Parasitology Review: Clinical Presentation, Laboratory Diagnosis, and Common Pathogens
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This document discusses the clinical presentation, laboratory diagnosis, and most common pathogens involved in parasitology. It describes the symptoms, life cycles, microscopic appearance, and diagnostic methods for protozoan parasites commonly found in stool, blood, and tissues. These include Entamoeba histolytica, Giardia lamblia, Cryptosporidium, and Trypanosoma among others.
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Parasitology Review: Clinical Presentation, Laboratory Diagnosis, and Common Pathogens
- 2. Clinical presentation Travel history or poor sanitation put you at the highest risk for parasitic infection Sporadic symptoms, Poor immune status higher risk Dysentery not common (amebiasis) Most usual symptoms: • Abdominal pain, cramping, long term nausea, and malaise, mucous in stool, and +/- fever
- 3. Laboratory Diagnosis Limited Currently based on microscopic exam, however utility/availability of: molecular panels are in the • Serology near future • Stool • Fluorescent stains • Non-stool • PCR Perianal specimen • • Sigmoidoscopic specimen Duodenal aspirates Liver abscess Sputum Urine Urogenital Blood Tissue
- 4. Two-vial collection kit for Stool 10% formalin Concentration with ethyl acetate to eliminate fecal debris Wet mount and DFA staining Helminth eggs, larvae, microsporidia, and protozoan cysts PVA with fixative Polyvinyl alcohol Permanent stained smear • Trichrome stain Protozoan trophozoites and cysts Mercury based fixatives being phased out for safety – Zinc fixatives are now used
- 5. Most Common Pathogens Protozoa • Intestinal & urogenital E histolytica, Blastocystis hominis, Giardia lamblia, Dientamoeba fragilis, Balantidium coli, Cryptosporidium sp., Cyclospora sp, Cyclospora, (Isospora) belli, and Microsporidia • Blood & tissue Plasmodium, Babesia, Trypanosomes Toxoplasma gondii, Leishmania Naegleria, Acanthamoeba, Balamuthia Helminths • Nematodes Ascaris, Trichuris, hookworm, pinworm, and Strongyloides • Cestodes Taenia, Hymenolepis, Diphyllobothrium • Trematodes Fasciola, Fasciolopsis, Schistosoma, Paragonimus, Clonorchis
- 6. PROTOZOA Amebae (found in stool) • • • • • Entamoeba coli Entamoeba histolytica Endolimax nana Iodamoeba butschlii Dientamoeba fragilis Ciliates, Coccidia, Blastocystis • • • • • • • Balantidium Cryptosporidium Isospora belli Sarcocystis Cyclospora Microsporidium Blastocystis hominis Blood-Borne Protozoa • • • • • Flagellates (found in stool) • Giardia lamblia • Chilomastix mesnili Babesia Leishmania Trypanosoma brucei T. cruzi Plasmodium Other • • • Toxoplasma Naegleria fowleri Acanthamoeba
- 7. Protozoa Found in Stool: Amebae pathogen
- 8. Intestinal amoeba Entamoeba coli Entamoeba histolytica/dispar Entamoeba hartmanni Endolimax nana Iodamoeba butschlii
- 10. Entamoeba histolytica/dispar E. histolytica is a pathogen and E. dispar is a nonpathogenic species that can also occur in the large intestine. Morphologically indistinguishable E histolytica • Cysts = infectious form • trophozoites = invasive form • Contaminated water and poor sanitation • Colon biopsy shows “flask-shaped” ulcer • Non-intestinal disease = extraintestinal amebiasis (liver abscess) Serology
- 11. Entamoeba histolytica/dispar Cysts <= 10 um In diameter Up to 4 nuclei in the cyst Clean chromatin Bulls-eye nucleoli
- 12. Entamoeba histolytica/dispar Trophozoites & Trophozoite with ingested rbcs Cysts
- 13. Amebic abscess Amebic liver abscess Entamoeba histolytica Serology – high % positive in extraintestinal cases Flask-shaped ulcer of intestinal amebiasis
