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Parasite Types Classification Flipbook PDF
Medical Parasitology Review P. C. Iwen, PhD Parasite Types • Protozoa – Single-celled parasites • Helminths – Multi-cell
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Medical Parasitology Review P. C. Iwen, PhD
Parasite Types • Protozoa
• Protozoa
– Single-celled parasites
– Kingdom = Protista – Traditional groups
• Helminths – Multi-celled parasites
• Arthropods – Insects
Classification
• • • •
Intestinal Urogenital Blood Tissue
Classification • Arthropods
• Helminths
– Kingdom = Animalia – Traditional groups
– Kingdom = Animalia – Traditional groups • Trematodes flat) • Cestodes • Nematodes
Classification
(flukes, leaf-like and (flatworm) (roundworm)
• Vectors • Annoying parasites
Protozoa
– Malaria falciparum
• Intestinal protozoa – Amebic dysentery – Giardiasis – Cryptosporidiosis parvum – Cyclosporiasis cayatenensis
Entamoeba histolytica Giardia lamblia Cryptosporidium Cyclospora
Plasmodium Plasmodium malaria Plasmodium vivax
• Tissue – Leishmaniasis
Leishmania donovani Leishmania
braziliensis Leishmania tropica Toxoplasma
– Toxoplasmosis gondii
• Urogenital protozoa – Trichomoniasis
Protozoa • Blood
Trichomonas vaginalis
• Blood and Tissue Trypanosomiasis
Trypanosoma brucei
Intestinal Protozoa • Characteristics
Intestinal Protozoa
– No intermediate host – Cyst is infectious – Generally mild GI disease – Laboratory diagnosis • Cyst or trophozoite in stool
Intestinal Protozoa
Entamoeba histolytica
• Entamoeba histolytica (motile amoeba/ histo, within tissues; lytica, lysis) – Pseudopodia – Human only – No intermediate host
• Disease
Trophozoite→
Cyst→ Cyst→
1000x
• Amebic dysentery • Liver abscess
• Laboratory diagnosis • Stool wet mount • Trophozoite and cyst
Stool wet mount
1000x
Entamoeba histolytica
Intestinal Protozoa • Giardia lamblia / Giardia intestinalis (Alfred Giard / lamblia, to move hastily) – Flagellated trophozoite – Human and animal – No intermediate host
(reservoir)
• Disease • Giardiasis • Malabsorption syndrome
• Laboratory diagnosis Liver abscess
Giardia lamblia
• Stool wet mount • Trophozites and cysts
Intestinal Protozoa • Cryptosporidium parvum
Trophozoite → Trophozite → ←Cyst
(Crypto, hidden; sporidium, spores/ parvus, small) – Sporozoa – Human and animals (reservoir) – No intermediate host – Resistant to chlorination
• Disease • Cryptosporidiosis • Wasting disease in AIDS
Stool wet mount, 1000x
Stool trichome stain, 1000x
• Laboratory diagnosis • Stool acid-fast stain • Oocyst
Cryptosporidium parvum
Intestinal Protozoa • Cyclospora cayatenensis (Cyclo, related to cyanobacteria/ cayatana, place in Lima, Peru)
Oocyst →
– Sporozoa – Similar to Cryptosporidium
• Disease • Mild GI • Guatemala raspberries
Stool acidacid-fast, 1000x
• Laboratory diagnosis • Stool acid-fast stain • Oocyst
Cyclospora cayatenensis
Urogenital Protozoa Cyst→ Cyst→
Stool acidacid-fast stain, 1000x
Urogenital Protozoa
Trichomonas vaginalis
• Trichomonas vaginalis (Tricho, hairlike; monas, single/ vaginalis, relating to vagina)
– Flagellated trophozoite – No cyst form – Human only
• Disease – “Trich” – Sexually transmitted disease
• Laboratory diagnosis – Vaginal secretion wet mount – Trophozoite
Trichrome stain, trophozoite, 1000x
Blood Protozoa • Plasmodium falciparum/ malariae/ vivax (Reference to plasma / falciparum, sickle shaped/ malariae, bad air/ vivax, living)
– Sporozoa – Mosquito vector • Mosquito cycle
Blood Protozoa
(female Anopheles) (sporogamy)
– Ingest ♀ and ♂ gametocytes from blood – Fertilization to form sporozoite (infective form)
