Alterations of plasma circulating microRNAs in BALB/c mice with Toxocara canis visceral and cerebral larva migrans.

BACKGROUND: Human toxocariasis is a neglected parasitic disease characterised by the syndromes visceral, cerebral, and ocular larva migrans. This disease is caused by the migrating larvae of Toxocara roundworms from dogs and cats, affecting 1.4 billion people globally. Via extracellular vesicles (EVs), microRNAs have been demonstrated to play roles in host-parasite interactions and proposed as circulating biomarkers for the diagnosis and follow-up of parasitic diseases. METHODS: Small RNA-seq was conducted to identify miRNAs in the infective larvae of T. canis and plasma EV-containing preparations of infected BALB/c mice. Differential expression analysis and target prediction were performed to indicate miRNAs involved in host-parasite interactions and miRNAs associated with visceral and/or cerebral larva migrans in the infected mice. Quantitative real-time polymerase chain reaction (PCR) was used to amplify circulating miRNAs from the infected mice. RESULTS: This study reports host and parasite miRNAs in the plasma of BALB/c mice with visceral and cerebral larva migrans and demonstrates the alterations of these miRNAs during the migration of larvae from the livers through the lungs and to the brains of infected mice. After filtering unspecific changes in an irrelevant control, T. canis-derived miRNAs and T. canis infection-induced differential miRNAs are predicted to modulate genes consistently involved in mitogen-activated protein kinase (MAPK) signalling and pathways regulating axon guidance and pluripotency of stem in the infected mice with visceral and cerebral larva migrans. For these plasma circulating miRNAs predicted to be involved in host-parasite crosstalk, two murine miRNAs (miR-26b-5p and miR-122-5p) are experimentally verified to be responsive to larva migrans and represent circulating biomarker candidates for visceral and cerebral toxocariasis in BALB/c mice. CONCLUSIONS: Our findings provide novel insights into the crosstalk of T. canis and the mammalian host via plasma circulating miRNAs, and prime agents and indicators for visceral and cerebral larva migrans. A deep understanding of these aspects will underpin the diagnosis and control of toxocariasis in humans and animals.

Visceral larva Migrans in a Young Italian Patient: A Diagnostic Dilemma.

BACKGROUND: The association of fever, focal hepatic lesions and peripheral hyper-eosinophilia (FHLH) can be observed in both infectious and non-infectious conditions. Fascioliasis, capillariasis, toxocariasis, all causes of visceral larva migrans (VLM), represent most of the former, whilst lymphomas, eosinophilic leukemias and mastocytosis belong in the non-infectious conditions. METHODS: We prospectively followed a young patient presenting with FHLH in the Tuscany region of Italy. RESULTS: The patient was subject to serological and parasitological examination in an attempt to clarify the origin of the lesions. Serologies for both Fasciola hepatica and Toxocara spp. were positive, with the latter presenting a higher index. We opted for treatment with a prolonged course of albendazole due to the serological results and being toxocariasis more frequent in our setting. The patient was then subject to radiological follow-up. The patient responded to treatment with albendazole as shown by a decrease in eosinophils, seronegativization for Toxocara spp., clinical and radiological improvement. Toxocariasis was hence considered the most likely diagnosis. CONCLUSIONS: Parasitic infections cannot be disregarded in the presence of FHLH. Differential diagnosis between these parasitic infections can be challenging due to the presence of similar clinical presentations and serological cross-reactions, and follow-up of the patient is needed to ensure optimal treatment outcomes.

Liver abscesses caused by visceral larva migrans: Aimless wanderer separated from the host.

Visceral larva migrans (VLM) is a systemic zoonotic parasitic disease caused by migration of the second stage larva through viscera of humans. Despite being a foremost public health problem in low- and middle-income countries (LMICs) such as India, larva migrans remains an untended zoonosis. Here, we report two cases of VLM who presented with fever and abdominal pain for a prolonged duration. On further investigation, marked peripheral eosinophilia with multiple confluent necrotizing eosinophilic granulomas were identified on histopathological examination of the liver.

Status of human toxocariasis, a neglected parasitic zoonosis in Iran: a systematic review from past to current.

