Helminthic Infections Flashcards
Major component of inflammatory response to helminths?
- Eosinophils (contain basic toxic proteins)
Cylindrical organisms with tubular digestive tracts?
- Roundworms (nematodes)
Dorsoventrally flattened organsims with digestive tracts that end in blind loops?
- Flatworms (trematodes)
Segmented organisms with separate head and body parts lacking a digestive tract and absorb nutrients through outer walls?
- Tapeworms (cestodes)
Inflammatory parasitic infection of lymph vessels cause by roundworms Wuchereria bancrofti and Brugia malayi?
- Lymphatic filariasis
Lymphatic Filariasis
- adult worms inhabit lymphatics in inguinal, epitrochlear, and axillary LNs, testis, epididymis
- if obstruction, severe lymphedema
- mosquito bites transmit infectious larvae that mature in LNs
- most severe form = elephantiasis
- worms are surrounded by inflammatory mediators
Chronic Inflammation of skin, eyes and lymph caused by filarial nematode O. volvulus?
- Onchocerciasis - river blindness!
Oncocerciasis
- transmitted by bites of blackflies
- adult worms live as coiled tangled masses in deep fasciae and subcutaneous tissue and release millions of microfilariae which migrate
- when migrate to all regions of the eye = blindness
- microfilarie die and produce vigorous inflammatory response
- can become encapsulated by fibrous scar and form nodules
Infection by filarial nematode Loa loa
- Loiasis, African eyeworm
Loiasis
- infection transmitted by mango flies
- adult worms can migrate in skin and cross beneath conjunctiva
- static worms surrounded by inflammatory cells
Most common helminthic infection of humans, large roundworm and usually asymptomatic?
- Ascariasis, A. lumbricoides
Ascariasis
- adult worms live in small intestine, penetrate bowel wall and reach lungs though venous circulation
- after leaving pulmonary capillaries, enter alveoli to glottis and are swallowed to again reach small bowel
- heavy infections can cause vomiting, malnutrition, and sometimes intestinal obstruction
Trichuris trichiura
- Trichuriasis, intestinal nematode (whipworm)
- adult worms live in feces and upper colon and bury their anterior portion into the superficial mucosa
Hookworms
- Necator americanus and Ancylostoma duodenale
- intestinal nematodes, infect human small bowel
- cause blood loss and anemia
- most important cause of chronic anemia worldwide
Strongyloidiasis
- small intestinal infection with nematode S. stercoralis (threadworm)
- in immunocompromised, can progress to lethal disseminated disease
- adult females bury in crypts of duodenum or jejunum, lay eggs that hatch quickly and release rhabditiform larvae
- may reproduce in human hosts by autoinfection
Pinworm
- Enterobiasis vermicularis, intestinal nematode
- perianal itching
- adult resides in cecum but migrates to perianal skin to deposit eggs
Myositis associated with eating pork?
Trichinosis, from roundworm Trichinella spiralis
Trichinosis
- inadequately cooked meat with encysted T. spiralis larvae
- larvae burrow into intestinal mucosa and develop into adult worms then enter circulation
- can only survive in striated skeletal muscle and elicits an intense inflammatory infiltrate
- in severe infections, eosinophilia can be extreme
Infection of deep organs by visceral larva migrans, transmitted by cats and dogs?
Toxocariasis
Toxocariasis
- infection of deep organs by helminthic larvae
- larvae invade intestinal wall, are carried to liver, and die in tissues to form small granulomas
Cutaneous larva migrans
- larval nematodes migrating through skin and causing pruritis and serpiginous urticarial trails
Dracunculiasis
- guinea worm, features long adult worms beneath skin
- transmitted in drinking water
- reddish papule with anterior end of female worm underneath, which can burst forward and spew larvae in water
Schistosomiasis
- most important human helminthic disease (greater morbidity and mortality)
- damage to the liver, intestine, or urinary bladder
- alternate between asexual reproduction in snail and sexual reproduction in vertebrate host
- S. mansoni and S. japonicum deposit eggs in intestinal venules
- S. haematobium lays eggs in urinary bladder
- cicumscribed granuloma or cellular infiltrate of eosinophils and neutrophils around an egg
- progresses from granulomas to fibrosis
Inhabits branches of IMV (affects distal colon, liver)
S. mansoni
Inhabits veins of rectum, bladder, pelvic organs
S. haematobium
Inhabits branches of SMV (affects small bowel, ascending colon, liver)
S. japonicum
Infection of the hepatic biliary system by Chinese liver fluke
- Clonorchiasis (Clonorchis sinensis)
Clonorchiasis
- sometimes associated with bile duct stones, cholangitis, and bile duct cancer
Paragonimiasis
- pulmonary infection by oriental lung fluke
- peripheral eosinophilia common
Biliary disease acquired from sheep?
Fascioliasis (sheep liver fluke F. hepatica)
Fascioliasis
- hepatic abscesses and granulomas
Fasciolopsiasis
- F. buski
- attaches to duodenal or jejunal wall which may ulcerate
Tapeworms
Taenia saginata (beef) Taenia solium (pork) - cysticercosis - systemic Diphullobothrium latum (fish) Echinococcus granulosus (dog feces) - liver and lungs
