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Protista / Protozoa Microbiology 2314
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Protozoa Can Be Human Parasites A parasite is an organism that obtains food and shelter from another organism and derives all benefits from this association.
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Characteristics Abundant / Simplest Animals / Few are Pathogenic
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Characteristics Unicellular / Eukaryotic Chemoheterotrophic (Saprophytic)
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Characteristics Aquatic and Terrestrial Diverse / Population Size Varies by Location
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Characteristics Important in Water Quality Prominent in Soil
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Growth Aerobic pH 3.5 to 9.0 Mesophiles (High Temps are Detrimental) Water / Required for Ciliated Forms Flagellated Forms are More Drought Resistant Not All Cysts Can Resist Dessication
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Life Cycle Active – Trophozoite Stage Inactive – Cyst Phase
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Balantidium coli cyst
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Balantidium coli trophozoite
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Feeding Saprophytic Phagocytic Pinocytic
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Selective Feeders
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Termites & Protozoa = Symbiosis Protozoa are critical in the digestion of cellulose. Protozoa live in the gut of termites and obtain food from the foraging activities of the insects. In return, the protozoa use their specialized enzymes to break down cellulose, a polymer of glucose, for the insects.
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How does the toxic substance Sulflurimid work?
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Protozoa Have An Effect On The Structure And Function Of Microbial Communities
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Predator Prey Relationship Increases in a bacterial populations are followed by an increase in a protozoan population Alleopathy (The harmful effect of one organism on another. Protozoa Can Keep A Microbial Group From Dominating A Given System * Hudson Bay Trading Company
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When discussing protozoans and bacteria populations, which is the predator and which is the prey?
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Methods of Reproduction Asexual 1. Fission 2. Schizogony 3. Budding Sexual
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Amoeba
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Amoebas Phylum Amoebozoa Subphylum Sarcodina Move by Pseudopodia Entamoeba histolytica / Amoebic Dysentery (Destruction of Red Blood Cells) Survival Structures / Cysts
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About 10 percent of the world's population is infected with E. Histolytica. It is the third most common cause of death (after Schistosomiasis and Malaria) from parasitic infections, and second protozoal cause (after malaria).
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Very common in South and Central America, West Africa and Southeast Asia. Rare in temperate climates. About 90% of infections are asymptomatic and the remaining 10% produce a spectrum of disease varying from dysentery to amoebic liver abscess.
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Cyst of Entamoeba histolytica in a fecal smear Obtained via Fecal/Oral Route
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Cyst
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Fecal-Oral Route Protective cysts pass out of the intestines with the feces and are ingested via contaminated food and water by the next host.
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After ingestion, the trophozoites hatch and penetrate the walls of the large intestine causing ulcerations and symptoms of dysentery.
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May result in “Bloody Diarrhea”
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Histological preparation showing cross-section of ulcer. Note the high degree of necrosis in center of ulcer. The amoeba are advancing laterally under the intact mucosa.
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Smear showing several hematophagous trophozoites.
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Trophozoite of Entamoeba histolytica.
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E. histolytica is found primarily in the colon where it can live as a non-pathogenic commensal or invade the intestinal mucosa (green). The amoeba can metastasize to other organs via a hematogenous route (purple); primarily involving the portal vein and liver. The amoeba can also spread via a direct expansion (blue) causing a pulmonary infection, cutaneous lesions or perianal ulcers
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Acanthamoeba One of the most common protozoans found in soil Common in “warm” lakes Can survive in the space between the contact lens and the eye
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Acanthamoeba can infect the eye (resulting in blindness), blood, spinal cord, and brain. It is transmitted by waterborne cysts picked up while swimming in contaminated water.
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Acanthamoeba can enter the skin through a cut, wound, or through the nostrils.
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Once inside the body, this ameba can travel to the lungs and through the bloodstream to other parts of the body, especially the central nervous system (brain and spinal cord).
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Trophozoite of Acanthamoeba spp. within necrotic tissue at higher magnification
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Acanthamoeba results in lesions of the skin, eye, brain, etc.
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Flagellates
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Euglena
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Phylum Euglenozoa Flagella / Undulating Membrane Giardia lambia / Giardiasis Trichomonas vaginalis ( Male and Female Infections) Trypanosoma bruicei gambiens
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Trypanosoma gambiense in a blood smear
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Trypanosomites T. gambiense and T. rhodesiense cause the disease African sleeping sickness or African trypanosomiasis.
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They are transmitted to humans by the bite of an infected tsetse fly (a vector) with East African wild bovine as the reservoir.
