helminths
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HelminthsHelminths
Kingdom AnimaliaSub-kingdom Invertebrata
• I. Phylum Platyhelminthes - flatworms
• II. Phylum Nematoda - roundworms
• III. Phylum Annelida - segmented worms
• IV. Phylum Arthropoda –tics, mites, lice
Phylum PlatyhelminthesPhylum Platyhelminthes flatwormsflatworms
A. A. Class CestodaClass Cestoda -tapeworms -tapeworms
1. 1. Taenia Taenia pisiformispisiformis. -. -
B. B. Class Trematoda Class Trematoda - Flukes- Flukes
2. 2. ClonorchisClonorchis sinensissinensis - liver fluke - liver fluke
3. 3. FasciolopsisFasciolopsis buskibuski - giant intestinal fluke - giant intestinal fluke
44. . SchistosomaSchistosoma mansonimansoni female blood fluke female blood fluke
C. C. Class TurbellariaClass Turbellaria - free-living flatworms, ie. not parasitic - free-living flatworms, ie. not parasitic
5. 5. Planaria spp.Planaria spp.
Class CestodaClass Cestoda -tapeworms -tapeworms
Taenia Taenia pisiformispisiformis
Head (scolex)Head (scolex)
SuckersSuckers
HooksHooks
Segments (proglottids)Segments (proglottids)
TestesTestes
OvariesOvaries
Class Trematoda Class Trematoda - Flukes- Flukes
ClonorchisClonorchis sinensissinensis - liver fluke - liver fluke
Oral suckerOral sucker
PharynxPharynx
Intestines (cecum)Intestines (cecum)
UterusUterus
TestesTestes
Class Trematoda Class Trematoda - Flukes- Flukes
FasciolopsisFasciolopsis buskibuski - giant intestinal - giant intestinal flukefluke
Label: mouth, ventral sucker, Label: mouth, ventral sucker, intestines (cecum), testesintestines (cecum), testes
Class Trematoda Class Trematoda - Flukes- Flukes
SchistosomaSchistosoma mansonimansoni female blood female blood fluke; ventral sucker, ovary, mouthfluke; ventral sucker, ovary, mouth
Class TurbellariaClass Turbellaria - free-living - free-living flatworms, ie. not parasiticflatworms, ie. not parasitic
Planaria spp.Planaria spp. Label: pharynx, Label: pharynx, eyespots, gastrovascular cavityeyespots, gastrovascular cavity
Kingdom AnimaliaSub-kingdom Invertebrata
• I. Phylum Platyhelminthes - flatworms• II. Phylum Nematoda - roundworms• III. Phylum Annelida - segmented worms• IV. Phylum Arthropoda –tics, mites, lice
6. Enterobius vermicularis female – pinworm; Label: mouth, pharynx
Ascaris lumbricoides - intestinal round worm- plastimount; Label: male, female
8. Necator americanus- American hookworm; Label: teeth, muscular pharynx, posterior bursa and rays (male)
Trichinella spiralis- threadworm encysted in muscle; Label: cyst, muscle, larva
Kingdom AnimaliaSub-kingdom Invertebrata
• I. Phylum Platyhelminthes - flatworms• II. Phylum Nematoda - roundworms• III. Phylum Annelida - segmented worms• IV. Phylum Arthropoda –tics, mites, lice
Class Hirudinea 10. Leech; Label: anterior sucker, mouth, intestine, posterior sucker
Kingdom AnimaliaSub-kingdom Invertebrata
• I. Phylum Platyhelminthes - flatworms• II. Phylum Nematoda - roundworms• III. Phylum Annelida - segmented worms• IV. Phylum Arthropoda –tics, mites, lice
Phylum Arthropoda
• Class Arachnia
• Class Insecta
Class Arachnia
11. Dermacentor spp.- tick; Label: head, thorax, abdomen, legs
Class Arachnia
Sarcoptes scabiei - itch mite; Label: mouth, legs, bristles on rear
legs, bristles on abdomen
Class Arachnia
Dermatophagoides spp.- dust mite; Label: thorax, legs,
abdomen
Phylum Arthropoda
• Class Arachnia
• Class Insecta
Flea; Label: head, thorax, abdomen, legs
CLASS INSECTA
Pediculus humanis corporus - human body louse; Label: abdomen, thorax, head, antennae, eyes, plates, legs
CLASS INSECTA
