Visceral larva migrans typically occurs in young children and results from nematode larvae entering extraintestinal viscera, causing a phagocytic attack. It is caused by the larvae of Toxocara canis or Toxocara cati. T. canis and T. cati have complex life cycles involving dogs/cats and paratenic hosts like rodents or insects. Symptoms vary depending on the localization of larvae and include fatigue, abdominal pain, cough, and occasionally seizures. Diagnosis involves clinical examination, serology, biopsy of affected tissues like the liver, and detection of secretory antigens. Prevention includes regular deworming of pets and good hygiene.

1. VISCERAL
LARVA
MIGRANS

2.  typically found in young children.
 occurs when a nematode larvae gain
entry to extraintestinal viscera of the
host.
 results in phagocytic attack on the
larvae.
 caused by: Toxocara canis
Toxocara cati

3. Toxocara canis (dog ascarid)
• DH: Dogs and other canids
• PH: Rodents
• AH: Human
Morphology
o Male
 4-6 cm long
 posterior end is curved ventrally
 tail is bluntly pointed
 single tubular testis
 simple spicules (allows for direct
sperm transfer)

4. oFemale
 6.5-10 cm long
 has ascarid lips
 cervical alae are longer than
broad
 vulva is about 1/3 of the
body length from the anterior
end
 ovaries are very large and
extensive
 uteri contain up to 27 million
eggs

5. o Eggs
 85x75 µ
 subglobose and pitted
superficially
 dark brown in color
 unembryonated when laid
 very resistant to various
weather and chemical conditions.

6. Life Cycle

7. Cross-section of Toxocara
Larvae in liver tissue

8. Toxocara cati (cat ascarid)
• DH: Cats
• PH: Earthworms, Ants and Other soil-
dwelling invertebrates
• AH: Human
Morphology
o Male
 4-6 cm long
 has typical slender shape
 thin head and tail
 has simple chitinous spicules

9. o Female
 4-12 cm long
 has ascarid lips
 pair of broad, lateral cervical
alae
 large ovaries
 uteri contain up to 30 million
eggs

10. o Eggs
 65x70 µ
 almost spherical in shape
 thin shelled and delicately
pitted
 contain single cell

11. Life Cycle

12. Symptoms
 Physical symptoms: includes fatigue,
anorexia, weight loss, pneumonia, fever,
cough, bronchospasm, abdominal pain,
headaches, rashes, and, occasionally
seizures
 Clinical symptoms: depend on the
localization and degree of pathological
changes and include non-specific and
varied conditions such as eosinophilia,
leukocytosis, hepatomegaly, mild
gastrointestinal disorders, asthmatic
attacks, pneumonic symptoms, urticarial
skin changes, central nervous disorders
with paralyses

13. Diagnosis
 Clinical Picture – ectopic foci
 ELISA using secretory excretory
antigen
 Biopsy – liver (demonstrate the
characteristic granuloma surrounding
a juvenile)
 Serology – hemagglutination test
– microprecipitation test

14. Prevention
• Periodic deworming of household
dogs and cats
• Wash your hands with soap and
water after playing with your pets or
other animals, after outdoor
activities, and before handling food.
• Clean your pet's living area at least
once a week.
• Prevent children from eating dirt.