Pathogenic Human Helminthes Parasitic Worms Pathogenic Human Helminthes

Characteristics Multicellular Well developed organ systems Reproductive Dioecious Hermaphrodite Worldwide Tropical, subtropical Survival of eggs Survival of larval stages Less developed Sanitation Intermediate host survival

Life Cycle Host Definitive: a vertebrate in which the parasite reproduces sexually and causes infection Intermediate: an invertebrate (eg mollusc) in which parasite develops or reproduces asexually Cycle Egg  ingestion Larvae ingestion, penetration, migration Infectious stage  intermediate host Adultreproduces

Overview of Generic Life Cycle

Helminth Types Platyhelminths Nematoda Flatworms Roundworms Flukes Trematodes Flat, leaf shaped Suckers Named for location Tapeworms Cestodes Long body Scolex Proglottid Nematoda Roundworms Cylindrical body Cuticle Dioecious Hookworms Pinworms Whipworms Strongyles Filaria

PLATYHELMINTHS Flat body Hermaphrodites Parasitic Trematodes Cestodes

FLUKES (Trematodes) Schistostomiasis Fascioliasis Intestinal Fluke Chinese Liver Fluke Lung Fluke Life Cycle Eggs Miracidia (ciliated larva) Intermediate host Cercariae Second intermediate host Metacercariae (juvenile) Definitive host Adult fluke

Fluke Anatomy and Life Cycle Miracidia Adult Fluke

Liver Flukes Fasciola hepatica Chinese Liver Fluke Typical life cycle Snail intermediate host Humans exposed to metacercaria by eating watercress Intestine  Liver  Bile Ducts  eggs in feces Chinese Liver Fluke Typical life cycle Snail intermediate host Humans exposed to metacercaria by eating undercooked fish Intestine  Liver  Bile ducts eggs in feces

Flukes: Fasciola sp.

Flukes of other Organs : Lungs Paragonimus westermani Eggs coughed and swallowed, passed in feces that contaminate water Cercaria in snails Metacercaria in crabs Humans eat crabmeat Adult flukes migrate from GI Blood  Lungs Signs: Coughing Egg Adult Fluke

Flukes of other Organs: Urine Schistostoma (blood flukes) Eggs in urine, feces Miracidia in snails Cercaria in snails Penetrate skin Schistosomulae in liver Adults migrate to urinary system Signs: damage to liver, and urinary bladder

Schistostoma Life Cycle

Flukes DX TX Prevention Eggs in feces Antihelmenics Thoroughly cook meats Cook vegetables Proper Sanitation

TAPEWORMS: (Cestodes)

Life Cycle of Tapeworms Eggs in proglottids passed in stool Larval phase in Intermediate host Intestine  blood  Skeletal muscle and other tissue  cysts Acquire by eating raw meat with cysts Cysts  adult worms in intestines

Tapeworm Life Cycle

Tapeworm Anatomy Scolex with hooks Adult Tape worm Proglottids

Taenia tapeworms Taenia saginata (beef) Taenia solium (pork) Symptoms Abdominal discomfort Diagnosis Worm segments Eggs in stool Treatment Antihelminics Prevention Cook meat Good Hygiene

Taenia species

Tapeworms Taenia eggs Ecchinococcus Diplidium canium

Tapeworm

Sheep Fluke

NEMATODES “Roundworms” Cyclindrical body Dioecious Cuticle

Filaria Worms

FILARIASIS Elephantitis Loaisis Wuchereia bancrofti Mosquito Lymphatics Microfilaria in blood Adults in LN Blockage Swelling Loaisis Onchocerca volvulus Biting flies CT Microfilaria in blood Adults in conjunctiva Inflammation swelling

Fliaria Summary DX TX Prevention Id microfilaria in blood Diethylcarbamazine Prevention Control of intermediate hosts Wuchereia bancrofti

Elephantitis

Loaisis

Roundworms Ascaris lumbriocoides Fecal contaminated food Eggs ingested Larvae released and migrate GI  lymph/blood  lung alveoli  coughed  swallowed Adults mature in upper GI (stomach and SI)

ASCARIASIS

Roundworms (Ascarids) Symptoms Asymptomatic Respiratory GI DX Eggs in stool Adults in vomitus TX Prevention Sanitation Cook food

Toxocariasis Toxacaris canis, T. cati Eggs in environment Fecal  oral Larvae hatch in GI  Blood  Liver  Lung  any tissue aka Visceral Larval Migrans Zoonosis

Toxocariasis Symptoms Resp: cough, fever, wheezing Organomegaly Skin: rash Eye: inflammation DX Blood work Biopsy Eggs in stool TX Prevention Hygiene Deworm animals

Hookworms Ancylostoma, Necator Eggs in feces hatch Larvae mature in soil and penetrate skin Skin  Lymphatic Blood  Lungs coughed & swallowed Adults develop in SI by attaching mouth parts to lining  blood meals

Hookworm

Hookworm Life Cycle

Hookworms Symptoms DX TX Prevention Skin rash, pruritic Resp GI: pain Anemia DX Eggs / larvae in stool TX Prevention Limit soil exposure

Trichuriasis

Whipworms Trichuris trichura Eggs in soil, ingestion of contaminated food Larve hatch in SI, migrate to cecum Larvae mature to adult stage

Whipworm Symptoms DX TX : Antihelminthics Prevention GI: pain, diarrhea, bleeding, anemia, rectal prolapse DX Eggs in stool Colonoscopy to view adults TX : Antihelminthics Prevention Sanitation Wash vegetables

Pinworms Enterobiasis vermicularis Eggs @ perineum Fecal-oral Eggs hatch  Lower GI to mature Female moves to perineal region to deposit eggs in sticky substance HUMANS ONLY !! DX: GI itching, eggs Worms in colon TX: Anthelminthics Prevetion: Hygiene Wash clothing

Trichinosis

Trichinosis Trichinella spiralis Larvae in skeletal m. Exposure by eating uncooked meat Cyst  larvaeadult in intestine mature and release larvae Larvae –> migrate using blood/lymph  penetrate muscles to form cysts

Trichinosis Symptoms Asymptomatic GI: cramps, diarrhea Muscle: stiffness, pain, soreness Skin: rash Eyelid: swelling, pain, injected sclera DX: symptomatic TX Prevention Cook Freeze

Strongyloidiasis Eggs hatch in SI mucosal glands Larva Strongyloides stercoralis Eggs hatch in SI mucosal glands Larvae passed in stool Exposure: larvae migrate through skin Skin  Lungs  coughed and swallowed  Intestines Larvae mature to adult stage Larva Adult

Guinea Worm Disease Drancunculus Larvae in water Crustacean (IH) Humans ingest uncooked meat Larvae released  skin  Adult in blister like lesion Larvae produced and released with water

Drancunculus removal