Although human toxocariasis can lead to serious complications including neurological, ocular and visceral complications, there is a lack of comprehensive epidemiological information about the seroprevalence of Toxocara species in humans. In the present study, we analysed and reviewed the overall seroprevalence of human toxocariasis in Iran. The data collection was systematically undertaken on published articles using the PubMed, Google Scholar, ScienceDirect and Scopus databases. A total of 27 studies from the past two decades reporting seroprevalence of human toxocariasis met our eligibility criteria. The pooled proportion of Toxocara infection was estimated as 6.58% (95% confidence interval = 3.98-9.77). A wide variation between different studies was observed (Q statistic = 799.37, df = 26, P < 0.0001, and I2 = 96.7%). The seroprevalence rate of toxocariasis in the Iranian population is relatively high; contamination of the environment by eggs from the host as well as from household dogs and cats should be blamed.

Visceral larval migrans of Toxocara canis and Toxocara cati in non-canid and non-felid hosts.

Toxocara canis and Toxocara cati are considered the most ubiquitous gastrointestinal helminths in domesticated canids and felids. Ascarid eggs passed in the faeces of canids and felids in a suitable environment may remain infective for years and are capable of infecting not only canids and felids, but a large range of other vertebrate paratenic hosts, including man. Infection with Toxocara species also occurs following the ingestion of paratenic hosts containing infective larvae. As infective larvae are incapable of completing their lifecycle in these hosts, they instead travel to different parts of the body, sometimes inducing inflammatory responses, and in some cases remaining entrapped in the body for years. Migration routes depend on the host species; however, nearly all organs may be affected with varying quantities of larval burdens.

Immune response to chronic Toxocara canis infection in a mice model.

AIMS: The zoonotic nematode Toxocara canis causes larva migrans syndrome that induces an immune response characterized by the production of antibodies and eosinophilia. A Th2 polarization has been associated with the infection, but there are still details of the cellular and humoral immune response that need to be described. Thus, the aim of this study was to describe the systemic host immune response to T canis chronic infection in a mouse model. METHODS AND RESULTS: BALB/c mice were inoculated once with 500 T canis embryonated eggs, per os. After 49 days, the amounts of larval found in brain and muscle tissues were statistically two and four times higher, respectively, than the amounts found in lung, liver, kidney or heart tissues. Splenic proportions of F4/80+ cells, as well as B, cytotoxic T and CD4+ Foxp3+ lymphocytes, were statistically higher (P ≤ .05, P ≤ .01, P ≤ .001 and P ≤ .001, respectively) as compared with control mice. In lymph nodes, some of these proportions changed, with the exception of F4/80+ cells. IgG1 levels in infected mice sera were increased. IL-4, IL-10 and VEGF levels were statistically higher in spleen (P ≤ .05, all) and sera (P ≤ .01, P ≤ .05 and P ≤ .05, respectively) in the infected mice. Also, in infected animals, IL-5 serum levels were increased (P ≤ .01). CONCLUSION: These results suggest that T canis chronic infection in BALB/c mice results in a type 2 response with an incipient regulatory response.

Síndrome de larva migrans visceral y absceso hepático: Reporte de un caso / Visceral larva migrans syndrome and hepatic abscess: A case report

La infección por T oxocara canis o catis es una zoonosis diseminada en el ser humano. La toxocariasis puede coexistir con otras parasitosis endémicas. El hombre actúa como huésped no natural y adquiere la infección a través de la ingesta de huevos del geohelminto. Estos pueden localizarse en la tierra, los patios y los juegos de los niños, y son eliminados, principalmente, por perros o gatos. Existen distintos espectros en la presentación clínica; algunos de ellos son toxocariasis ocular, larva migrans visceral, toxocariasis encubierta y neurotoxocariasis. Se presenta el caso de un paciente de 2 años y 3 meses de edad, con antecedente de síntomas respiratorios, fiebre prolongada y hepatomegalia, con resultados de laboratorio que informa hipereosinofilia, hipergammaglobulinemia y serología positiva para toxocariasis (ensayo por inmunoabsorción ligado a enzimas). Se plantea el diagnóstico de síndrome de larva migrans visceral.

