Toxocara

Background

Genus of nematode
Includes two species of medical importance:
- Toxocara canis, the dog roundworm
- Toxocara cati, the cat roundworm
Dogs/cats are the definitive hosts, while humans are incidental hosts
- In humans, the larva are unable to mature into adult worms or to release eggs
Distributed worldwide, particularly in low-resource settings with high numbers of feral dog or cat populations
About 20% of the global population is seropositive, though there is variation
- Africa 40%, Southeast Asia 34%, Western Pacific 24%, Americas 23%, Europe 11%, Eastern Mediterranean 8%
Risk factors include contact with outdoor dogs and cat, and children

Most common in children less than 5 years of age
Fevers, malaise, weight loss, respiratory symptoms, hepatomegaly, rash, lymphadenopathy
Most commonly affects lung and liver, but can also affect cardiac and urinary systems
Often see peripheral eosinophilia
Pulmonary disease
- Coughing, wheezing, dyspnea
- May present as eosinophilic pneumonia or as asthma
Liver disease
- Fevers, abdominal pain, peripheral eosinophila
- Liver lesions can mimic Fasciola hepatica, bacterial infection, and malignancy
- Can be complicated by bacterial abscess
Cardiac disease
- Rare
- Primarily myocarditis, but also pericarditis and Loeffler endocarditis

Invasion of larvae into the CNS
Syndromes can include meningoencephalitis, myelitis, spinal abscess, optic neuritis, and cerebral vasculitis
May present with epilepsy, cognitive impairment, and behaviour changes

Painless (though painful in 30%) unilateral vision loss
Photophobia and floaters
On ophthalmoscopy, may see vitreitis, posterior of intermediate uveitis, traction retinal detachment, granuloma formation, endophthalmitis, optic neuropathy, and crystoid macular edema
Vision loss is usually permanent

Non-specific symptoms in seropositive patients
Abdominal pain, anorexia, nausea, vomiting, lethargy, hedaches, myalgias, behaviour change
May have eosinophilia

Albendazole 400 mg p.o. twice daily for 5 days
Alternatively mebendazole, DEC
Neoadjuvant corticosteroids should be given be antihelminthic therapy and continued throughout treatment for patients with: cardiac disease, VLM with severe peripheral eosinophilia, ocular infection, neurotoxocariasis
- Followed by taper