part i protozoans. parasitism: two organisms living together one benefits from the relationship at...
TRANSCRIPT
Part I Protozoans
Parasitism:Two organisms living together
One benefits from the relationship at the expense of the other
Three groups of parasites Protozoan Metazoan Exoparasites
All the parasites are eukaryotes.
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.
Classified by the way they move.
Amoeba (sarcodina)
Flagellates (mastigophora)
Ciliates (ciliophora)
Sporozoans (apicomyplexa)
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.
Most sarcodines are free living; others are parasitic. They are found in aquatic
and terrestrial habitats.
Entamoeba histolytica is the causative agent of
dysentery.
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.
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.
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.
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.
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.
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.
The ciliates are a group of protistscharacterized 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.
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 host’s digestive system.
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.
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 350–500 million cases of malaria,
killing between one and three million people, the majority of whom are
young children in Sub-Saharan Africa.
.
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.
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.
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.