-
Name the larval tapeworms and their diseases
- Spirometra (human sparganosis)
- Taenia solium (human cysticercosis)
- Echinococcus granulosus (Hyatidosis, echinococcosis, hydatid disease)
- Echinococcus multilocularis (Hyatidosis, echinococcosis, hydatid disease)H. nana (rare)
-
Why is the disease called human sparganosis
disease caused by plerocercoid larvae (spargana) of Spirometra tape worm (kinda like Diphyllobothrium)
-
Spirometra life cycle (normal)
- Matches D. latum
- eggs released into water become coracidium
- procercoid found inside cyclops (crustacean)
- plerocercoid in amphibean/fish/snake/etc
- cat/dog is definitive host
-
What are the methods of infection for Sparganosis?
- 1. Drinking water contaminated w/ cyclops copepods (most common)
- **plerocercoids in copepod
- 2. Ingestion of undercooked fish, amphibians, reptiles, birds, pigs, snake, etc
- **plerocercoids in muscle
- ex- oriental tradition of eating raw snake
- 3. poulticing wound (vag, ulcer, eye) with split flesh of vertebrate
- **worm crawls from flesh into applied area
-
Describe what happens after eating meat infected with Spirometra w/ symptoms
- Spargana (plerocercoids) wander in the deep tissues, migrate to eyes (swelling, conjunctivitis, blindness), muscles, subcutaneous tissues (lumps)
- Chills and fever
- Can grow up to 15"
- May be misdiagnosed as cancer
- **NOTE- eye infection VERY common
-
Spirometra - diagnosis, treatment, prevention, control
- Diagnosis: detection of parasite in tissues
- Treatment: surgical removal of larva
- praziquantel
- Prevention/control: proper cooking of meat
- boil/filter water
- don't apply animal flesh to skin
-
T. solium - common sites
- Virtually every organ and tissue of the body
- subcutaneous tissue
- eyes
- brain
- muscles
- heart
- liver
- lungs
- coelom
- HIGHLY PATHOGENIC
-
T. solium - how does infection occur, what are the most common methods of infection?
- Infection occurs when embryonated eggs pass through the stomach and hatch in the intestine
- 1. Consuming T. solium eggs (pig shit contaminated food, salad, water)
- 2. Autoinfection: gravid proglottid migrates into stomach (reverse peristalsis)
-
T. solium symptoms
- Human cysticercosis
- Clinical disease mostly caused by presence of cysts in brain and eyes
- Spasms and weakness are common (muscles, liver, skin, liver)
- neurological disorders, paralysis, vomiting, headache (brain, CNS)
- **If a cysticercus dies it causes a SEVERE inflammatory response (any location)
- neurocysticercosis: present in brain, often fatal
- *NOTE - most common parasitic infestation of nervous system
-
T. solium - diagnosis, treatment, prevention/control
- Diagnosis: observing and feeling subcutaneous nodules, confirmed with biopsy
- X-Ray can detect calcified cysts
- CT scan can determine brain damage
- Treatment: surgical removal
- Praziquantel or Albendazole
- *NOTE - treatment must not cause vomiting! (autoinfection)
- Prevention: thoroughly wash salad, vegetables, keep up hygiene, sanitation, boil water, etc
- Control: sanitary disposal of feces and pork inspection
-
Describe the difference between the three types of Echinococcus disease
- E. granulosus: cystic (unilocular) echinococcosis
- very few, large cysts
- *NOTE - most common, least harmful
- E. granulosus: osseous echinococcosis
- Occurs worldwide, frequent in rural areas
- E. multilocularis: alveolar echinococcosis
- many small cysts
- *NOTE - most pathogenic
- causes liver cancer
- Occurs in Northern hemisphere (Europe, Asia, and NA)
-
Echinococcus - describe morphology
- smallest tapeworm (2-8mm)
- only 3 proglottids (immature, mature, gravid)
- Scolex has rostellum w/ 2 rows of 28-50 hooks, 4 suckers
- Carnivores (eg dogs, cats) are definitive host
-
Echinococcus - life cycle (normal)
- Eggs passed in feces from definitive host (dogs)
- Ingested by humans and intermediate hosts (contamination)
- Hatch into oncosphere in small intestine
- Oncospheres penetrate intestinal wall (small size)
- Carried all over body by circ system
- become lodged in capillary beds (liver, lung, kidney, splean, heart, etc)
- Hydatid cysts develop (containing protoscolices (AKA hydatid sand))
- protoscolices are ingested by dog (def. host) via ingestion of meat
- Protoscolices develop into adults in small intestine of dogs
-
Give examples of Echinococcus intermediate hosts
- Rabbit, sheep, cattle, squirrel, goat, camel
- human is dead end (unless eaten....)
