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Protozoa Are single celled animals Trophozoites are motile Cysts are involved in transmission
GENERALITIES: Parasites are organisms that obtain food and shelter by living on or within another organism. The parasite derives all benefits from association and the host may either not be harmed or may suffer the consequences of this association, a parasite disease. The parasite is termed obligate when it can live only in association with a host or it is classified as facultative when it can live both in or on a host as well as in a free form.
Parasites which live inside the body are termed endoparasites whereas those which exist on the body surface are called ectoparasites. Parasites that cause harm to the host are pathogenic parasites while those that benefit from the host without causing it any harm are known as commensals
What needs to be known? Organism name ( scientific & common) Morphology (cyst, egg, larva, tophozoite, adult – M & F ) Etiology Epidemiology Life Cycle Symptoms, Pathology, Immunology Diagnosis, Treatment & Prevention
INTESTINAL AND LUMINAL PROTOZOA Organism that harbors the parasite and suffers a loss caused by the parasite is a host. The host in which the parasite lives its adult and sexual stage is the definitive host The host in which a parasite lives as the larval and asexual stage is the intermediate host. Other hosts that harbor the parasite and thus ensure continuity of the parasites life cycle and act as additional sources of human infection are known as reservoir hosts. An organism (usually an insect) that is responsible for transmitting the parasitic infection is known as the vector.
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)
Organism Transmission Symptoms Diagnosis Treatment GI: Iodoquinol or Dysentery with blood Stool: cysts with 1-4 MetronidazoleEntameba histolytica Oro-fecal and necrotic tissue. nuclei and/or trophs. Abscess: Chronic: abscesses Trophs in aspirate. Metronidazole Fowl-smelling, bulky Stool: typical old man Iodoquinol or Giardia lamblia Oro-fecal diarrhea; blood or giardia troph and/or Metronidazole. necrotic tissue rare. cyst. Dysentery with blood Oro-fecal; Stool: ciliated trophs Iodoquinol or Balantidium coli and necrotic tissue zoonotic but no abscesses. and/or cysts. Metronidazole. Cryptosporidium Paromycin parvum Oro-fecal Diarrhea Ooocysts in stool (investigational) Isospora belli Oro-fecal Giardiasis-like Ooocysts in stool Sulpha drugs Trichomonas Vaginitis; occasional Flagellate in vaginal Mebendazole; vingar vaginalis Sexual urethritis/prostatitis. (or urethral) smear. douche; steroids
Entamoeba histolytica Causes disease of the large intestine – amoebic dysentery – wherein trophozoites feed on RBC causing ulcers. Also the liver and lung abscesses are possible Naegleria – free-living amoeba in hot water sources. Causes primary amoebic meningoencephalitis ( PAM) Acanthamoeba – free living amoebas
AMOEBIASIS (amoebic dysentery, amoebic hepatitis) Trophozoite: This form has an ameboid appearance and is usually 15-30 micrometers in diameter, although more invasive strains tend to be larger. The organism has a single nucleus with a distinctive small central karyosome. The fine granular endoplasm may contain ingested erythrocytes. The nuclear chromatin is evenly distributed along the periphery of the nucleus. Cyst: Entameba histolytica cysts are spherical, with a refractile wall; the cytoplasm contains dark staining chromatoidal bodies and 1 to 4 nuclei with a central karyosome and evenly distributed peripheral chromatin
Flagellates Giardia lamblia - a human parasite of the gastrointestinal tract. The organism is spread by direct contact or through contaminated food and water. Giardia spp. are pear-shaped, with hair-like flagella for motility. They cause the disease giardiasis (or lambliasis), an infection of the small intestine most common in tropical areas. Giardia spp. attaches by means of sucking discs to microvilli in the human intestine. Abdominal cramps, swelling, diarrhea and nausea may occur
Balantidium coli This is a parasite primarily of cows, pigs and horses. The organism is a large (100 x 60 micrometer) ciliate with a macro- and a micro-nucleus . The infection occurs mostly in farm workers and other rural dwellers by ingestion of cysts in fecal material of farm animals. Man-to-man transmission is rare but possible. Metronidazole and iodoquinol are effective.
Trichomonas vaginalis Trophozoite with undulating membrane and polar flagella Presents with fishy-smelling yellow discharge (guess where) Males usually asymptomatic Sexually transmitted
Organism Transmission Symptoms Diagnosis TreatmentS. mansoni, skin penetration Dermatitis, abdominal Eggs in stool Praziquantel pain, bloody stool,S. japonicum by cercaria peri-portal fibrosis, hepato-splenomegaly, ascites, CNSSchistosoma skin penetration Dermatitis, urogenital Eggs in urine Praziquantel cystitis, urethritis andhematobium by cercaria bladder carcinomaFasciolopsis Metacercaria on Epigastric pain, Eggs in stool Praziquantel, nausea, diarrhea,buski water chestnut edema, ascitesC. sinensis, Cysts in fish Inflammation and Eggs in stool Praziquantel deformation of bileO. felinus, or O. duct, hepatitis, anemiaviverini and edema Cough (dry / rusty brown sputum),Paragonimus Cyst in crab meat pulmonary pain, Eggs in sputum Praziquantelwestermani pleurisy, tuberculosis- like
Trematodes ( Flukes )Schistosomes
Schistosoma japonicum, mansoni
Fasciolopsis buski ( Giant intestinal fluke)
Paragonimus westermanii ( Lung fluke )
Clonorchis sinensis ( Chinese liver fluke )
Echinococcus granulosus *(hydatid cyst)
Organism Transmission Disease/ Diagnosis Treatment symptomsTrypanosoma Tsetse fly. Sleeping Hemoflagellate in Blood stage:brucei sickness; cardiac blood or lymph Suramin or failure. node. petamidine isethionate;T. cruzi Reduvid (kissing) Chagas disease: Hemoflagellate in CNS: bug. megacolon, blood or tissue. melarsoperol cardiac failure. Nifurtimox and Benzonidazole.Leishmania Sand fly Visceral leish- Intracellular Pentosam;donovani maniasis, (macrophages) Pentamidine granulomatous leishmanial isethionate. skin lesions. bodies.L. tropica Sand fly. Cutaneous As for L. As for L. lesions. donovani. donovani.L. braziliensis Sand fly Mucocutaneous As for L. As for L. lesions. donovani. donovani.
