Table of Contents
Definition / general | Epidemiology | Reservoirs | Diagrams / tables | Classification of T. solium | Clinical features | Transmission | Diagnosis | Radiology images | Case reports | Treatment | Neurocysticercosis treatment | Microscopic (histologic) description | Microscopic (histologic) images | Additional referencesCite this page: Fadel H. Taenia solium (neurocysticercosis). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologytaeniasolium.html. Accessed April 26th, 2024.
Definition / general
- Tapeworm infections were first reported in 1500 B.C. and are considered one of the earliest human parasites
Epidemiology
- United States:
- Not a public health threat; infection has a specific and limited distribution
- ~1,000 cases occur per year, usually in Latin American immigrants in major urban centers with large immigrant populations (Chicago, Los Angeles, New York City)
- Worldwide:
- 50 million people are affected, 50,000 die annually, mainly from complications of cysticercosis
- Highest incidence in Central South America (some regions of Mexico have 4% prevalence) and Africa
- Also prevalent in Southeast Asia, India, Philippines, China, Eastern Europe
Reservoirs
- Two known reservoirs of T. solium are pigs and humans
- Humans serve as the definitive host; pigs serve as primary intermediate host
- Less common hosts are cats, dogs, primates, sheep
Diagrams / tables
Classification of T. solium
Kingdom | Animalia |
Phylum | Platyhelminthes |
Class | Cestoida |
Order | Cyclophyllidea |
Family | Taeniidae |
Genus | Taenia |
Species | solium |
Clinical features
- T. solium infection can progress to a disease state in 10 days or as slowly as 10 years
- Taeniasis:
- Typically, adult tapeworm does not produce eggs in stool (taeniasis) for 8 - 12 weeks
- Most intestinal infections are asymptomatic but some patients exhibit abdominal pain, anorexia, malaise, weight loss, megaly (brain, eye, heart)
- Common complications include appendicitis, obstruction of bile ducts / pancreatic ducts, ectopic tapeworm growth, mild eosinophilia
- Neurocysticercosis:
- 3 common symptoms: convulsions / seizures, intracranial hypertension, psychiatric disturbances
- Common sites are subcutaneous tissue, eye, brain
Transmission
- Consumption of raw / undercooked pork products
- Human to human or pig to human transfer of T. solium eggs through direct contact with feces
- Human to human or pig to human transfer of T. solium eggs through consumption of food / water containing fecal matter (indirect)
- Autoinfection
Diagnosis
- Made by finding eggs in stool (using direct or concentration techniques) or in perianal folds (using cellophane tape technique)
- Eggs are spherical and measure 31 - 43 μm in diameter
Case reports
- 21 year old man with lacrimal sac cysticercosis (Case Rep Ophthalmol Med 2014;2014:961815)
- 44 year old woman with facial swelling due to cysticercosis infestation (Acta Med Indones 2014;46:54)
Treatment
- Treament with anthelimintic drugs is often sufficient to eliminate the parasite
- Treatment of choice is single dose of praziquantel (5 - 10 mg/kg)
- Praziquantel acts by increasing the permeability of the cell membrane, resulting in a efflux of intracellular calcium, leading to muscle tetany and the eventual paralysis and elimination of the worm
- In cases of taeniasis, praziquantel is close to 100% effectiveness
- Must also examine stools weekly for gravid proglottids for 5 weeks, to ensure clearance of parasite
Neurocysticercosis treatment
- Much more complicated than treatment for taeniasis; often tailored to each patient
- Either surgical intervention or an anthelmintic drug (i.e. praziquantel)
- If an anthelmintic agent is used, a glucocorticoid is also prescribed to relieve the inflammation caused by the death of cysticerci in organ tissue
Microscopic (histologic) description
- Proglottids of taeniids have a characteristic lateral protrusion known as the genital pore
- Careful injection of India ink through the genital pore, using a tuberculin needle and syringe, may outline the uterus
- The gravid uterus of T. saginata has 15 - 20 lateral branches compared to 7 - 13 for T. solium
- Proglottids may be cleared overnight in glycerol or stained with carmine or hematoxylin using published procedures
- If recovered, the scolex of T. solium has four suckers and a hook on the crown or rostellum
- Shell is thick, radially striated and contains a six hooked embryo
- Eggs of all Taenia species are indistinguishable and should be reported only as Taenia eggs
Microscopic (histologic) images
Additional references