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Toxocariasis

Toxocariases

Toxocariasis is a zoonosis caused by the larvae of toxocara canis and toxocara cati. The disease is transmitted when humans, especially children, accidentally consume soil contaminated with the eggs present in cat or dog feces. The eggs release larvae which spread through the human body causing inflammation and symptoms of toxocariasis. The disease can manifest as visceral larva migrans or ocular toxocariasis or may be covert.


Presentation

Toxocariasis is a tropical disease caused by the roundworm, toxocara. It is transmitted to humans with the accidental consumption of soil contaminated with the eggs of the parasite excreted in cat or dog feces [1]. The eggs release larvae which puncture the intestinal wall and migrate through the circulatory system to various organs of the human body (brain, eyes, heart, liver, lungs and muscle) where they cause inflammation leading to symptoms of toxocariasis.

The clinical presentation of toxocariasis depends upon the organ system involved and can be classified as:

  • Visceral larva migrans (VLM) - involving all major organs
  • Ocular larva migrans (OLM) - involving the eyes and the optic nerve
  • A covert form which is difficult to diagnose.

VLM affects mainly children under the age of five [2] who present with fever, pain in abdomen, hepatosplenomegaly, eosinophilia, bronchospasm, seizures, neuropsychiatric or cognitive symptoms or encephalopathy depending on the organ system involved.

OLM, on the other hand, affects children in the five to ten year age group and is associated with unilateral visual impairment and, strabismus [3]. In severe cases of OLM, there may be retinal invasion with granuloma formation in the posterior pole, heteropia and macular detachment [4]. There may also be endophthalmitis, papillitis followed secondarily by glaucoma and blindness.

The covert form of toxocariasis can present insidiously with headache, coughing, abdominal pain and hepatosplenomegaly or symptoms resembling asthma e.g. dyspnea, wheezing and coughing [1] [5].

