Other Organ Systems

Question 1

Bebezia spp. LC

Answer 1

• Babesia–> Red Water/Texas Fever- multiply mainly in RBCs
• Theileria–> East Coast Fever- multiply mainly in lymphocytes
• Infected tick feeds on mammalian (intermediate) host & transmits the babesia parasite–>
• Sprozoites enter RBCs–> asexual reproduction –>micro- & macro-gametes are formed
• Female tick (definitive host) ingests infected–> RBCs sexual reproduction within the tick gut
• Asexual reproduction follows–> vermicules which migrate to tick salivary glands, ready to infect
• Vermicules can also –>to ovary of tick & infect the eggs so the next generation will be pre-infected

Question 2

Canine Babesiosis

Answer 2

B. canis - a large species (3 spp- B. canis canis= most important)

Virulence varies with species and strain

May be sub-clinical in immune dogs

Main vectors in Europe: Dermacentor & Rhipicephalus

Not endemic in UK British dogs have NO immunity- Pet Travel Scheme reports deaths every year

• Control: prevent tick bites

Question 3

Toxoplasma gondii spp. LC

Answer 3

Cyst- forming coccidia Toxoplasma

World’s most successful parasite?!

• Can infect most warm blooded- animals and tissues

“facultatively heteroxenous”- intermediate Host is not essential for the completion of the life cycle as direct transmission (via Faecal-oral route) is also possible.

Cat–> Definitive Host

Intestinal life-cycle= similar to Eimeria Infections in chickens

Oocysts= very small (~10 m) sporulate in 2-3 days (2 sporocysts, each with 4 sporozoites)

• Cats may be infected by swallowing sporulated oocysts (PPP ~ 3 weeks)
• Or by eating tissues of an infected intermediate host (e.g. small rodent), PPP= 3 - 10 days.
• *Self-limiting**: oocysts are only shed for 1-2 weeks. Shedding can occur later if immunity wanes or if the animal is immuno-compromised.

Question 4

Toxoplasma gondii spp. (Sheep)

Answer 4

• Toxoplasmosis is commonly asymptomatic- Immune after ~ 2 weeks
• Chronic phase = bradyzoites
• Pregnant sheep which are non-immune & become infected with Toxoplasmosis are at risk of: foetal

death, abortion or stillborn/ weak lambs, depending on the stage of gestation when the infection occurred.

• Placenta after toxoplasma abortion can show small white

foci of necrosis ~2 mm in diameter in cotyledons of the placenta Epidemiology: Up to 80% in some examples

Likelihood of infection ↑ with age initially, plateau’s from two to three years

Question 5

Toxoplasma gondii spp.

(Infections Sources)

Answer 5

• Oocysts from environment contaminated by cat faeces
• Eating cysts in tissues of other infected hosts (carnivorism or in undercooked meat)
• Transplacental transmission in some host species during acute phase of infection