• Human cycle
(pre-erythrocytic)
– Sporozoite invades liver cells (merozoites to blood)
• Human cycle
(erythrocytic, schizogomy)
– Merozoites infect RBCs » Ring forms, trophozoites, schizonts, gametocytes
– Human to human via vector and blood
• Disease • Malaria • Life-threatening hemorrhage and necrosis • Fever cycles
• Laboratory diagnosis • Blood smear • Ring form / merozoite/ gametocyte
Plasmodium species
Ring form→ form→
Plasmodium falciparum
Gametocyte ↓
←Schizont
Blood Wright’ Wright’s stain, 1000x
ChloroquineChloroquine-resistance, encephalitis
Tissue Protozoa • Leishmania tropica/ braziliensis/ donovani (Leishman, British surgeon/ tropica, SA tropics; braziliensis, Brazil; donovani, Donovan, Irish surgeon)
Tissue Protozoa
– Flagellated trophozoite form) – Tissue – Sandfly vector – Human and animal
(promastigote stage, infective (amastigote stage) (reservoir)
• Diseases – – – –
Chronic disease Oriental sore on skin Mucocutaneous Visceral or kalazar
(L. tropica) (L. braziliensis) (L. donovani)
• Laboratory diagnosis – Histopathology • Amastigote form (donovan body)
Leishmania species
Tissue Protozoa • Toxoplasma gondii (Toxon, bow-shaped/ gondii, refers to rodent)
Promastigote form
Amastigote form
– Sporozoa – Cat is definitive host • Sexual reproduction • Ingestion of oocysts
• Disease 1000x
1000x
• Asymptomatic • Transplacental transmission • Immunocompromised patient, AIDS – Brain infection
Insect gut Wright’ Wright’s stain
Tissue H&E stain
• Laboratory diagnosis • Serology • Cysts in brain tissue (tachyzoites)
Toxoplasma gondii
Blood and Tissue Protozoa Tachyzoites→ Tachyzoites→
Brain tissue
Brain H & E stain, 1000x
Blood and Tissue Protozoa
Trypanosoma cruzi
• Trypanosoma cruzi (Trypano, auger-shaped/ Cruzi, Brazilian physician)
– – – –
Flagellated trypomastigote (infectious form) Reduviid bug vector Human and animal (reservoir) Human to human via vector or blood transfusion
Trypomastigote form ↓
• Disease • Chaga’s disease • Acute, Chagoma at site • Chronic, myocarditis
• Laboratory diagnosis • Blood smear – Trypomastigote form
Blood Wrights stain, 1000x
• Heart tissue – Amastigote form
Helminths • Trematodes – Intestinal flukes – Liver flukes – Lung flukes westermanii – Blood flukes haematobium
Helminths • Cestodes
Fasciolopsis buski Fasciola hepatica Paragonimus Schistosoma Schistosoma japonicum Schistosoma mansoi
– Fish tapeworm – Dog tapeworm granulosus – Rat tapeworm – Beef tapeworm – Port tapeworm
Diphyllobothrium latum Echinococcus Hymenolepis nana Taenia saginata Taenia solium
Helminths • Intestinal Nematodes – Ascariasis – Hookwork infection duodenale – Trichuriasis – Pinworm infection vermicularis
Helminths • Tissue Nematodes
Ascaris lumbricoides Ancylostoma Necator americanus Trichuris trichiura Enterobius
– Trichinosis – Lymphatic filariasis bancrofti – Onchocerciasis
Trichinella spiralis Wuchereria Onchocerca volvulus
Trematode
Trematode Helminth
Fluke example
Trematode
Schistosoma species
• Schistosoma haematobium/ japonicum/ mansoni (Schisto, split; oma, body/ haema, blood; japon, Japan; Manson, physician)
– – – –
Blood fluke Snail intermediate host Transmitted by cercaria in water Human and animal (reservoir)
• Disease • Schistosomiasis • Pathogenesis – – – –
Adults pair up in hepatic portal vein, migrate to: Veins of colon (mansoni) Veins of small intestine (japonicum) Urinary bladder (haematobium)
• Laboratory diagnosis • Stool wet mount/ urine • Ova
Adults, 400x
Cercaria, Cercaria, 400x
Schistosoma species S. haematobium
S. japonicum
Cestode Helminth S. mansoni Ova, 400x
Taenia species