Toxocariasis canis or catis is a zoonotic infection disseminated in humans. Human beings can act as non-natural hosts in which the parasite can survive for long periods of time and they become infected by the ingestion of geohelminth eggs. These can be located on the ground, playgrounds and children's games, and are mostly eliminated by dogs or cats. There are different spectra in the clinical presentation of this infection, which can vary from an asymptomatic host to the production of serious organic lesions; some of them are ocular toxocariasis, visceral larva migrans, covert toxocariasis and neurotoxocariasis. In this case report a patient who presents with a history of respiratory problems, prolonged fever, and hepatomegaly. Laboratory analyses show hypereosinophilia, hypergammaglobulinemia and serodiagnosis is positive for toxocariasis. Preliminary diagnosis: Visceral Larva Migrans Syndrome.

[Visceral larva migrans syndrome and hepatic abscess: A case report]. / Síndrome de larva migrans visceral y absceso hepático: Reporte de un caso.

Toxocariasis canis or catis is a zoonotic infection disseminated in humans. Human beings can act as non-natural hosts in which the parasite can survive for long periods of time and they become infected by the ingestion of geohelminth eggs. These can be located on the ground, playgrounds and children's games, and are mostly eliminated by dogs or cats. There are different spectra in the clinical presentation of this infection, which can vary from an asymptomatic host to the production of serious organic lesions; some of them are ocular toxocariasis, visceral larva migrans, covert toxocariasis and neurotoxocariasis. In this case report a patient who presents with a history of respiratory problems, prolonged fever, and hepatomegaly. Laboratory analyses show hypereosinophilia, hypergammaglobulinemia and serodiagnosis is positive for toxocariasis. Preliminary diagnosis: Visceral Larva Migrans Syndrome.

La infección por T oxocara canis o catis es una zoonosis diseminada en el ser humano. La toxocariasis puede coexistir con otras parasitosis endémicas. El hombre actúa como huésped no natural y adquiere la infección a través de la ingesta de huevos del geohelminto. Estos pueden localizarse en la tierra, los patios y los juegos de los niños, y son eliminados, principalmente, por perros o gatos. Existen distintos espectros en la presentación clínica; algunos de ellos son toxocariasis ocular, larva migrans visceral, toxocariasis encubierta y neurotoxocariasis. Se presenta el caso de un paciente de 2 años y 3 meses de edad, con antecedente de síntomas respiratorios, fiebre prolongada y hepatomegalia, con resultados de laboratorio que informa hipereosinofilia, hipergammaglobulinemia y serología positiva para toxocariasis (ensayo por inmunoabsorción ligado a enzimas). Se plantea el diagnóstico de síndrome de larva migrans visceral.

Space Occupying Lesion in the Liver Caused by Hepatic Visceral Larva Migrans: A Case Report.

Visceral larva migrans (VLM) is one of the clinical syndromes of human toxocariasis. We report a case of hepatic VLM presenting preprandial malaise and epigastric discomfort in a 58-year-old woman drinking raw roe deer blood. The imaging studies of the abdomen showed a 74-mm hepatic mass featuring hepatic VLM. Anti-Toxocara canis immunoglobulin G (IgG) was observed in enzyme-linked immunosorbent assay (ELISA) and western blot. Despite anthelmintic treatment, the patient complained of newly developed cough and skin rash with severe eosinophilia. Hepatic lesion increased in size. The patient underwent an open left lobectomy of the liver. After the surgery, the patient was free of symptoms such as preprandial malaise, epigastric discomfort, cough, and skin rash. Laboratory test showed a normal eosinophilic count at postoperative 1 month, 6 months, 1 year, and 4 years. The initial optical density value of 2.55 of anti-T. canis IgG in ELISA was found to be negative (0.684) at postoperative 21 months. Our case report highlights that a high degree of clinical suspicion for hepatic VLM should be considered in a patient with a history of ingestion of raw food in the past, presenting severe eosinophilia and a variety of symptoms which reflect high worm burdens. Symptom remission, eosinophilia remission, and complete radiological resolution of lesions can be complete with surgery.

Seroprevalence and associated risk factors of Toxocara infection in Korean, Manchu, Mongol, and Han ethnic groups in northern China.

