Download presentation
Presentation is loading. Please wait.
1
Introduction to Parasitology
2
What is Parasitology? A parasite is an organism that live on or within another organism called the host . Parasitology is a science of studying parasitism and a discipline dealing with the biology of parasites (including its morphology, embryology, physiology, biochemistry and nutrition, etc.), ecology of parasitism with emphasis on parasite-host and parasite-environment interactions.
3
the parasites studied in this discipline involve parasitic protozoa, parasitic helminthes, certain lesser groups of worms, parasitic arthropods, and the vectors of parasites, that is, parasitology is largely an amalgamation of protozoology, helminthology, entomology and acarology. Parasitology has also been subdivided into medical or human parasitology, veterinary parasitology, fish parasitology and plant nematology
4
What is Medical Parasitology?
Medical parasitology or human parasitology is restricted to studying those parasites that are living in or on the body of humans and with aspects of the host-parasite relationship having medical significance. In other words, medical parasitology is the subject which deals with the parasites that infect man, the diseases caused by them, clinical picture and the response generated by man against them.
5
Parasites Parasitic diseases
Medical Parasitology Parasites Parasitic diseases Morphology Life Cycle Pathogenesis Diagnosis Treatment Transmission Prevention
6
Medical parasitology Medical protozoology Medical helminthology
Medical arthropodology i.e. Medical entomology
7
Medical Parasitology in Medical Education
Public Health & Clinical Preventive Medicine Medicine Medical Parasitology Biology,Biochemistry,Anatomy, Histology,Physiology,Immunology
8
History of Human Parasitology
Early written records 3000 to 400 BC, the first written records of parasitic infections come from Egyptian medicine, particularly the Ebers papyrus of 1500 BC discovered at Thebes. Intestinal roundworms and tapeworms. 800 to 300 BC, writings of Greek physicians such as Hippocrates. Worms from fishes, domesticated animals, and humans. 3000 to 300 BC, writings of physicians from China. 2500 to 200 BC, from India. 700 BC to 400 AD, from Rome. Latter part of the first millennium, from the Arab Empire. Arabic physician Avicenna (AD 980 to 1037) , wrote important medical works that contain a great deal of information about diseases clearly caused by parasites. He recognized not only Ascaris, Enterobius, and tapeworms but also the guinea worm, Dracunculus medinensis.
9
History of Human Parasitology
Modern times Manson in filariasis Laveran in malaria parasite Ross in 1897 malaria life cycle Bruce in and Chagas in 1908 trypanosomiasis Leishman and Donovan in leishmaniasis …… 1879 (Ringer) , 1880 (Manson) : Paragonimus westermani 1875 (McConnell) : Clonorchis sinensis 1905 (Logan) : Schistosoma japonicum in China
10
Patrick Manson(1844-1922) “Father of modern tropical medicine”
In England Manson became Medical Advisor to the Colonial Office and in this capacity persuaded the then Secretary of State for the Colonies, Joseph Chamberlain, of the need for providing facilities in Britain for educating doctors in tropical diseases. One consequence of his influence was the creation of School of Tropical Medicine in both Liverpool and London in 1898 Patrick Manson( ) “Father of modern tropical medicine” The first President (and Ronald Ross Vice-President) of the Society of Tropical Medicine and Hygiene (1907) The first to discover (1877–79) that an insect (mosquito) can be host to a developing parasite (the worm Filaria bancrofti) that is the cause of filariasis
11
1907 Nobel Laureate in Medicine
in recognition of his work on the role played by protozoa in causing diseases Alphonse Laveran 1902 Nobel Laureate in Medicine for his work on malaria, by which he has shown how it enters the organism and thereby has laid the foundation for successful research on this disease and methods of combating it Ronald Ross
12
Conceptions related to medical parasitology
Symbiosis Parasite and type of parasites Host and common type of host Life cycle and type of life cycle
13
Symbiosis The relationship between two living things (animals). Two living things live together and involve protection or other advantages to one or both partner. Commensalism Mutualism Parasitism
14
Commensalism Both partners are able to lead independent lives, but one may gain advantage from the association when they are together and least not damage to the other A female pea crab in the mantle cavity of its mussel host. The crab does not damage the mussel and uses its shell purely for protection Mussel
15
Mutualism An association which is beneficial to both living things
A selection of ciliates from the rumen of cattle or sheep. The rumen contains enormous numbers of ciliates that break down cellulose in the feed
16