- 14. Entamoeba coli cyst and trophozoite Trophozoite is the form that invades intestines Cyst >=15 mm Up to 8 nuclei Shed from host Lives in environment Nucleus has a chromatin ring The cytoplasm appears dirty
- 15. Entamoeba coli Trophozoites & Cysts
- 16. Endolimax nana trophozoite Mostly thought to be a non-pathogen, Seen in HIV/AIDS patients, Some literature suggesting it can cause intermittent or chronic diarrhea
- 17. Iodamoeba butschlii cysts with starch Staining inclusion Iodine preparation – name from appearance with iodine staining
- 18. Flagellates Giardia lamblia Dientamoeba fragilis Trichomonas vaginalis
- 19. Protozoa Found in Stool: Flagellates
- 20. Giardia lamblia Contaminated water, undercooked foods Mild diarrhea to severe malabsorption Foul, watery diarrhea Day-care center outbreaks Cysts/trophozoites may be seen in stool, but can be hard to find; Fluorescent stains available Duodenal aspirations CYSTS TROPHOZOITE “falling leaf” motility
- 21. Giardia lamblia trophozoite Waxing and waning symptoms Can be irregularly Shed in stool material & can be difficult to find Russia & Mexico -Hot beds Only invades intestine Flagyl (Metronidazole) is drug of choice
- 25. Only invades intestinal tissue
- 26. Chilomastix mesnili cyst Nonpathogen Mimics Giardia lamblia cyst – except for clear space at end of cyst Internal structure looks like “shepherd’s crook” or safety pin
- 27. Chilomastix mesnili cyst Clearing Nipple Chilomastix mesnili trophozoite
- 28. Dientamoeba fragilis Diarrhea, anal pruritus Co-infection with Enterobius (pinworm)
- 29. Trichomonas vaginalis Urogenital protozoan Scant, watery vaginal discharge Four flagella, short undulating membrane
- 30. Protozoa Found in Stool: Ciliates, Coccidia, Blastocystis
- 31. Ciliates Balantidium coli • Mainly in swine • Contact with swine & poor hygiene • Only ciliate that’s pathogenic to humans • Similar disease as amebiasis, but extraintestinal invasion rare • Largest (50-200 um) trophozoite; surface covered with cilia; macronucleus • Cyst 40-60 um • Readily identified in fresh, wet mounts
- 32. Only protozoa with cilia 50 microns In intestine can cause flask-shaped ulcers like those caused by E. histolytica
- 33. Intestinal Sporozoa (coccidia) Isospora Cryptosporidium Cyclospora Sarcocystis } All are Partial acid fast +
- 34. Isospora belli Contaminated food/water, oral-anal Found most commonly in HIV/AIDS Infects intestinal epithelium Malabsorption syndrome mimicking giardiasis Modified acid fast stain
- 35. Isospora belli
- 36. Cryptosporidium parvum Contaminated water Resistant to usual water-purification procedures (chlorination, ozone) Daycare center outbreaks (fecal-oral) Watery diarrhea; more severe in AIDS
- 37. Cryptosporidium Partial Acid Fast Positive
- 38. Enzyme immunoassay for the antigen Direct Fluorescence Antibody stain – of C. parvum is also available. Cryptosporidium parvum False negatives may result due to low organisms numbers (Asymptomatic carriers) in both the EIA and DFA assays Combo stain for Cryptosporidium And Giardia lamblia C. parvum Giardia
- 39. C. Parvum in intestine C. Parvum in intestine just below the plasma membrane
- 40. Cyclospora cayetanensis Contaminated fruits and vegetables Watery diarrhea; more sever in HIV/AIDS Infects upper small bowel Found in vacuoles in cytoplasm of jejunal epithelium, villous atrophy, crypt hyperplasia
- 41. Cyclospora cayetanensis PAF + 6-8 microns Autofluorescence on FA scope Also positive on Calcofluor white stain
- 42. Microsporidia Obligate intracellular pathogen Enterocytozoon and Encephalitozoon species Primitive eukaryotic organism (fungi) Many genera Infection by ingestion of spores Chronic diarrhea in AIDS patients Myositis, hepatitis, peritonitis, keratitis