Toxocariasis is a very prevalent zoonotic disease worldwide. Recently, investigators have focused more on Toxocara spp. seroprevalence in humans. Information regarding Toxocara seroprevalence in people from different ethnic backgrounds in China is limited. For this study, blood samples were collected from a total of 802 Han, 520 Korean, 303 Manchu, and 217 Mongol subjects from Jilin and Shandong provinces. The overall Toxocara seroprevalence was 16·07% (14·21% Han, 20·58% Korean, 11·22% Manchu, 18·89% Mongol). Living in suburban or rural areas, having dogs at home, exposure to soil, and consumption of raw/undercooked meat were risk factors for Toxocara infection. Exposure to soil was identified as the major risk factor for Toxocara seropositivity in all of the tested ethnicities. To the best of our knowledge, this is the first report concerning Toxocara infection in Manchus and Mongols in China. The present study provided baseline data for effective prevention strategies of toxocariasis in northeast China and recommends improvements in personal hygiene standards to achieve this goal.

Enhanced resolution of eosinophilic liver abscess associated with toxocariasis by albendazole treatment.

BACKGROUND/AIMS: Visceral larva migrans, caused by Toxocara canis and Toxocara cati, has emerged as a significant cause of eosinophilic liver abscess (ELA). Differentiation of ELA associated with toxocariasis (ELA-T) from metastasis or primary liver malignancy is sometimes difficult. However, the role of albendazole treatment remains uncertain in this condition. The aim of this study was to evaluate whether albendazole can enhance the radiologic resolution of ELA-T. METHODS: We retrospectively reviewed the medical records of the patients diagnosed with ELA-T at our institution between January 2008 and December 2011. ELA-T was diagnosed based on the imaging findings on computed tomography or magnetic resonance imaging and the presence of positive serum IgG antibody for Toxocara canis. Among a total of 163 patients, 32 patients received albendazole (albendazole group) and 131 did not (control group). Baseline characteristics and fate of liver nodules were compared between the two groups. RESULTS: Baseline characteristics (age, sex, number and maximal size of lesions, eosinophil count) were similar between the two groups. Median duration for achieving radiologic resolution in the albendazole group was significantly shorter than in the control group (207 days [range 186-228] vs. 302 days [range 224-380], p=0.023). In Cox regression analysis of the cumulative rates of radiologic resolution, the hazard ratio for albendazole treatment was 1.99 (95% confidence interval, 1.22-3.23). CONCLUSIONS: Radiologic resolution of ELA-T can be accelerated with albendazole treatment. Hence, inconvenience associated with long-term follow-up and unnecessary worries among patients can be eliminated with albendazole treatment.

Immunoblot for the detection of Ascaris suum-specific antibodies in patients with visceral larva migrans (VLM) syndrome.

Visceral larva migrans (VLM) syndrome caused by Toxocara canis larvae was first described in the 1950s. The role of other nematode larvae, i.e. the pig roundworm Ascaris suum as a causative agent of visceral larva migrans-associated symptoms like general malaise, cough, liver dysfunction, hypereosinophilia with hepatomegaly and/or pneumonia, was discussed controversially during the last decades. Recent serological screening studies for specific A. suum antibodies carried out in the Netherlands and Sweden yielded remarkable high seroprevalences, while a number of case reports from Japan report pulmonal, hepatic and cerebral symptoms caused by A. suum larvae after ingestion of infected raw meat (liver) or contaminated vegetables. We present here a sensitive and specific larval excretory-secretory (E/S) antigen-based immunoblot (As-IB) for the serodiagnosis of A. suum-infected patients suffering from symptoms associated to the VLM syndrome. In total, 34 sera from patients with hypereosinophilia and other clinical symptoms associated to the VLM syndrome tested negative for Toxocara sp. antibodies but positive in our newly established As-IB, 30 sera from healthy volunteers, 53 sera from patients with clinically and serologically confirmed toxocarosis and other helminthoses as well as 3 sera from patients with intestinal ascariosis due to Ascaris lumbricoides were included in the study. When evaluated with 30 sera from healthy volunteers and 53 sera from patients suffering from different helminthoses, the calculated specificity of our new As-IB is 95%. Problems hampering the establishment of simple serological screening tests for specific A. suum antibodies, like extensive antigenic similarities between the nematodes Ascaris and Toxocara or the absence of suitable experimental animals, are discussed. We assume that specific serological testing for antibodies of A. suum is very important for the treatment of individual patients on one hand and seroepidemiological investigations will help to clarify routes of transmission on the other hand. Further studies will be necessary to learn more about the extent of A. suum as a causative agent of the VLM syndrome and the role of pigs and their manure as the main source of human Ascaris infections in Austria and other industrialized countries.

