Flashcards in Test 1 Notes Deck (84):
Factors Influencing Distribution of Parasitic Disease
1. Rapid Travel
3. Increased number of immunocompromised patients
Amebia of duck, geese and swan. Its accidental parasite of humans causing meningitis
Intestinal flagella without flagellum or pseudopodia that causes diarrhea in humans
Parasitic Organism or arthropod that live on surface of a host without multiplication
Invasion and multiplication of a pathogenic parasite in the body with accompanying reaction by the host
any damage of hot tissue or organs that leads to malfunction of an organ caused by a parasite
Unicellular microscopic eukaryoticorganism
worms, muticellular, often visible to the naked eye
insects lice etc.
hard exoskeletons, jointed appendages
Most Prevalent Tropical Diseases
7 out of 8 are parasites
Most harmfull infective diseases afflicting humans
5 out of are parasites
More than 1,000,000 people are
afflicted by parasites
Humans play host to
dozens of parasites
Parasites can also infect
animals and plants
Any arthropod or other living organism that transports a pathogenic microorganism form an infected to a non-infected host
Usually an intermediate Host
the host organism in which a parasite passes its adult and or sexual reproduction phase (trophozoite)
The host organism in which a parasite passes its larval stage or asexual reproduction phase
Vector is usually an intermediate host
Mosquitos in Malaria
Anopheles mosquitos carry plasmodium and transmit malaria from host to host. The mosquito is the Final host.
Humans are intermediate hosts.
An animal that harbors a species of parasite and can serve as a source of parasitic infection for human
Can also be the intermediate host
usually an intermediate Host, an invertebrate (insect) that transmits the larval or juvenile parasite by its bite. It is a vehicle by which some parasites are transmitted from host to host
Immunity, generally of a low level, resulting from the continued presence of the parasite (chronic). It does not eliminate the original infective parasite but is prevents hyper infection
A poorest who has been infected is producing immunity but is not strong enough to wipe out he parasite
interruption of the normal function of an organ and or a morbid change in a tissue
acquisition of a microorganism that may establish itself (grow and reproduce) in/on a host or may be transient in a host
microorganism living on the surface of a host. Pets with Flees
All parasites elicite immune responses including the formation of
IgM, IgG, and IgA antibodies
Host's immune response to parasitic infection is complex and time consuming and sometimes ineffective. Why?
1. Rapid rate of reproduction
2. Large size
3. Production of slime layer
4. Complex life-cycle (various morphological forms and antigen conversions)
5. Masking of there surface antigens withe n host cell maker (HLA= Human leukocyte Antigen)
6. By=production can prevent the function of antibodies macrophages lymphocytes and cause immunosuppression
7. Production of high level of IgE Antibody (Helminth Worm)
8.Induce T-Cell delayed hypersensitivity response (protozoa)
10. Parasitic organism that had a long coevolution with their host
Parasites larval form can be destroyed by host antibodies, and the presence of these antibodies provide resistance to reinfestation by new larvae
Single Celled organism, animal like, microbes usually having motility
Classification of Protozoa
1. style of movement
2. Mode of reproduction
3. Stages in life Cycle
Pseudopdia (false feet)
some flagella during reproduction
most are not infectious
Reprodution Binary Fission
Usual form cyst
only human pathogen ameba
flagella with some ameboid species
sexual and asexual reproduction
most free living
Trypanosoma and Leishmania
Flagellata parasites with one flagellum
Flagellata parasite with 4 flagellum
Flagellata parasite with 6 flagellum
Moved by Cilia
also used for attachment and feeding
Transverse fission = asexual
majority free living
only pathogenic Ciliate
lives in animals intestines may infect humans
Movement not characteristic
soe flagella or pseupoda preset
well developed asexual and sexual stages
most form cyst
ALL ARE PARASITIC
100-300 million cases/year in world
Transition of protozoa
ingestion infected stage or protozoa
1. Motile and parasite to human intestine
2. Reproduce by simple asexual division
3. Most common in the lower GI tract
4. Some form of non-feeding, non-motile cyst stage
which is infective to humans
5. Transmission by ingestion of cyst in fecaffy contaminated food or water
Morphological Life Cycle of Amebea:
Trophozoite---Active feeding cell
This stage is metabolizing stage and sensitive to environmental change.
Cyst---A dormant form that can survive for periods outside the host.
Morphological Life Cycle of Amebea:
It is surrounded by mineral wall, mostly calcium, and is resistant to environmental changes ( e.g....heat, cold ...etc.).
May have 1-8 nuclei depending to species Each nucleus can produce one adult trophozoite during excyst stage
Infection usually acquired by ingestion of food or drink contaminated with cyst
Cyst survive the oral and gastric secretions but alkaline pH and digestive juice stimulate excystation within 24 hours.
Cyst to Trophozoites
One nucleus = one Trophozoite
Encystation - Amebea
As trophozoites moves along with bowel
movement, the environemnt becomes drier and the trophozoites start to undergo encystation
cannot occur in active dysentery because the feces are so rapidly flushed from body.
