Parasitology

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Parasitology

• Part I Protozoans

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Parisitology

• Parasitism
• Two organisms living together
• One benefits from the relationship at the
  expense of the other
•  

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Parasitolgy

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• Three groups of parasites
• Protozoan
• Metazoan
• Exoparasites
• All the parasites are eukaryotes.

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Protozoan (single celled)

• All protozoans have 2 important stages of life
• Trophozoite active, free swimming state of
  protozoan
• Cyst dormant phase. In most cases this is the
  infective stage.

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Protozoan
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Protozoan (single celled)

• Classified by the way they move.
• Amoeba (sarcodina)
• Flagellates (mastigophora)
• Ciliates (ciliophora)
• Sporozoans (apicomyplexa)

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Sarcodina (Protozoan)

• Sarcodina the largest phylum
• (11,500 living species) of
• protozoans.
• It comprises the amebas and
• related organisms which are all
• solitary cells that move and
• capture food by means of
• pseudopods, temporary extensions
• of the cell.
• Most sarcodines are free living
• others are parasitic. One of these
• parasites is the causative organism
• of amebic dysentery.

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Sarcodina (Protozoan)

• Most sarcodines are free
• living others are parasitic.
• They are found in aquatic and
• terrestrial habitats.
• Entamoeba histolytica is the
• causative agent of dysentery.

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Sarcodina (Protozoan)

• Acanthamoeba is the etiology
• of amoebic keratitis and
• encephalitis.
• Encephalitis is caused by
• Acanthamoeba entering cuts or
• through the nares and
• spreading to the central
• nervous system.

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Flagellates (Protozoan)

• Most of the approximately
• 1,500 species of Mastigophora
• are propelled by one or more
• flagella, and members of the
• group are referred to as
• flagellates.

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Giardia - Flagellates (Protozoan)

• Giardiasis, infection of the small intestine
• by a protozoan, Giardia lamblia.
• Giardia is spread via the fecal-oral
• route, most commonly by eating food
• contaminated by the unwashed
• hands of an infected person or by
• drinking groundwater polluted by the
• feces of infected animals such as dogs
• and beavers (hence the nickname
• "beaver fever" ).
• It attaches itself to the walls of the
• small intestine and there multiplies
• quickly.

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Trichomonas - Flagellates (Protozoan)

• Trichomoniasis is caused by a
• Trichomonas vaginalis and is
• passed almost 100 of the time
• through sexual contact.
• Trichomoniasis is primarily an
• infection of women's vaginal and
• urinary tracts.
• A woman is most susceptible to
• infection just after having completed
• her menstrual period.
• Men also may carry the organism
• unknowingly, since infection in men
• may cause mild or no symptoms.

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Trichomonas
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Trypanosoma - Flagellates (Protozoan)

• Human African Trypanosomiasis,
• also known as sleeping sickness,
• is a vector-borne parasitic
• disease.
• The parasites concerned are protozoa
• belonging to the Trypanosoma Genus.
• They are transmitted to humans by
• tsetse fly (Glossina Genus) bites
• which have acquired their infection
• from human beings or from animals
• harbouring the human pathogenic
• parasites.

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Trypanosoma Flagellates (Protozoan)

• Chagas diseases occurs in 15 Central
• and South American countries.
• The symptoms of Chagas disease vary
• over the course of an infection. In the
• early, acute stage, symptoms are mild
• and usually produce no more than
• local swelling at the site of infection.
• As the disease progresses, over the
• course of many years, serious chronic
• symptoms can appear, such as heart
• disease and malformation of the
• intestines. If untreated, the chronic
• disease is often fatal.

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Protozoan - Ciliates

• The ciliates are a group of protists
• characterized by the presence of
• hair-like organelles called cilia.
• Cilia are identical in structure to
• Flagella but typically shorter and
• present in much larger numbers
• with a different undulating pattern
• than flagella.

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Balantidium coli

• Infection occurs when a host
• ingests a cyst, which usually
• happens during the consumption
• of contaminated water or food.
• Once the cyst is ingested, it passes
• through the hosts digestive system.

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Protozoan Apicomplexa (Sporozoan)

• The Apicomplexa are a large group of
• protists, most of which possess a
• unique organelle called apicoplast and
• an apical complex structure involved in
• penetrating a host's cell.
• They are unicellular, spore-forming,
• and exclusively parasites of animals.
• They are non-motile protozoans and
• rely on the fluid structures of the body
• for movement.

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Sporozoan Major Pathogens
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Plasomdium - Malaria

• Malaria is a vector-borne infectious
• disease caused by a eukaryotic protist
• of the genus Plasmodium.
• It is widespread in tropical and
• subtropical regions, including parts of
• the Americas, Asia, and Africa.
• Each year, there are approximately
• 350500 million cases of malaria,
• killing between one and three million
• people, the majority of whom are young
• children in Sub-Saharan Africa.

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Plasomdium - Malaria Life Cycle

• .

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Toxoplasma gondii

• Toxoplasmosis is a parasitic disease
• caused by the protozoan Toxoplasma
• gondii. The parasite infects most
• genera of warm-blooded animals,
• including humans, but the primary host
• is the felid (cat) family.
• Animals are infected by eating infected
• meat, by ingestion of faces of a cat
• that has itself recently been infected, or
• by transmission from mother to fetus.
• Cats have been shown as a major
• reservoir of this infection.

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Cryptosporidium parvum

• Cryptosporidiosis, also known as
• crypto, is a parasitic disease caused by
• Cryptosporidium, a protozoan parasite
• in the phylum Apicomplexa.
• It affects the intestines of mammals
• and is typically an acute short-term
• infection.
• It is spread through the fecal-oral
• route, often through contaminated
• water the main symptom is self-
• limiting diarrhea in people with intact
• immune systems.

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Cryptosporidium parvum

• In immunocompromised individuals,
• such as AIDS patients, the symptoms
• are particularly severe and often fatal.
• Cryptosporidium is the organism most
• commonly isolated in HIV positive
• patients presenting with diarrhea.
• Treatment is symptomatic, with fluid
• rehydration, electrolyte correction and
• management of any pain. Despite not
• being identified until 1976, it is one of
• the most common waterborne diseases
• and is found worldwide.
• The parasite is transmitted by
• environmentally hardy microbial cysts
• (oocysts) that, once ingested, exist in the
• small intestine and result in an infection of
• intestinal epithelial tissue.

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Cryptosporidium Life Cycle