Introduction to Parasites Flashcards
State what is meant by the term ‘parasite’.
A symbiont that gains benefit in terms of nutrients/food at the expense of its host
The parasitic disease that causes the most deaths globally is
Malaria
State the 3 groups of parasites.
- Protozoa
- Helminth
- Arthropods
Describe the features of protozoa parasites.
- Microscopic, one-celled organisms (unicellular)
- Free living OR parasitic
- Multiply in human host
Protozoa that live in a human’s intestine are transmitted via
Fecal-oral route
Protozoa that live in the blood or tissue of humans are transmitted via
Arthropod vectors
The disease malaria is caused by what type of parasite?
Protozoa
State the symptoms of malaria.
Fever, chills and flu-like illness
In malaria, sporozoites that are injected under the skin by a mosquito travel
Through the blood (and enter the liver).
Once sporozoites mature and re-enter circulation, they’re known as
Meroziotes
Describe the features of plasmodium falciparum
- Ring stage with double chromatin dots
- Crescent-shaped gametocytes
State the 3 examples of helminths
- Cestodes (tapeworms)
- Nematodes (roundworms)
- Trematodes (flatworms)
Describe the features of helminth parasites
- Long and thin worms
- Contain ova
State 3 examples of arthropods
- Lice
- Ticks
- Mites
Explain fully the pathology of malaria.
- Involves plasmodium parasite and mosquito vector
- Sporozoites are injected under the skin by the mosquito
- Sporozoites travel through the blood and into the liver - - They re-enter circulation and mature to become meroziotes
- Meroziotes invade and destroy red blood cells, using them to multiply
- Sexual forms are taken up by the mosquito vector
How do you prevent malaria?
- Insecticide treated mosquito nets (ITN’s)
- Prophylaxis
Describe Amoebic Dysentery
Protozal Infection → Entamoeba histolytica
Symptoms include:
- Diarrhoea with blood/pus
- Liver abscess
- Intestinal and extra intestinal infections
Microscopy: Cysts in formed stool
Describe Leishmaniasis
Protozoal infection → multiple types of Leishmania species.
Sandfly bite is the vector
Symtoms include:
- Skin or mucosal ulceration
- Fever
- Weight loss
- Hepatosplenomegaly
How do you detect leishmaniasis?
Diagnosis by histology of biopsy material
Describe the features of Enterobiasis (pinworm) including how to diagnose.
- It is a helminth nematode
- Typically found in children
- 1cm, threadlike
- Diagnosis: Ova can be seen on microscopy
State the features of Ascaris Lumbricoides.
- Nematode Helminth
- Largest nematode in the human intestine
State the symptoms caused by Ascarias Lumbricoides.
- Often asymptomatic
- Transient pulmonary symptoms (Loeffler’s syndrome)
- Mass of worms may obstruct small intestine or common bile duct
Describe the pathology of Ascarias Lumbricoides.
- Ingested eggs hatch in the intestine
- Larvae carried by circulation to lungs
- Adult worms develop in and inhabit small intestine
State how to detect Ascarias Lumbricoides.
Ova seen in the faeces by microscopy
