Helminths

Question 1

What is the most common cause of malaria?

Answer 1

P.falciparum

Question 2

What is the main cause of malaria outside of africa?

Answer 2

P.vivax

Question 3

How is malaria transmitted?

Answer 3

Tranmisted by female mosaquitos (only 10% of anophodes carry malaria)

Question 4

Discuss the symptoms of malaria

Answer 4

Uncomplicated symptoms occur in stages. 6-10 hours of

• cold stage ‘shivering’
• hot stage ‘fever’
• sweating stage

other = headache, body aces, nausea, vomiting, enlarged spleen

Severe symptoms = cerebral malaria, shock, severe anaemia

Question 5

Malaria chemoprophylaxis in areas without drug resistance

Answer 5

Chloroquine (Aciclovor/nivaquine)

Proguanil

Question 6

Malaria chemoprophylaxis in areas with little resistance

Answer 6

Proguanil and chloroquine

Question 7

Malaria chemoprophylaxis in areas with resistance

Answer 7

Mefloquine
Doxycycline
Atovaquone-proguanil (Malarone)

Question 8

How do Artemisinin based combination therapies (ACTs) work?

Answer 8

Rapid parasite clearance and resolution of symptoms
Active on blood of all four species
Reduce gametocyte carriage and hence transmission.

Question 9

Outline the life cycle of malaria

Answer 9

1. Mosquito infects blood with sporozoites which enter the blood stream
2. Multiplies in the liver for approx. 2 weeks until the liver cells rupture and merozite is released
3. RBC penetration
4. asexual reproduction and development into gametocytes

Question 10

What are helminths?

Answer 10

Multiceullar parasites with differentiated organs (but no circulatory tract). 3 main classes:

1. nematodes
2. cestodes
3. trematodes

Question 11

Briefly describe namatode

Answer 11

Also called ‘roundworms’

Cylindrical body and alimentary canal

Question 12

Briefly describe what a cestode is

Answer 12

Tapeworms

Flat, ribbon shaped; no digestive tract - instead nutrients are absorbed through the cuticle

Question 13

Briefly describe what Trematodes are

Answer 13

Flukes

Leaf shaped, blind branched with alimentary tract

Question 14

Outline the lifestyle of Ascariasis infection (nematode, round worm)

Answer 14

1. mature females produce >200,000 eggs/day
2. eggs are excreted in faeces
3. eggs mature in soil (2-3 weeks)
4. eggs ingested
5. larvae hatch in small intestine and penetrate wall
6. enter blood/lymphatic vessels–> carried to the liver hear tnad lung and molt in alveoli
7. coughing and swallowing brings larvae into intestines and matures into adults

Question 15

What does lymphatic filariasis cause?

Answer 15

Causes enlargement of body parts

Question 16

What does onchocerciasis cause?

Answer 16

enters tissues of eye and causes inflammation and blindness

Question 17

What is Schistosomiasis?

Answer 17

Caused by blood flukes. Main route of contamination is through infected water.

Symptoms occur within a few days - rash/itchy skin. After 1/2 months get fever, chills, cough and muscle aches

Question 18

Outline the life cycle of Schistosomiasis

Answer 18

1. free living larvae, hatch in water and infect snail
2. snail forms larve with large swimming tail
3. infective larvae penetrate the skin of human host
4. migrate through the blood to lung, heart and eventually liver
5. in the liver worms mature and form male-female paris that move on to the final destination (veins/bladder/bowel)