- 43. Microsporidia -Common in HIV/AIDS -Watery persistent diarrhea Positive on modified Trichrome and Calcofluor white stains -Longer staining time will eventually allow for it to work its way into the spore
- 44. Blastocystis hominis cysts Nuclear blobs Around the periphery Can be a pathogen Small #s: can be commensal Large #s: pathogenic Dirty H20 Traveler’s diarrhea Trichrome stain Iodine wet mount
- 45. Blood-Borne Protozoa Organism Transmission Disease/Symptoms Diagnosis Treatment Trypanosoma brucei Tsetse fly African trypanosomiasis; Sleeping sickness Encephalitis; cardiac failure Hemoflagellate in blood or lymph node Blood stage: Suramin or petamidine isethionate T. cruzi Reduvid (kissing) bug American trypanosomiasis; Chagas disease: megacolon, cardiac failure. Hemoflagellate in blood or tissue. C- or commashaped CNS: melarsoperol Nifurtimox and Benzonidazole. Leishmania donovani Phlebotomine sandfly Visceral leishmaniasis (Kala-azar), granulomatous skin lesions Iraq/Iran/Afghanistan Intracellular (macrophages) leishmanial bodies with kinetoplast Pentosam; Pentamidine isethionate. Babesia microti Ixodes tick Hemolytic anemia, Jaundice, fever, hepatomegaly Maltese cross in rbc None; self resolving.
- 46. Trypanosomes 2 different diseases • Chagas disease (American trypanosomiasis) Trypanosoma cruzi Reduviid / Triatome (kissing) bug • African sleeping sickness (African trypanosomiasis) T. brucei (gambiense and rhodesiense) Tsetse fly
- 47. Trypanosoma brucei Sleeping sickness (African trypanosomiasis) Vector: Tsetse fly The two T. brucei species that cause African trypanosomiasis are indistinguishable morphologically • T. b. gambiense • T. b. rhodesiense A typical trypomastigote has: • A small kinetoplast located at the posterior end • A centrally located nucleus • An undulating membrane, and • A flagellum running along the undulating membrane, leaving the body at the anterior end • 14 to 33 µm in length Trypomastigotes are the only stage found in patients.
- 48. Trypanosoma brucei gambiense in a blood film Filamentous structures found in blood
- 50. Trypanosoma cruzi Chagas (American trypanosomiasis) Vector: Reduvid/Triatoma (kissing) bug Trypomastigotes are the only stage found in the blood of an infected person; may be seen in CSF in CNS infections Motile circulating trypomastigotes are readily seen on slides of fresh anticoagulated blood in acute infection but are rarely detectable by microscopy in chronic T. cruzi infection. A typical trypomastigote has: • • • • A large, subterminal or terminal kinetoplast, A centrally located nucleus, An undulating membrane, and A flagellum running along the undulating membrane, leaving the body at the anterior end. • 12 to 30 µm in length. Amastigote stage parasite may be seen in histopathology specimens from affected organs. C-shape
- 51. Reduvid bug Trypanosoma cruzi - Possible cardiac infiltration->Chagas
- 52. Leishmania Obligate intracellular parasite Vector: female sand fly bite Visceral leishmaniasis (kala azar) • L. donovani Cutaneous leishmaniasis • L. • L. tropica braziliensis
- 53. Leishmania
- 54. Leishmania amastigotes • Macrophages filled with amastigotes (arrows), several of which have a clearly visible nucleus and kinetoplast • Amastigotes are being freed from a rupturing macrophage
- 55. Leishmania – Clinical Disease Cutaneous • Single or few chronic, ulcerating lesions; many species • Latin America, southern Europe, Middle east, southern Asia, Africa • Mucocutaneous in Latin America Visceral • primarily L. donovani complex (Asia), L. infantum/chagasi (Africa and Latin America), others • Hepatosplenomegaly, anemia, cytopenias, systemic symptoms • India, Bangladesh, Nepal, Sudan, and Brazil • Important OI in HIV infection
