Pathogenesis Of Parasitic Infections

Question 1

What are the three main species of schistosomiasis?

Answer 1

S. Mansoni
S. Haematobium
S. Japonium

Question 2

What can schistosomiasis result in?

Answer 2

Cercarial dermatitis

Question 3

What is a key feature of immune response to schistosomiasis?

Answer 3

Granuloma formation

Question 4

What is hepatointestinal schistomiasis caused by?

Answer 4

Immune response to eggs

Question 5

What causes cercarial dermatitis?

Answer 5

Allergic-type reaction to cercariae from animal or bird schistomes

Question 6

What causes urinary schistosomiasis?

Answer 6

Repeated inflammatory episodes resulting in neoplastic changes

Question 7

What is onchocerciasis?

Answer 7

Major blinding disease

Question 8

What is onchocerciasis caused by?

Answer 8

Filarial parasite

Question 9

What is onchocerciasis transmitted by?

Answer 9

Black flies

Question 10

What is the vector of onchocerciasis?

Answer 10

Simulium

Question 11

How do black flies transmit onchocerciasis?

Answer 11

Takes a blood meal and transmits larvae to the skin

Question 12

How does simulium act as a vector for onchocerciasis?

Answer 12

Digs a hole in the skin and creates a pool of blood which it then feeds from

Question 13

What is the pathology of onchocerciasis?

Answer 13

Repeated inflammatory episodes caused by microfilariae -> permanent damage and scarring of skin and eyes

Question 14

What are the skin disease types of onchocerciasis?

Answer 14

Acute papular onchodermatitis
Chronic onchodermatitis
Sowda

Question 15

What are the anterior segment eye diseases caused by onchocerciasis?

Answer 15

Punctuate keratitis
Acute iridocyclitis
Sclerosing keratitis

Question 16

What are the posterior segment eye diseases caused by onchocerciasis?

Answer 16

Optic neuritis/atrophy

Chorioretinopathy

Question 17

What is the immune pathogenesis of onchocerciasis?

Answer 17

Acute infection -> stimulation of Th2 cells -> eosinophil and B cell activation-> inflammatory response

Question 18

What are some examples of hard tick bourne disease?

Answer 18

Tick typhus
Viral encephalitis
Viral fevers
Viral haemorrhagic fevers
Tularaemia
Tick paralysis
Human babesiosis

Question 19

What are some examples of soft tick bourne disease?

Answer 19

Q fever

Relapsing fever

Question 20

What happens in tick paralysis?

Answer 20

Progressive flaccidity due to a failure of acetylcholine liberation in the neuromuscular junction

Question 21

What do head lice do?

Answer 21

Suck blood from scalp and lay eggs on hair

Question 22

How are head lice spread?

Answer 22

Close contact

Question 23

What do body lice do?

Answer 23

Suck blood from body and lay eggs on clothing

Question 24

How are body lice spread?

Answer 24

Bodily contact, sharing of clothing or bedding

Question 25

How do botflies spread disease?

Answer 25

Catches mosquito mid flight and lays its eggs

When the mosquito lands on the animal it brushes its eggs

Question 26

How can you control parasitic infections?

Answer 26

Behaviours
Environmental interventions
Poverty reduction

Question 27

What types of behaviour control parasitic infections?

Answer 27

Education, hand washing and hygiene behaviours

Question 28

What types of environmental interventions control parasitic infections?

Answer 28

Spraying of residual insecticides for household vectors 
Mosquito nets
Improved housing
Sewage disposal
Potable water
Swamp drainage

Question 29

Why must parasitic treatment be given periodically over long periods of time?

Answer 29

Re infections are rapid or the treatment kills larval rather than adult stages