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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Pediatrics

Recognizing the Signs: The Different Types of Toxocariasis

At a Glance

Toxocariasis symptoms depend on where the roundworm larvae travel in the body. The four main types are visceral (affecting organs like the liver and lungs), ocular (affecting the eye), neurological (affecting the brain), and covert (causing mild, hidden symptoms like cough and stomach pain).

Because Toxocara larvae cannot grow into adults in the human body, they wander through different tissues. The symptoms your child experiences depend entirely on where these larvae travel and how their immune system reacts [1][2].

Doctors generally group toxocariasis into four main categories based on which part of the body is affected.

1. Visceral Larva Migrans (VLM)

This is a systemic (whole-body) reaction that occurs when larvae travel through internal organs, most commonly the liver and lungs [1]. It is often seen in younger children who may have accidentally eaten contaminated dirt [3].

  • Common Symptoms: High fever, a cough that won’t go away, wheezing, and an enlarged liver (hepatomegaly) [4][5].
  • Warning Signs: You or your doctor might feel a mass or firmness in the upper right side of the child’s abdomen [6].
  • What it mimics: Because it causes organ swelling and fever, VLM can sometimes be mistaken for asthma, pneumonia, or even more serious conditions like leukemia [6][7].

2. Ocular Larva Migrans (OLM)

This occurs when a single larva travels to the eye [8]. While OLM is less likely to cause a fever, it is very serious because it can lead to permanent vision loss if not caught early [9].

  • Common Symptoms: Blurred vision, redness in one eye, or a “white glow” in the pupil when light hits it [10][11].
  • Warning Signs: A sudden “lazy eye” or crossed eyes (strabismus) in a child who previously had straight eyes [9].
  • What it mimics: OLM can look very similar to retinoblastoma (a rare childhood eye cancer). It is critical for an eye specialist (ophthalmologist) to examine the eye to tell them apart [10].

3. Neurotoxocariasis

In rare cases, the larvae can enter the central nervous system (the brain and spinal cord) [12]. This is a serious condition that requires immediate medical attention.

  • Common Symptoms: Severe headaches, confusion, or changes in behavior [13][14].
  • Warning Signs: The sudden onset of seizures (which may look like epilepsy) or signs of meningitis, such as a very stiff neck and high fever [13][12].
  • What it mimics: Because it affects the nerves and brain, it can sometimes be confused with multiple sclerosis (MS) or other inflammatory brain diseases [12].

4. Covert Toxocariasis

This is the most common form in children and can be the hardest to spot because the symptoms are “covert” or hidden [15].

  • Common Symptoms: Chronic cough, mild stomach pain, headaches, and trouble sleeping [16][17].
  • Warning Signs: A child who is frequently “under the weather” without a clear explanation [15].
  • What it mimics: It is often mistaken for common childhood allergies or recurrent viral infections [15].
  • Prognosis: Importantly, Covert Toxocariasis often has a very positive prognosis; in many cases, it resolves on its own over time or requires only minor symptom management [18].

A Note on Blood Tests

If your doctor suspects any form of toxocariasis, they will likely look for eosinophilia—a high level of a specific type of white blood cell (eosinophils) that the body produces to fight parasites [19][20]. While high eosinophils are a major clue, they are not always present in every type of toxocariasis, especially the ocular form [21]. Your doctor will use a combination of tests detailed in Understanding the Diagnosis to build a complete picture [15].

Common questions in this guide

What are the symptoms of visceral larva migrans (VLM)?
VLM causes a whole-body reaction when roundworm larvae travel through internal organs like the liver and lungs. Common symptoms include a persistent cough, high fever, wheezing, and an enlarged liver.
Can toxocariasis affect my child's eyes?
Yes, a condition called ocular larva migrans (OLM) occurs when a larva travels to the eye. It can cause blurred vision, a red eye, a white glow in the pupil, or a lazy eye. It requires immediate evaluation by an ophthalmologist to prevent permanent vision loss.
What is covert toxocariasis?
Covert toxocariasis is the most common and mildest form of the infection in children. Symptoms are often hidden or mimic common allergies, including chronic cough, mild stomach pain, headaches, and trouble sleeping.
Can toxocariasis cause neurological problems?
In rare cases, larvae can enter the brain and spinal cord, causing neurotoxocariasis. This serious condition can lead to severe headaches, behavioral changes, confusion, or sudden seizures, requiring immediate medical attention.
How does a doctor test for toxocariasis?
Doctors often use blood tests to look for eosinophilia, which is a high level of specific white blood cells the body produces to fight parasites. However, eosinophils may not be elevated in all types of the infection, particularly the ocular form.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Given my child's symptoms, which subtype of toxocariasis do you suspect most?
  2. 2.Could these symptoms be caused by something else, like asthma, a different parasite, or a more serious eye condition like retinoblastoma?
  3. 3.If we are testing for Ocular Larva Migrans, will we need to test the fluid inside the eye as well as the blood?
  4. 4.What does an elevated eosinophil count mean in the context of my child's symptoms?
  5. 5.Are there specific neurological tests, like an MRI or a lumbar puncture, if we are concerned about brain involvement?
  6. 6.Does my child need a baseline exam from a pediatric ophthalmologist just to be safe?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (21)
  1. 1

    Atypical Toxocara canis-Induced Hepatic Visceral Larva Migrans: Diagnostic Challenges and Literature Review.

    Huynh TM, Tran KQL, Dinh TH, et al.