Fever
  • Symptoms were fever, inactivity, weakness, tiredness and loss of appetite. She was followed clinically and with blood samples throughout a period of three years and four months.[ncbi.nlm.nih.gov]
  • Abstract Background A 56-year-old female presented to the emergency room with a 2-week history of fevers, chills and right upper quadrant pain. She had no sick contacts, had not traveled recently and denied high-risk sexual behavior.[ncbi.nlm.nih.gov]
  • Toxocariasis and, commonly, T. canis, is a disease commonly seen in children, which is characterised by hypereosinophilia, hepatomegaly, fever, transient pulmonary infiltration, and hypergammaglobulinaemia.[ncbi.nlm.nih.gov]
  • We report the case of a 64-year-old man who developed a purpura along with fever, respiratory failure, abdominal pain and myalgia.[ncbi.nlm.nih.gov]
  • A 23-year-old woman with fever, myalgias, stridor, pelvic cramping, lower abdominal pain, and profound eosinophilia was presumed to have toxocariasis.[ncbi.nlm.nih.gov]
Epilepsy
  • Several studies have evidenced high seropositivity rates for T. canis among people with epilepsy suggesting that toxocariasis could play a role in the incidence of epilepsy in endemic areas.[ncbi.nlm.nih.gov]
  • This increased for those with late-onset partial epilepsy to an OR of 18.22 (95% CI 2.10 to 158.10).[neurology.org]
  • […] that toxocariasis may be an etiologic factor in epilepsy. 177 This hypothesis remains unsettled.[epilepsy.com]
  • Understanding the cerebral host-parasite relationship may shed some light on the cryptic symptoms of human infection where patients often present with other CNS disorders such as epilepsy and mental retardation. [Indexed for MEDLINE] Free full text[ncbi.nlm.nih.gov]
  • Brain involvement can evoke meningitis, encephalitis, or epilepsy. Ocular involvement may cause loss of visual acuity or unilateral blindness. Pulmonary and hepatic forms can cause protracted symptoms if the patient does not receive treatment.[emedicine.com]
Pallor
  • Patients can present with pallor, fatigue, weight loss, anorexia, fever, headache, rash, cough, asthma, chest tightness, increased irritability, abdominal pain, nausea, and vomiting.[en.wikipedia.org]
Vietnamese
  • Comparison of 264 nucleotides of internal transcribed spacer 2 (ITS2) of ribosomal DNA was done between our Vietnamese Toxocara canis and other Toxocara geographical isolates, including Chinese T. canis, Japanese T. canis, Sri Lankan T. canis, and Iranian[ncbi.nlm.nih.gov]
Cough
  • The covert form of toxocariasis can present insidiously with headache, coughing, abdominal pain and hepatosplenomegaly or symptoms resembling asthma e.g. dyspnea, wheezing and coughing.[symptoma.com]
  • ., which may involve many organs, but pulmonary symptoms such as coughing and wheezing and allergic symptoms are seen in more than 80% of patients.[ncbi.nlm.nih.gov]
  • The most common pulmonary symptoms in our review were cough and dyspnea, and the most common finding on chest imaging was bilateral pulmonary nodules. Risk factors for Toxocara infection primarily included exposure to dogs.[ncbi.nlm.nih.gov]
  • Although most infected individuals are asymptomatic, clinical manifestations may include fever, fatigue, coughing, wheezing, or abdominal pain (visceral toxocariasis) or vision loss, retina damage, or eye inflammation (ocular toxocariasis).[ajtmh.org]
  • A 2-year-old girl presented monthly episodes of fever and cough for approximately 1 year.[n.neurology.org]
Rhinitis
  • We report three cases presenting as dermatitis, rhinitis, asthma, and conjunctivitis which were diagnosed and unsuccessfully treated as allergy. The correct diagnosis was established after detecting anti-Toxocara antibodies by Western blotting.[ncbi.nlm.nih.gov]
  • In addition, among these 113 patients, 19 had eosinophilia due to allergic disease, diagnosed based on a MAST score higher than 3 and the presence of asthma, allergic rhinitis, etc. Eosinophilia due to a drug reaction was diagnosed in two patients.[kjim.org]
Abdominal Pain
  • We report a 13-year-old girl with recurrent abdominal pain who, despite positive toxocara serology, was extensively investigated for other abdominal pathology.[ncbi.nlm.nih.gov]
  • We report on a case that presented to our emergency department (ED) with abdominal pain.[ncbi.nlm.nih.gov]
  • We report the case of a 64-year-old man who developed a purpura along with fever, respiratory failure, abdominal pain and myalgia.[ncbi.nlm.nih.gov]
  • A 23-year-old woman with fever, myalgias, stridor, pelvic cramping, lower abdominal pain, and profound eosinophilia was presumed to have toxocariasis.[ncbi.nlm.nih.gov]
  • The covert form of toxocariasis can present insidiously with headache, coughing, abdominal pain and hepatosplenomegaly or symptoms resembling asthma e.g. dyspnea, wheezing and coughing.[symptoma.com]
Lower Abdominal Pain
  • A 23-year-old woman with fever, myalgias, stridor, pelvic cramping, lower abdominal pain, and profound eosinophilia was presumed to have toxocariasis.[ncbi.nlm.nih.gov]
Morning Stiffness
  • A 3-year-old girl was referred to our service with severe painful chronic polyarthritis for a period longer than 10 weeks and morning stiffness of 30min. Dog contact exposure history in the recreational areas of neighborhood was reported.[ncbi.nlm.nih.gov]
Eczema
  • No statistical excess of risk was observed for patients with atopic dermatitis, pruritus or non-atopic eczema. Conclusion: The authors conclude that patients suffering from urticaria or prurigo should be tested for Toxocara infection.[karger.com]
Grieving
  • Grieve, and D. D. Bowman. 1987. Immune-mediated adherence of eosinophils to Toxocara canis infective larvae: the role of excretory-secretory antigens. Parasite Immunol. 9 : 133 -143. 3. Basualdo, J. A., M. L. Ciarmela, P. L. Sarmiento, and M. C.[doi.org]
  • Grieve, and D. D. Bowman. 1987 . Immune-mediated adherence of eosinophils to Toxocara canis infective larvae: the role of excretory-secretory antigens. Parasite Immunol. 9 : 133 -143. 3. Basualdo, J. A., M. L. Ciarmela, P. L. Sarmiento, and M. C.[doi.org]
Irritability
  • Patients can present with pallor, fatigue, weight loss, anorexia, fever, headache, rash, cough, asthma, chest tightness, increased irritability, abdominal pain, nausea, and vomiting.[en.wikipedia.org]
  • Fecal transplant is used to treat gut infections and is now being studied as a treatment for obesity, urinary tract infections, irritable bowel syndrome and more.[nytimes.com]
Memory Impairment
  • Preliminary data have also suggested a possible link between significant memory impairment and cytokine production associated with T. canis infection.[ncbi.nlm.nih.gov]

Workup

The diagnosis of the disease is based mainly on the history and symptoms of multi-organ or ocular involvement. Serological testing and biopsy or autopsy specimens showing larvae help to confirm the diagnosis.