-
Describe the anatomy of each type of hydatid cyst
- UNILOCULAR CYSTS
- *NOTE- larvae with inverted scolices develop within the cysts (protoscolices)
- forms after hatching and migration of oncosphere
- Up to 30cm
- containing liters of fluid
- 1mm thick, 3 layered cyst wall
- pericyst: outermost layer containing CT and fibers (host origin)
- ectocyst: thick-layered non-cellular wall
- endocyst: inner, thin layer that produces protoscolices
- brood capsules attach to cyst wall via pedicel
- each brood capsule contains numerous protoscolices
- hydatid sand: ruptured cysts sink to the base of the capsule
- OSSEOUS CYSTS
- represent 1-2% of total cysts
- develop in marrow cavities
- much smaller than unilocular cysts
- *contain no fluid
- *contain no protoscolices
- provoke very little host rxn, but bones can be destroyed during development
- ALVEOLAR CYSTSmost commonly found in liver (Alveolar liver echinococcosis)
- cysts grow ~1mm per month, become noticeable ~20cm
- compression of liver = jaundice
- *typically lack protoscolices
-
What are the most common relationships that propagate sylvatic echinococcosis? domestic echinococcosis?
- sylvatic
- Wolf-moose in US/Canada
- Dingo-wallaby
- other carnivore-herbivore
- domestic
- domestic herbavores raised with dogs
- dogs feed on byproduct of butchered animals
- sheep-raising areas heavily infected
- VERY common
-
How does echinococcosis infection typically occur (worldwide, multiple examples)
- intimate contact w/ dogs (accidental ingestion of Echinococcus eggs) - MOST COMMON
- Kenyan tribes eat dog intestine roasted over campfire (high rate of infection)
- Nursing dogs "clean up mess" on children in Kenya (child infection)
- Kenyans do not bury all dead - corpses fed on by wild dogs
- Dog feces used in tanning solution in Lebanon, leads to infection by users
-
Describe the symptoms of echinococcosis (a lot of info)
- Effects of a hydatid cyst may not be apparent for MANY years (20+ years of slow growth)
- symptoms include slowly increasing pressure in cyst area (resembles tumor growth)
- *liver is most commonly affected organ
- cysts in lungs (20-30%) can cause hempotysis (coughing up blood) and dyspnea (difficulty breathing)
- cysts in brain/spinal cord (~3%) cause inflammatory response
- osseous cysts (1-2%) lead to fragile/degraded bones
- Cysts can become HUGE (>15L fluid) if growing in an unrestricted location
- *NOTE- cysts can rupture, enter circulation, and produce secondary echinococcosis
- ***anaphylactic shock occurs if hydatid fluid enters the blood stream (death is typically instantaneous)
-
echinococcosis- diagnosis, treatment, prevention/control
- diagnosis: often found during routine x-rays
- CAT scans
- hepatic hypertrophy / jaundice
- immunological tests
- treatment: surgical removal of cysts
- hydatid fluid removed first
- 2% formalin injected to kill protoscolises
- formalin removed and cyst is removed
- Mebendazole and/or Albendazole useful to prevent additional cyst growth after surgery
- prevention/control: reduce contact between dogs and intermediate hosts
- personal hygiene in relation to dog handling
- treatment campaigns against adult tapeworm in dog (praziquantel)
- sanitary disposal of offa/viscera of slaughtered food animals
- public education
-
define offal
- The waste/leftovers from a slaughtered animal
- Infective to dogs who eat offal of animals that had echinococcosis
|
|
