Zoonoses Flashcards
What are zoonoses?
Infections that pass between living animals and humans
source of disease is from the animal
Why are the following NOT considered zoonoses?
- Malaria
- Schistosomiasis
- Oncoceriasis (river blindness)
- Elephantiasis (lymphatic filariasis)
Because they depend on the human host for part of their life cycle
What are Anthroponosis?
‘reverse zoonoses’ in that humans transfer a disease to animals
Examples: Influenza Strep throat Leishmaniasis Chytridiomycosis
What type of pathogen can zoonoses be?
Virus, bacteria, parasites or fungi
What examples of bacterial zoonoses are there?
Salmonella Campylobacter Shigella Anthrax Brucella E Coli Leptospirosis Plague
What examples of viral zoonoses are there?
Rabies Avian influenza Ebola virus disease West Nile Fever Yellow fever
What examples of parasitic zoonoses are there?
Toxoplasmosis
Visceral larva migrans
Echinococcosis
What examples of fungi zoonoses are there?
Dermatophytoses
Sporotrichosis
What examples of other (prions) zoonoses are there?
CJD virus
note- creutzfeldt-jakob disease
What zoonoses are common in the UK?
Salmonella
Campylobacter
Toxoplasma
Ringworm
What are uncommon zoonoses in the UK?
Anthrax
Rabies
Bubonic plague
Acute brucellosis
What is rabies?
A viral infection transmitted form the bite of an infected animal e.g. dogs, bats
What are the features of rabies?
incubation + route of infection
Incubation period = 2 weeks to several months
Virus travels to the brain via peripheral nerves
What are the symptoms of rabies?
Causes an acute encephalitis, symptoms include: - malaise, headache, fever - Mania, lethargy, coma - over production of saliva - unable to swallow Death by respiratory failure
How do you diagnose rabies?
PCR of saliva or CSF
Note- Often confirmed post mortem on brain biopsy
What is the treatment for rabies?
Immediate post-exposure prophylaxis
- human rabies immunoglobulin
Give 4 doses of rabies vaccine over 14 days
Note- always fatal if untreated
What is Brucellois?
What is the incubation period?
A small, gram negative coccobacilli
It is rare
Incubation period 5-30 days, up to 6 months
How are humans infected by Brucellois?
What risks are there?
Humans are infected:
- during milking of infected animals (organisms are excreted in the milk)
- during parturition
- handling carcases of infected animals
- consumption of unpasteurised dairy products
Therefore occupational risks:
Farmers
Vets
Slaughterhouse workers
What are the symptoms from Brucellois?
- Acute: high fever, weakness, sweats, splenomegaly
(1-3 wks) - Subacute: fever, joint pains
(> 1 month) - Chronic: flu-like, malaise, depression, chronic arthritis
(months-years) - Subclinical: most common, 50% of exposed have positive serology
What is the treatment for Brucellois?
Long acting doxycycline (for 2-3 months)
plus
Rifampicin or IM gentamicin (for 1st week)
What is Leptospirosis?
also known as Weil’s disease
Thin, highly mobile spirochaetes
Penetrates abraded skin/ mucous membranes
Causes systemic illness
What are the symptoms from Leptospirosis?
Flu-like symptoms, fever, myalgia, jaundice, renal failure
Severe disease in ~10%
- pulmonary haemorrhage (>50% fatality)
- Weil’s disease: jaundice
What are the causes for spread of Leptospirosis?
Contact with environment (water) contaminated with urine of infected animal
or
from direct contact with the infected animal
How is Leptospirosis diagnosed?
Think: fever in a cattle farmer, exposure to water or rats
- ELISA serology- suboptimal
- PCR
- Culture- take at least one week on special media
How is Leptospirosis treated?
Antibiotics:
Doxycycline for mild disease
IV penicillin - severe
early Tx, painkillers
What is Lyme Borrelios?
Lyme disease
-Spirochaete found in wild deer
-Transmitted by tick
-Commonest in summer months
Bacterial cause= Borrelia burgdorferi
What skin condition is seen during Lyme disease?
Erythema migrans
Rash occurs 3-90 days after bite
single/ multiple lesions
What 2 uncommon skin condition can occur in late stage of Lyme disease?
Acrodermatitis Chronica Atroficans (ACA)
=Discolouration occurs on distal limbs
Lymphocytoma = painless nodule
What is Neuroborreliosis? (NB)
Is a neurological manifestation of Lyme disease
Triad of facial nerve palsy, radicular pain + lymphocytic meningitis
occurs ~15% of patients
How do you diagnose Lyme disease?
Clinical diagnosis by erythema migrans
or
ACA and lymphocytoma + serology
or
High serology indication from PCR of synovial fluid
or
Neurological symptoms from Neuroborreliosis
What is the treatment for Lyme Disease?
Oral doxycycline or amoxicillin or IV ceftriaxone
treat for 21 days
