Summary about Disease
Toxocariasis is a parasitic infection caused by roundworm larvae, primarily Toxocara canis (from dogs) or *Toxocara cati* (from cats). Humans become infected by accidentally ingesting soil contaminated with roundworm eggs from animal feces. The larvae migrate through the body, causing various symptoms depending on the organs affected. There are two main forms: visceral larva migrans (VLM) and ocular larva migrans (OLM).
Symptoms
Symptoms vary depending on the extent of larval migration and the organs involved.
Visceral Larva Migrans (VLM): Fever, fatigue, cough, wheezing, abdominal pain, hepatomegaly (enlarged liver), splenomegaly (enlarged spleen), and in some cases, neurological symptoms. Eosinophilia (increased eosinophils in the blood) is a common finding.
Ocular Larva Migrans (OLM): Vision loss, eye inflammation, strabismus (crossed eyes), and leukocoria (white pupil). OLM typically affects only one eye.
Covert Toxocariasis: A milder form with vague symptoms like abdominal pain, nausea, headache, or behavioral disturbances, often accompanied by elevated eosinophil counts.
Causes
Toxocariasis is caused by ingesting Toxocara eggs present in contaminated soil. Common routes of infection include:
Contact with contaminated soil: Children who play in sandboxes or dirt where dogs or cats have defecated are at higher risk.
Ingestion of unwashed fruits and vegetables: If grown in contaminated soil.
Eating undercooked infected meat: While less common, some animals can harbor Toxocara larvae in their tissues.
Direct contact with infected animal feces: Although less frequent, direct contact can also lead to infection.
Medicine Used
Albendazole: A commonly used antihelminthic drug to kill the larvae. Dosage and duration depend on the severity of the infection and the patient's age and weight.
Mebendazole: Another antihelminthic drug used as an alternative to albendazole.
Corticosteroids: Used to reduce inflammation, particularly in cases of ocular larva migrans or when significant organ inflammation is present.
Other Medications: In some cases, medication to control seizures or other symptoms may also be prescribed.
Is Communicable
Toxocariasis is not communicable from person to person. Humans are infected by ingesting eggs from contaminated soil, not directly from other infected individuals.
Precautions
Practice good hygiene: Wash hands thoroughly with soap and water after contact with soil or animals, especially before eating.
Control pet hygiene: Regularly deworm pets, especially puppies and kittens. Promptly clean up pet feces.
Cover sandboxes: When not in use to prevent animals from defecating in them.
Wash fruits and vegetables: Thoroughly before consumption, especially those grown in gardens.
Teach children: About the importance of handwashing and avoiding contact with animal feces.
Avoid eating undercooked meat.
How long does an outbreak last?
Toxocariasis does not typically occur in outbreaks. It is usually a sporadic infection. An individual's symptoms may persist for weeks, months, or even years, depending on the severity of the infection and the organs involved. The larval migration eventually ceases, but any damage caused can be long-lasting, especially in cases of ocular larva migrans.
How is it diagnosed?
Diagnosis typically involves:
Medical History and Physical Examination: Review of symptoms and potential exposure history.
Blood Tests:
Eosinophil count: Elevated eosinophils are a common finding.
Toxocara antibody test (ELISA): Detects antibodies against *Toxocara* larvae. A positive result indicates previous or current infection.
Imaging Studies:
CT scans or MRI: May be used to visualize organ involvement (e.g., liver lesions in VLM).
Ophthalmological Examination:
Dilated fundus examination: To visualize the retina and detect signs of ocular larva migrans.
Biopsy: Rarely needed, but may be performed in cases where other diagnoses need to be ruled out.
Timeline of Symptoms
The timeline of symptoms can vary significantly:
Ingestion: Eggs are ingested.
Incubation: Eggs hatch in the intestine, and larvae migrate through the body (days to weeks).
Initial Symptoms (VLM): Fever, fatigue, cough, and abdominal pain may develop within weeks to months after infection.
Ocular Symptoms (OLM): Vision changes can occur months or even years after the initial infection. OLM might present without prior VLM symptoms.
Chronic Symptoms: Some individuals may experience chronic or intermittent symptoms for months or years.
Important Considerations
Differential Diagnosis: Toxocariasis symptoms can mimic other conditions, such as asthma, allergies, or other parasitic infections. Accurate diagnosis is crucial.
Severity: The severity of toxocariasis can range from mild, self-limiting infections to severe, organ-damaging disease.
Prevention is key: Emphasize preventative measures, especially good hygiene and pet deworming.
Treatment: Prompt treatment with antihelminthic medications and, if necessary, corticosteroids can help reduce symptoms and prevent complications.
Ophthalmological Follow-up: Individuals with ocular larva migrans require close monitoring by an ophthalmologist to prevent vision loss.