Covert Toxocariasis Research Articles

Who Let the Dogs Out? Unmasking the Neglected: A Semi-Systematic Review on the Enduring Impact of Toxocariasis, a Prevalent Zoonotic Infection.

Toxocariasis remains an important neglected parasitic infection representing one of the most common zoonotic infections caused by the parasite Toxocara canis or, less frequently, by Toxocara cati. The epidemiology of the disease is complex due to its transmission route by accidental ingestion of embryonated Toxocara eggs or larvae from tissues from domestic or wild paratenic hosts. Even though the World Health Organization and Centers for Disease Control classified toxocariasis amongst the top six parasitic infections of priority to public health, global epidemiological data regarding the relationship between seropositivity and toxocariasis is limited. Although the vast majority of the infected individuals remain asymptomatic or experience a mild disease, the infection is associated with important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Toxocariasis is a disease with multiple clinical presentations, which are classified into five distinct forms: the classical visceral larva migrans, ocular toxocariasis, common toxocariasis, covert toxocariasis, and cerebral toxocariasis or neurotoxocariasis. Anthelmintic agents, for example, albendazole or mebendazole, are the recommended treatment, whereas a combination with topical or systemic corticosteroids for specific forms is suggested. Prevention strategies include educational programs, behavioral and hygienic changes, enhancement of the role of veterinarians, and anthelmintic regimens to control active infections.

Helminth Infections in Children.

Helminth Infections in Children.

A study on the prevalence of gastrointestinal parasites in carnivores and its potential implications on human health

Zoonoses contribute an estimated 75% of new or re-emerging infectious diseases in humans with Covid-19 being the latest addition. Carnivores act as definitive hosts and reservoirs for several endoparasites with varied effects on human health. These interactions are fluctuating and adaptive, changing in response to various biotic and abiotic conditions. With the development of ‘One health movement’ more focus has been laid on zoonotic infections and their management. The present study showed that carnivores of Dampa Tiger Reserve (DTR) are host to several infectious parasites with a prevalence rate of 90.47%. Families like Felidae, Canidae, and Viverridae were found to host the maximum number of parasites. The parasite Paragonimus spp. were recorded to be present in the highest number (33 nos.) of scat samples followed by <i>Strongyle spp</i>. (27 nos.), <i>Ascaris lumbricoides</i> (23 nos.), and <i>Isospora spp</i>. (19 nos.). These parasites are known to infect humans through different modes like faecal-oral route, uncooked meat, fishes, and contaminated water and induced health implications like inflammatory in the brain, bronchitis, covert toxocariasis, acute lung inflammation etc. As the surrounding landscape of DTR continuous to shrink and humans are more prone to these parasites through their daily activities and lifestyle, the study will be crucial for providing a platform for future epidemiological study and diseases management in the region.

Measurement of the IgG Avidity Index in the Diagnosis of Clinical Toxocariasis Patients

Toxocara spp. are parasitic nematodes responsible for human toxocariasis, a common zoonotic helminth infection. The five main features of human toxocariasis are the classical ocular toxocariasis and visceral larva migrans syndrome, followed by covert toxocariasis, common toxocariasis and neurotoxocariasis. The diagnosis of toxocariasis is feasible by considering clinical symptoms, anamnestic history and serology laboratory results; however, serological criteria cannot be used to distinguish active Toxocara infection from past exposure, which is an area of much discussion in clinical practice. In this context, we developed avidity tests (ELISA and immunoblotting) and evaluated their clinical usefulness in distinguishing past from active toxocariasis. Our study involved 46 patients divided into two groups: “active toxocariasis” (n = 14) and “chronic toxocariasis” (n = 32). According to the avidity indices obtained for both the chronic and active toxocariasis groups, we proposed two thresholds: first, an AI lower than 32% supports an active infection; secondly, a threshold above 42% can exclude an active infection. In order to use this assay in routine clinical practice, however, is still requires standardisation with regards to the method and threshold values, which can be established through studies involving larger populations.

