Parasites

Question 1

helminths (worms) types

Answer 1

• Nematodes (roundworms)

* Platyhelminths (flat worms)

Question 2

Nematodes (roundworms) types

Answer 2

– Ascaris lumbicoides (25% of world infected)

– Trichuris trichiura (whipworm (shellworm))

– Hookworms

• Enterobius vermicularis (pinworm)

Question 3

Platyhelminths (flat worms) types

Answer 3

– Trematodia (liver flukes, Fasciola hepatica) – Cestodia (tapeworm, Taenia sp)

Question 4

nematodes is what type of worm

Answer 4

roundworm

Question 5

platyhelminths worm type

Answer 5

flat worm

Question 6

liver fluke info

Answer 6

platyhelminths/flat worm

Leaf shaped animal approx 25 mm in length
• Establishes in bile duct and feeds on liver
• Produces large eggs which are passed out into faeces, gets into water system
• Eggs eaten by water snails – larvae released (survive 1 year in water)
• Mostly ingested by sheep and cattle
• Rare human ingestion (raw, undercooked watercress)
• Causes Fascioliasis:
– Fever, tiredness, loss of appetite, pain around liver
– Diagnosed by finding eggs in faeces

Question 7

cestodia info

Answer 7

nematodes/roundworm
• Tape worms
– Taenia solium (pork)
– Taenia saginata (beef)
– Diphyllobothrium latum (fish)
• Long ribbon-like flat worms have human as definitive host (Mature worm can only develop in humans)
• Larvae (cysticerci) develop in wide range of tissues including muscle
• Worm adsorb nutrients through surface (have no digestive system)
• Abdominal pain, anaemia, nervous disorders (epilepsy), irritation of gut
• If reverse peristalsis occurs, mature worm may lay eggs in stomach, invade central nervous tissue – fatal.
• More severe in young

Question 8

Roundworm info

Answer 8

• Nematodes
• Estimated that 3.2 billion people world wide infected with intestinal nematodes
• Detect eggs in faeces (diagnosis)
• Most faecal oral transmission via water, contaminated hands
• Trichinella spiralis most notorious in food (pork)

Question 9

malaria info

Answer 9

• Protozoan infection
– Plasmodium.falciparum, P.vivax, P.ovale, P.malariae
• Insect vector – Anopheles mosquito
• Insect bites human – sporozoite enters and goes to liver – reproduces in liver over several days – release metrozoites into blood – infect red blood cells (RBC) – bursts RBCs releasing more metrozoites

• Lysis (bursting) of RBCs causes fever, chills, nausea and headache
• Metrozoites produce trophozoites which can be taken up by a mosquito to continue life cycle

Question 10

giardia lamblia contamination reason

Answer 10

mostly water but also food (salads)

Question 11

Entamoeba histolytica contamination reason

Answer 11

Faecal – oral (poor hygiene)

Question 12

Cryptosporidium parvum contamination reason

Answer 12

Faecal oral, water mostly but also food

Question 13

Toxoplasma gondii contamination reason

Answer 13

Raw or undercooked meat,
primary host cats,
oocysts in faeces,
usually mild influenza like illness,
In immuno-suppressed: pneumonitis, myocarditis, hepatitis, cerebral toxoplasmosis (fatal)