    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 2024; (83(6)):247-252 doi:10.4166/kjg.2024.051.

    PMID: 38918038
  2. 2

    Genetic analysis of Toxocara cati (Nematoda: Ascarididae) from Guangdong province, subtropical China.

    He X, Lv MN, Liu GH, Lin RQ

    Mitochondrial DNA. Part A, DNA mapping, sequencing, and analysis 2018; (29(1)):132-135 doi:10.1080/24701394.2016.1258404.

    PMID: 28141958
  3. 3

    Prevalence of Toxocara eggs in Latin American parks: a systematic review and meta-analysis.

    Bonilla-Aldana DK, Morales-Garcia LV, Ulloque Badaracco JR, et al.

    Le infezioni in medicina 2023; (31(3)):329-349 doi:10.53854/liim-3103-7.

    PMID: 37701393
  4. 4

    Hepatic Visceral Larva Migrans Causing Hepatic Venous Thrombosis and Prolonged Fever.

    Kaur J, Gupta A, Wadhwa N

    Indian pediatrics 2017; (54(10)):882-884 doi:10.1007/s13312-017-1155-6.

    PMID: 29120339
  5. 5

    Presumptive pulmonary toxocariasis in a patient affected by acute myeloid leukemia and Hodgkin lymphoma: case report and review of the literature in immunocompromised hosts.

    Lupia T, Crisà E, Sangiorgio V, et al.

    Le infezioni in medicina 2024; (32(1)):103-112 doi:10.53854/liim-3201-14.

    PMID: 38456027
  6. 6

    Chronic polyarthritis as isolated manifestation of toxocariasis.

    Viola GR, Giacomin MF, França CM, et al.

    Revista brasileira de reumatologia 2016; (56(2)):185-7.

    PMID: 27267534
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    Abdominal Mass Secondary to Human Toxocariasis.

    Ghoroobi J, Mohajerzadeh L, Khoddami M, et al.

    APSP journal of case reports 2017; (8(1)):4 doi:10.21699/ajcr.v8i1.490.

    PMID: 28164001
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    Pulmonary Toxocariasis: Initial and Follow-Up CT Findings in 63 Patients.

    Lee KH, Kim TJ, Lee KW

    AJR. American journal of roentgenology 2015; (204(6)):1203-11 doi:10.2214/AJR.14.13700.

    PMID: 26001229
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    Ocular Toxocariasis Associated with Blurred Vision and Visual Impairment: Report of Four Cases.

    Zibaei M, Mahdavi FS, Firoozeh F, et al.

    Iranian journal of parasitology 2022; (17(1)):118-123 doi:10.18502/ijpa.v17i1.9034.

    PMID: 36046564
  10. 10

    NONINVASIVE DIAGNOSTIC STRATEGY OF OCULAR TOXOCARIASIS BASED ON CLINICAL FEATURES.

    Jiang Z, Sun L, Huang L, et al.

    Retina (Philadelphia, Pa.) 2022; (42(5)):934-941 doi:10.1097/IAE.0000000000003388.

    PMID: 34923511
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    Unilateral Vision Loss in a Child Revealing Ocular Toxocariasis.

    El Korno O, Hilali Z, Tachfouti S, et al.

    Cureus 2025; (17(12)):e99150 doi:10.7759/cureus.99150.

    PMID: 41531620
  12. 12

    Cerebral Toxocariasis as a Cause of Epilepsy: A Pediatric Case.

    Bossi G, Bruno R, Novati S, et al.

    Neuropediatrics 2021; (52(2)):142-145 doi:10.1055/s-0040-1721701.

    PMID: 33472248
  13. 13

    The first two cases of neurotoxocariasis in Taiwan.

    Lee KP, Shen PC, Shih YC, et al.

    Journal of the Formosan Medical Association = Taiwan yi zhi 2021; (120(7)):1520-1525 doi:10.1016/j.jfma.2021.01.025.

    PMID: 33593692
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    Toxocariasis affecting brain stem and skull base.

    Gomez Serrano M, Jimenez Rodriguez-Madridejos R, Merino Menendez S, et al.

    BMC infectious diseases 2021; (21(1)):1242 doi:10.1186/s12879-021-06867-1.

    PMID: 34895158
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    Measurement of the IgG Avidity Index in the Diagnosis of Clinical Toxocariasis Patients.

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    Pathogens (Basel, Switzerland) 2021; (10(9)) doi:10.3390/pathogens10091086.

    PMID: 34578119
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    Current epidemic situation of human toxocariasis in China.

    Kong L, Peng HJ

    Advances in parasitology 2020; (109()):433-448 doi:10.1016/bs.apar.2020.01.016.

    PMID: 32381211
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    Seroprevalence and risk factors of Toxocara infection among children in Shandong and Jilin provinces, China.

    Cong W, Meng QF, You HL, et al.

    Acta tropica 2015; (152()):215-219 doi:10.1016/j.actatropica.2015.09.008.

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    Human toxocariasis.

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    [Visceral larva migrans syndrome and hepatic abscess: A case report].

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    Archivos argentinos de pediatria 2018; (116(6)):e753-e756 doi:10.5546/aap.2018.e753.

    PMID: 30457730
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    Human Toxocara Infection: Allergy and Immune Responses.

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This page is for informational purposes only and does not replace professional medical advice. Always consult your pediatrician or specialist if you suspect your child is showing signs of toxocariasis.

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