Parasites Flashcards
What is a parasite
An organism that lives in another organism (host) and gets its food at the expense of the host
What are the 3 classes of parasites
Protozoa, Helminths (worms) and Ectoparasites
What are examples of protozoa
Malaria, Amoebae and Flagellates
Define protozoa
Single-celled organism
What are the two ways of transmission of protozoa
- Protozoa that live in a humans intestine - faecal-oral route
- Protozoa that live in the blood or tissue of humans - insect vector
How is malaria spread
Through insect vector (mosquito)
Which protozoa is responsible for malaria
Plasmodium parasites (5 species)
What symptoms does patient with malaria experience
Fever, chills, and flu-like illness. If left untreated, the patient could worsen or die
How is malaria diagnosed
Blood microscopy used to find the plasmodium parasites (thick and thin blood films)
How is amoebae transmitted
Faecal-oral route
What is the source of nutrient for amoebae
Red blood cells
What are the symptoms of amoebae
Dysentery (blood diarrhoea) and if left for longer, could cause liver abscess
Which protozoa is responsible for amoebae
Entamoeba histolytica
How is amoebae diagnosed
Cyst found in stool
What are examples of Helminths (worms)
Nematodes (round worms), cestodes (tape worms), and tematodes (flat worms)
How are nematodes transmitted
Faecal-oral route
What does the nematode Enterobiasis (pinworm) cause
Anal itch especially at night (mostly in children)
How to diagnose Enterobiasis
Press adhesive sellotape in perianal region in the morning and any eggs will be seen down the microscope
What is the treatment for Enterobiasis
Anti-helminth treatment (taken on day 1 and then the second dose taken on day 7)
What is a common nematode
Ascaris Lumbricoides
What does Ascaris Lumbricoides cause
The ingested eggs hatch in the bowel/i testine and grow to become adult worms which release eggs into the stool which can be seen down the microscope
What symptoms does Ascaris Lumbricoides cause?
Usually asymptomatic but may cause failure to thrive in children. A mass of worms may obstruct the small intestine or common bile duct
What are the 2 most common species of cestodes
Taenia saginata (beef) and taenia solium (pork)
How are cestodes spread
Human is infected by eating raw or uncooked beef or pork meaning they eat larval cysts which mature into adult tapeworms in the gut and come out in the stool
What complications can Taenia solium (pork) cause
Neurocysticerosis (cyst travels to the brain)
How are tematodes (flatworms) transmitted
Insect vector
How are cestodes transmitted
Insect vector
Which 3 common species cause schistosomiasis
Schistosomes species: S. haematobium (bladder), S. mansoni (intestinal), and S. japonicum (intestinal)
Where are high rates of tematodes found
Infected fresh water
What is the intermediate host for tematodes
Snails
How do tematodes infect the body
Cercaria penetrate humans. Skin - bloodstream - liver - either bowel or bladder - release egg into the urine or stool
What symptom do tematodes cause
Swimmers itch
What complications (if left untreated) can tematodes cause
Liver failure and bladder cancer
How are ectoparasites described as
Parasites that live outside the body with most of them being insects or arachnids
What are examples of ectoparasites
Lice, ticks and mites
What do ticks transmit
- Lyme disease/borelliosis in Scotland
- Rocky Mountain Spotted Fever in the USA
- Crimean Congo Haemorrhagic Fever in the Middle East
What findings can be found when diagnosing Helminth
- Eosinophilia (WBC called eosinophils is high in the body)
- Elevated IgE
What indirect testing can be used for parasite diagnosis
- Rapid diagnostic test
- Serology (detection of antibodies)
Where do protozoa that are transmitted by the faecal-oral route live
Human intestine
Where do protozoa that are transmitted by a insect vector live
Blood or tissue of humans
What can be identified from microscope
Ova, cysts, and parasites
