(continued…) Survey of eucaryotic microbes

Helminths ► Multicellular, have organs  mouthparts for attachment to or digestion of host tissues  most have well-developed sex organs that produce eggs and sperm.  fertilized eggs go through larval period in or out of host body ► Some parasitize host tissues (either adults or larvae)

Major groups of helminths 1. flatworms (_____________) – flat, no definite body cavity; segmented; digestive tract a blind pouch; simple excretory & nervous systems; hooks or suckers for attachment _____________(tapeworms) – segmented body; basically reproductive factories; absorb food (no digestive tract)_____________(tapeworms) – segmented body; basically reproductive factories; absorb food (no digestive tract) _____________or flukes, are flattened, nonsegmented worms with sucking mouthparts_____________or flukes, are flattened, nonsegmented worms with sucking mouthparts

Major groups of helminths (cont’d) 2. roundworms (_____________)- round-ish, a complete digestive tract, a protective surface cuticle, spines & hooks sometimes present on mouth; excretory & nervous systems poorly developed

Parasitic Helminths ► 50 species parasitize billions of humans ► Transmission routes: acquired though…  ingestion of larvae or eggs in food;  from soil or water (ingestion or penetrate skin);  some are carried by insect vectors ► Most intestinal helminths identified by __________________________

► Platyhelminthes:  Cestodes – tapeworms – Taenia spp.  Trematodes – flukes – Schistosoma spp., liver flukes (Fasciola hepatica) ► Nematodes –  Pinworms (Enterobius vermicularis)  Ascaris (Ascaris spp.)  Whipworms (Trichuris trichiura)  Hookworms (N. americanus, A. duodenale)  Filiarial worms (Dirofilaria immitis, Wuchereria bancrofti) Parasitic Helminths - some examples

Platyhelminthes

Taenia saginattaT. solium Fasciola hepatica Schistosoma spp.Platyhelminthes

Life cycles of Platyhelminthes ► Life cycles of platyhelminthes frequently involve two hosts ► _____________host – where the adult worm lives ► _____________host – where the larva form lives (larva can be encysted in the tissues of this host)

Taenia life cycle

Nematodes ► “_____________” ► Worm curls up in a ball when outside host ► Either adults or larvae (or both) can cause disease/pathology ► Like platyhelminths, usually diagnosed by _____________

Intestinal nematodes

Ascaris lumbricoides life cycle Pinworm life cycle-Enterobius vermicularis Fecal/oral transmission

Hookworm life cycle (Ancylostoma duodenale and Necator americanus) Infection is caused by contact with ___________, which burrow in skin and migrate to intestines (via blood stream – “Hepatotracheal migration”)

Filarial nematodes ► Larvae (infective stage - _____________) live in blood and/or lymphatics ► Transmitted by blood-sucking insects (flies, mosquitoes) ► Pathology is associated with __________________________– what are they blocking?

Filarial nematodes Dirofilaria immitis How would these be diagnosed? Wuchereria bancrofti - elephantiasis microfilaria