- 56. Leishmania Diagnosis • Biopsy of infected tissue (skin, bone marrow) Multiple, tiny 2-5 um amastigotes within histiocytes Distinct kinetoplast (bar-like structure adjacent to nucleus) • PCR • Urinary antigens (visceral) DDx of multiple tiny intracellular organisms • • • Leishmania – kinetoplast Histoplasma – budding Toxoplasma – somewhat curved, mostly extracellular
- 57. Leishmania donovani Skin lesion Sand Fly Kinetoplast next to nucleus
- 58. Babesia Ixodes tick Protozoan: B. microti, B. divergens Zoonosis (deer, cattle, rodents; humans accidental host) Transmission by Ixodes tick bite Infects red blood cells Found world-wide B. microti along the Northeast US • Nantucket Island, Martha’s vineyard, Shelter Island Malaria-like syndrome • Fever but without periodicity, “B-symptoms”, hemolytic anemia, hemoglobinuria, renal failure Dx: • Blood smear examination Ring form only (mimics P. falciparum) Tetrads (unlike P. falciparum) Maltese cross (tetrads)
- 59. Babesia
- 60. MALARIA Protozoan Transmitted by the anopheles mosquito Endemic to tropical areas
- 61. Malaria Symptoms Fever and chills Splenomegaly Headache Abdominal pain Diarrhea Myalgia Blackwater fever (hemolysis, hemoglobinuria, renal failure) – P falciparum only
- 62. Malaria Symptoms Fever pattern Parasite Disease Plasmodium falciparum P. vivax Malignant tertian malaria Benign tertian malaria P. ovale Benign tertian malaria P. malariae Quartan malaria Tertian = q 48 hours (every other day) Quartan = q 72 hours
- 63. Malaria Physical exam findings • • • Fever Splenomegaly P. falciparum Jaundice Hepatomegaly Increase in respiratory rate CNS involvement Diagnosis: peripheral blood smear (gold standard) Molecular tests are available but not yet widely used
- 64. Malaria Distinction is between P. falciparum and non-falciparum • P. falciparum = rapidly progressive and LETHAL (malignant tertian fever), often chloroquine-resistant • Non-falciparum = rarely cause severe manifestations, often chloroquine sensitive Relapsing malaria • Dormant hepatic phase Hypnozoites of P. vivax and P. ovale
- 65. Two in the Liver/Two Not!! Two types of malaria that don’t recur from the liver: • P. falciparum – high incidence and severity • P. malariae – lower incidence and severity Two types of malaria that do recur from the liver: • P. vivax – high incidence, most of the world except Western Africa • P. ovale – lower incidence, occupies the niche in Western Africa
- 66. Life Cycle of Plasmodium Species MALARIA
- 67. RBC forms Merozoites Ring form Trophozoite Schizont (ruptured schizont) Gametocyte
- 68. Plasmodium species Plasmodium Plasmodium Plasmodium Plasmodium falciparum vivax ovale malariae
- 69. P. falciparum P. vivax, P. ovale P. malariae Babesia Vector Mosquito Mosquito Mosquito Ixodes tick RBC Any RBC Young RBC; enlarged Mature RBC; Not enlarged Ring Multiple can be seen; delicate; “appliqué” Rarely >1; thickened Schizont Rarely seen Commonly seen Bananashaped Round none None None Present No Yes No Brown No 5-10% Gametocyte Extra-RBC form Schüffner dots Pigmentation Infection rate >2% <2% Protective polymorphism s Hemoglobin S, C,E, alpha and beta thal, G6PD Duffy negative (P. vivax) 1-12 Tetrads (Maltese cross) Delicate Rings only “rosette” none
- 70. Malarial Preparations Thick smear Drop of blood on slide Water rinse to eliminate rbc’s Stain with Giemsa stain (not WrightGiemsa) with proper pH Concentrated to spot malaria parasites Thin smear Feather edge smear For optimal morphology, stain with Giemsa (not Wright-Giemsa) stain with proper pH Speciation of malaria Parasitemia (%)