Parasitism An association which is beneficial to one partner and harmful to the other partner. The former that is beneficial to is called parasite, the latter that is harmful to is called host. e.g., Human / Hookworm Anterior end of a hookworm
17
Other classification Parasites may be classified according to different ways: Obligate parasite: a parasite which cannot survive in any other manner, e.g., filaria Facultative parasite: an organism which may exist in a free-living state and which if opportunity presents itself may become parasitic, e.g., Strongyloides stercoralis
18
Endoparasite and ectoparasite
A parasite which lives in or on the body of the host is called endoparasite (protozoa and helminthes) or ectoparasite (arthropods)
19
Host and type of host Host : an organism that harbors the parasite usually larger than the parasite Intermediate host : the host harboring the larvae or asexual stage of parasite Final host (definitive host) : the host harboring adult or sexual stage of parasite
21
Host and type of host Reservoir host : animals harboring the same species of parasites as man, e.g., schistosome/human, buffalo Potential sources of human infection Paratenic host (transport host) : a host which acts as a transporting agent for the parasite and in which, the parasite, usually a larval stage, dose not undergo any further development but if they could go into a final host by accident it would continue to develop till sexual maturity, e.g., Paragonimus Westermani /human, wild boar
22
Life cycle and type of life cycle
Life cycle : the whole biological course of growth, development and reproduction of a parasite The direct type : only one host (final host, no intermediate host). e.g., Ascaris lumbricoides, Hookworm, and Enterobius vermicularis The indirect type : life cycle with more than one host (intermediate host and final host) . e.g., plasmodium, lymphatic filaria
25
Classification of parasites
Protozoa Parasites Helminthes Arthropods (Unicellular) (Multicellular ) Nematodes Trematodes Cestodes (Endoparasite) (Ectoparasite)
26
Protozoa Plasmodium RBC
28
Ciliates, Coccidia, Blastocystis Blood-Borne Protozoa
Amebae (found in stool) Entamoeba coli Entamoeba histolytica Endolimax nana Iodamoeba butschlii Dientamoeba fragilis Flagellates (found in stool) Giardia lamblia Chilomastix mesnili Ciliates, Coccidia, Blastocystis Balantidium Cryptosporidium Isospora belli Sarcocystis Cyclospora Microsporidium Blastocystis hominis Blood-Borne Protozoa Babesia Leishmania Trypanosoma brucei T. cruzi Plasmodium Other Toxoplasma Naegleria fowleri Acanthamoeba
29
Intestinal and luminal protozoa significant to human health include
Entamoeba histolytica (Amoebae) Balantidium coli (Ciliates) Giardia lamblia and Trichomonas vaginalis (Flagellates) Cryptosporidium parvum and Isospora belli (Sporozoa)
30
Protozoa Found in Stool: Amebae
pathogen
31
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
33
Entamoeba histolytica/dispar
Cysts <= 10 um In diameter Up to 4 nuclei in the cyst Clean chromatin Bulls-eye nucleoli
34
Amebic abscess Amebic liver abscess Entamoeba histolytica
Serology – high % positive in extra-intestinal cases Flask-shaped ulcer of intestinal amebiasis
35
Entamoeba histolytica/dispar
Trophozoites & Cysts Trophozoite with ingested rbcs
36
Entamoeba coli Trophozoites & Cysts
37
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
38
Protozoa Found in Stool: Flagellates
39
“falling leaf” motility
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
40
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
41
Giardia lamblia cysts
42
Giardia lamblia cysts
43
Giardia lamblia trophozoites
44
Trichomonas vaginalis
Urogenital protozoan Scant, watery vaginal discharge Four flagella, short undulating membrane
45
Protozoa Found in Stool: Ciliates, Coccidia, Blastocystis
46
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 ( um) trophozoite; surface covered with cilia; macronucleus Cyst um Readily identified in fresh, wet mounts
47
Only protozoa with cilia
50 microns In intestine can cause flask-shaped ulcers like those caused by E. histolytica
48
Blood-Borne Protozoa None; self resolving. Maltese cross in rbc
Hemolytic anemia, Jaundice, fever, hepatomegaly Ixodes tick Babesia microti Pentosam; Pentamidine isethionate. Intracellular (macrophages) leishmanial bodies with kinetoplast Visceral leishmaniasis (Kala-azar), granulomatous skin lesions Iraq/Iran/Afghanistan Phlebotomine sandfly Leishmania donovani CNS: melarsoperol Nifurtimox and Benzonidazole. Hemoflagellate in blood or tissue. C- or comma-shaped American trypanosomiasis; Chagas disease: megacolon, cardiac failure. Reduvid (kissing) bug T. cruzi Blood stage: Suramin or petamidine isethionate Hemoflagellate in blood or lymph node African trypanosomiasis; Sleeping sickness Encephalitis; cardiac failure Tsetse fly Trypanosoma brucei Treatment Diagnosis Disease/Symptoms Transmission Organism
49
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
50
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.
