Exam 2 Zoonoses from Carnivores Flashcards
When are cats usually infected with Toxoplasma gondii?
Early in life, excrete oocycts for 1-3 weeks and then appear to recover
Toxoplasma gondii oocyst sporulation take how long in the soil?
1-5 days
What cells are affected in initial Toxoplasma gondii infections of intermediate hosts
macrophages
-rapid replication, release, systemic spread
Tachyzoites=
fast
Bradyzoites=
slow
What cells are affected by Toxoplasma gondii as immunity kicks in?
infected cells typically encyst into muscular or neurological tissues
-possibly cats are latently infected?
When a mouse gets Toxoplasma gondii it loses its fear of cats (T/F)
True, even once the infection has cleared
Two ways of human exposure to Toxoplasma gondii
- Oocysts in soil: wash or cook to remove/kill
- Ingestion of tissue bradyzoites: cook or freeze (primarily from pork)
People affected by Toxoplasma gondii
- people with poor immunity–>tachyzoites out of control
- severe problems in AIDS patients
- severe problems in pregnancy
Reduce exposure for Toxoplasma gondii
- serologically testing for antibodies
- get older cats
- keep off counters
- wash veggies
Areas of larval migration
- visceral
- cutaneous
- ocular
- neurologic
Common roundworms of pet animals
- Toxocara canis
- Toxocara cati
- Toxocara vitulorum
Do not reach adult stage in humans
Human Toxocariasis
- children between 1 & 4, pica & geophagia
- visceral larval migrans is most common
- ocular or neurologic migration is rare, but can happen
Prevention of Toxocariasis
- reduce the reservior: treat puppies & kittens
- cover sand pits, 20-40% may have toxocara eggs
Baylisascara procyonis
- raccoon roundworm
- tropism for ocular or neurologic tissue
Cestodes: Humans become intermediate host by eating ______.
Symptoms are caused by the _______
larvated eggs.
cysts
Clinical signs of cestodes in intermediate hosts
- systemic cysts
- primary organ affected dependent on species of parasite
- sometimes anaphylactic symptoms follow rupture of cyst
Echinococcus granulosus
- hydatid cyst disease
- liver most common
- sometimes brain
- slow growing (10-20 years)
Echinococcus multilocularis
- alveolar cyst disease
- multilocular, small, solid cysts in tissues
- often liver, can spread into lungs
- cysts grow over 10 years
- metastatic, usually inoperable by discovery
Cystic Echinococcosis
- canids are reservoirs
- associated with sheep industry
- sylvatic cycle, between wolves & moose, in large parts of Canada
Prevention of Cystic Echinococcosis
- regularly treat dog with praziquantel
- dog control
- condemn infected offal
- educate people
Alveolar Echinococcosis
- naturally between foxes & rodents
- rare in humans, but high fatality rate if untreated
- northern hemisphere: very common in China
Control of E. multilocularis
- routine antihelminth treatment
- reduce exposure of pets to rodents
- treat foxes
- education
- dog control
