Parasitic infections Flashcards
Giardia affects
GI tract
Giardia is activated by
stomach acid
What type of parasite is Giardia?
Simplest parasite
Water-borne
Pathogenesis of Giardia
Activated by stomach acid, ends up in duodenum where attaches to duodenum and interacts with blood-gut environment. Causes damage and depletes the host of nutrients. Interacts with bile acid so lipid metabolism is hindered. Water enters the large intestine due to osmotic effect and causes bulky stool.
How does Trichomonas vaginalis spread?
Via close sexual contact from one mucosal membrane to another.
Why can the Trichomonas vaginalis only live in the vagina?
Cytoplasm-filled sac. Bursts if not present in the mucosal membrane.
Why should we care about Trichomonas vaginalis?
Affects 180 million women worlwide, though the mortality rate is low
Trypanosome affects
The heart. Both physically by its presence and by affecting it biochemically via interactions with nerves.
How does Malaria transmit?
Through mosquitoes. Takes blood meal from infected person and injects parasites into next host (zone of inoculation)
How are mosquitoes specialised?
Their stylettes have countercurrent system by which both saliva and blood can be taken in/ out respectively.
Where does the parasite develop?
In the salivary gland. The parasites have to go through life cycles before being able to be transmitted.
Schistomoses is commonly known as what?
The blood flu
How does Schistomoses develop?
The ova with spikes travels throughout the tissue causing damage. Immune system is triggered and encapsules the ova in WBC. Forms granuloma.
Are granulomas beneficial?
They are both beneficial and unbeneficial. Granulomas cause structural damage to the tissue whilst protecting the host from the parasite.
Why do symptoms arise in Leishmania?
Due to host response to the pathogen
Initial pathogenesis of Leishmania
Lesions form at site of infection inoculated with protozoa. Secondary bacteiral infection leads to puss.
Progression of Leishmania infection
Ulceration spreads to the macrophages which causes and infected spleen and break down of mucucutaneous tissue
What protozoa type is FIlaria?
Filaria is a group of long-lived worms
What 2 clinical presentations distinguish the species of worm you are infected with in Filariosis?
One type of species causes blindness due to accumulation of the parasite and immune agents in the eye. The other causes lymphatic disease due to the blockage of lymph vessels as there is a gross immune response.
What is the common presentation of filariosis?
Fibrosis of the skin
Difference between the intestinal nematodes ascaris vs hookworms
Ascaris is transmitted foecally, hookworms are blood-borne.
Ascaris causes allergic pneumonia and is characterised clinically by formation of bolus of worms following antihelminthic drugs.
Hookworms migrate through skin and lungs causing damage which leads to anaemia, protein loss heamorrhage and pneumonia.
Both ascaris and hookworms mature in the gut.
Parasitism definition
Activity of an organism that spends a portion of its life in direct contact with the host species at the expense of the host.
Mechanisms of pathogenesis of parasites
- Invasion of host tissues leading to physical injury
- Physical presence leading to blockage
- Induction of the immune response leading to inflammation
Example of zoonotic parasitic infection
Beavers contaminate water with giardia
Definition of exocystation
Dormant or enclosed cyst opens up to release a parasitic form to complete next stage of life
Where are Toxoplasma cysts often found?
Meat
How to Toxoplasma transmit?
Through transmission of contaminated food
What do Toxoplasma do?
Cause a disruption of host immune responses via invasion of macrophages
What part of the body does Toxoplasma affect?
Central nervous system - particularly the brain
What are the immediate hosts of Toxoplasma?
Felines
The reason why cats are often kept away from pregnant women - causes miscarriage or deformities to fetus
Effect of Toxoplasma on immune system
Th1 cells release IL-12 and ILg that activates anti-parasitic mechanisms.
In immunocompromised patients, the ILg decreases due to a decrease in CD4+ cell count and leads to reactivation of the parasite.
Symptom of Toxoplasma reactivation
Cerebral encephalitis
Who is susceptible to Toxoplasma infection?
Immunocompromised individuals