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The disease primarily involves the lymphatic and nervous systems of humans and is diagnosed by microscopically looking for Trypanosoma in the blood, in aspirated fluid from lymph nodes, or in spinal fluid.
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T. cruzi causes South American sleeping sickness or Chagas' disease and is transmitted by infected Triatomid bugs (kissing bugs) with the Spiny Anteater as the reservoir.
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An autopsy shows the megacolon and megaoesophagus of the victim who yielded to American typanosomiasis, also known as Chagas’ Disease.
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Transmission can also occur by blood transfusion. In Santa Cruz, Bolivia, WHO reports more than 50% of blood donors are reported to be infected.
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Current World Health Organization (WHO) estimates show that 16 to 18 million people are infected. Additionally, migration has brought infected persons into major world-wide cities and the United States.
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Giardiasis Giardiasis is the most common protozoan intestinal disease in the U.S. and is transmitted by the fecal-oral route. Results in uncontrollable “Greasy” Diarrhea.
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Cysts of the organism are ingested through food, water, etc. that is contaminated with feces.
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Giardiasis is diagnosed by microscopically looking for cysts of G. lamblia in fecal smears.
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This tear-drop shaped flagellated protozoan lives in the small intestine and is transmitted primarily when the infective cysts are ingested in water. It is an example of what is known as a Zoonosis, a parasite found in wild animals which can be transmitted to humans.
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Giardiasis gained notoriety some years ago when an outbreak occurred in Banff National Park and was termed by the Media as BEAVER FEVER because the local beavers were thought to be the source of contamination of the water supply.
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Campers are at risk
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Massive numbers of trophozoites can cover the epithelial surface resulting in a cobblestone road like appearance
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Trichomoniasis can be defined as an infection of male and female urino-genital tracts by Trichomonas vaginalis. Trichomonas vaginalis, is a flagellated protozoan that is sexually transmitted. It is frequently encountered among 50% of women complaining of abnormal vaginal discharge and itching. Trichomoniasis
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Genital Trichomoniasis (STD) There are an estimated 2.5 million cases per year in the U.S. In females, it usually appears as vaginitis with itching and a white discharge.
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In males it is often asymptomatic but may cause urethritis. It is transmitted mainly by sexual contact and is diagnosed by microscopically looking for T. vaginalis trophozoites in vaginal discharge and urine
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A barb on its flagella assists in attaching to the host.
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Trichomonas vaginalis in Vaginal Discharge
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Prevalence FYI Worldwide >120 million females are infected annually New York 47% Los Angeles 19.4% In Kenya 34.4% Africa varies between 2% and 50% depending on location
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Lishmaniasis A protozoan infection involving a number of species of the genus Leishmania. There are two distinct groups of clinical presentations.
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Visceral leishmaniasis: presenting with a systemic illness of fever, splenomegaly and lymphadenopathy -- other names Kala azar, Dum Dum fever.
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A 12-year-old boy suffering from visceral leishmaniasis. The boy exhibits splenomegaly and severe muscle wasting.
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Cutaneous leishmaniasis: presenting with a skin ulcer or ulcers. A varient can also involve mucous membranes of nose and throat.
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These are almost always zoonoses with a dog or rodent reservoir, and are transmitted to man by sandfly bite. They are distributed throughout the tropics.
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Sandfly Vector
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Lishmania Protozoa in Smear
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Shows up in saliva and causes painful ulcers in the mouth.
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The most commonly used drug against kala-azar, pentavalent antimony, has been the cornerstone of therapy worldwide for more than 70 years. It has to be administered through a drip and is painful, toxic, with dangerous side effects, and can be fatal. In addition, this medicine is no longer effective against the disease in large parts of India.
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'Baghdad Boil' The sores are not painful or contagious, but left untreated they can last up to 18 months and leave permanent, burn-like scars.
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Doctors at Walter Reed have seen 653 cases of leishmaniasis (2010), and the hospital's infectious disease wards until recently overflowed with soldiers undergoing a 20-day treatment regimen. Some units have had up to 1/3 or their men contract the disease and require treatment.
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Oklahoma Wood Rat Occasional cases of cutaneous leishmaniasis which were caught in the US have been reported among residents of Texas and Oklahoma.
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Dog with Leishmaniasis
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Phylum Ciliophora
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Ciliates The only pathogen in this group is Balantidium coli, which causes a diarrhea- type infection called balantidiasis.
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Balantidium coli in a fecal smear
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Hosts Pigs are the most significant reservoir hosts, though they show few if any symptoms. Other hosts include wild boars, rats, primates (including humans), horses, cattle and guinea pigs.