Pthirus pubis- crab louse; Label: thorax, abdominal segments, eyes, legs, antennae
CLASS INSECTA
TaxonomyTaxonomy
Phylum: Platyhelminthes (Flatworms)Phylum: Platyhelminthes (Flatworms)• Class: Cestodes (tapeworms)Class: Cestodes (tapeworms)
Pork tapeworm (Pork tapeworm (Taenia soliumTaenia solium)) Beef tapeworm (Beef tapeworm (Taenia saginataTaenia saginata) ) Fish tapeworm (Fish tapeworm (Diphyllobothrium latumDiphyllobothrium latum) )
Characteristics of Tapeworms
• Monoecious
• Missing an entire system
• Scolex: suckers, hooks, or grooves
• Segmented– proglottids
• Gravid proglottids• Strobilia• Uterine branches
Beef Tapeworm Scolex
Pork Tapeworm Scolex
Pork Tapeworm Scolex
Pork Tapeworm Scolex
Pork Tapeworm
• Uterine branches in proglottid
Beef Tapeworm
• Uterine branches in proglottid
Pork and Beef Tapeworm Diseases
• 1. TAENIASIS (Pork and Beef)
• 2. CYSTICERCOSIS (Pork only)
Life Cycle:
Taenia
Tapeworms inside intestines
Taenia Egg
Taenia Egg
CYSTICERCOSIS
Broadfish Tapeworm
• Operculated eggs contain ciliated coracidium.
• Copepods eat the coracidium.– They become procerocoid larvae
• Minnows eat the copepod.
• Predator fish eat the minnows.
• Humans eat the predator fish. – The infective stage is in the fish.
Broadfish Tapeworm
• The larvae are released from the cysts.
• They invade the intestines and mature.
• They attach by bilateral grooves called brothria.
• The proglottids are passed in the feces, and return to the water.
• They become embryonated and become operculated eggs.
Fish Tapeworm
Bilateral grooves
Fish Tapeworm
• Proglottids
Operculated Broadfish Tapeworm (Diphyllobothrium) egg.
Has a ciliated coracidium inside
Operculum
Knob
Diphyllobothrium Egg
KnobOperculum
Diphyllobothrium Egg
Operculum Knob
Diphyllobothrium Egg
Copepod
Walleye Pike
TaxonomyTaxonomy
Phylum: Platyhelminthes (Flatworms)Phylum: Platyhelminthes (Flatworms)• Class: Trematodes (flukes)Class: Trematodes (flukes)
SchistosomesSchistosomes• S. japonicumS. japonicum• S. mansoniS. mansoni• S. haematobiumS. haematobium
Schistosoma spp.
• Schistosomiasis
Schistosoma spp.
• Eggs are eliminated with feces or urine. • The eggs hatch and release miracidia, which
swim and penetrate specific snail intermediate hosts.
• The stages in the snail include 2 generations of sporocysts and the production of cercariae (which have a forked tail). Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host, and shed their forked tail, becoming schistosomulae.
Schistosomal miracidum
Schistosoma cercariae
Schistosoma spp.
• The schistosomulae migrate to the veins:– S. japonicum and S. mansoni inhabit the
mesenteric veins draining the intestines.– S. haematobium inhabit the urinary bladder
venous plexus.– The females are smaller and live inside the
male. They deposit eggs in the small venules. The eggs are moved progressively toward the lumen of the intestine and are eliminated with feces or urine.
Schistosoma
Schistosoma
Male
Female
Schistosoma spp.
• Human contact with water is thus necessary for infection by schistosomes. Skin penetration is required.
• Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs, but skin penetration is still required.
• Geographic Distribution: Schistosoma mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematobium in Africa and the Middle East; and S. japonicum in the Far East. Schistosoma mekongi and S. intercalatum are found focally in Southeast Asia and central West Africa, respectively.
Schistosoma spp.
– Symptoms include: Katayama fever, granulomas (occasionally in brain or spinal cord).
– S. haematobium schistosomiasis also includes: hematuria, and bladder cancer.
