Toxocara Flashcards
Aetiology
Toxocara canis, toxocara cantis
Natural parasites in the intestine of dogs and cats
Accidentally infect humans causing disease states known as visceral larvae migrans, Ocular larvae migrans
Epidemiology
Worldwide
Infected dogs and cats pose a threat to humans for T.Canis and T. Cantis
Especially children who are exposed more readily to contaminated soil and tend to put objects in their mouth
Definitive host Life cycle ( dogs and cats)
Eggs are passed in faeces> ingestion of eggs > eggs hatch in the LI> larvae migrate to the liver, heart and lungs and eventually mucus layer of trachea> larvae are swallowed and mature to adults in the small intestine> vertical transmission-transplacental/ transmammary> eggs passed in faeces
Life cycle in paratenic host ( rabbits, birds)
Embryonated egg( environmental or food borne) is ingested by humans> eggs hatch> and L3 larvae migrate to tissue( encysted) > ingestion of paratenic host
Life cycle in Dead end host (man)
Incidental
Embryonated eggs( environmental or food borne) with L3 larvae are ingested by humans > eggs hatch into larval forms that cannot follow normal developmental cycle in the natural host> penetrate the human gut> blood stream> migrate as larvae in various tissue sites and encyst in tissue
Clinical features
VLM, OLM, NLM
May invade any tissue of the body: bleeding, formation of eosinophilic granuloma, and necrosis
Covert Toxicariasis: in children
Mild subclinical, febrile illness
Symptoms: cough, difficulty sleeping, abdominal pain, headaches, behavioral problems
Exam: +hepatomegaly, lymphadenitis
Visceral larva migrans
Organs involved: lungs, heart, kidney, liver, skeletal muscles, eyes, CNS
Complications: fatigue, anorexia, weight loss, pneumoniae, bronchospasm, abdominal pain, headaches, seizure.
May develop pleural effusions, chronic urticaria
Brain damage
Occular larva migrans
May be mistaken for retinoblastoma
In older children and young adults
- vision, red eye leukokoria(white pupil) inflammation, seeing floaters
Typically in one eye
Serum Abs often absent or low titers
Neural larval migrans is a common sequence of
Baylisascaris procoynis
NLM
Worms naturally parasites in intestines of raccoons
Complications: blindness, CNS lesions, seizure, coma, death
T/F: Baylisascaris procoynis also causes VLM and OLM
True
Diagnosis of VLM, NLM, OLM
Clinical findings - high index of suspicion
Serological confirmation - ELISA and Western Blot
Definitive diagnosis - tissue examination for larvae or tissue digestion- CT and ultrasound
Eosinophilia
Known exposure to dogs, cats or raccoons
Faeces in diagnosis of VLM, OLM and NLM
Human faeces are not useful since egg laying adults are not there
Faeces from infected pets support diagnosis
Treatment, prevention and control
Most patients recover without therapy
- anthelmintic drugs- albendazole, mebendazole, diethylcarbamazine, thiabendazole(severe)
- corticosteroid therapy- control symptoms of infection
Worm eradication by pet owners
Cleaning up pet fecal matter from yards and playgrounds
Monitor children’s okay area and sand boxes
Discourage keeping of racoons as pets