Splenic abscess caused by Toxocara spp. in a lung transplant recipient, Marseille, France.

Infections represent one of the leading causes of morbidity and mortality in solid organ transplantation (SOT) recipients. Although Toxocara species are prevalent worldwide, toxocariasis is an important neglected human disease that can manifest as visceral or ocular larva migrans, or covert toxocariasis. Herein, we report and discuss the first documented case of a splenic abscess associated with toxocariasis in a 69-year-old lung transplant recipient, in France. This case emphasizes the need to include prevention of toxocariasis in the management of lung transplant patients.

APPLICATION OF PCR METHOD FOR DETECTION AND SPECIES IDENTIFICATION OF TOXOCARA SPP.

The ascaridoid nematodes of dogs and cats T. canis and T. cati are with widespread distribu-tion and causative agents of a disease in human and animals named Toxocariasis. Human dis-ease has several clinical forms with different clinical manifestation such as visceral, ocular, neurotoxocariasis and covert toxocariasis. The morphological methods used to differentiate the two species, especially to identify eggs or larvae, can lead to inaccurate diagnosis. This requires the use of more reliable methods, such as PCR, for identification of Toxocara species. The aim of our research is to develop in our conditions a PCR method for species identification of Toxocara and to determine its applicability on different stages of parasites. The method used by Khademvatan et al. (2013), we performed with some modifications in different forms of Toxocara - eggs, larvae and adult parasites. We used species-specific oligonucleotide primers from the ITS2 gene sequence of the ribosomal DNA - Tcan1/NC2 for T. canis and Tcat1/NC2 for T. cati. The presence of a band with a size of 380 bp, specific for T. canis, was found for all stages of the studied parasite. The described method will allow species differentiation of Toxocariasis causative agents and improve the diagnosis of the disease, as well as determine the actual spread and reservoirs of these parasites.

TOXOCARIASIS: VISCERAL AND OCULAR LARVA MIGRANS

Toxocariasis is a neglected socioeconomically important zoonotic nematode parasite that afflicts millions of the pediatric and adolescent populations worldwide, especially in impoverished communities. This disease is caused by infection with the larvae of Toxocara canis and T. cati, the most ubiquitous intestinal nematode parasite in dogs and cats, respectively. Human infections can lead to syndromes called visceral larva migrans (VLM), ocular larva migrans, neurotoxocariasis, and covert toxocariasis. Infection is not often fatal, but the inflammatory response to migrating larvae is associated withincreased leukocytosis, including generalized lymphadenopathy, endophthalmitis, granulomatous hepatitis, asthma, endomyocarditis, and high eosinophilia (>30%) as well as malignancy

Toxocara seroprevalence in Canada-Climate, environment and culture.

Human infection with larvae of canine and feline roundworms belonging to the genus Toxocara can lead to devastating visceral, neural or ocular larvae migrans disease. However, such overt disease represents a fraction of cases. Far more common is covert toxocariasis, a less severe, but clinically symptomatic form of disease, and those who are exposed to infective larvae and seroconvert, but appear to be asymptomatic. Canada represents a unique epidemiological environment for Toxocara infection and exposure. Although the freezing conditions of the vast Arctic Tundra region of the North are thought unlikely to support the lifecycle of Toxocara spp., exposure and seroconversion does occur in people belonging to Inuit communities of this region. Further south, in the sub-Arctic of northern Quebec and Saskatchewan, there is a higher seroprevalence in many Canadian First Nations communities. The epidemiology of these infections is different to that seen in the non-Indigenous communities of the Humid Continental region. Poverty and climate play a major part in the risk of Toxocara seropositive status in Canada, but other factors such as unique cultural practices, population density of humans and reservoir hosts, and contact with wildlife are also factors in exposure and subsequent seroconversion in Canadian communities. This review discusses previous Toxocara seroprevalence studies performed in Canada, summarizes the data for domestic and wild animal reservoir hosts of Toxocara canis, Toxocara cati, Toxocara vitulorum and the closely related helminth, Toxascaris leonina. It also discusses how the unique and varied aspects of climate, culture and environment impacts human Toxocara exposure in Canada.

