Parasitology Flashcards
What is a parasite?
Organism that lives on or in a host organism and gets its food from or at the expense of its host
What are the 3 main classes of parasites that can cause disease in humans?
Protozoa
Helminths
Ectoparasites
What is a Protozoa?
Microscopic single celled organism that is free living or parasitic
Are Protozoa able to multiply in humans?
Yes
How are Protozoa transmissed?
If in the intestine the fecal-oral route
If in the blood or tissues - arthropod vector
What are the types of Protozoa?
Amoeba
Flagellates
Ciliates
Sporozoney plasmodium
What are the medically important Protozoa infections?
Entamoeba histolytica Gordia lambton Trichomonas vaginalis Malarias Toxoplasma gondii Cryptosporidium Leishmania species Trypanosoma Cruzi Trypanosoma brucei
What does entamoeba histolyca cause?
Ulcers in the duodenum, dysentery
What does gordia lambton cause?
Diarrhoea
What does trichomonas vaginalis cause?
Infections in the genital tract
What is toxoplasma gondii transmitted through?
Cats
What does cryptosporidium cause?
Diarrhoea
What does leishmania cause?
Ulcers in skin and systemic disease
What are helminths?
Large multicellular worms
Can helminths multiply in humans?
Not in its adult stages
What are the types of helminths?
Nematodes
Trematodes
Cestodes
What are the types of nematodes?
Soil transmitted helminths
Filarial parasites
Others
What type of worms are nematodes?
Roundworms
What type of worm are trematodes?
Flukes
What is special about the male/ female trematodes?
Males are larger and the females live inside them
What are the medically important trematodes?
Schistosoma mansoni/haematobium/japonicum
Clonorchis sinensis
Fasciola hepatica
Paragonimus
What does clonorchis sinensis cause?
Carcinoma of the bladder
Where does fasciola hepatica live?
In the liver
Where does paragonimus live?
In the lungs
How long are cestodes?
2-3 metres long
What type of worm are cestodes?
Tapeworms
What are medically important cestodes?
Taenia saginata
Taenia solium
Echinococcus granulosus
What are ectoparasites?
Blood sucking arthropods that attach or burrow into the skin and remain there for relatively long periods of time
What are the medically important ectoparasites?
Mites
Ticks
Lice
Flies
What are the types of mites?
Scabies
Trombiculid
Where are scabies found?
Animal infected sand
Where are trombiculid found?
Found in vegetation
What are the types of ticks?
Hard and soft
What are some examples of lice?
Pediculus humans capitals
Pediculus humanus
Pthirus pubis
What are some examples of neglected tropical diseases?
Lymphatic filariasis
Onchocerciasis
Guinea worm disease
What are the types of parasitic host?
Intermediate
Definitive
What is an intermediate host?
Host in which larval or asexual stages develop
What is a definitive host?
Host in which adult or sexual stage occurs
What are the types of parasitic vectors?
Mechanical
Biological
What is a mechanical vector?
No development of parasite in vector
What is a biological vector?
When some stages of the life cycle occur
What is the life cycle of schistosomiasis?
Eggs expelled in urine or faeces
Develop in fresh water
Invade snails
Asexual reproduction that amplifies parasite number
Infect people when they come into contact with the infected water
What is the primary determinant of parasite distribution in human populations?
Relative wealth
What does DALY stand for?
Disability adjusted life expectancy
What are the mode and opportunities for parasitic infection?
Faeco-oral
Food
Complex life cycles
Etc
How can you decrease the faeco-oral transmission of parasites?
Household sanitation
Access to clean water
Personal hygiene behaviours
How can you decrease the food transmission of parasites?
Animal husbandry,
Surveillance
Regulations and government controls
How is chagas spread?
Bitten by bug which defecates on the skin
If you scratch the bite the faeces will enter
What is chagas infected with?
Metacyclic trypomastigotes
What do metacyclic trypomastigotes do?
Multiply in cells and burst them, spreading disease further
What are the phases of chagas?
Acute
Chronic indeterminate
Chronic determinate
What are the organs most affected in chronic chagas?
Heart and intestines
Why does chronic chagas affect the heart and intestines?
Damages the autonomic nervous system
What complications in the mega colon are caused by chronic chagas?
Hecatoma Obstruction Sigmoid volvulus Ulceration Perforation
What is the pathogenesis of acute chagas?
Tissue damage caused by inflammatory response to parasite
What is the pathogenesis of indeterminate chronic chagas?
Regulatory immune response characterised by IL-10 and IL-17
Where are visceral leishmaniasis found?
Asia
Middle East/ Africa
Latin america
Where (geographically) are cutaneous leishmaniasis found?
Mediterranean
Central and South America
What is the lifecycle of a leishmaniasis?
Sandfly bite
Promastigotes enter immune cells and replicate to form amastigotes
What is the old world vector of leishmaniasis?
Sergentomyia
What are the new world vectors of leishmaniasis?
Phlebotomus
What is the reservoir of leishmaniasis?
Domestic dogs and rodents like sloth
How do cutaneous leishmaniasis present?
Small Papule that grows into a plaque
How do you get a sample for cutaneous leishmaniasis?
Scrape from the edge of the plaque onto a slide, then stain with giemsa