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Balantidiasis can be diagnosed through sampling of the patient's stools and searching for cysts or trophozoites under a microscope. Photo shows Numerous trophozoites in intestinal tissue
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Infection is transmitted within or between these species by fecal- oral transmission.
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Symptoms Nausea Vomiting Anorexia Weight loss Headache Chronic bloody diarrhea Abdominal pain and cramping Colitis (inflammation of the colon) More severe and marked fluid loss
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Apicomplexans Nonmotile Reproduce Asexually and Sexually Apical Complexes (Complex of Organelles)
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Asexual Reproduction Sexual Reproduction
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Apicomplexans Cause Malaria
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Malaria is probably one of the oldest diseases known to mankind.
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Man and Malaria seem to have evolved together and it has been known to mankind for millennia. It was always part of the ups and downs of nations, of wars, and of upheavals. Mentions of this disease can be found in the ancient Chinese, Indian and Egyptian writings.
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The disease supposedly had its origins in the jungles of Africa, where it is still very much rampant.
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Life Cycle Asexual reproduction (or schizogony) of the Plasmodium occurs within liver cells and red blood cells of the infected human. With malaria caused by P. vivax and P. ovale, a dormant form or hypnozoite remains in the liver and may cause later relapses. The infected cells in which the organism is reproducing by schizogony are called schizonts.
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The typical recurring malarial fever is a result of the lysis of the infected red blood cells, causing release of merozoites and their metabolic by-products. Fever cycles of 24, 48, or 72 hours usually occur depending on the infecting species.
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Malaria is diagnosed by microscopically looking for the parasite within infected red blood cells.
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Malaria Kills More People Each Year than AIDS
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Malaria affects 500 million people worldwide and kills at least 2 million per year.
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In fact, malaria, tuberculosis and Aids together killed more people in the last 50 years, than the combined death toll of all the wars during the same time.
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So Why Aren’t We Doing More About It?
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Over one million Africans die yearly (mostly children). 30,000 Europeans and North Americans are affected.
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Young malaria patient near Alem Kitmama North East of Addis-Ababa, Ethiopia, Africa
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In 1880, Dr. Louis Laveran, a French physician working in Algeria, first identified the causative agent for human malaria. He was awarded the Nobel Prize in 1907.
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On August 20th, 1897, Sir Ronald Ross, while working as a military physician in India, demonstrated the malarial oocysts in the gut tissue of female Anopheles mosquito, thus proving the fact that Anopheline mosquitoes were the vectors for malaria. That day is observed as Mosquito Day. He was awarded the Nobel Prize in 1902. (Ross never aspired to be a physician, he wanted to be a writer. He only did so to please his father.
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Toxoplasma gondii This protozoan causes the disease toxoplasmosis. In adults, the disease is usually mild and resembles infectious mononucleosis. It also causes severe disease in immunosuppressed individuals such as people with AIDS.
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However, new-born infants who contracted toxoplasmosis in utero commonly have severe central nervous system damage.
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Symptoms Fever Sore throat Sore muscles and tiredness Swollen glands in the neck, armpits or groin Temporary blurred vision or loss of vision
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Most people who are infected do not show any signs of the disease. Persons who are pregnant or are experiencing a suppressed immune system due to AIDS, cancer or following organ transplants are at higher risk for illness.
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Domestic cats, who pick up the organism from eating infected rodents, may act as carriers of T. gondii, and their feces may contain oocysts of the protozoan. However, the organism may be found in practically every mammal. Cysts can last in the environment for up to one year.
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Toxoplasma gondii can also be contracted by eating raw or undercooked meat. It infects 225,000 and kills 750, and is particularly dangerous to the unborn children of pregnant women who become infected
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Common ways for people to become infected with toxoplasmosis include: Eating raw or undercooked meats; Drinking unpasteurized milk Cleaning cat litter boxes Working in gardens or playing in sandboxes that contain cat feces.
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Retinal Scar from Totoplasmosis
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Brain Abscess
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Sample Questionaire for Parents with Children with Toxoplamosis http://www.ich.ucl.ac.uk/ich/html/academ icunits/paed_epid/chad_3yrquestionnaire.pdf
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Cryptosporidium Cryptosporidium is an intracellular parasite that causes diarrhea, although in people who are immunosuppressed it can also cause respiratory and gallbladder infections. It is transmitted by the fecal-oral route.
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Cryptospordia oocyts in a stool sample.
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The nation's largest outbreak -- classified as a water-borne outbreak -- struck 403,000 people in a five-county area around Milwaukee with cryptosporidiosis in 1993. The disease is caused by the parasite cryptosporidium parvum. Nearly a third of the residents became ill after public drinking water became contaminated.
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Why Was There An Outbreak?
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What Was the Solution?
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