51
Trypanosoma brucei gambiense in a blood film
Filamentous structures found in blood
52
TRYPANOSOMA GAMBIENSE
53
Leishmania Obligate intracellular parasite
Vector: female sand fly bite Visceral leishmaniasis (kala azar) L. donovani Cutaneous leishmaniasis L. tropica L. braziliensis
54
Leishmania
55
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
56
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
57
Leishmania donovani Kinetoplast next to nucleus Skin lesion Sand Fly
58
MALARIA Protozoan Transmitted by the anopheles mosquito
Endemic to tropical areas Blackwater fever (falciprium and think black pee) 58
59
Malaria Symptoms Fever and chills Splenomegaly Headache Abdominal pain
Diarrhea Myalgia Blackwater fever (hemolysis, hemoglobinuria, renal failure) – P falciparum only
60
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 Exception for non-falcirpium is P. vivax where chlorquine resistance is seen in Papua New Guinea and Indonesia 60
61
MALARIA Life Cycle of Plasmodium Species
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 . Life Cycle of Plasmodium Species 61
62
Malarial Preparations
Thick smear Drop of blood on slide Water rinse to eliminate rbc’s Stain with Giemsa stain (not Wright-Giemsa) 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 (%)
63
Malaria Diagnosis Microscopy is most often used
Antigen detection – EIA available Molecular methods
64
Most prevalent Widest geographical distribution 64
65
Enlarged RBC; fimbriated/ragged rbc
65
66
Fever cycle every 72 hours (quartan), can remain dormant in the blood for years.
Untreated infections may last as long as 20 years “Rosette” schizont 66
67
Other Protozoa Toxoplasma
68
Toxoplasma gondii Organism Transmission Disease/Symptoms Diagnosis
Treatment Toxoplasma gondii Oral from cat fecal material or meat Adult: flu like; congenital: abortion, neonatal blindness and neuropathies Intracellular (in macrophages) tachyzoites Sulphonamides, pyemethamine, possibly spiramycin (non-FDA)
69
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
70
Toxoplasma gondii Diagnosis Serology EIA PCR
Anti-toxo IgM – congenital and acute infection; may persist for months Anti-toxo IgG – common; if positive, gestations safe from intrauterine toxoplasmosis infection PCR
71
Toxoplasma gondii Can be diagnosed by serology
72
Toxoplasma gondii Toxoplasma gondii cyst in brain tissue stained with hematoxylin and eosin
74
HELMINTHS Nematodes (roundworms) Trematodes (flukes)
Cestodes (tapeworms)
75
Nematodes Enterobius Ascaris Trichuris
Necator and Ancylostoma (Hookworm) Microfilaria – Wucheria, Brugia, Loa loa, Mansonella, and Onchocerca
76
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
77
Enterobius vermicularis (pinworm) eggs
Asymmetrical eggs
78
Pinworm larvae
79
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 15-30cm with a curved tale Can cause intestinal obstruction
80
Ascaris lumbricoides
81
Ascaris eggs Unfertilized eggs-large & oval, mammillated
layer is pronounced Fertilized eggs- smaller, rounder, mammillated layer is less obvious
82
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
83
Trichuris trichiura
84
Necator americanus, Anclyostoma duodenale (Hookworms)
Soil transmitted 2nd most common helminth infection Enter via exposed skin Necator or Ancylostoma – Hookworm egg
85
Trichinella spiralis Tissue nematode All stages occur in single host
-usually an incidental finding in muscle
86
Loa loa (eye worm)
87
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
88
Trematodes ( Flukes ) Schistosomes
89
Schistosoma japonicum, mansoni
90
Fasciolopsis buski ( Giant intestinal fluke)
91
Distinct nose Fasciola hepatica
92
Fasciolopsis buski Fasciola hepatica
93
Fasciolopsis buski Fasciolopsis buski
94
Cestodes (Tapeworms) Examples Diphyllobothrium latum Taenia saginata
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
95
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
96
Diphyllobothrium latum
97
Sucking plate Diphyllobothrium latum
98
Taenia Species – two species Outstanding characteristics
Taenia Solium Pig tapeworm Ring of thorns/crown on scolex <13 uterine branches in proglottids Ingestion of cysticerci in pork Intestinal infestation Ingestion of eggs -> Cysticercosis Taenia saginata Beef tapeworm 4 suckers on scolex >13 uterine branches in proglottids Ingestion of cysticerci in beef Intestinal infestation Ingestion of eggs -> Non-human pathogen
99
Taenia eggs Identical eggs for the two species
100
Taenia saginata Proglottid > 12 uterine branches
102
Taenia solium Scolex - Ring of thorns
Proglottis – fewer uterine branches (<=12 uterine branches)
103
Medical arthropods Fly Sandfly Mosquito Soft tick Hard tick Louse Flea
104
Maggots Bot fly larvae Extrudes from the skin
105
Ticks of importance Soft tick - Expands with blood engorgement
Hard Ticks Soft tick - Expands with blood engorgement
106
Hour glass On tummy Black Widow spider
107
Body louse Body Louse Hair nit Flea Crab louse
108
Tiny eggs under skin Mite Scabies
109
THANK YOU
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.