Taenia Solium Cysticercosis Dr I Burger Dept Neurology

Taenia Solium Cysticercosis Dr I Burger Dept Neurology IALCH

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

Epidemiology

Life Cycle

Biology and life cycle Ø Cycle starts when humans ingest undercooked pork meat that contains cysticeri Ø Cysticerci represent the larvae of the tapeworm Ø 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

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

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

Biology and life cycle Hooks Suckers Scolex s d ti Pr ot l og Neck

Biology and life cycle

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

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

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

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

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

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

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

Neurocysticercosis Ø After entering the CNS the cysticerci are viable and elicit very little inflammation Ø It can remain like this for long time protected by the Blood-Brain-Barrier Ø 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 Ø MOST of the symptoms direct result of the host inflammatory response due to cyst degeneration Ø Therefore clinical manifestations depend on: Ø l l Number Location Size Hosts immune response to the cysts

Neurocysticercosis Ø Epilepsy Ø Headaches Ø Paraparesis Ø Psychiatric Ø Strokes Ø Dementia

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

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

Treatment Ø The decision if and how to treat patients with neurocysticercosis is complex and controversial Ø When a decision is made to treat it involves three different interventions l l l 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 Ø Health education Ø Improved hygiene and sanitation Ø Treatment of Taeniasis Ø Improved pig husbandry Ø Effective disposal of pig carcasses Ø Vaccination of pigs Ø Chemotherapy for infected swine

Courtesy – FOYACA SIBAT