Helminths Flashcards
Helminths (metazoa)
Greek word meaning worm
Large multicellular animals with specialized tissues and organs similar to their hosts
Classification for Helminths
- Nemathehelminthes (Nematodes) elongated , cylindrical (round body)
- Platyhelminthes — thin segmented body ( Flat worm)
A. Custoda— tape worm (ribbon like)
B. Trematoda— flukes
Who are the major targets for Helminths
Young malnourished children
Transmission for helminths
- Recalls contaminated soil, food and water
2. By the vector (bite of insect)
Nematode general characteristics ( round worm)
- Most abundant
- Majority free living of soil and fresh water
- Few parasites
- Distinct male and female
- Human parasite
- Intestine round worm
- tissue round worm
Enterobius vermicularis (pinworm, seatworm)
1 type of round worm in the USA
- humans are the only host
- infection is self limited
Describe how pinworm infects humans
Freshly dropped eggs have a sticky coating that causes them to lodge beneath fingernails]
Dried eggs can be spread by air current
Life cycle of the pinworm
Parasite does NOT attach to the intestine and feed.
Eggs rarely found in fecal samples because3 release is external to intestine
The female pinworm will travel down the hosts pre-anal area to lay the eggs
Symptoms of pinworms
- Hypersensitivity reaction- itching
- Mild nausea, vomiting and diarrhea
- Slight irritation to intestinal mucosa
- Loss of sleep
- Velva irritation( eggs can spread to this region in girls)
Treatment for pinworms
Mebendazole,
Warm water enema
Whole family should be treated
Trichuiris trichiura ( whipworm)
Parasite attaches and penetrates into intestinal mucosa of large intestine by their LONG THIN head… the thicker tail hangs out in the lumen
Life cycle of whipworm
Entire life cycle requires 90 days … infestation can last for 2 years
Pathology and symptoms of the whipworm ( light infestation)
Asymptomatic , sometime slightly painful, self recovery
Pathology and symptoms for whipworm ( heavy infestation)
Heavy load of parasites that feeding and anchoring on the intestinal mucosa can damage intestine and cause the symptoms: bloody diarrhea, weight loss, abdominal pain, colitis and rectal prolapse
Treatment for whipworm
mebendazole
Where is the whipworm most prevalent
in warm climate and poor sanitation ( warm, humid down south)
usually occurs with Ascaris
Ascaris Lumbricoides
large intestinal round warm
considered the largest round worm (300mm)
Where is Acaris Lumbricoide most prevalent
most prevalent in the work
most common in the USA
What happens when infected with Ascaris Lumbricoides
Death can occur
worms are not attached to intestinal mucosa and feed
They can move around and explore different parts of the body
What stages occur in humans
both larval and adult stages occur
Life cycle of Ascaris Lumbricoides in humans
- Larvae move to small intestine and penetrates the intestinal wall & enter lymphatic and circulatory drainage > gets to heart
- from heart will be pumped through pulmonary arties to the lung
- then can migrate to respiratory tree to the glottis
- worms that enter the throat will be swallowed and returns to the small intestine or coughed up
Pathology and Symptoms of Ascaris Lumbricoides
- Pneumonia , cough , low grade fever ( first sign)
- Intestinal obstruction ( bile duct & small intestine)
- Vomitting and abdominal pain due to adult migration
- protein malnutrition in children w/ heavy infection
- Retardation in mental and physical development in young children with malnutrition
- Adult may exit by nose, mouth, or anus ( large creamy worm)
can be deadly
Where is Ascaris Lumbricoides prevalent & the treatment
in warm countries with poor sanitation found most in mountains of was, south and west
can leave double infection with T. trichina
Treatment: Mebendazole
Trichnella spiralis
Trichina worm
Different than most worms- Larvae infects humans not eggs
- entire life cycle occurs in mammals
- Larvae encysted in muscles (nurse cell)
- Encysted form remains in mammal > transmits when consumed
- undercooked pork is main cause of infection
What are the 5 phases of the Trichinella spirals life cycle
- Intestinal Phase
- occurs first week
- small intestine edema & inflammation
- Migration Phase
- Lasts one month
- Larvae may get into circulation searching for muscle (high fever , blurred vision
- on their way they may penetrate lung, heart and lesions
- during 4th&8th wk - death may occur
- Muscular phase
- Acute local inflammation with edema, pain of muscle, weakness & fatigue
- Larvae get into bundle of muscle & curl up to form cyst
- Focal Lesion
- Periorbotal edema ,
Strongyloides stercolis (thread worm) characteristics
- similar to hookworm
- eggs are similar to hookworm
- larvae have a simple buccal cavity ( mouth cavity )
- is the worm which reproduces in human body
- has only one adult form (female)
- Parthenogenic - female reproduce by itself
Which hemilnths have only one adult form
Strongyloides stercolis
Anisakidae marina characteristics
Herring Worm
causes infection gasterio- intestinal tract
- human is not principal host
- parasite never reaches maturity in human
- stomach of birds , fishes and marine mammals ( natural habitat)
- Male and female of the parasite occur with marine mammals
Life Cycle of the Herring worms
- females eggs into lumen of intestine
- ## eggs are passed out into the ocean where smaller fish
Where is the Herring worm
where row fish is common food
Symptoms and pathology of herring worm
- local ulceration at site of attachment, stomach and bowel mucosa
- abdominal pain and nausea and vomitting
- chronic may mimic GI disorders