Toxocariasis should be suspected in a child with a history of pica, contact with dogs or cats, clinical signs of unexplained febrile illness with hepatosplenomegaly, eosinophilia or ocular symptoms. A complete blood count will reveal eosinophilia, although it may be absent in some cases of OLM and covert toxocariasis.

Confirmation of the diagnosis relies on the laboratory demonstration of specific anti-toxocara antibodies in either the serum or aqueous or vitreous fluid of the infected individual. The enzyme-linked immunosorbent assay (ELISA) test which uses antigens from the second stage larva is the best indirect test for the diagnosis of toxocariasis. Although histopathology of tissue samples with the identification of larvae or the detection of larval DNA in tissues is definitive, it is difficult to obtain such infected tissue samples [6] [7].

The diagnosis of OLM is based on clinical criteria and ophthalmic examination as immunodiagnostic tests are not as reliable as for VLM [8]. Neuroimaging, especially magnetic resonance imaging (MRI) is recommended to detect granulomas in the cortical or subcortical layers of the brain in patients with neuropsychiatric symptoms. MRI findings combined with cerebrospinal detection of eosinophil is indicative of toxocara infection.

Wuchereria Bancrofti
  • Filarial-specific IgG4 response correlates with active Wuchereria bancrofti infection. J. Immunol. 145 : 4298 -4305. Lynch, N. R., L. K. Wilkes, A. N. Hodgen, and K. J. Turner. 1988. Specificity of Toxocara ELISA in tropical population.[jcm.asm.org]
Brugia Malayi
  • A recombinant antigen-based IgG4-ELISA for the specific and sensitive detection of Brugia malayi infection. Trans. R. Soc. Trop. Med. Hyg. 95 : 280 -284. Schantz, P. M. 1989. Toxocara larva migrans now. Am. J. Trop. Med. Hyg. 41 : 21 -34. Shetty, A.[jcm.asm.org]
Gnathostoma Spinigerum
  • spinigerum in the eye; and 100 serum samples came from healthy individuals.[jcm.asm.org]

Treatment

  • Furthermore, for patients suspected of eosinophilia of unknown origin who have positive results for T. canis , albendazole treatment may be considered a valuable treatment option.[ncbi.nlm.nih.gov]
  • CONCLUSIONS: The differential diagnosis of ocular toxocariasis and review of the available treatments are presented.[ncbi.nlm.nih.gov]
  • Albendazole is one of the treatment choices for toxocariasis, with a currently recommended regimen of 10 mg/kg/day in two doses (400 mg twice daily) for 5 days. However, there is no precise consensus about the duration of the treatment.[ncbi.nlm.nih.gov]
  • 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.[ncbi.nlm.nih.gov]
  • PURPOSE: To investigate the clinical characteristics and treatment results of adult patients with ocular toxocariasis.[ncbi.nlm.nih.gov]

Prognosis

  • We suggest that the visual prognosis need not be so poor as commonly believed, and outline a suggested plan of management.[ncbi.nlm.nih.gov]
  • Surgical intervention may play a role in improving the prognosis, but the place of specific chemotherapy remains undefined.[nature.com]
  • Prognosis appears favorable with adequate treatment except in case of neurological involvement.[ncbi.nlm.nih.gov]

Etiology

  • RESULTS: Of 238 patients with uveitis of unknown etiology, 71 (29.8%) were diagnosed with OT, and 80 (33.6%) had positive ELISA results for serum anti-Toxocara IgG.[ncbi.nlm.nih.gov]
  • The etiology of Wells' syndrome or eosinophilic cellulitis is unknown. Various triggering factors, such as myeloproliferative disorders, lymphoma, infections/infestations, insect bites and drugs have been reported.[ncbi.nlm.nih.gov]
  • Nevertheless, longitudinal data are required to confirm an etiological connection between toxocariasis and cognitive function, as well as the true population attributable risk for toxocariasis and its chronic sequelae. Copyright 2012.[ncbi.nlm.nih.gov]
  • Toxocara GWC analysis, however, can be of value when diagnosing patients with posterior focal lesions or vitritis of unknown etiology.[ncbi.nlm.nih.gov]
  • Author information 1 Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia. 2 State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou[ncbi.nlm.nih.gov]

