Misc Infectious Disease cards

Question 1

Describe the general features of cryptosporidium

Answer 1

Most significant water pathogen in developed countries, protozoan parasite which sheds oocysts in the faeces of it’s host. Only a small pathogen load is needed to become ill. Is resistant to chlorine but temperature sensitive. Causes chronic diarrhoea which lasts 7-10 days. C. parvum and C. hominis are the most significant strains.

Question 2

What diseases are ticks vectors for?

Answer 2

Borreliosis (lyme disease) spread by ixodes ricinus, rhipencephalus sanguineous and dermacentor reticulatuus. Gram negative bacteria causing fever, lameness, joint swelling, lethargy, in-appetence and swollen lymph nodes in dogs. Zoonotic
African swine fever spread by the ornithodrus (soft) tick. Notifiable spread by tick bites, contaminated feed and aerosol. Can survive in meats for a very long time, cures, chilled or frozen. Caused by a DNA arbovirus

Question 3

What diseases are midges vectors for?

Answer 3

Blue tongue – severe disease of sheep, mild disease of cattle. Orbivirus. Notifiable
Schmallenburg – causes birth defects and abortions in ruminants
African horse sickness – notifiable, orbivirus causing severe disease in horses and mild disease in donkeys

Question 4

What diseases are sand-flies vectors for?

Answer 4

Leishmania – kinetoplastid parasite leishmanial infantum. Transmitted by the phlebotamus sand fly. Clinical signs – skin lesions or cachres, enlarged lymph nodes, weight loss, anorexia and weakness

Question 5

What diseases are mosquitoes vectors for?

Answer 5

West Nile virus – zoonotic, affects horses with birds as a reservoir. Flavivirus
Heart worm – dirofilaria immitus and repens affects dogs and cats, zoonotic

Question 6

What causes transmissible spongiform encephalopathy?

Answer 6

Prions - proteins present in the body which have mutated to a pathogenic form
PrPC is non-pathogenic and present in normal animal tissues
PrPsc is a pathogenic form which is resistant to being destroyed and has the ability to convert PrPc to itself
The accumulation of PrPsc is what causes disease
There appears to be different strains resulting in different pathologies

Question 7

Describe the general features of scrapie

Answer 7

endemic disease of sheep and goats
clinical signs: ataxia, tremors, loss of condition, rubbing and scratching - death within 1-3 months of signs appearing
2-5 year incubation
strong genetic links, some genotypes are resistant, used for control
goats have no genetic resistance
transmission types: vertical, horizontal, iatrogenic, pseudovertical, contaminated pasture

Question 8

Describe the general features of bovine spongiform encephalopathy

Answer 8

5 year incubation
oral transmission 
little genetic resistance
2 known strains
no evidence of breed differences
clinical signs: aaxia, nervousness, touch sensitivity

Question 9

Describe the general features of chronic wasting disease

Answer 9

affects deer
only TSE seen in the wild population
unknown zoonotic potential
limited genetic control
spread via ingestion of contaminated faeces, saliva and urine
Clinical signs: polyuria, polydypsia, loss of condition, oedema, ataxia, nervousness, separation from the herd, listlessness
16 month incubation