Taenia Solium Cysticercosis Dr I Burger Dept Neurology IALCH

Introduction Human tapeworm (Cestode) Complex two-host life cycle Taenia Solium Complex two-host life cycle Infection causes two diseases: Relationship adult tapeworm and cysticerosis only established in 1855 Kuchenmaister fed infected pork to condemned prisoners and recovered the worms from their intestines Taeniasis [Definitive hosts: humans] Cysticercosis [Intermediate hosts:Pigs & humans]

Epidemiology

Life Cycle

Biology and life cycle Cycle starts when humans ingest undercooked pork meat that contains cysticeri Cysticerci represent the larvae of the tapeworm The larvae evaginate in the small intestine and the scolex attaches to the mucosa and starts forming segments (proglottids)

GARCIA et al LANCET NEUROLOGY OCTOBER 2005;4:653-661

GARCIA et al LANCET NEUROLOGY OCTOBER 2005;4:653-661

Biology and life cycle The worm attaches to the mucosa of the small intestine by means of hooks and suckers located in the scolex (head) It feeds on nutrients from ingested food Causes minimal inflammation at the implantations site

Biology and life cycle It has head (scolex), neck, strobila (body) that consists of hundreds of segments (proglottids) After about 2 months gravid distal proglottids begin the detach from the worm and is excreted in the faeces Each proglottid contain 50 – 60 thousand fertile eggs

Biology and life cycle Hooks Suckers Scolex Neck Proglottids

Biology and life cycle

Biology and life cycle Eggs are ingested by either humans or pigs that are exposed to human faeces (faecal-oral) Many humans (15-25%) infect themselves Other infections from household member Eggs contain an embryo that is called an oncosphere Action of gastric acid and intestinal fluids (bile salts) release the embryos from the eggs

Biology and life cycle Oncospheres then actively cross the bowel wall, enter the bloods stream and migrate to internal organs Predilection for muscle, brain and eyes Within organs they encyst reaching their definitive size of 1cm within 2 months Cells within the cyst differentiate into scolex – mature Taenia Solium larva

Biology and life cycle It will remain alive and viable for a variable period of time – during this phase there is no immune response to the parasite After some time it starts to degenerate resulting in inflammation finally leaving only a calcified scar Vesicular, Colloidal, Granular, Calcific stages

Biology and life cycle Undercooked pork is then ingested, larvae is released in the intestinal tract Scolex is released and attaches to the bowel wall Adult tapeworm then develops from behind scolex

Biology and life cycle GARCIA et al LANCET NEUROLOGY OCTOBER 2005;4:653-661

Clinical manifestations Taeniasis (tape worm infestation) Minimal symptoms or none at all In severe infestations; Malnutrition Abdominal discomfort Occasionally patients may notice the passage of proglottids within their stools

Clinical manifestations Cysticercosis Divided into extraneural Skin: Small painless mobile nodules Muscle: Asymptomatic or pseudohypertrophy Eyes: Asymptomatic or variable degrees of visual loss Neurocysticercosis

Neurocysticercosis After entering the CNS the cysticerci are viable and elicit very little inflammation It can remain like this for long time protected by the Blood-Brain-Barrier After variable amount of time the cyst starts to degenerate resulting in inflammation

Neurocysticercosis Cysts cause disease by acting as mass lesions, blocking CSF flow MOST of the symptoms direct result of the host inflammatory response due to cyst degeneration Therefore clinical manifestations depend on: Number Location Size Hosts immune response to the cysts

Neurocysticercosis Epilepsy Headaches Paraparesis Psychiatric Strokes Dementia

Neurocysticercosis Diagnosis X-rays of the muscles Imaging of the brain and spinal cord (CT & MRI) Serology CSF examination

Brain imaging: Colloidal Vesicular Calcified Granular Garcia, H. H. et al. N Engl J Med 2004;350:249-258

Treatment The decision if and how to treat patients with neurocysticercosis is complex and controversial When a decision is made to treat it involves three different interventions Anti-parasitic agent (albendazole or praziquantel) Anti-inflammatory agent (prednisone) Surgery (shunting or surgical removal of a cyst)

Treatment guidelines GARCIA et al LANCET NEUROLOGY OCTOBER 2005;4:653-661

Epidemiological control

Epidemiological control Health education Improved hygiene and sanitation Treatment of Taeniasis Improved pig husbandry Effective disposal of pig carcasses Vaccination of pigs Chemotherapy for infected swine

Courtesy – FOYACA SIBAT