Flashcards in Introduction (Classification & Life Cycles) Deck (61)
Parasite - Definition
an organism baring food and shelter temporarily or permanent and living in or on another organism
Parasite - Types
Facultative parasite: both free living and parasite lifestyle e.g. Strongyloides spp.
Obligate parasite: living permanently in a host and cannot live without a host e.g. Trichomonos spp.
Coprozic (spurious) parasites: foreign, pass through alimentally canal without affect.
animal parasites of man and their medical importance.
Parasites - Divisions
a. Roundworms (nematodes)
b. Flatworms - Cestodes (tapeworm)
Parasite vs Host
Parasite - living at the expense of the other and harmful
Host - larger organism that harbours a smaller, harmful organism
Host - Classifications
1-Definitive host: harbors the adults/ final stages/ sexual stages (♂♀) in the development of parasite e.g. man.
2-Intermediate host: larva stages or Inter mediate stages in the development. E.g. Taenia adult------ man; Larva –--- cattle
3-Reservoir host (carrier): the carrier host is well adapted to the parasite and tolerates the infection but serve as source of the infection to other organisms.
Symbiosis: permanent association between two organisms
Mutualism: two organisms living together, the two organisms benefit.
Commensalism: Two organisms Living together, one is benefited and the other is not been affected.
When the other organism become affected, then the relationship turns = Parasitism.
Zoonosis: disease of animals but can be transmitted to a man. Ex: Hymenolepis nana.
Protozoa - Classification
- Blood and tissue
Blood and Tissue Protozoa Diseases
Urogenital tract Protozoa
Roundworms - Ascaris lumbricoides
Flatworms - Taenia saginata
Flukes - Bilharzia (Schistosomiasis)
Mode of locomotion : Pseudopodia (false feet)
Poor sanitation areas
Habitat: in the lumen of the large intestine
Pathogenic: because it can invade intestinal walls
Reservoir: major: humans
minor: dogs, pigs, monkeys
Entamoeba histolytica (morphology)
Cyst - infective stage - polluted water and food
Trophozoite - pathogenic stage
Entamoeba histolytica - Life cycle
1 . Cyst -infective stage
2 . Enters mouth via contaminated food, water or via human feces as fertilizer
3 . Moves to large intestine and change to trophozoite (pathogenic stage)
4 . Produce lytic enzymes (lysis+ulcer)
5 . Flask shaped ulcer
6 . Can do erosion through BV to liver + other organs
Amoebiasis - Clinical features
Dysentery: blood+mucous diarrhea (from flask shape ulcer wall invasion)
Severe abdominal pain
Tenesmus: sense of incomplete evacuation
(the patient at this point should be seeking medical advice)
Amoebiasis - Intestinal complications
Peritonitis, appendicitis, Hemorrhage
Amoebiasis - Extraintestinal complications
liver (most common) - hepatitis (severe right abdominal pain)
- amoebic liver abscess ( inflammation (pus)
- shoulder pain + Toxemic manifestations
Also in lung, skin, and brain
Fluid composed of white blood cells and dead cells that typically forms when your body fights off infection
Blood contains toxins produced by body cells at a local source of infection or derived from the growth of microorganisms.
Also called blood poisoning.
Malaria - Reemergence Issues
Problems of controlling malaria:
- inadequate health structures
- poor socioeconomic conditions
- increased resistance to anti parasitic drugs
Malaria - Protozoan parasites
-most widespread and dangerous of the five
-if untreated it can lead to fatal cerebral malaria.
P. vivax. Plasmodium ovale. Plasmodium malaria. P. knowlesi
Malaria - Carrier
Transmission: via female anopheles mosquito
Malaria - Reproduction
Malaria parasite is a sporozoan; has 2 reproductive stages
1. Sexual reproduction: in anopheles mosquito
2. Asexual reproduction: in human
-host infected with ingested cysts
-cysts divide to produce sporozoites
-sporozoites enter host cells
-cells burst releasing merozoites
-merozoites infect new host cells until gamonts produced
-gamonds form gametes
-gametes fuse to form cysts
- no flagella, cilia, or pseudopodia
- capable of gliding movements
Malaria - life cycle
Plasmodium develops in the gut of mosquito and is passed on in the saliva of an infected insect
Sporozoites carried by blood to the victim's liver where they form cyst-like structure containing thousands of merozoites
After 9-16 days they return to the blood and penetrate the red cells, where they multiply again, progressively breaking down the red cells