Life Cycle:
Types of Schistosoma eggs
S. mansoni S. haematobium S. japonicum
Schistosoma haematobium egg
Schistosoma haematobium egg
Schistosoma mansoni egg
Schistosomiais
Swimmer’s Itch
Schistosomiais: Swimmer’s Itch
TaxonomyTaxonomy
Phylum: Nematodes (roundworms)Phylum: Nematodes (roundworms) PinwormPinworm WhipwormWhipworm HookwormHookworm Intestinal RoundwormIntestinal Roundworm Pork RoundwormPork Roundworm
Pinworm
• Enterobius vermicularis
Life Cycle:
Pinworm• Eggs are deposited on perianal folds. Self-infection
occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area. Person-to-person transmission can also occur through handling of contaminated clothes or bed linens or contact with contaminated curtains, carpeting, etc.
• Some small number of eggs may become airborne and inhaled. These would be swallowed and follow the same development as ingested eggs.
• Following ingestion of infective eggs, the larvae hatch in the small intestine and the adults establish themselves in the colon.
• Gravid females migrate nocturnally outside the anus and deposit their eggs while crawling on the skin of the perianal area.
Pinworm
Geographic Distribution:Worldwide, with infections more frequent in school- or preschool- children and in crowded conditions. Enterobiasis appears to be more common in temperate than tropical countries. The most common helminthic infection in the United States (an estimated 40 million persons infected).
Pinworm
Female
Enterobius vermicularis egg
Pinworm
Pinworm
Alae
Esophagus
Esophageal bulb
Pinworm adultAlaeEsophagus
Esophageal bulb
Eggs
Pinworm
Whipworm
• Trichuris trichiura
Life Cycle:
Trichuris trichiura
• The unembryonated eggs are passed with the stool. In the soil, the eggs become infective.
• After ingestion (soil-contaminated hands or food), the eggs hatch in the small intestine, and release larvae that mature and establish themselves as adults in the colon.
• Female worms in the cecum shed up to 20,000 eggs per day. The life span of the adults is about 1 year.
• Geographic Distribution:The third most common round worm of humans worldwide, with infections more frequent in tropical areas and poor sanitation practices, and among children. It is estimated that 800 million people are infected worldwide. Trichuriasis occurs in the southern United States.
Whipworm
Prolapsed Rectum from whipworm
Prolapsed Rectum from whipworm
Whipworm egg
Whipworm egg
Whipworm, female and male
Hookworm
• Ancyclostoma duodenale
• Necator americanus
Life Cycle:
Hookworm
• Eggs are passed in the stool. The released rhabditiform larvae grow in the feces and/or the soil, and after 5 to 10 days they become filariform larvae that are infective.
• These infective larvae contact the human host, penetrate the skin and are carried through the veins to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed.
• The larvae reach the small intestine, where they reside and mature into adults. Adult worms attach to the intestinal wall with resultant blood loss by the host.
Hookworm
• Geographic Distribution:The second most common human helminthic infection (after ascariasis). Worldwide distribution, mostly in areas with moist, warm climate. Both N. americanus and A. duodenale are found in Africa, Asia and the Americas. Necator americanus predominates in the Americas and Australia, while only A. duodenale is found in the Middle East, North Africa and southern Europe.
Male hookworm
Copulatory Bursa of Male Hookworm
Copulatory Bursa of Male Hookworm
Hookworm cutting plates
Necator americanus
Hookworm teeth
•Ancyclostoma duodenale
Hookworm teeth
•Ancyclostoma duodenale
Hookworm egg
Hookworm egg
Hookworm: creeping eruption
Ascariasis
• Ascaris lumbricoides
Life Cycle:
Ascariasis
• Adult worms live in the lumen of the small intestine. A female may produce approximately 200,000 eggs per day, which are passed with the feces
• After infective eggs are swallowed, the larvae hatch, invade the intestinal mucosa, and are carried to the lungs. The larvae penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed.
• Upon reaching the small intestine, they develop into adult worms.
Ascariasis
Geographic Distribution:The most common human helminthic infection. Worldwide distribution. Highest prevalence in tropical and subtropical regions, and areas with inadequate sanitation. Occurs in rural areas of the southeastern United States.
Ascariasis
Ascariasis
Ascaris Adult
Ascaris egg
Ascaris egg
Trichinellosis
• Trichinella spiralis
Life Cycle:
Trichinellosis
• Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) of Trichinella. After exposure to gastric acid, the larvae are released from the cysts and invade the small bowel mucosa where they develop into adult worms.
• The females release larvae that migrate to the striated muscles where they encyst. Ingestion of the encysted larvae perpetuates the cycle.