- 71. Malaria Diagnosis Microscopy is most often used Antigen detection – EIA available Molecular methods
- 74. P. ovale
- 76. P. malariae
- 77. P. vivax Amoeboid ring form P.Vivax – benign tertian malaria (every 48 hours), Duffy negative RBC is protective Africans lack Duffy rbc antigen and this prevents rbc invasion. Untreated infections last several years; dormant in the liver for years Patients can survive years without treatment, but chronic infection can lead to brain, kidney and liver damage
- 78. P. falciparum
- 79. P. falciparum Malignant tertian malaria Black water fever
- 81. P. falciprium Vector Mosquito NonFalciparum Mosquito Babesia RBC All RBC Young RBC Ring 1-3 delicate Rarely >1 thickened Gametocyte Banana shaped round none Extra-RBC form None None Present Pigmentation Black brown none Infection rate >2% <2% 5-10% Protective polymorphis ms Hemoglobin S, Duffy negative C,E, alpha and beta thal, G-6PD Ixodes tick 1-12 Tetrads Delicate Rings only
- 83. Organism Toxoplasma gondii Transmission Oral from cat fecal material or meat Disease/Sympto ms Adult: flu like; congenital: abortion, neonatal blindness and neuropathies Diagnosis Intracellular (in macrophages) tachyzoites Treatment Sulphonamides , pyemethamine , possibly spiramycin (non-FDA)
- 84. Toxoplasma gondii Coccidian protozoan House cat = definitive host Ingestion of infective oocysts from contaminated cat feces Ingestion of improperly cooked meat from animals that serve as intermediate hosts (rodents) Symptoms • Predilection for lung, heart, lymphoid organs, CNS/eye • Infectious mono-like; lymphadenitis, hepatitis, rash, encephalomyelitis, myocarditis, chorioretinitis • Transplacental infection 1st trimester spontaneous abortion, stillbirth or severe disease 2nd/3rd trimester CNS infections (epilepsy, encephalitis, intracranial calcifications, MR, chorioretinitis, blindness, hearing loss), jaundice, rash • AIDS - Encephalitis; mass lesions in brain
- 85. Toxoplasma gondii Strongly associated with young Kittens
- 86. Toxoplasma gondii Diagnosis • Serology EIA Anti-toxo IgM – congenital and acute infection; may persist for months Anti-toxo IgG – common; if positive, gestations safe from intrauterine toxoplasmosis infection • PCR
- 87. Toxoplasma gondii Can be diagnosed by serology
- 88. Toxoplasma gondii Toxoplasma gondii cyst in brain tissue stained with hematoxylin and eosin
- 90. Free-living Amoeba Naegleria fowleri Acanthamoeba Balamuthia
- 92. Amoebic meningoencephalitis Most commonly caused by Naegleria fowleri Granulomatous amoebic encephalitis or brain abscess(es) caused by Acanthamoeba and Balamuthia Clinical scenario: swimming or diving in fresh-water pools
- 93. Naegleria fowleri -Found in warm fresh water -Breath-in through nose-> brain Brain tissue with Naegleria fowleri trophozoite
- 94. Brain tissue with Naegleria fowleri trophozoites
- 95. Contact-lens keratitis Caused by Acanthamoeba Can be cultured on a “lawn of E. coli” • Take corneal scapings • Visible trail of ameba moving across plate ingesting E. coli
- 96. Acanthamoeba
- 97. HELMINTHS Nematodes (roundworms) Trematodes (flukes) Cestodes (tapeworms)
- 98. Nematodes Enterobius Ascaris Trichuris Necator and Ancylostoma (Hookworm) Microfilaria – Wucheria, Brugia, Loa loa, Mansonella, and Onchocerca
- 100. Enterobius vermicularis (pinworm) Humans considered only host Females 8-13mm, males 2-5 mm Dwell in the cecum ¼-1/2 inch in thickness, white, lloks like string in stool Lay up to 15,000 eggs • Oval with a flattened side: 50-60um by 20-30um Diagnosis- Scotch tape test or anal swab Most common helminth in US