Cestode • Taenia saginata/ solium (Taenia, tape/ saginatal, arrow shaped; solium, solo or alone)
– Intermediate host • Cattle • Pig
(larval form) (saginata) (solium)
= beef tapeworm = pork tapeworm
– Cysticercus (larva) in meat – Human is definitive host (adult form) – Human may be intermediate host for T. solium • Cysticercosis = brain
• Disease
100x
– Taeniasis
• Laboratory diagnosis • Stool wet mount • Ova/ proglottids • Speciation
Stool wet mount
– Requires an adult (either scolex or proglottid)
Taenia saginata
Nematode Helminth
Proglottid form
400x
Intestinal Nematode
Ascaris lumbricoides
• Ascaris lumbricoides (Askaris, German = worm/ lumbricus, worm)
– Humans only – Eggs hatch in small intestine, larva to blood to lungs to alveoli to bronchi to trachea and swallowed – Adults live in small intestine – Eggs become infectious in external environment (14d) • Embryonic egg
• Disease • Ascariasis • Intestinal obstruction • Ascaris pneumonia (Loeffler’s syndrome)
100x
400x
• Laboratory diagnosis – Stool wet mount
Stool wet mount
• Ova
– Respiratory sample or stool • Adult
Ascaris lumbricoides
Intestinal Nematode •
Ancylostoma duodenale (Old World) (Ancylo, hooked; stoma, mouth/ duodenum)
Necator americanus (New World) (Necator, ???/ relating to America)
– – – –
hookworms Eggs hatch in soil (rhabditiform larva) Mature in soil to filariform larva (infectious form) Filariform larvae enter foot to blood to lungs to alveoli to bronchi to trachea and swallowed – Adults • Small intestine feeding on blood
•
Disease • Hookworm infection • Primary = pneumonia • Secondary = anemia
•
Laboratory diagnosis – Stool wet mount • Ova
Adult worm
– Adult to identify species • Culture adult in vitro from viable eggs
Hookworm species
Intestinal Nematode • Trichuris trichiura (Trich, hair-like tail)
– Humans only host – Ova becomes infectious in soil (3w) • Embryonated egg
Ova
– Eggs hatch in small intestine, larvae to colon, adult and mating, eggs passed in stool
• Disease • Trichuriasis • Abdominal pain and weight loss
• Laboratory diagnosis 400x
Stool wet mount
– Stool wet mount • Ova
Trichuris trichuria
Intestinal Nematode • Enterobius vermicularis (Entero, intestine/ vermiculus, a small worm)
– – – –
Ova
Humans only Ova infectious (fecal/oral) Eggs hatch in small intestine to larva to large intestine Females to perianal region • Lay eggs
• Disease • Pinworm infection • Perianal pruritis • Asymtomatic carriers common
• Laboratory diagnosis
400x
• Scotch tape prep of perianal area • Ova
Stool wet mount
Enterobius vermicularis
Tissue Nematode • Trichinella spiralis (Trich, hair-like/ spiralis, coiled)
– Zoonotic nematode – Reservoir hosts are pig, bear, and cougar • Encysted larvae in muscle
(Infective stage)
– Larva become adults in small intestine, fertilize, release larva into blood, and encyst in muscle cells – Encysted larva, calcifications
• Disease Wet mount, 400x
Adult female, 50x
• Trichinella • Muscle pain
• Laboratory diagnosis – Histopathology • Larvae in muscle
– Serology
Ova in adult, 400x
Trichinella spirallis
Arthropods • Annoying parasites – Head lice capitis – Body lice corporis – Crab lice – Scabies
Encysted larvae
Pediculus humanus Pediculus humanus Phthirus pubis Sarcoptes scabei
• Vectors 400x
Muscle H & E stain
– Viral encephalitis Malaria – Plague – Lyme disease
Mosquito Flea Tick
Annoying Parasite
Lice
• Pediculus humanus capitus • Disease • Head lice infestation • Pediculosis
• Laboratory diagnosis • Adult • Nits on hair shaft
Annoying Parasite
Nits on hair, 400x
Adult, 20x
Sarcoptes scabiei
• Sarcoptes scabei • Disease • Scabies • Mange
• Laboratory diagnosis • Skin scrapping Adult, 100x