Toxocara and its species.

Abstract This systematic review focuses on the nematode genus Toxocara and its zoonotic and non-zoonotic species and provides an update to that published by Warren almost half a century ago. Currently, 26 species of Toxocara have been described morphologically and four differentiated by molecular techniques. The most frequently reported and wide spread zoonotic species is Toxocara canis . Zoonotic infection with T. cati remains controversial and only a few infections, mostly in children with ocular larval migrans (OLM), have been reported. To date, none have been confirmed using molecular techniques. Only a single-suspected case of human infection with T. pteropodis has been reported and this species has yet to be confirmed as zoonotic. Of the non-zoonotic species T. vitulorum is of major economic importance and there are 13 minor species: T. alienata , T. apodemi , T. genettae , T. indica , T. leonine , T. mackerrasae , T. malaysiensis , T. paradoxura , T. pearsei , T. sprenti , T. surkattae , T. tanuki and T. vajrasthirae . Nine species have been reported only once: T. canarisi , T. cynonycteridis , T. elephantis , T. herpestum , T. hippopotami , T. lyncis , T. manzadiensis , T. vincenti and T. warreni . Toxocara occurs in many definitive host species: canids, felids, civets, mongoose, cattle, raccoons, bats and rodents. In humans, T. canis infections can result in four distinct syndromes: visceral larval migrans, OLM, neuro-toxocariasis and covert toxocariasis. Serological tests supplemented by molecular and imaging techniques provide the basis of diagnosis and may also add to the longitudinal monitoring of treatment. Seroprevalence in humans in developed countries ranges from 3 to 22% and in developing countries from 10 to 92%. Vertical transmission of the parasite in definitive hosts facilitates the earliest potential production of eggs from young animals and provides challenging yet important control opportunities. Climate change and increasing human and companion animal populations have facilitated an expansion in the geographical range of this zoonosis. Behavioural changes coupled with increased urbanization enhance potential transmission, as people and dogs become increasingly crowded together facilitating opportunities for T. canis transmission, and a greater understanding of these factors should be examined to facilitate appropriate and cost-effective control programmes. Anthelminthic used in the elimination of adult parasites from dog or cat intestines can provide an effective control with toxocariasis. Control measures using a one health approach coordinating the expertise of physicians, veterinarians, public health workers, dog owners and aided by legislation facilitates a best practice approach to control.

Toxocara canis Mimicking a Metastatic Omental Mass from Sigmoid Colon Cancer: A Case Report.

Toxocara canis is an important roundworm of canids and a fearsome animal parasite of humans. Human infections can lead to syndromes called visceral larva migrans (VLM), ocular larva migrans, neurotoxocariasis, and covert toxocariasis. VLM is most commonly diagnosed in children younger than 8 years of age, but adult cases are relatively frequent among those infected by ingesting the raw tissue of paratenic hosts in East Asia. This research reports the case of a 59-year-old man with sigmoid colon cancer, who visited our institution for surgery. An intraperitoneal mass was found on preoperative computed tomography, and it was thought to be a metastatic mass from sigmoid colon cancer. A postoperative histologic examination and serum test showed eosinophilic granuloma due to toxocariasis. Diagnosis of VLM is often difficult and highly suspicious in adults. Researchers suggest, although rarely, that VLM be included in the differential diagnosis as a cause of intraperitoneal tumors.

Toxocara Seroprevalence and Associated Risk Factors in the United States.

