Helminths Flashcards
Learn all about helminths
What are the 3 nematodes (roundworms) that are acquired thru ingestion of eggs?
Ascaris lumbricoides Trichuris trichura (whipworm) Enteribius vermicularis (pinworm)
To remember: TRIplet oSCAR ENTER in EGG form
What are the 2 nematodes (roundworms) that are acquired thru penetration of skin?
Necator americanus (hook work) Strongyloides stercoralis
To remember: Capt. HOOK is a STRONG AMERICan.
What nematode (roundworms) is acquired thru ingestion of pork meat?
Trichinella spiralis
To remember: TRICky PORK
Which nematodes migrate into the human lungs in larval form?
Ascaris lumbricoides (can produce 200K eggs per day in the small intestine) Nescator americanus (lives in the soil as a larva. When inside the human body, goes to the lungs as larva. Travels to the small intestines as an adult. Attaches to the intestinal wall and sucks blood, copulate and releases more eggs.) Strongyloides stercoralis (eggs don't pass to the stools but can cause auto-infection, direct cycle and indirect cycle).
To remember: the AMERICAN oSCAR has STRONG LUNGS.
What is the medicine for nematodes?
Mebendazole, albendazole, Thiabendazole.
To remember: Worms BEND a lot.
Pyrantel pomoate (alternative for ascaris, necator and enterobius.)
What are the symptoms of hookworm infection?
Diarrhea Abdominal pain Weight loss Iron deficiency anemia Itchiness and rash (at penetration site) Cough Local infiltrate in the lungs Eosinophilia
Note: relate the symptoms to the life cycle of hookworm
Describe the infection caused by Trichinella spiralis.
Encysted larvae in pork meat is ingested.
The cysts travel to the small intestines where larvae leave their cysts.
Larvae mature and copulate.
Adult males pass on to feces while adult females penetrate intestinal mucosa and prduce thousands of larvae.
The larvae pass into the blood stream, reaching other organs and skeletal muscles.
Larvae can get encysted in the skeletal muscles and stay there for decades.
To remember: TRICky pork is MUSCULAR.
These are the two mildest worm infections.
Note: mild means no lung and muscle invasions. They stay only in the intestinal track.
Trichuris tricura (whip worm) Enterobius vermicularis (pin worm)
The pinworm, Enterobius vermicularis, is known to cause intense perianal itch at night.
Explain the phenomenon.
After ingestion of eggs (50-60 micra), they mature in the caecum and ascending large intestines.
The female migrates at night to the perianal area and lays there thousands of eggs which become infective in 4-6 hrs., causing severe Itchiness and lack of sleep.
This infection is more of a nuisance than a danger.
Which nematodes are acquired thru intermediate hosts?
Onchocerca volvulus (via black flies) "ONCHOCERCIASIS" Wucheria bancrofti (via mosquito) "ELEPHANTIASIS" Brugia malayi (via mosquito) Dracunculus medinensis (via crustacean - freshwater copepad)
To remember: Cancer (ONChO), like worms, is a WitCH, BRUhA and a DRACUla.
Describe the infection, diagnosis and treatment of ONCHOCERCIASIS.
An infected black fly transmits the microfilariae (larvae) to humans. The microfilariae matures into adult form. They can be found coiled up in fibrous nodules in the skin and subcutaneous tissues.
After mating, more microfilariae are produced that migrate through the dermis and connective tissues and eyes.
(This phenomenon causes pruritic skin rash, popular lesions aka interepithelial granuloma and blindness.)
Diagnosis can be done through skin biopsies and slit lamp examination of the eyes to demonstrate the microfilariae or adult worms.
Treatment is through IVERMECTIN that prevent the birth of new microfilariae. Adult worms will eventually die.
Also treated with DIETHYLCARBAMAZINE.
Describe the infection, diagnosis and treatment of ELEPHANTIASIS.
An infected mosquito transmits the microfilariae (larvae) to humans. The microfilariae matures into adult form within the lymphatic vessels and lymphatic nodes of the genitals and lower extremities. After mating, microfilariae are produced and enter the nearby blood vessels.
(This phenomenon causes enlarged lymph nodes, acute febrile episodes. Repeated exposures cause fibrous tissues around microfilariaein the lymph nodes, which can plug the ducts, thus causing the swelling of the genitals and legs).
Diagnosed through isolation of microfilariae in blood drawn at night and Immunofluorescence of antibody titers.
Treated with DIETHYLCARBAMAZINE.
Describe the infection, diagnosis and treatment of Guinea worm (Dracuncula medinensis)
The ingestion of water with microscopic crustacean (copepods) transmits the larvae to humans. The larvae penetrate the intestines and migrate to subcutaneous tissues where they mature and copulate. The male dies and the female continues to grow for up to a year. It continues to move to the skin, releasing thousands of larvae when it’s uterus touches water.
During the release of larvae, the person experiences nausea, vomiting, hives and breathlessness.
What are the 2 groups of FLATWORMS (PLATYHELMINTHES)?
Note: flat = plat
Trematodes or flukes
Cestodes or tapeworm
Describe the infection, diagnosis and treatment of SCHISTOSOMIASIS (Trematodes).
Schistosomes (cercariae form), found in water, penetrate the skin and invade the venous system where they mate and lay eggs. The eggs may enter the intestines or the bladder and eventually be excreted into a nearby lake or stream. The eggs only hatch in water. The larva emerges and finds its way to freshwater snail. In it, they mature. They are called cercariae which look like tadpoles with suckers and tails . Upon release from the snails, they are already infective to humans.
Systemic syndromes
- Dermatitis in the area of penetration
- Katayama fever during the laying of eggs
- Chronic Fibrosis of the organs and blood vessels from chronic inflammation surrounding the deposited eggs.
Diagnosed by the presence of eggs in the stool or urine; high eosinophil in the blood.
Treated with Praziquantel ( a drug for both cestodes and trematodes.)
Control measures: management of human fecal waste disposal; elimination of snails.
To remember: 4S Schistosomiasis Snail Skin Syndromes