PH14: Zoonoses Flashcards
Define zoonoses
Disease and infections which are naturally transmitted between vertebrate animals and man.
This does not include:
- fish and reptile toxins
- Allergies to invertebrates
- Experimentally transmitted diseases
Define anthropozoonoses
Infections transmitted to humans from animals which act as reservoirs
Define zooantroponoses
Diseases present in humans but could be transmitted to animals
Define amphixenosis
The disease in which both man and animals could act as reservoir hosts
What is the role of the vet in tackling zoonoses?
Raise awareness and promote prevention
Enhance detection (some zoonotic diseases are notifiable and reportable)
What is another name for psittacosis?
Parrot Fever
What causes Psittacosis?
The bacterium Chlamydia psittaci
What are the risk factors to Psittacosis?
- Inadequate ventilation
- Poor cleaning
- Overcrowding
- Long survival in the environment (resistant to drying)
How is Psittacosis transmitted?
Humans: inhalation of dried bird faeces, direct contact with birds, discharges
Bird-to-bird: vertical transmission via egg or trough feeding by regurgitation
Who is most at risk of contracting Psittacosis?
Children, immunocompromised, pregnant women (high mortality of foetuses or new-borns)
How do you prevent psittacosis?
Preventative husbandry: no overcrowding, good ventilation, avoid mixing birds from different sources
Quarantine newly acquired birds
Detain and isolate affected birds followed by C&D
Extra care during PM of infected birds
What causes toxoplasmosis?
Toxoplasma gondii
Who is the reservoir and who is the definitive host?
Reservoir: rodents
Definitive host: cats
How is toxoplasmosis transmitted?
Transmitted by consumption of infectious oocysts in cat faeces
Consumption of tissue cysts in infected meat
Transplacental transfer of tachyzoites from mother to foetus
Who is most at risk of toxoplasmosis?
Pregnant women - might lead to miscarriage, stillbirth, CNS damage to foetus
Immunosuppressed
Sheep - mummified foetus, leathery placenta with multiple white foci of necrosis
How do you prevent toxoplasmosis?
Humans
- Cook food thoroughly
- Wash veggies
- Hand washing
- Correct kitchen hygiene
- Pregnant women to avoid all contact with cat, pregnant animals, raw meat, or soil
- PPR when handling soil, cat faeces, aborted materials
Cat
- Do not feed raw meat
- Clean litter daily
- Discourage hunting
Sheep
- Keep aborted ewes (they can pass down immunity)
- Vaccination
- Medicated feed
- Keep only adult, neutered cats on farm
What causes toxocariasis?
Dogs: toxocra canis
Cats: toxocara cati/mystax
How is toxocariasis transmitted?
Animals: transplacental infection
HumansL by accidnetal ingestion of oocytes
How do you prevent toxocariasis?
- Deworming
- Sourcing animals from approved breeders
- Older animals are more immune
- Clean your pet’s living area (safe disposal of faeces
- Do not allow children to play in areas that are soiled with faeces
- Wash hands with soap and warm water
- Teach children that it is dangerous to eat dirt or soil
What are the two types of toxocariasis?
Visceral larva migrans
Ocular larva migrans
What causes Q Fever?
Coxiella burnetti
What are the risk factors of Q Fever?
- Close contact with ruminants
- Environmentally resistant spores
- Occupational disease: vets, house workers, farmers
How is Q fever transmitted?
Animals: direct contact with infected birth fluids, milk, urine, mother to foetus or indirectly via vectors
Humans: aerosol, mucosa/skin abrasion in contact with infected material, drinking unpasteurized milk/dairy products, ticks and fleas
How do you control against Q Fever?
- Identify, segregate, eliminate infected animals
- Disinfection of abortion area
- Vaccine
- Control of ectoparasites on livestock
- Good personal hygiene
- PPE when handling abortion
- Reduce exposure to infected tissues and fluids
- Pasteurization of milk
What causes Glanders?
Burkholderia mallei
Where does Glanders occur?
Middle-east, South America, India
How is glanders transmitted?
Horses: ingestion of contaminated food and water
Humans: via discharges from infected horses via skin abrasions, mucous membranes, or aerosols
Who is the reservoir of glanders?
equidae
Who is at particular risk of glanders?
Vets, horse-workers, butchers
Where are the lesions for glanders? for farcy?
Glanders: lesions seen in the nostrils, submaxillary lymph nodes and lungs
Farcy: located on the surface of limbs or body
- Acute: nasal discharge, coughing, high fever, and ulceration o the nasal mucous
- Chronic: nodules develop subQ and ulcerate
How do you prevent glanders?
- Banning imports from countries where the disease has been reported
- Cull affected animals
- Use adequate PPE
