Parasitology Flashcards
How do you test for pinworms?
Sticky tape test
Pinworm infection is the most common helminth infection seen in the US
Generally seen in urban settings under crowded conditions
PInworm name
Enterobius Vernicularis
Pinworm life cycle
- Eggs ingested by humans
- Larvae hatch inside small intestine (cecum)
- Adult females migrate to perianal region at night to lay eggs.
- Eggs mature into larvae in 4-6 hours and the kids scratch and get them in their fingernails.
HUMANS ARE DEFINITIVE HOST
SCOTCH TAPE TEST
Host
Organism in which parasite lives
Reservoir
Host which maintains the parasite in nature as a source for continued transmission
Definitive host
Host in which sexual reproduction takes place
Humans are a definitive host for strongyloides because sexual reproduction takes place within us
Intermediate host
Host in which development occurs, possible asexual …but NOT sexual
Accidental Host
Host in which parasite cannot complete life cycle
Types of endoparasites
Metazoan and Protozoan
Metazoan characteristics
- Multicellular organisms
- Helminths (worms)
- Life cycle includes egg, larval, adult
Roundworms— nematodes
Flatworms— Trematodes and Cestodes
Protozoan
Single celled eukaryotes
- Flagellates
- Amoebas
- Sporozoea
What are the Helminths (metazoans) that are transmitted through the soil
- Ascariasis
- Trichuriasis
- Hookworm
Whipworm life cycles
- Eggs in soil
- Swallowed
- Hatch
- Attach to gut wall/ eggs excreted in feces
Hookworm is the one that penetrates the skin through an open wound
ok….It is a significant cause of illness around the equator
MOST SIGNIFICANT CAUSE OF ANEMIA IN CHILDREN POOR COUNTRIES
Hookworm life cycle
How do you prevent hookworm infection
- Eggs are excreted in feces, hatch in the environment. The larvae penetrate the skin and enter the bloodstream where they go to the lungs. THey are then coughed up and swallowed. Go to small intestine where sexual repro occurs. FEEDS BY SECRETING AN ANTICOAGULANT
- Where shoes, treat carriers, sanitation
Ascariasis causes
Intestinal infection
Global morbidity around 1 billion per year
Large worm burdens can cause intestinal obstruction and perforation.
Can also cause pancreatitis
CAN ALSO INFECT LUNGS AND CAUSE LAOEFLER SYNDROME
Toxocara Canis and Toxocara Cati cause
visceral Larval Migrans- Larva penetrate into mucosa and enter circulation, carried to the liver, lungs, eyes - cause inflammatory necrosis
What is cutaneous larval migrans
Also caused by Toxocara Canis and Cati…. larva penetrates skin, migrates in subcutaneous tissue and causes inflammation
Strongyloidiasis clinical features
- frequently ASYMPTOMATIC EOSINOPHILIA Symptoms related to three phases: 1) skin invasion- purpuric papule 2) Lung migration 3) Gi invasion- abdominal pain and diarrhea
Maintains chronic infection by autoinfection
What is strogyloides hyperinfection KNOW
When you get a disseminated infection in an immunocompromised host that leads to a massive parastie burden in the lungs which causes respiratory failure. Massive invasion of GI causes sepsis. Absent immune response
lab dx of strongyloides infection
larvae in stool or sputum
Trichinenella infection usually acquired how
consumption of undercooked pork or meat which carries the encysted larvae
Larvae are then released in the small intestine of humans, turn into adults where sexual reproduction occurs, more larvae come and enter the circulation where they can go to different parts of the body.
Signs, symptoms of trichinosis
ranges from asymptomatic to bad
- initially gastroenteritis followed by fever, muscle weakness,
What causes elephantitis (Lymphatic filariasis)
Wuchereria Bancrofti—– transmitted by different types of moquitoes.
They ingest microfilaria from an infected host, inject it into another human where it develops into an adult worm in the lymphatics and causes obstruction. Obstruction increases when it dies due to calcification
EARLY INFECTION DETECTED BY MICROSCOPY OF BLOOD OR LYMPH
Beef tapeworm is
Taenia Saeginata
Pork tapeworm is
Taenia salium
What is the proglottid section of a tapeworm?
segments with branched uteri designed to produce thousands of eggs… the proglottids closest to the scolex (head) are immature but those at the terminal end break off and are released along with numerous eggs