Helminths

Match each category with its corresponding term: Nematodes, trematodes, cestodes Flukes, roundworms, tapeworms

Nematodes- roundworms Trematodes- flukes Cestodes- tapeworms

Anisakis

*Fish helminth* *Symptoms:* tingling sensation in throat few hours after eating sushi/sashimi (anisakis larvae trying to burrow into tissue; acute GI pain, cramping, vomiting Expelled w/o further symptoms

Diphyllobothrium latum

*Fish helminth* Tapeworm Humans= definitive host

Taenia saginata

*Helminth:* cestode/tapeworm (beef tapeworm) *Disease:* taeniasis *Life cycle:* cycle c *Transmission:* cows infected by ingesting in fields with proglottids or egg contamination Humans infected by eating raw beef *Symptoms:* mild abdominal pain, nausea

Taenia solium

*Helminth:* cestode/tapeworm (swine tapeworm) *Disease:* cysticercosis (rare) *Source:* endemic in areas consuming raw/partially cooked pork *Life cycle:* cycle C Cycsticercosis- larvae migrate to different tissues-> form peculiar cysticerci *Symptoms:* tissue damage (heart, eye, brain)

Ascaris lumbricoides

*Helminth:* intestinal nematode *Disease:* Ascariasis *Life cycle:* cycle A Larva and adult in humans -> embryonic eggs in feces-> food contamination -> oral entry -> intestine -> circulation -> heart -> lungs -> throat -> SI -> 200,000 embryos/day *Symptoms:* severe inflammatory reactions mark migratory route; allergic reactions; heavy worm loads retard physical and mental development Worms retain motility, do not attach

Strongyloides

*Helminth:* intestinal nematode *Disease:* Strongyloidiasis, threadworm infections *Life cycle:* cycle B Larvae burrow in skin -> circulation -> lung -> throat -> SI *Symptoms:* bloody diarrhea, liver enlargement, bowl obstruction, malabsorption

Trinchella spiralis

*Helminth:* intestinal nematode *Disease:* Trinchosis Raw meat from swine or bear *Life cycle:* encysted larval form in muscles, mammalion host Trinchella in pigs -> ingestion -> SI -> circulation -> muscles *Symptoms:* Initially- fever, diarrhea, nausea, abdominal pains, sweating Second phase- intense muscle and joint pain, SOB, eosinophilia; heart and brain damage, death *Prevention:* cook meat, freezing kills worm larvae (T nativa in Alaska bear and walrus meat is cold-resistant)

Hookworms

*Helminth:* intestinal nematode *Life cycle:* (cycle b) larvae burrow in skin -> circulation -> lung -> throat -> SI *Symptoms:* dermatitis (ground itch), pneumonia, N/V, pain, bloody diarrhea, chronic fatigue, anemia

Onchocerca volvulus

*Helminth:* tissue nematode *Disease:* Onchocerciasis, River blindness *Source:* black flies *Symptoms:* inflammation, granulomatous lesions, invasion of eyes, blindness

Wuchereria bancrofti

*Helminth:* tissue nematode *Disease:* bancroftian filariasis *Symptoms:* elephantiasis (inflammation and blockage of main lymph channels -> fluid accumulation)

Dracunculus medinesis

*Helminth:* tissue nematode *Disease:* dracontiasis *Source:* dragon worm, cyclops in water *Life cycle:* i dont careeeeeeeee *Symptoms:* ouchie *Prevention:* slap it

Loa Loa

*Helminth:* tissue nematode African eye worm *Source:* fly *Symptoms:* can be felt *Treatment:* pull the worm out, diethylcarbamazine

Filarial nematodes

*Helminth:* tissue nematode Long threadlike worms *Disease:* filariasis *Life cycle:* cycle E Biphasic life cycle- alternates between humans and mosquitoes/flies *Major species:* Wuchereria bancrofti and Oncocerca volvulus

Liver or lung flukes

*Helminth:* trematode/fluke *Life cycle:* cycle D Snails = intermediate host Humans = sexual development Larva hatch and crawl into bile duct -> mature -> shed eggs into intestinal tract -> feces into standing water -> snails -> cercariae -> fish *Transmission:* infection by ingesting inadequately cooked/raw freshwater fish/crustaceans *Symptoms:*

Schistosomes

*Helminth:* trematodes/flukes (blood fluke) *Disease:* renal schistosomiasis *Life cycle:* cycle D infected humans -> eggs -> ciliated larva (miracidium) -> snails -> forked larva (cercaria) -> human skin -> circulation -> liver -> intestine -> feces *Symptoms:* fever, chills, diarrhea, cough Chronic infections: hepatomegaly, splenomegaly, bladder obstruction, kidney damage, blood in urine, brain damage *Control:* snail-eating fish

Cycle C

*Route of infection:* oral *Source:* contaminated meat 1. Encystment in muscles 2. Larva is released in digestive tract and mature and mates in intestines 3. Eggs released into environment 4. Eggs taken up by livestock

Cycle A

*Route of infection:* oral *Source:* food and water contaminated with mature eggs 1. Larva hatches in tissues and migrate into intestines to mature and mate 2. Embryonic eggs are released to environment

Cycle B

*Route of infection:* skin penetration *Source:* contaminated soil or other environmental contacts 1. Larva migrates to intestine to mature and mate 2. Eggs get released to environment

Cycle E

*Route/source of infection:* bug bite 1. Parasites transferred through insect bites 2. Infected larvae lodge in tissues 3. New larvae released to circulation 4. taken up by insect to be transferred to new host

Nematode, cestode, or trematode: headless worms with smooth, protective outer cuticle that is shed as the worm grows

Nematode

Cycle D

*Routes/sources of infection:* eating contaminated meat, direct skin penetration 1. Parasites migrate into intestines or bladder to mature and mate 2. Release eggs into environment 3. Eggs undergo first larval stage 4. Larva infect intermediate host and undergo second larval stage 5. Taken up by meat or skin penetration

Nematode, trematode, or cestode: sexual reproduction via separate sexes only

Nematodes (trematodes- separate sexes or hermaphroditic, cestodes- hermaphroditic only)

What occurs in the definitive (final) host?

Adulthood and mating

What are some sources of infection and what is the route of infection?

Contaminated food, soil, water, infected animals; Oral, penetration of skin

Nematode, trematode, or cestode: have heads with suckers but no mouth, and a ribbon composed of reproductive segments

Cestode

Schistomiasis, filariasis, hookworm diseases, ascariasis, and oncoceriasis affect which populations?

Children in rural tropics/subtropics

What is the difference between the larva in cycle A and B?

Cycle A- larva develops inside the host Cycle B- larva develops in the outside environment to be able to penetrate the skin

What are major pathologies of helminth infection?

Enlargement of organs, hemorrhage, weight loss, anemia

How do worms cause damage into tissues?

Enzymes to liquefy and penetrate tissues and cause blocked ducts and organs, toxic secretions

When term is used to describe an increase in the number the granular leukocyte that destroys worms, which is a sign of a helminth infection?

Eosinophilia

True or false: nematodes are one of the most abundant animal groups and most nematodes are parasites

False

What causes continuing infections?

Human excrement for fertilizer, eating raw meat/fish, exposing bare feet in contaminated soil/water

Pinworm and trichinosis affect which populations?

Individuals in developed nations

In which host does larval development occur?

Intermediate (secondary) host

What features of helminths make it difficult to gain complete immunity from them?

Protective coverings, large, inaccessible, migrate