Trypanosoma – flagellate with Tsetse fly as vector Causes African sleeping sickness Trypanosoma cruzii – Chaga’s disease kissing bug as vector Leishmania – Sandfly as vectors Visceral, cutaneous & mucocutaneous lesions
Blood & Tissue Protozoans
Organism Transmission Disease/ Diagnosis Treatment symptomsPlasmodium Female Malarial Plasmodia in rbc, Quininefalciparum anopheline paroxysm: chills, typical of the derivativesP. ovale, mosquito. fever, headache, species involved. ProguanilP. malariae and P. nausea cycles. LariamvivaxBabesia microti Tick Hemolytic Typical organism None; self anemia, (Maltese cross) in resolving. Jaundice and rbc. feverToxoplasma Oral from cat Adult: flu like; Intracellular (in Sulphonamides,gondii fecal material; congenital: macrophages) pyemethamine, or meat abortion, tachyzoites. possibly neonatal spiramycin (non- blindness and FDA). neuropathies. Trimethoprim andPneumocystis Pneumocystis in Cough droplets Pneumonia sulphamethoxazojiroveci sputum. le.
Sporozoans Cryptosporidium parvum – found in waters, a self limited diarrhea Plasmodium species cause malaria Anopheles mosquito as vectors Complicated life cycle. P. vivax, P. ovale, P. malariae, P. falciparum Toxoplasma gondii – reservoir in cats Human ingest cyst from cats feces or undercooked meat. Danger in fetus development
Organism Transmission Symptoms Diagnosis Treatment Abdominal pain,Ascaris Stool: corticoid oval Oro-fecal weight loss, distended egg (40-70x35-50 μm) Mebendazolelumbricoides abdomen Depends on worm location and burden: gastroenteritis; edema, muscle pain, Medical history,Trichinella Poorly cooked corticosteroid and spasm; eosinophilia, eosinophilia, musclespiralis pork Mebendazole tachycardia, fever, biopsy, serology chill headache, vertigo, delirium, coma, etc. Abdominal pain, Stool: lemon-shapedTrichuris Oro-fecal bloody diarrhea, egg (50-55 x Mebendazoletrichiura prolapsed rectum 20-25μm) Peri-anal pruritus, rare Stool: embryonatedEnterobius Pyrental pamoate or Oro-fecal abdominal pain, eggs (60x27 μm), flat Mebendazolevermicularis nausea vomiting on one side
Strongyloides stercoralis (threadworm)
Organism Transmission Symptoms Diagnosis Treatment Itching at infection site, rash due to larval migration, verminous pneumonia, mid- Stool: rhabditiformStrongyloides Soil-skin, Ivermectin or epigastric pain, larvae (250xstercoralis autoinfection nausea, vomiting, 20-25μm) Thiabendazole bloody dysentery, weight loss and anemia MaculopapularNecator erythema (ground Stool: ovalamericanes; Oro-fecal (egg); itch), broncho- segmented eggsAncylostoma skin penetration pneumonitis, Mebendazole (60 x 30duodenale (larvae) epigastric pain, 20-25μm) GI hemorrhage, anemia, edema
Necator americanus (hookworm)
Dracunculus medinensis (Guinea worm)
Organism Transmission Symptoms Diagnosis Treatment Blistering skin,Dracunculus Oral: cyclops in Physical irritation, Mebendazolemedinensis water examination inflammation Medical history, Recurrent fever,Wuchereria physical lymph-adenitis, Mebendazole;bancrofti; W. examination, Mosquito bite splenomegaly, Diethyl-brugia malayi microfilaria in lymphedema, carbamazine(elephantiasis) blood (night elephantiasis sample) Nodular and Medical history, erythematous physical Mebendazole;Onchocerca dermal lesions, Black fly bite examination, Diethyl-volvulus eosinophilia, microfilaria in carbamazine urticaria, nodular aspirate blindness As in As in
Organism Transmission Symptoms Diagnosis Treatment Epigastric pain, Proglottids orTenia saginata Cyst in beef vomiting, eggs in stool or Praziquantel diarrhea perianal area Epigastric pain, Proglottids orTenia solium Cyst in pork vomiting, eggs in stool or Praziquantel diarrhea perianal area Muscle pain and Roentgenograph weakness, T. solium y, anti- Oro-fecal ocular and PraziquantelCysticercosis cysticercal neurologic antibody (EIA) problems
Organism Transmission Symptoms Diagnosis Treatment Abdominal pain, loss of weight, Proglottids or anorexia,D. latum Cyst in fish eggs in stool or Praziquantel malnutrition and perianal area B12 deficiency problems Large cysts Roentgenograph Surgery, produce various y, anti-hydatid formalin symptomsE. granulosus Oro-fecal fluid antibody injection and depending on (EIA), Casoni drainage, the location of skin test Praziquantel the organism. Surgery,E. multiloculoris Oro-fecal As above As above Albendazole