- 101. Enterobius vermicularis (pinworm) eggs Asymmetrical eggs
- 102. Pinworm larvae
- 103. Ascaris lumbricoides (roundworm) 1-1.2 billion people infected • More common in children 20,000 death Largest helminth to affect humans Females 20-35cm long, males 1530cm with a curved tale • Can cause intestinal obstruction
- 104. Ascaris lumbricoides
- 106. Ascaris eggs Unfertilized eggs-large & oval, mammillated layer is pronounced Fertilized eggs- smaller, rounder, mammillated layer is less obvious
- 107. Trichuris Trichiura (whipworm) Soil transmitted Can be similar to amebiasis PVA preserved samples inferior to formalin Adults attach to large intestine and are rarely recovered Thinnest part- head Males are smaller than females
- 108. Trichuris trichiura
- 109. Necator americanus, Anclyostoma duodenale (Hookworms) Soil transmitted 2nd most common helminth infection Enter via exposed skin Necator or Ancylostoma – Hookworm egg
- 110. Hookworm life cycle
- 111. Strongyloides stercoralis Soil transmitted Larval form-does not have eggs or other forms It has internal structures Strongyloides larvae
- 112. Strongyloides stercoralis Can be found in intestines or stools In real sick can go to lung and cause pneumonia
- 113. Trichinella spiralis -Tissue nematode -All stages occur in single host -usually an incidental finding in muscle
- 114. Microfilariae Sheathed • Wucheria bancrofti and Brugia malayi Elephantiasis (lymphangitis/lymphedema) • Loa loa Calabar swellings & migrating worms in the conjunctiva Not sheathed • Onchocerca volvulus • Mansonella species Allergic skin reactions, edema, Calabar swellings
- 116. How to tell them apart Are they sheathed? • Yes: Wucheria, Brugia, Loa loa • No: Onchocerca, Mansonella How far do nuclei extend? • Terminal and subterminal nucleus: Brugia • To the end: Loa loa
- 117. Identification of microfilariae is based on the presence of a sheath covering the larvae, as well as the distribution of nuclei in the tail region A, W. bancrofti. B, B. malayi. C, L. loa. D, O. volvulus. E, Mansonella perstans. F, Mansonella streptocerca. G, Mansonella ozzardi.
- 118. Filaria Identification a. W. bancrofti • a. B. malayi • a. Sheathed, two small nuclei in tail O. volvulus • a. Sheathed, nuclei stop short of end of tail Unsheathed, from skin, not blood Loa loa • Sheathed, nuclei to continue to end of tail
- 119. Wucheria bancrofti
- 121. Brugia malayi
- 122. Brugia malayi
- 123. Loa loa
- 124. Loa loa (eye worm)
- 125. Mansonella perstans
- 127. Onchocerciasis
- 128. Trematodes (Flatworms) Intestinal and Liver flukes • Fasciolopsis buski • Fasciola hepatica Liver flukes • Clonorchis sinensis (Chinese liver fluke) Paragonimus westermani – oriental lung fluke Schistosomes • S mansoni – intestinal bilharziasis • S haematobium - urinary • S japonicum – blood fluke, found in intestines
- 129. Intestinal and liver flukes
- 134. Paragonimus westermani Transmission: Crab or crayfish Symptoms: chest pain, hemoptysis cough, pulmonary infiltrates, cerebral lesions Diagnosis: Eggs is sputum or feces Egg is operculate, unembryonated, thick shell, asymmetrical and large
- 136. Schistosoma mansoni Schistosoma haematobium Schistosoma jajonicum
- 137. Cestodes (Tapeworms) Flattened dorsoventrally, segmented Head with armed or unarmed scolex Proglottids immature, mature (sex organs) Gravid (with eggs) Internal structure of proglottids Hermaphroditic-ovary, testes, vitellaria, uterus, genital pore and ducts Lateral excretory and nervous system No gut-tegument absorbs nutrients Muscles-longitidinal and horizontal Examples Diphyllobothrium latum Taenia saginata Taenia solium Hymenolepis nana Hymenolepis diminuta Echinococcus granulosis