• Rats and rodents are primarily responsible for maintaining the endemicity of this infection. Pigs or bears feed on infected rodents.
• Humans are accidentally infected when eating improperly processed meat of these carnivorous animals (or eating food contaminated with such meat).
• Geographic Distribution:Worldwide. Most common in parts of Europe; in the United States, it is most common in Alaska from eating infected bear meat.
Trichinellosis
• Eosinophilia develops in response to the presence of the worm. Patients who develop neurologic and cardiac dysfunctions have marked hypereosinophilia associated with arteriolar microthrombi leading to areas of cerebral and myocardial infarction. Immunologic reactions also are deemed responsible for one of the hallmark clinical findings—palpebral edema.
• The direct trauma of the larva encysting in muscle cells, coupled with the immunologic response, is responsible for other clinical features (eg, fever, myalgias). Ultimately, the intramuscular cysts typically calcify.
Trichinella cyst
Trichinella cysts
Filariasis
• Caused by nematodes that produce a thread-like larvae called microfilariae.
• They inhabit the lymphatic system of humans.
• They require the bite of a mosquito.
Elephantitis
• Wuchereria bancrofti
• Mosquito: anopheles or Culex (Asia)
• Blocks lymph drainage
Life Cycle of Wuchereria bancrofti:
Elephantitis
• During a blood meal, an infected mosquito introduces filarial larvae onto the skin of the human host, where they penetrate into the bite wound.
• They develop in adults that commonly reside in the lymphatics.
• The microfilariae migrate into lymph and blood channels moving actively through lymph and blood.
• Another mosquito ingests the microfilariae during a blood meal and work their way to the mosquito's midgut and develop into infective larvae.
• The infective larvae migrate through to the mosquito's prosbocis and can infect another human when the mosquito takes a blood meal.
Elephantiasis
River Blindness
• Onchocerca volvulus
• Requires bite of Black Fly (Simulium)
• Itchy nodules under skin and head
• Treatment is Ivermectin
Life Cycle of Onchocerca volvulus:
River Blindness
• During a blood meal, an infected blackfly (genus Simulium) introduces filarial larvae onto the skin of the human host, where they penetrate into the bite wound.
• In subcutaneous tissues the larvae develop into adult filariae, which commonly reside in nodules in subcutaneous connective tissues. Adults can live in the nodules for approximately 15 years. Some nodules may contain numerous male and female worms. Some of them get into the bloodsteam.
• Another blackfly ingests the microfilariae during a blood meal and migrate to the thoracic muscles. There they develop into infective larvae and migrate to the blackfly's proboscis and can infect another human when the fly takes a blood meal.
River Blindness
River Blindness
River Blindness
Guinea Worm
• Dracunculus medinensis
• Geographic Distribution:Restricted to rural, isolated areas in a narrow belt of African countries.
Life Cycle:
Guinea Worm• Humans become infected by drinking unfiltered water containing
copepods (small crustaceans) which are infected with larvae of D. medinensis.
• Following ingestion, the copepods die and release the larvae, which penetrate the host stomach and intestinal wall and enter the abdominal cavity and retroperitoneal space.
• After maturation into adults and copulation, the male worms die and the females migrate in the subcutaneous tissues.
• Approximately one year after infection, the female worm induces a blister on the skin, generally on the distal lower extremity, which ruptures. When this lesion comes into contact with water, the female worm emerges and releases larvae.
• The larvae are ingested by a copepod and develop into infective larvae.
Guinea Worm
Loa loa
• The “eye worm”
Life Cycle of Loa loa:
Loa loa• The vector for Loa loa filariasis are flies from two species of the
genus Chrysops, C. silacea and C. dimidiata. • During a blood meal, an infected fly (genus Chrysops, day-biting
flies) introduces filarial larvae onto the skin of the human host, where they penetrate into the bite wound.
• The larvae develop into adults that commonly reside in subcutaneous tissue but can migrate into spinal fluids, urine, and sputum. During the day they are found in peripheral blood, but during the noncirculation phase, they are found in the lungs.
• The fly ingests microfilariae during a blood meal, which migrate to the thoracic muscles and develop into infective larvae. They migrate to the fly's proboscis and can infect another human when the fly takes a blood meal.
Loa loa
Loa loa
Loa loa
“My worm collection”
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