Caused by the parasitic nematodes Toxocara canis and cati, toxocariasis in humans can result in covert toxocariasis, ocular toxocariasis, visceral larval migrans, and neurotoxocariasis. A common infection, toxocariasis exposure varies widely within and between countries, with a previous estimate of Toxocara seroprevalence using data from 1988 to 1994 in the United States of approximately 13%. Age, poverty, sex, educational attainment, ethnicity, and region have been associated with Toxocara seroprevalence. In this study, we sought to determine the seroprevalence of and factors associated with Toxocara seropositivity in the United States using data from the National Health and Nutrition Examination Survey from 2011 to 2014 to provide a more recent estimate of Toxocara seroprevalence in the United States. We found an overall Toxocara seroprevalence of 5.1%. Increasing age, male sex, low educational attainment, low income, and immigration status each was associated with Toxocara seropositivity. Mexican Americans had reduced odds of exposure. These findings show that exposure to Toxocara continues in the United States and that several demographic factors influence the risk of exposure.

Helminth Infections and Cardiovascular Diseases: Toxocara Species is Contributing to the Disease.

Toxocariasis is the clinical term used to describe human infection with either the dog ascarid Toxocara canis or the feline ascarid Toxocara cati. As with other helminths zoonoses, the infective larvae of these Toxocara species cannot mature into adults in the human host. Instead, the worms wander through organs and tissues, mainly the liver, lungs, myocardium, kidney and central nervous system, in a vain attempt to find that, which they need to mature into adults. The migration of these immature nematode larvae causes local and systemic inflammation, resulting in the “larva migrans” syndrome. The clinical manifestations of toxocariasis are divided into visceral larva migrans, ocular larva migrans and neurotoxocariasis. Subclinical infection is often referred to as covert toxocariasis. One of the primary causes of death all around the world is cardiovascular disease that accounted for up to 30 percent of all-cause mortality. Cardiovascular disease and more precisely atherosclerotic cardiovascular disease, is predicted to remain the single leading cause of death (23.3 million deaths by 2030). A-quarter of people presenting the disease does not show any of the known cardiovascular risk factors. Therefore, there is considerable interest in looking for novel components affecting cardiovascular health, especially for those that could improve global cardiovascular risk prediction. This review endeavours to summarize the clinical aspects, new diagnostic and therapeutic perspectives of toxocaral disease with cardiovascular manifestations.

Epidemiology of human toxocariasis in Poland - A review of cases 1978-2009.

Toxocariasis is a helminthozoonosis due to the infection of humans with larvae belonging to the Toxocara genus. Humans become infected as a result of accidental consumption of infected eggs containing third stage larvae (L3) nematodes from Toxocara canis or Toxocara cati species. Toxocariasis was recognized for the first time in the early 1950s, and the first cases of toxocariasis in Poland were described a few years later. Toxocariasis is clinically classified into several types: classic and incomplete visceral larva migrans (VLM) syndrome, ocular larva migrans (OLM) syndrome, neurological toxocariasis (NLM), covert toxocariasis and asymptomatic toxocariasis. In 1994-2005, 18,367 sera of people suspected of being infected with Toxocara were analysed, 1.8-76% had anti- Toxocara antibodies. In the period 1978-2009, 1,022 clinical cases of toxocariasis were recognized in Poland. In the opinion of the authors, in order to reduce the frequency of toxocariasis in human populations, some prophylaxis should undertaken, e.g. public education of zoonotic diseases, systematic control of animal, deworming of pets, cleaning pets' faeces by the owners.

Toxocariasis in North America: a systematic review.

Toxocariasis is an important neglected tropical disease that can manifest as visceral or ocular larva migrans, or covert toxocariasis. All three forms pose a public health problem and cause significant morbidity in areas of high prevalence. To determine the burden of toxocariasis in North America, we conducted a systematic review of the literature following PRISMA guidelines. We found 18 articles with original prevalence, incidence, or case data for toxocariasis. Prevalence estimates ranged from 0.6% in a Canadian Inuit community to 30.8% in Mexican children with asthma. Commonly cited risk factors included: African-American race, poverty, male sex, and pet ownership or environmental contamination by animal feces. Increased prevalence of Toxocara spp. infection was linked in a group of case control studies conducted in Mexico to several high risk groups including waste pickers, asthmatic children, and inpatient psychiatry patients. Further research is needed to determine the true current burden of toxocariasis in North America; however the prevalence estimates gathered in this review suggest that the burden of disease is significant.