Alteration of cytokine production during visceral larva migrans by Toxascaris leonina in mice.

To determine alteration of immune responses during visceral larva migrans (VLM) caused by Toxascaris leonina at several time points, we experimentally infected mice with embryonated eggs of T. leonina and measured T-helper (Th) cell-related serial cytokine production after infection. At day 5 post infection (PI), most larvae were detected from the lungs, spleen, intestine, and muscle. Expression of thymic stromal lymphopoietin (TSLP) and CCL11 (eotaxin) showed a significant increase in most infected organs, except the intestine. However, expression of the CXCL1 (Gro-α) gene was most highly enhanced in the intestine at day 14 PI. Th1-related cytokine secretion of splenocytes showed increases at day 28 PI, and the level showed a decrease at day 42 PI. Th2-related cytokine secretion of splenocytes also showed an increase after infection; in particular, IL-5 level showed a significant increase at day 14 PI, and the level showed a decrease at day 28 PI. However, levels of Th17-related cytokines, IL-6 and IL-17A, showed gradual increases until day 42 PI. In conclusion, Th1, Th2, and Th17-related cytokine production might be important in immune responses against T. leonina VLM in experimental mice.

Toxocara spp. infections in paratenic hosts.

The zoonotic roundworms Toxocara canis and T. cati are not only present worldwide in their definitive hosts; they also frequently occur in other animal species, including humans. In those so-called paratenic hosts, the larvae do not develop into the adult stage, but rather migrate throughout the somatic tissue and persist as infectious L3 stage for extensive periods. Those arrested larvae may lead to severe inflammatory reactions and consequently to a wide range of pathological and clinical manifestations. However, the infected paratenic hosts also constitute a potential source of infection for the definitive hosts or humans who may also function as paratenic hosts. In the present review, current knowledge of larval migration in a variety of possible paratenic hosts is summarized including variations of migration routes and susceptibilities. Furthermore, information about the clinical and pathological changes for the presented species and possible consequences of the somatic migration of larvae, i.e. the resulting tissue damage as well as adverse host reactions to arrested larvae are reviewed. There are still many questions unanswered regarding larval behaviour in hosts other than their definitive host. Therefore, it is of great importance to continue further elaboration on the biology of Toxocara spp. to prevent further spreading of larvae in both the paratenic and the definitive host.

Factors affecting disease manifestation of toxocarosis in humans: genetics and environment.

Toxocara canis is regarded as the main cause of human toxocarosis but the relative contribution of T. cati is probably underestimated; serological and other diagnostic methods used in most studies of this zoonotic disease do not distinguish between the two parasites. The definitive hosts for T. canis are caniidae. Pups generally have higher infection rates than adult animals and are a major source of eggs in the environment. Humans usually acquire T. canis infection by accidental ingestion of embryonated eggs or encapsulated larvae from the environment or contaminated food, such infections may lead to visceral larva migrans (VLM), ocular larva migrans (OLM) or covert toxocarosis (CT). Although a mixed Th1- and Th2-mediated immunological response, particularly with high levels of IgE and eosinophilia is observed, the underlying mechanisms of molecular and immunopathogenesis for the development of the symptomatic syndromes of VLM, OLM, or of asymptomatic CT are largely unclear. Studies have indicated that immunological defences against various infectious diseases may be highly influenced by complex interactions of environmental and host genetic factors e.g. MHC class I and II, also known as human leucocyte antigen (HLA). Toxocara spp. infections are associated with a polarized CD4(+) Th2 response with high IgE levels and eosinophilia, mediated mainly by HLA class II molecules. Associations have been made between HLA class II and pathological severity and host genetic effects on exposure to infection. Recent research suggests Foxp3(+) CD4(+)CD25(+)-expressing T regulatory (Treg) cells play a role in regulation of the immunopathology of granulomas in experimental toxocaral granulomatous hepatitis and in enhanced expression of TGF-ß1, which is an important factor for the local survival and function of Treg observed during T. canis invasion in the mouse small intestine, liver, muscle, and brain. Since the potential susceptibility loci HLA class II molecules, are considered involved in the regulation of a Th2-dominant immunity which is highly controlled by Foxp3(+) CD4(+)CD25(+) Treg cells by stimulation through TGF-ß1, which thus provides a beneficial environment to T. canis larvae but severe injuries to local organs. However, TGF-ß1 variant Leu10Pro known to be involved in disease severity warrants further elucidation as this too may have a role in the severity of human toxocarosis. Exploration of TGF-ß1 polymorphism, Foxp3(+) CD4(+)CD25(+) Treg cells, and MHC polymorphisms may allow insight into the contribution made by environmental and genetic factors in influencing disease syndrome type and severity in humans with toxocarosis.