Epidemiology

  • MAIN TEXT: Over the past two decades, we have come far in our understanding of the biology and epidemiology of toxocariasis.[ncbi.nlm.nih.gov]
  • PURPOSE: To provide an updated insight of concepts regarding the overview, epidemiology, risk factors, clinical manifestations, diagnosis, treatment and prevention of ocular toxocariasis. DESIGN: Perspective of literature review.[ncbi.nlm.nih.gov]
  • The aim of this study is to study epidemiology of toxocariasis in Iran using meta-analysis and systematic review. Using main key words of toxocariasis including epidemiology, Toxocara spp.[ncbi.nlm.nih.gov]
  • For each individual, a questionnaire was completed that contained epidemiological and clinical data. The data analysis was performed using multiple logistic regression.[ncbi.nlm.nih.gov]
  • Author information 1 Department of Epidemiology and Biostatistics, School of Public Health, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America. 2 Department of Epidemiology and Biostatistics, School of[ncbi.nlm.nih.gov]
Sex distribution
Age distribution

Pathophysiology

  • In addition, risk factors for acquiring infection need to be better defined, and research needs to be conducted to better understand the pathophysiology and clinical course of toxocariasis.[ncbi.nlm.nih.gov]
  • Pathophysiology: Human infection with Toxocara, the parasitic larvae of canine or feline roundworms, is known as visceral larval migrans (VLM) systemically and ocular larva migrans (OLM) when it affects the eye.[web.archive.org]
  • Pathophysiology Most frequently, human toxocariasis is caused by T. canis, a nematode roundworm of the family Ascaridae. Adult T. canis female worms are usually found in young puppies and lactating female dogs.[emedicine.com]

Prevention

  • PURPOSE: To provide an updated insight of concepts regarding the overview, epidemiology, risk factors, clinical manifestations, diagnosis, treatment and prevention of ocular toxocariasis. DESIGN: Perspective of literature review.[ncbi.nlm.nih.gov]
  • However studies by the US Centers for Disease Control and Prevention (CDC) have found that, among all age groups, toxocariasis is more common in non-Hispanic blacks than in Mexican Americans and non-Hispanic whites.[emedicine.com]
  • Author information 1 Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America. 2 National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention[ncbi.nlm.nih.gov]
  • A high index of suspicion is needed to diagnose this otherwise preventable parasitic disease.[ncbi.nlm.nih.gov]

References

Article

  1. Global Health - Division of Parasitic Diseases and Malaria (2013) Parasites - Toxocariasis (also known as Roundworm Infection). Atlanta, GA: Centers for Disease Control and Prevention.
  2. Worley G, Green IA, Frothingham TE. Toxocara canis infection: clinical and epidemiological associations with seropositivity in kindergarten children. J. Infect. Dis. 1984;149:591-597.
  3. Dinning WJ, Gillespie SH, Cooling RI, Maizels RM. Toxocariasis: a practical approach to management of ocular disease. Eye. 1988; 2:580-582.
  4. Small KW, McCuen BW, De Juan E, Machemer R. Surgical management of retinal retraction caused by toxocariasis. Am. J. Ophthalmol.1989; 108:10-14.
  5. Barry MA, Weatherhead JE, Hotez PJ, Woc-Colburn L. Childhood parasitic infections endemic to the United States. Pediatric clinics of North America. 2013; 60: 471–485.
  6. Magnaval JF, Glickman LT, Dorchies P, Morassin B. Highlights of human toxocariasis. Korean J. Parasit.2001; 39:1-11.
  7. Smith HV. Antibody reactivity in toxocariasis. In: LEWIS, J.W. & MAIZELS, R.M., ed.Toxocara and toxocariasis: clinical, epidemiological and molecular perspectives. London, Institute of Biology.1993; p. 91-109.
  8. Schantz PM. Toxocara larva migrans now. Am J Trop Med Hyg. 1989;41(Suppl.):21-34.

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Last updated: 2019-07-11 22:24