Comparison of Toxocariasis Frequency in Hyper- eosinophilic and Non- Eosinophilic Individuals Referred to Abadan Health Centers

Background: Toxocariasis is a zoonotic helminthic infection of humans and animals caused by the larvae of intestinal parasites of dogs and cats (Toxocara canis and Toxocara cati, respectively). These nematodes develop in to their adult stage in the intestines of cats and dogs. Three clinical entities have been recognized in humans; visceral larva migrans, ocular larva migrans and covert toxocariasis. Eosinophilia is a common finding in infected patients Objectives: In this study the frequency of toxocariasis in eosinophilic and non-eosinophilic individuals referred to the laboratory of Abadan health centers was compared. Materials and Methods: Serum samples were collected from individuals attending the laboratory of health centers for any medical problem and were tested for complet blood count (CBC). The samples of patients were divided in to two groups, those with more than 10% peripheral eosinophils, as the eosinophilic group (n = 54) and those with normal eosinophils (0-3%) as the non-eosinophilic group (n = 54). Samples were examined for anti-oxocara IgG by the enzyme linked immunosorbent assay (ELISA) and confirmed western blotting. Results: Anti-oxocara IgG was detected in the sera of six (11.11%) cases from the eosinophilic group and two (3.7%) of the non-eosinophilic group by the ELISA method, but all had negative results for the western blot analysis. Conclusions: The results of this study indicated that the eosinophilic individuals might beexposed to other helminthic infections or allergic agents. Further studies are required with more samples with different ages and occupations.

Case report: A rarely seen cause of brain abscess - neurotoxocariasis

Background: Toxocariasis is associated with three syndromes in human beings which are visceral larva migrans, ocular larva migrans and covert toxocariasis. Although neurotoxocariasis is defined as the fourth syndrome of toxocariasis, it is usually considered as a neurological disease which is usually concomitant with visceral larva migrans. In this abstract we report a case of brain abcess caused by toxocariasis. Methods & Materials: A 56 years-old female patient admitted at our hospital with headache, pain referring to right side of her face and teeth, numbness of forth and fifth finger of her right hand. Cranial diffusion weighted, dynamic magnetic resonance imaging (MRI) revealed a few nonspesific intensities at supratentorial white matter, and an approximately 13x12mm lesion without contrast enhancement which had a significant edema around the whitematter in the left frontal cortex. Histologic examination after stereotactic biopsy of the lesion revealed diffuse histiocyte infiltration in histological examination. Results: A spesific agent could not be detected in histochemical examination.Western-blot test toxocariasis in serumand CSFwere positive. She was transferred to the infectious diseases and clinical microbiology clinic.Albendazole 400mg q12h was started. A total of onemonthduration for albendazole treatmentwasplanned after regression of the cranial MRI findings on the 14th day of therapy. The patient is recalled for cranial MRI control three months later. However, we found out that she continued albendazole for three months. Compared to the previous MRI, there were two stabilized T2A hyperintense lesions in left cranial hemisphere and minimally regressed lesions at the level of left frontal centrum semi-ovale. There was no relapse after six month follow up. The Conclusion: The presented case suggests that although rarely neurotoxocariasismaybe encountered in the etiology of encephalitis/brain abcess. The patient was successfully treated with albendazole. To our knowledge this is the first reported case of neurotoxocariasis n Turkey.

