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Parasites - Metazoa - Coggle Diagram

- - - - mild clinical picture
      - produced by pork, beef, fish orrodent tapeworms
      - unlikely to have diarrhea
    - - serious infection
      - pork tapeworm (cysticercosis)
        echinococcosis (dog tapewrom)
        beef tapeworm (Taenia saniata)
      - Beef tapeworm=Taneia sagniata
        
        life cycle requires both humans and cattle
        
        infectious tissue larvae ingested by humans in infested meat, mature into adult tapewroms in intestie
        
        eggs passed in feces and may be taken up by cattle
        
        mild symptoms
        
        hermaphrodites 雌雄同体
      - Pork tapeworm=Taenia solium
        
        same life cycle as beef tapeworm, but intermediate host is pig
        
        more dangerous than beef tapeworm
        
        larvae can escape and migrate to reside and become encysted in the brain
        
        person to person transmission
        
        cerebral cysts cause cysticercosis
        
        larvae in CNS encyst and a major cause of seizures and syncope
        
        2 modes of infection
        
        infection by egg
        
        result in hatching of larva in intestine, which escape and penetrate body tissues including brain
        
        infection by larvae
        
        result in adult worm in intestine
        
        ingestion of larvae and survive in stomach acid and attach to the intestinal wall with suckers/hooks on their scolexes
      - Dog tapeworm=echinococcus granulosus
        
        small tapeworm found in canines (dogs, coyotes, foxes and wolves)
        
        humans are dead end hosts
        
        humans are accidental hosts if the eggs that canines excrete are ingested
        
        eggs hatch and larvae travel through the BS to the organs where the hydatid cyst develops
        
        larva develops into a hydatid cyst with hundreds of worm parts but cannot form a whole tapeworm in humans
        
        corms hydatid cysts in liver of lungs of humans
        
        cysts are brood capsules and contain heads of tapeworms and these cannot be developed into tapeworms in human but can grow in size and cause irritation and inflammation of tissue
        
        cause life threatening if the hydatid cysts are disrupted and break apart
- - - - Enterobius vermicularis (pinworm)
        
        small, 1 cm, lives in the large intestine
        
        female migrate to anus and lay eggs on skin around anus
        
        spends whole life cycle in human
        
        produce a glue (irritant) to stick the eggs to the skin
        
        eggs are the infectious stage and transmitted by direct contact with eggs or ingestion of eggs stirred up in dust
        
        usually not serious but very infectious in daycare settings
      - Ascaris lumbriocoides
        
        large round worms, 30cm long
        
        live in small intestine of pigs, cows, horses
        
        eggs are hardy because of thick pro coat around egg
        
        adult worms distinct sexes, dioecious
        
        diagnosis of infection by examination of feces
        
        eggs reported as fertilized or unfertilized
        
        fertilized eggs may have large infestation
        
        eggs hatch in intestine of human and migrate to lungs where they continue growth and development
        
        crawl up respiratory passages and exit by the nose or mouth
        
        larvae can also find they way to joints where the adult worm may develop
    - - Hookworms
        
        infected by entering intact skin of bare feet
        
        larvae penetrate intact skin and migrate to lymphatic system and ended up in circulation
        
        carried to lungs, coughed up and swallowed down to SI where they attach by books on the scolex
        
        suck blood and cause anemia
        
        cannot complete life cycle in host, eggs excreted to soil for recycling
        
        only found in warm climates
        
        Anisakis (sushi)
        
        fish nematodes, accidentally infect humans in larval form
        
        rare type of infection but increasing in prevalence
        
        prevention
        
        heat to 60 °C for 10 mins or blast freeze to -35 °C for 7 days
        
        cleaning of fish (evisceration) ASAP
      - Trichinella spiralis
        
        smallest nematode parasite of humans
        
        acquired from infected undercooked meat
        
        ingestion of encysted larvae in undercooked pork, boar, bear, walrus
        
        larvae encyst in striated muscle fibers and heart
        
        larvae are in nurse cells in teh striated muscle
        
        nurse cells release larvae in the stomach bc of low pH
        
        larvae escape and enter the circulation and tissues where they encyst and cause muscle weakness
        
        difficult to treat
      - Blood nematodes (filaria)
        
        transmitted by mosquitoes
        
        forms lumps in skin
        
        larvae lack O2 and try to get to the surface
        
        diagnosis by skin snips where a lump is incised the fluid examined in a microscope
        
        highly prevalence in Africa, Asia and tropical Latin America
        
        main filarial infections
        
        lymphatic filariasis (elephantiasis)
        
        adult worms live in lymph tissue
        
        microfilariae
        
        offspring of adult worms circulate through BS or migrate through subcutaneous tissue
        
        onchocerciasis (River blindness)
        
        adult worms live in subcutaneous tissue
- - - - S. haematobium
        
        urinary schistosomiasis ( bilharzia)
        
        results in inflammation of bladder wall, chronic sequalae-cancer
        
        in Africa, Middle East
      - S. japoniucum
        
        Intestinal parasite
        
        found in Far East
      - S. mansoni
        
        intestinal parasite
        
        found in SA, Africa, Caribbean
        
        eg. swimmers itch
        
        caused by duck schistosome
        
        cercariae do not enter human circulation
        
        self limiting causes skin itching due to the immune response