Parasitic zoonoses

Question 1

Cryptosporidium spp.

Answer 1

Apicomplexan parasite of vertebrates (mammals, birds, reptiles) which causes zoonotic major waterborne disease

Question 2

Cryptosporidium spp

Answer 2

• worldwide distribution
• Direct life cycle
• Transmission: faecal-oral route, via feed and water contaminated w cysts, animal-human
• oocyst: passed in faeces, each contain 4 sporozoites
• developmental stages attach to brush border w ‘feeder organelle’
• prepatent period: 3-5 days
• young are more susceptible

Question 3

Cryptosporidium spp. Pathogenesis

Answer 3

• decrease absorption and enhanced secretion, villous atrophy and crypt hyperplasia, with mixed inflammatory-cell infiltrate within lamina propria

Question 4

Cryptosporidium Diagnosis

Answer 4

Faecal floation (small size so difficult to diagnose)
- immunofluorescence

Question 5

Cryptosporidium treatment

Answer 5

non available

Question 6

Cryptosporidium control

Answer 6

• good management of calf-pens

Question 7

Trichinosis/trichinellosis

Answer 7

food-borne parasitic disease caused by consumption of raw/undercooked meat esp pork/wild game infected w Trichinella larvae

Question 8

Infection of trichinsos is commonly seen in

Answer 8

animals w cannibalistic and scavenging behaviour

Question 9

Most important and pathogenic Trichinella towards human is

Answer 9

T. spiralis

Question 10

Trichinosis was previously common worldwide but

Answer 10

prevalence has decreased due to establishment of new legislation regarding food prep
- absent from aus

Question 11

Trichinella spp. worms

Answer 11

• smallest worm of human that causes worst pain

Question 12

Trichinella transmission

Answer 12

• ingestion of cysts in undercooked / raw meat/game

- humans usually present end to transmission (unless human is eaten lol)

Question 13

2 cycles of transmission of trichinosis

Answer 13

1. Sylvatic cycle: all Trichinella species and centres around wildlife transmission through ingestion of infected prey.
2. Domestic cycle: feeding of garbage containing raw pork scraps and carrion to swine. Rats may become infected through contact w swine and ingestion and therefore spread infection to other animals.

Question 14

Life cycle of trichinella spp

Answer 14

1. Ingested infectious larvae break free form their cysts due to acidity of stomach allowing larvae to enter small intestine
2. In SI, mature into adults and mate depositing newborn larvae into intestinal mucosa in 3 days
3. larvae enters lymphatic vessels and travel around body via bloodstream & enter various organs
4. Only larvae that penetrate skeletal muscles survive and reach full size in a month

Question 15

Encystation involves 3 major stages

Answer 15

1. formation of host cell into nurse cell
2. encapsulation of larve
3. development of capillary network around nurse cell. These infected cells can remain infectious for months or years

Question 16

Echinococcus granulosus diagnosis

Answer 16

• detection of eggs in faeces

- Identification of E. granulosus in intestinal purge

Question 17

Echinococcus granulosus Treatment

Answer 17

• treat host w praziquantel
• prevent reinfection
• control free roaming and wild dogs
• vaccination (recombinant oncosphere proteins)

Question 18

Echinococcus granulosus Epidemiology

Answer 18

• dog-sheep-dog is domestic cycle
• each fertile cyst may contain up to 4 mill protosolices
• eggs can remain viable for several months in suitable env
• involvement of feral pigs and kangaroos unresolved