- 139. Diphyllobothrium latum Poorly-cooked fresh-water fish(salmon) Scandinavian, Russia, Canada, N. USA, Alaska Broad fish tapeworm Longitudinal sucker Eggs have non-shouldered operculum and knob • They are not embryonated Causes Vit B12 deficiency
- 142. Taenia Species – two species Outstanding characteristics Taenia saginata Taenia Solium Beef tapeworm 4 suckers on scolex >13 uterine branches in proglottids Ingestion of cysticerci in beef Intestinal infestation Ingestion of eggs -> Non-human pathogen Pig tapeworm Ring of thorns/crown on scolex <13 uterine branches in proglottids Ingestion of cysticerci in pork Intestinal infestation Ingestion of eggs -> Cysticercosis
- 143. Taenia species
- 144. Taenia eggs Identical eggs for the two species
- 145. Taenia saginata Proglottid > 12 uterine branches
- 147. Taenia solium Scolex - Ring of thorns Proglottis – fewer uterine branches (<=12 uterine branches)
- 148. Cysticercosis Caused by the ingestion of T. solium eggs Not eating infected pork
- 150. Hymenolepis nana
- 151. Larger outer shell No radial striations Hooklets inside Hymenolepis nana Most common cestode recovered in USA Worm is 2-4 cm Egg has inner & outer shell separated space Water /food contaminated by rodent droppings
- 152. Hymenolepis diminuta Uncommon tapeworm Big egg @ 80 microns in diameter
- 153. Echinococcus – hydatid cyst
- 154. Echinococcus – hydatid cyst Sand like material Contained in the cyst Short tapeworm
- 155. Tapeworms
- 156. Relative size of Helminth eggs http://www2.bc.cc.ca.us/bio16/pal/Parasitology.htm
- 157. Insects of interest – not already mentioned
- 158. Maggots Bot fly larvae Extrudes from the skin
- 159. Ticks of importance Hard Ticks Soft tick Expands with blood engorgement
- 160. Hour glass On tummy Black Widow spider
- 161. Flea Hair nit Body Body louseLouse Crab louse
- 162. Mite Scabies Tiny eggs under skin
Notes de l'éditeur
- Particularly difficult to differentiate from falciprium
- Hallmark of babesiosis is the tetrad (Maltese cross; cruciform body)
- Blackwater fever (falciprium and think black pee)
- Microscopic examination
- Exception for non-falcirpium is P. vivax where chlorquine resistance is seen in Papua New Guinea and Indonesia
- The malaria parasite life cycle involves two hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host. Sporozoites infect liver cells and mature into schizonts, which rupture and release merozoites. (Of note, in P. vivax and P. ovale a dormant stage [hypnozoites] can persist in the liver and cause relapses by invading the bloodstream weeks, or even years later.) After this initial replication in the liver (exo-erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ). Merozoites infect red blood cells . The ring stage trophozoites mature into schizonts, which rupture releasing merozoites. Some parasites differentiate into sexual erythrocytic stages (gametocytes). Blood stage parasites are responsible for the clinical manifestations of the disease. The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal . The parasites’ multiplication in the mosquito is known as the sporogonic cycle . While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes . The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts . The oocysts grow, rupture, and release sporozoites , which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle .
- Presence of absence of various stages in the blood Morphology of the gametocyte Size of the infected RBC
- Most prevalent Widest geographical distribution
- Enlarged RBC; fimbriated/ragged rbc
- Fever cycle every 72 hours (quartan), can remain dormant in the blood for years. Untreated infections may last as long as 20 years
- P