The influence of winter on the prevalence of urogenital schistosomiasis in rural southern KwaZulu-Natal

Background: Toxocariasis is associated with three syndromes in human beings which are visceral larva migrans, ocular larva migrans and covert toxocariasis. Although neurotoxocariasis is defined as the fourth syndrome of toxocariasis, it is usually considered as a neurological disease which is usually concomitant with visceral larva migrans. In this abstract we report a case of brain abcess caused by toxocariasis. Methods & Materials: A 56 years-old female patient admitted at our hospital with headache, pain referring to right side of her face and teeth, numbness of forth and fifth finger of her right hand. Cranial diffusion weighted, dynamic magnetic resonance imaging (MRI) revealed a few nonspesific intensities at supratentorial white matter, and an approximately 13x12mm lesion without contrast enhancement which had a significant edema around the whitematter in the left frontal cortex. Histologic examination after stereotactic biopsy of the lesion revealed diffuse histiocyte infiltration in histological examination. Results: A spesific agent could not be detected in histochemical examination.Western-blot test toxocariasis in serumand CSFwere positive. She was transferred to the infectious diseases and clinical microbiology clinic.Albendazole 400mg q12h was started. A total of onemonthduration for albendazole treatmentwasplanned after regression of the cranial MRI findings on the 14th day of therapy. The patient is recalled for cranial MRI control three months later. However, we found out that she continued albendazole for three months. Compared to the previous MRI, there were two stabilized T2A hyperintense lesions in left cranial hemisphere and minimally regressed lesions at the level of left frontal centrum semi-ovale. There was no relapse after six month follow up. The Conclusion: The presented case suggests that although rarely neurotoxocariasismaybe encountered in the etiology of encephalitis/brain abcess. The patient was successfully treated with albendazole. To our knowledge this is the first reported case of neurotoxocariasis n Turkey.

Manifestaciones cardiovasculares de la toxocariasis humana

Toxocariasis is a parasitic infection produced by helminths that cannot reach their adult stage in humans. For their etiological species (Toxocara canis and Toxocara cati), man is a paratenic host. Infection by such helminths can produce a variety of clinical manifestations, such as: visceral larvae migrans syndrome, ocular larvae migrans syndrome and covert toxocariasis. In the visceral larvae migrans syndrome, the organs that are mainly involved include liver, lungs, skin, nervous system, muscles, kidneys and the heart. Regarding the latter, the importance of cardiovascular manifestations in toxocariasis, as well as its clinical relevance, has increasingly begun to be recognized. The current article is based on a systematic information search, focused mainly on the clinical and pathological aspects of cardiovascular manifestations in toxocariasis, including its pathophysiology, laboratory findings, diagnosis and therapeutical options, with the objective of highlighting its importance as a zoonosis and its relevance to the fields of cardiovascular medicine in adults and children.

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.

Human toxocariasis: diagnosis, worldwide seroprevalences and clinical expression of the systemic and ocular forms

Although human toxocariasis ranks among the most common zoonotic infections worldwide, it remains relatively unknown to the public. The causal agents are the nematode parasites Toxocara canis and T. cati, whose definitive hosts are dogs and cats, respectively. When embryonated eggs are accidentally ingested by humans, larvae hatch in the small intestine, penetrate the intestinal wall and migrate, via the bloodstream, to the liver, lungs, muscles, eye and central nervous system. Although most human infections are asymptomatic, two well-defined clinical syndromes are classically recognised: visceral larva migrans (a systemic disease caused by larval migration through major organs) and ocular larva migrans (a disease limited to the eyes and optic nerves). Two less-severe syndromes have recently been described, one mainly in children (covert toxocariasis) and the other mainly in adults (common toxocariasis). Here, the current laboratory diagnosis, epidemiology and main clinical features of both the systemic and ocular forms of human toxocariasis are reviewed. New developments in serological diagnosis are described, the available seroprevalence data are analysed, and the results of relevant clinical studies that have been published over the last decade are explored, to provide an updated overview of this neglected but highly prevalent human infection.