Laboratory diagnosis of human toxocariasis.

Toxocariasis is a helminth zoonosis caused by infection with the larvae of Toxocara spp. ascarid worms. Only two species, Toxocara canis and Toxocara cati, are recognised as causative agents of human disease. The best choice for serodiagnosis of the generalised forms of toxocariasis, visceral larva migrans (VLM) or covert toxocariasis, relies upon the initial use of TES-ELISA, after which any positive result should subsequently be tested by Western blotting (WB). Covert toxocariasis is mostly a benign infection, so a large majority of infected subjects are asymptomatic or have very few symptoms and therefore go undiagnosed. In this form, this helminthosis is often self-limiting, leaving residual specific antibodies. A positive serodiagnosis caused by residual antibodies that do not have any diagnostic significance can be associated with any infectious or non-infectious disease. If separated from the ongoing clinical and laboratory context, such a positive result has no diagnostic value and should be only taken into account after the possible etiologies of any observed syndromes have been ruled out. Unlike the methods used for the immunodiagnosis of bacterial, viral or protozoal (toxoplasmosis) infections, it is not possible with toxocariasis to assess the age of the presence of specific IgG using the levels of specific IgM because IgM antibodies can be found throughout the course of helminthiasis. The detection of other classes of immunoglobulins, namely IgE and IgA, the subclasses, namely IgG4 or circulating Ag was proven to be unable to discriminate between active and self-cured generalised toxocaral infections. Currently, the diagnosis of an active covert toxocariasis relies upon indirect arguments, e.g., the presence of otherwise unexplained symptoms along with blood eosinophilia and/or elevated levels of eosinophil cationic protein (ECP). This situation is far from ideal and more research should be carried out to solve this difficult problem.

Toxocara cati larva migrans in domestic pigs--detected at slaughterhouse control in Norway.

Routine Trichinella meat inspection at the slaughterhouse detected one larva in a pooled batch of 100 pig samples. The larva was sent to the Norwegian Veterinary Institute (NVI) for species identification.Morphological examination revealed that the larva was not Trichinella spp. Molecular analysis was performed. PCR and sequencing of 5S/ITS identified the larva as Toxocara cati. A second round of digests was carried out at the meat inspection laboratory, in smaller batches to try to identify the infected animal. No further larvae were detected and it was not possible to identify which of the 100 animals the larva had come from. This is the first time that Toxocara cati has been reported in slaughterhouse pigs in Norway.Although the infected individual could not be identified, the meat originated from one of six potential farms. A small survey regarding rodent control and cats was sent to each of these farms. Cats had restricted access to food storage areas (two farms reported that cats had access) whilst none of the farms allowed cats into the production housing. Cats were, however, present on all the farms (mostly stray cats of unknown health status). Half of the farms also reported seeing rodents in the pig housing during the previous six months and half reported finding rodents in the feed and straw storage areas. We were unable to narrow down the source of infection - however contamination of food or bedding material, with cat faeces or infected rodents, in addition to the presence of infected rodents in pig housing remain potential routes of infection.