis.     

Toxocara spp. seroprevalence in sheep from southern Brazil

Visceral toxocariasis is a neglected parasitic zoonosis that occurs through the ingestion of embryonated Toxocara spp. eggs. A wide range of animal species can act as paratenic hosts for this ascarid. The main risk factor for humans is the ingestion of the eggs from contaminated soil; however, infection can also occur through the ingestion of contaminated raw or undercooked infected meat from paratenic hosts. The aim of this study was to verify the presence of Toxocara spp.-specific antibodies in sheep and to determine the risk factors associated with the infection of sheep in Rio Grande do Sul (a major sheep-producing and sheep-consuming state) in southern Brazil. Serum samples collected from 1,642 sheep were tested using an IgG enzyme-linked immunosorbent assay based on the excretory–secretory Toxocara canis antigen. Seroprevalence was 29.0 % (477/1,642), and every farm included in the study contained at least one seropositive animal. These results indicate that T. canis infection is widely distributed among sheep herds in Rio Grande do Sul and that it represents a potential risk to human health.     

Aspects of Toxocara Epidemiology: Toxocarosis in Dogs and Cats

Abstract

Toxocara canis and Toxocara cati are common roundworms of dogs and cats. In this review the life cycles of these parasites are described, including the various routes of transmission, such as transplacental, transmammary infection, and infection through paratenic hosts. The somatic and tracheal migration in the body of the hosts after infection with Toxocara eggs or larvae is discussed, with special reference to age resistance and differences between dog and cat The clinical symptoms and pathology in adult and young dogs and cats are given. Diagnosis of patent infections can be obtained by fecal examination, and treatment consists of the use of anthelmintics. Control of the infection and disease is achieved by prevention of contamination of the environment, anthelmintic treatment strategy, and education. Special attention is given to the efficacy of anthelmintics against adult worms and against somatic larvae. It is concluded mat education on the life cycles of the parasites, hygiene, and anthelmintic treatment schedules is required because of the zoonotic risks of Toxocara spp. Deworming of pregnant dogs and cats is not recommended.     

Some observations on the biology of five strains ofEimeria necatrix

Five laboratory strains ofEimeria necatrix were characterised with regard to the size of their oocysts, pathogenicity, reproduction, cross-immunity, ability to grow in embryonated eggs, and electrophoretic variation of enzymes. Three strains were highly pathogenic whilst two caused only few deaths and milder changes to the mean body weight gains of infected chickens. Cross-immunity was incomplete judged by scores of lesions after heterologous challenge, and electrophoretic variation of the enzymes lactate dehydrogenase and isocitrate dehydrogenase from oocysts of the five strains was also found. All the strains completed their life cycle in embryonated eggs but only a few oocysts were recovered.     

Comparative reproduction of Cryptosporidium baileyi in embryonated eggs and in chickens

At 2 days of age, each of 20 chickens was perorally or intracloacally infected with 3?×?10⁵ oocysts of Cryptosporidium baileyi and maintained for 13 days post infection. In parallel, 20 embryonated chicken eggs were inoculated with 3?×?10⁵ oocysts at day 10 of embryonation and were incubated for a further 7 days. The average reproduction rates in the two groups of chickens were ×560 after peroral infection and ×533 after intracloacal infection as compared with ×256 in the eggs. Although the rate of reproduction of parasites seen in the eggs was only about 50% of that observed in chickens, large numbers of oocysts could be harvested (on average, 77 million per egg versus 161 and 168 million from chickens). Nearly the same number of oocysts could be obtained from two eggs as compared with one chicken. The use of embryonated eggs accommodates the sense of animal-protection regulations, is less expensive, and allows the isolation of oocysts under sterile conditions.