Parasitic Infections - Protozoa and Helminths Flashcards
What are the general features of Helminths?
Multicellular
Differentiated organs
No circulatory tract
Have suckers, hooks or plates on the anterior end for attachment
Most do not have a full life cycle in humans Touch cuticle (difficult for immune system to eradicate) Some (e.g. blood flukes) can camouflage by coating with host molecules
What are the 3 main classes of Helminths?
Nematodes (roundworms)
Cestodes (tapeworms)
Trematodes (flukes)
Which class of Helminths have a cylindrical body and an alimentary canal?
Nematodes (roundworms)
Which class of Helminths are flat, ribbon shaped and have no digestive tract?
Cestodes (tapeworms)
Which class of Helminths are leaf-shaped and have blind-branched alimentary tract?
Trematodes (flukes)
What are the main types of Nematodes?
Large roundworm (Ascaris lumbricoides)
Threadworm
Hookwork
Whipworm
What are the symptoms of Ascariasis (infection with Large Roundworm)?
Heavy infection: Abdominal pain, malnutrition
Severe infection: Blockage of intestines
What are the symptoms of infection with Threadworm?
Mild anal itching
What are the symptoms of infection with Hookworm?
Slows growth and development
Anaemia
What are the symptoms of infection with Whipworm?
Usually asymptomatic
Can cause bloody diarrhoea
How do you normally become infected with Ascariasis/Nematodes?
Ingestion of eggs from the soil
or larvae in soil penetrate skin in the case of hookworm
What can Filarial (Blood and tissue) Nematodes cause?
Lymphatic filariasis (Elephantiasis)
Onchocerciasis (River blindness)
Loiasis (infection with adult loa loa worm)
How do you normally become infected with Cestodes?
Humans are usually the primary host:
- Ingestion of cyst (resting/dormant stage) from undercooked meat/fish
How do you normally become infected with Trematodes (flukes)
Use snail as intermediate host (penetrates the skin of humans in water)
What can Trematodes cause?
Schistosomiasis (Snail fever)
What are the symptoms of Schistosomiasis (Snail fever)
Within days: rash or itchy skin (‘swimmers itch’)
After months: fever, chills, cough, muscle aches
Main damage is caused by the eggs stuck in tissues and so the reaction by the immune system
How are Intestinal nematodes/cestodes usually diagnosed?
Eggs/larvae in a faecal sample
How are Schistomas (Trematodes) usually diagnosed?
Eggs in faecal or urine sample
How are Tissue nematodes usually diagnosed?
Microfilaria in blood
difficult to diagnose as in tissue
What is normally used to treat filarial nematodes?
Ivermectin
What is normally used to treat Intestinal nematodes?
Albendazole or Melbendazole
What is normally used to treat tapeworms?
Niclosamide or Praziquantel
What is normally used to treat Roundworms?
Piperazine
What is normally used to treat Threadworm?
Piperazine
What is normally used to treat Flukes?
Praziquantel