1. Ingestion of the cyst stage in food/water and hand to mouth.
2. Via arthropod vector - such as the mosquito. Usually, these infect
subcutaneous tissues, deep organs etc.
3. Intimate contact - such as trichomonas found in the oral passage, urethra
of males, vaginal tract of females. We transmit the adult organism from person to person or host to host (sorry - the picture was cut out to avoid X-rating).
4. Penetration of the skin - usually these would be things like hookworms. The parasite is out in the environment and penetrates into the skin to the
circulatory system which takes it to the intestinal tract. Anther example is swimmer's itch.
requires ample food and moisture to remain active.
dormant, resting stage
when conditions in the environment become unfavorable for growth and feeding.
he trophozoite cell fOlmds up into a sphere, and its ectoplasm secretes a tough, thick cuticle around the cell membrane.
If provided with moisture and nutrients, a cyst break open and releases the active trophozoite.
adult stage of protozoa. There is lots of cytoplasm surrounding the nucleus. Trophozoites are produced by binary fission (asexual). The trophozoite has mobility. In humans, they are usually found in the small intestines which is very wet and highly acidic. As it passes to the rectum the pH rises and the oxygen content decreases so that by the rectum the stool is well formed. These changes are bad for the protozoa and since there is no more moisture and nutrient it undergoes excystment to cyst stage by the rectum.
dormant stage. Just a nucleus with very little cytoplasm. The cyst forms when the organism sense the pH, moisture and oxygen change and decides to condense its nucleus and squeeze out all of the free water. The only water left is bound water - water bound to the chromosomes. The DNA is double stranded and hydrogen bonding holds the strands together. That hydrogen bonding comes from water that is bound to the DNA Bound
water does not freeze nor does it become steam if you heat up that organism. As a result, the cyst can be out in the environment for long periods of time through freezing and ultra hot temperatures and survive. The cyst may contain 1-8 nuclei depending on the species. One cyst that contains 8 nuclei will give rise to four adult forms. (We said the cycle is both protective and reproductive ).
trophozoite vs cyst
The trophozoite usually produces the symptoms but we usually consume and excrete the cyst. cyst tends to be the infective stage
Host-Parasite Relationship: Depends on various factors:
I. Number of parasites: pathogenicity is usually proportional to the number of adults that are present.
2. Different people have different tolerance levels.
3. Toxic secretions - are what actually cause diarrhea to occur. 4. Host Response: Natural and acquired resistance.
Trophozoites in large intestinal
mucosa, liver, or other tissues
Ingestion of cyst in
fecally contaminated food or water
Amebiasis, amebic dysentery, amebic hepatitis (if the liver is involved)
and bloody dysentery Diagnosis: cysts and trophozoites in feces
abdominal pain, fever" diarrhea, fatigue, bloody dysentery and weight loss.
a. amebic hepatitis-necrotized
and fluid develop at the site of invasion of trophozoites Symptoms: Enlarged liver, fever, chills, and leukocytosis.
b. pulmonary amebiasis-by direct penetration of the diaphragm get to the lung.
c. Less frequently invade spleen, kidney, skin, and brain.
Chronic infection may last for years, and
amebiasis is often spread by chronic healthy carriers.
Dysentery is diarrhea with blood and mucous in it
Free living ameba---
Normally found among water fowls, ducks, geese
and swans. They are abundant in standing fresh
water, lake, ponds, and even swimming pools and hot tubs.
In animals it causes an intestinal infection with diarrhea or dysentery.
Accidental parasites of human, and may cause primary acute meningeoencephalitis.
trophozoite of Naegleria
small, flask- shaped that moves by a single broad pseudopod.
Primary acute meningoencephalitis
Infection begins through nasal passage as a result
of swimming or diving.
l nasal mucosa=>
2 multiplication =>
4 cross the
5 enters the brain and meninges
6 rapid destruction brain and spinal tissues
7 hemorrhage and coma
8 death within a week
(primary amebic (acute) meningoencephalit is (PAM)
How Disease Occurs
Accidental entrance of free living water-borne trophozoites through nasopharynx mucosa
Water up nose forcefully
MASTIGOPHORANS (THE FLAGELLATES)
1. Free living to parasitic
2. Inhabit the gastrointestinal tract, atria (an opening, in humans refers to the mouth, vagina, and urethra), bloodstream and tissues of human
3. Extensive role in human disease
human urogenital tract
Pathogen of the reproductive tract that causes
SID caned trichomonoiasis (Trichomonad vaginitis in females and urethritis in males).
Symptoms and sign:
creamy, odorous, green to yellowish vaginal discharge, vulvitis, cervicitis and urinary
frequency and pain.
persistant vaginal inflammation causes tenderness edema, and itching
asymptomatic infection- (for years that can lead to proctitis)
symptomatic infection- recurring urethritis with a milky discharge and prostate infection
majority of infected male are asymptomatic carriers
Disease Producing Form
Trophozoites in urethra or vagina
Trichomonad vaginitis, urethritis, trich
Irritating, frothy vaginal discharge in women; men usually asymptomatic Diagnosis: trophozoites in urine or vaginal smear (no cysts formed)